Food Biotechnology
Saeedeh Fatemizadeh; Mohammad Bagher Habibi Najafi; Dennis Sandris Nielsen
Abstract
IntroductionCronobacter sakazakii is an opportunistic pathogen, which has been linked to the contamination of powdered infant formula, and associated with outbreaks leading to fatalities in neonatal intensive care units. Few studies have explored the direct interaction between probiotics and C. sakazakii. ...
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IntroductionCronobacter sakazakii is an opportunistic pathogen, which has been linked to the contamination of powdered infant formula, and associated with outbreaks leading to fatalities in neonatal intensive care units. Few studies have explored the direct interaction between probiotics and C. sakazakii. In this study, the effect of a Lactiplantibacillus plantarum strain (M17) along with the standard strain Lactobacillus plantarum (ATCC 8014) and the well-characterized probiotic strain Lactobacillus rhamnosus GG on the adhesion of C. sakazakii to intestinal epithelial cells was analyzed. Materials and MethodsAcid and bile tolerance of M17 was evaluated in the presence of pepsin and pancreatin. L-arginine hydrolysis was investigated using an arginine-including medium. Auto-aggregation and co-aggregation assays were performed by absorbance measurement. Minimum inhibitory concentrations of the antimicrobials recommended by the European Food Safety Authority were established. Total lactic acid and the ratio of D/L lactate isomers were determined with a Megazyme enzymatic kit. The ability of the isolate to produce biogenic amines was tested by qualitative and quantitative monitoring. Hemolysis was assessed phenotypically on MRS agar enriched with sheep blood. The strain was tested for its capability to adhere to mucin and Caco-2 cells. The antagonistic effects of the strain against C. sakazakii were further evaluated in vitro on mucin and cultured Caco-2 cells. The LAB strain was added simultaneously with, before, and after C. sakazakii to Caco-2 cells for competition, exclusion and displacement assays, respectively. Data analysis was performed in R using one-way analysis of variance, and the experimental groups were compared with the controls using Tukey’s test. P values <0.05 were considered statistically significant. Results and DiscussionThere was no significant difference in the survival rate of M17 and L. plantarum ATCC 8014 at pH = 4. After 2 h of incubation at pH = 2.5, the survival rate of L. plantarum ATCC 8014 was estimated to be higher than strain M17, but this difference was not significant. After 4 hours of incubation at pH = 8, M17 showed a higher survival rate than L. plantarum ATCC 8014, and this difference was significant after transfer from pH = 4. These results confirm the appropriate viability of M17 in the gastrointestinal tract. Both M17 and L. plantarum ATCC 8014 developed the color yellow in the L-arginine hydrolysis assay, which confirms the safety of these strains. The percentage of auto-aggregation for M17, L. plantarum ATCC 8014, and Lactobacillus rhamnosus LGG was estimated at 24.38, 25.28, and 32 after 6 hours, respectively, and no statistically significant difference between the two isolates were noticed. Given the auto-aggregation and co-aggregation parameters of M17, this strain may constitute a defense mechanism against C. sakazakii. Strain M17 showed resistance to kanamycin and clindamycin antibiotics. With intrinsic resistance, the risk of transferring resistance genes is not only speculative, but practically impossible. Intrinsic resistance of lactic acid bacteria may be considered desirable because it ensures their survival when the host is treated with antibiotics. Both D and L isomers of lactic acid were produced by the studied strains. In humans, D(-)-lactic acidosis is a rare metabolic complication that has only been reported in individuals with short bowel syndrome). Clinical studies have shown that the consumption of probiotic bacteria producing D(-)-lactic acid is safe for children and does not cause a long-term increase in blood D(-)-lactic acid. The reference L. plantarum strain and M17 did not produce biogenic amine precursors, and had no ß-hemolytic activity. Mucin adhesion assay exhibited that M17 has less adhesion (12.10 ± 1.14 %) than L. plantarum ATCC 8014 (13.33 ± 2.30 %) and LGG (15.93 ± 2.06 %) although these differences were not statistically significant. However, the amount of adhesion for the positive control sample Escherichia coli K12 (25.19 ± 4.40 %) was significantly higher than those of the other strains. Compared to the positive control, M17 had a significantly lower adhesion rate (6.8 ± 1.41) to CaCo-2 cells. This value was estimated at 13.77 ± 3.53 % for the reference strain and 21.6 ± 7.54 % for Lactobacillus fermentum PCC (positive control). In antagonistic assays, M17 was able to reduce the adhesion of C. sakazakii to mucin and CaCo-2 cells in all three methods of exclusion/inhibition, competition and displacement. Statistical analysis of the results does not show a significant difference between M17 and LGG. Therefore, the performance of M17 is similar to that of the standard probiotic LGG. ConclusionLactic acid bacteria with acceptable ability to adhere to epithelial cells can be suitable for colonization in the intestine. They can act as a barrier to fight pathogens through various competitive mechanisms, such as co-aggregation with pathogens and adhesion. The M17 strain has an acceptable immune profile and probiotic properties because it shows an acceptable antagonistic activity against C. sakazakii invasion. AcknowledgementThis study was supported by Ferdowsi University of Mashhad (Research affairs) [project No.:46718] and the research infrastructure at the University of Copenhagen.
Food Biotechnology
Fatemeh Barmak; Mohammad Bagher Habibi Najafi; Reza Hajimohammadi Farimani; Mohammad Reza Edalatian Dovom
Abstract
Introduction: One of the most important factors in producing yogurt is choosing the right starter. Native isolates of any country are among the genetic resources of that country, which play a major role in the production and development of the organoleptic properties of fermented products. Therefore, ...
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Introduction: One of the most important factors in producing yogurt is choosing the right starter. Native isolates of any country are among the genetic resources of that country, which play a major role in the production and development of the organoleptic properties of fermented products. Therefore, it seems necessary to study the industrial applications of native isolates. In this study, the production of yogurt was investigated by using native starter isolates from traditional Khorasan yogurts and its comparison with yogurts produced with two types of commercial starters. Materials and methods: Six strains of Streptococcus thermophilus and three strains of Lactobacillus delbrueckii subsp. Bulgaricus isolated from traditional Khorasan yogurts were selected. The proteolytic activity of Streptococcus thermophilus strains was determined according to the method of Erkus et al(2012) and the proteolytic activity of Lactobacillus delbrueckii subsp. Bulgaricus was determined according to the method of Nespolo et al.(2010). Milk acidification activity byall examined strains was evaluated according to the method of Erkus et al.(2012). The production property of gamma-aminobutyric acid of native isolates was also evaluated using the method of Lacroix et al. (2013). Yogurt was produced using commercial starters and native isolates. Acidity and pH were measured according to Iranian National Standard No. 2852. Synersis of yogurt samples was measured using centrifugation according to Çelik (2007) method. In order to measure textural properties, a combination of backward extrusion techniques and Texture Profile Analysis (TPA) was used (Yang et al, 2010). Sensory characteristics of yogurt samples were evaluated by 20 panelists using five-point hedonic scale. This study was conducted based on factorial experiment using a completely randomized design. Statistical analysis of data was performed using Minitab Statistical Software (version 17) and ANOVA. Comparison of means was performed using Tukey’s test at the significant level (p < 0.05). Results and discussion: The results of proteolytic activity of Lactobacillus delbrueckii subsp. Bulgaricus showed that the L3 code was weaker than the other two strains. All Streptococcus thermophilus strains were positive protease. All Streptococcus thermophilus strains of the study decreased the pH of the milk to 4.6 in less than five hours, and Streptococcus thermophilus strain S6 code, as the fastest acid producer, decreased the pH of the milk to 4.6within 3 and half hours (Figure 2). The results of GABA production showed that among the streptococcus thermophilus strains, S1, S5 and S6 codes had distinct blue discoloration. Among the Lactobacillus strains, except the L3 strain, two other strains produced green color. Of the 18 samples of the yoghurt, S5L2 and S2L2 samples showed the highest decrease in pH and increased in acidity compared to other samples after being stored refrigerated overnight (P <0.05). The other samples had the same pH and acidity changes as the control samples after overnight refrigeration. The results show the ability of yogurt producion by native starters to compete with those produced by commercial starters in terms of technological characteristics. Thus, samples with codes S2L2, S3L1, S3L2, and S1L1 showed less Synersis of yogurt than commercial starters. This decrease in the Synersis of yogurt might due to the possibility of exopolysaccharide production by these strains. Textural characteristics of yogurt samples were the hardness of the samples in the range of 3 to 4 N, which was significantly different (P <0.05). The lowest hardness was observed for the S3L3, which can be attributed to the poor proteolytic activity of the strain. L3, S6L2, S3L2 and S2L2 had the highest hardness compared to other compounds and control samples (P <0.05). This differences in the hardness of the samples can be attributed to the possible production of some metabolites by the strains. There was no statistically significant difference in the adhesion properties of the samples (p <0.05). Considering the sensory evaluation scores, it was found that in all respects, S3L3 had the lowest score among the other samples (P <0.05). This was in good correlation with the results of the textural properties of the test. Therefore, this compound was eliminated compared to the control samples. Finally, considering the proteolytic behavior of the strains and the ability to produce acid and GABA, as well as the sensory, rheological and physicochemical properties of 18 samples in comparison to the two control samples, Streptococcus thermophilus strains with codes S4, S2, S5, S1, S6, and Lactobacillus delbrueckii subsp. Bulgaricus strains with codes L1 and L2 have the potential to be used as commercial starters in the form of compounds S1L1, S2L2, S5L1, S6L2, S4L2.
Saeid Afzali; Mohammad Reza Edalatian Dovom; Mohammad Bagher Habibi Najafi; Mostafa Mazaheri Tehrani
Abstract
Introduction: Yoghurt drink or Doogh has gained great attention in recent years in different countries. On the other hand, this desirable commodity has showed some drawbacks especially from microbial point of view. One of the main problems in Doogh production and storage is considered to be the presence ...
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Introduction: Yoghurt drink or Doogh has gained great attention in recent years in different countries. On the other hand, this desirable commodity has showed some drawbacks especially from microbial point of view. One of the main problems in Doogh production and storage is considered to be the presence and activity of gas producing microorganisms especially in warm conditions and environments. From the consumer point of view, blowing of container is not acceptable and is regarded as a defect. Since lactic acid bacteria (LAB) possess the potential use as adjunct or co-culture in fermented dairy products for inhibition of gas – producing microorganisms’ especially gas-producing yeasts in doogh, inclusion of these bacteria (LAB) can be a solution for this problem in aforementioned product. In this study, antimicrobial effects of two selected strains of Lactobacillus brevis assigned as M2 and M4 isolated from Motal cheese were investigated on the gas-producing and food spoilage microorganisms in Doogh.
Materials and methods: Two strains of lactobacillus namely M2 (Lactobacillus brevis KX572376) and M4 (Lactobacillus brevis KX572378) were selected from traditional Motal cheese isolates. Doogh production was carried out according to National Iranian Standard No. 2453. Each of these two strains was inoculated in Doogh at two levels of 106 and 108 cfu / ml and control sample was taken without inoculation followed by subjecting to microbial and sensory analysis at three temperatures of 4, 25 and 37°C, at intervals of 10, 7 and 7 days, respectively. Microbial profiles including coliforms, E. coli, Mold & yeast and Staphylococcus aureus were determined according to National Iranian Standard Number (2 and 1) –5486, 5234 and 5486, 997 and 6806, respectively. Sensory evaluation was carried out according to Iranian National Standard No. 4691. Sensory evaluation parameters such as taste, texture, color and total acceptance were evaluated by 10 senior food industry students.
Results and discussion: The results showed that sample inoculated with M4106 strain, received the highest score for antimicrobial activity at all three storage temperatures. Results demonstrated that, at 4 ° C, the control sample was contaminated (spoiled) on 50th day and was positive for mold and yeast count, but sample inoculated with M4106 was acceptable (negative) for mold and yeast count. At 25 C, mold growth was detected in control sample on the 14th day of storage, but the sample inoculated with M4106 remained completely un-spoiled until the 21st day. At 37°C, the control sample on day 7 was positive for mold and yeast count, but the sample inoculated with M4106, mold and yeast was not detected until the 14th day. Coliform, Staphylococcus and Escherichia coli counts in M4106 sample were negative. Sensory evaluation was carried out according to Iranian National Standard No. 4691.Sensory evaluation data showed that samples inoculated with M4106 were superior to the control sample. Doogh samples inoculated with Lactobacillus brevis strains experienced acceptable sensory evaluation so that they gained better score than control sample. The highest score was obtained for the M4106 sample. The texture of the Doogh samples showed a decreasing trend at all three temperatures during the storage period. Moisture and pH are factors influencing texture changes during the initial stages of storage. Based on the taste evaluation results, at 4°C, the highest score was related to M4108 until day-20, but from the 20th to the 60th day of storage, the M4106 has gained the highest one. At 25°C until day 7, the highest score belonged to sample M4108 but from this day on, M4106 has been more favorable. At 37°C on production day, highest score for the M4108 sample but on day- 7 and 14, the M4106 took the highest score. Regarding to color index, M2108 has gained the highest score at all 3 temperatures on the production day and for the rest of storage time, the highest scores were obtained for the M4108 and M4106 samples. Maximum total acceptance, was obtained for M2108 on the production day but this was replaced by M4106 for the rest of the time .The results showed that the Lactobacillus strain M4106 strain had the highest antimicrobial activity and the optimum score for sensory evaluation, as well as a significant increase in Doogh shelf life and reduced gas production in the bottle.
Samaneh Rezaei; Mohammad Bagher Habibi Najafi; Fereshteh Hosseini; Reza Karazhyan
Abstract
Introduction: Nowadays, with the increasing awareness of the side effects of synthetic additives, consumer’s demand for colorants from natural sources has been increased. Annatto is an allowed natural colorant used in food industries, textiles, cosmetics and pharmaceutical products. The colorant is ...
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Introduction: Nowadays, with the increasing awareness of the side effects of synthetic additives, consumer’s demand for colorants from natural sources has been increased. Annatto is an allowed natural colorant used in food industries, textiles, cosmetics and pharmaceutical products. The colorant is extracted from the seeds, which are covered by a red, resinous pericarp containing the pigments. The main pigment is bixin (methyl hydrogen 9′-cis-6, 6′-diapocarotene-6, 6′-dioate) which is responsible for the orange red color in the seeds (80% of total carotenoids). Smaller amounts of norbixin are also presented. Bioactive compounds like bixin and phenolic compounds reduce the risks of various chronic disorders, such as cancer, inflammation, cardiovascular, hypercholesterolemia, diabetes, and cataracts (Boschetto, et al., 2014; Somacal et al., 2015; Ezuruike & Prieto, 2014). Moreover many studies have proven antimicrobial activity of annatto extracts (leaves, capsules, seeds…) against several food spoilage and pathogenic bacteria such as Staphylococcus aureus, Escherichia coli and Bacillus subtilis, as well as few fungi such as Candida utilis, and Aspergillus niger. Annatto is a permitted natural food coloring with antioxidant properties, high therapeutic potential and antimicrobial effects. The aim of this study was to evaluate antimold activity of annatto natural dye on 3 important food pathogenic and spoilage molds, Aspergillus niger,Neurospora sitophila and Rhizopus stolonifer.
Material and Methods: Annatto dye was extracted by maceration method and after filtration it was dried by a vacuum oven. Anti-mold activity was evaluated by well diffusion and disk diffusion methods in 1 to 10 percent concentrations of acetone extract of annatto and minimum inhibitory concentration (MIC) was determined using agar dilution method at 48 and 72 h after incubation at 25 °C.
Results and Discussion: The results indicated promising anti-mold activity. The highest mean zones of inhibition in all concentrations were obtained for Aspergillus niger, Neurospora sitophila and Rhizopus stolonifer, respectively. This difference might be due to the more resistance and rapid growth of Rhizopus stolonifer and Neurospora sitophila compared to Aspergillus niger. No inhibitory effect was observed in the concentrations below than 1%, this result is in consistent with Irobi, et al., (1996) findings that proved annatto's organic extract has a weak effect on Aspergillus niger at low concentration (5 mg/ml).In all concentrations, Aspergillus niger showed the highest inhibition zone and the most sensitivity to annatto extract found at Aspergillus niger, Neurospora sitophila and Rhizopus stolonifer, respectively. Disk diffusion method was inefficient to inhibit mold growth. Minimum inhibitory concentration of annatto dye against Aspergillus niger and Neurospora sitophila was determined 6 percent while Rhizopus stolonifer showed 7 percent. According to the results annatto dye was effective to inhibit growth of Aspergillus niger, Neurospora sitophila and Rhizopus stolonifer. Therefore it can be concluded that annatto dye could be used as a functional and inhibitory agent against mold growth in the foods that are susceptible to mold spoilage (e.g. bakery goods).
Samira Abbaspour Monjezi; Mohammad Reza Edalatian Dovom; Mohammad Bagher Habibi Najafi; Arash Koocheki
Abstract
Introduction: Nowadays, consumers prefer foods produced without synthetic preservatives. These chemical preservatives have been gradually replaced by natural preservatives in formulation of edible films and coating. Since, edible films can be applied as carriers of antimicrobial agents, so, these aforementioned ...
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Introduction: Nowadays, consumers prefer foods produced without synthetic preservatives. These chemical preservatives have been gradually replaced by natural preservatives in formulation of edible films and coating. Since, edible films can be applied as carriers of antimicrobial agents, so, these aforementioned ingredients can be incorporated in such films. Among edible films, protein-based films such as whey protein concentrate (WPC)-based films are more attractive because they also supply valuable nutrients and introduce acceptable mechanical resistance. On the other hand, these films present moderate barriers to moisture due to the hydrophilic nature of whey proteins. Essential oils (Eos) can be incorporated in to edible films in order to compensate (overcome) this defect. Since no published research has been found on integrating mastic tree sap (Pistacia atlantica sub sp. kurdica) essential oil into whey protein edible films, this essential oil was applied for WPC-based film in this research. Some species belong to Penicillium have been known as contaminants of dairy and fruit products. Among Penicillium sp., P. expansum is more popular for causing post-harvest damage of apples. In this study, our objective was focused on mechanical and anti-fungal properties of WPC-based films incorporated with mastic gum essential oil.
Materials and methods: WPC, mastic tree sap and P. expansum were obtained from Multi Milk Company, Kurdistan mastic Gum Company and Persian Type Collection Culture, respectively. Extraction of EO from mastic gum was accomplished using water distillation or hydro distillation with the help of Clevenger-type apparatus for 5 hours to obtain a pale yellow oil. Solution (10%w/w) of WPC in distilled water was prepared. Glycerol (as plasticizer) was added to WPC solution at a ratio of 1:1 WPC: Glycerol. Then concentrations of EO (1000, 2000, 3000 and 4000 ppm) was added to solution and mixed for 2 min. In the next step, some characteristics of film were measured including: thickness and density, water solubility, stability in acidic and alkaline solutions, water vapor permeability and light transmission / film transparency. Some mechanical properties of films such as tensile strength (TS) and elongation at break (%E) of films were also determined.
Regarding microbial assays, following the activation and preparation of fungi spore, MIC was determined using Agar Dilution Method. Determination of antimicrobial activity of film was performed according to film disk agar diffusion assay
Results & Discussion: With increasing essential oil concentration, film thickness exhibited increasing trend which was due to entrapment of micro-droplets of essential oil in film. Along with increasing EO concentration in film samples, WVP declined significantly (P-value
Elham Shokooh Saremi; Mohammad Bagher Habibi Najafi; Mohammad Hossein Hadad Khodaparast; Masoumeh Bahreini
Abstract
Introduction: It has been well demonstrated that vegetables provide, in addition to other basic nutrients, bioactive substances with beneficial effects on human health. In fact, the consumption of vegetables has been associated with lower incidence and lower mortality rates of cancer and cardiovascular ...
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Introduction: It has been well demonstrated that vegetables provide, in addition to other basic nutrients, bioactive substances with beneficial effects on human health. In fact, the consumption of vegetables has been associated with lower incidence and lower mortality rates of cancer and cardiovascular diseases in humans. Increasing demand for natural additives has shifted the attention from synthetic to natural antimicrobial agents. Leafy vegetables are found to be good source of antimicrobial agents. This study was aimed to examine the antimicrobial activity of leaf extracts of pimpinella affinis. Pimpinella affinis is a member of the family Apiaceae. This biennial herb grows up to 110 cm tall and is native in central and northern parts of Iran. In traditional medicine this herb is being used as carminative agent, appetizer, diuretic, antispasmodic drug, antimicrobial, sedative and lactation medication. It has also been distinguished as an antioxidant and antibacterial agent. There are several methods of obtaining extract from plants including maceration, super critical fluid extraction, subcritical water extraction, microwave and ultrasonic assisted method.
Materials and Methods: After collection from natural habitats of Pimpinella affinis in Mazandaran Province, it was then approved by the Department of Botany of Faculty of Agriculture of University of Sari. The plant was dried in a dry and dark place away from the sun and then was pulverized in the mill and sieved by a mesh of 80 (800 microns). Pimpinella affinis extract obtained by using maceration extraction (ME), ultrasonic assisted method (UAE) and supercritical fluid extraction (SFE). Ethanol: water in 50:50 ratio used as solvent for extraction. Total phenolic content of different extracts was measured by Folin-ciocalteu method. The phenolic compounds fractions were determined using Liquid chromatography–mass spectrometry system. After preparing the mother culture medium, the bacteria were cultured in MHB medium (37 ° C) for 24-18 hours. Stock solutions were prepared from each of the extracts. Serial dilutions of the extracts at concentrations of 0.01 to 10 mg / ml in 2.5% dimethyl sulfoxide were prepared and then sterilized with 0.22 μm pore size syringe filter. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration assay (MBC) were determined by micro dilution method for listeria monocytogenes (ATCC19112), staphylococcus aureus (ATCC25923), pseudomonas aeruginosa (ATCC9027) and Escherichia coli (ATCC25922). Antimicrobial growth was inhibited by measuring the absorbance and ELISA Reader was used to determine the growth rate of microorganisms, and the first house with the lowest absorption read as MIC (mg /ml) was determined. Statistical analysis of MIC, MBC and phenolic compounds of extracts results was done in a completely randomized design and using SPSS software version 20. The comparison of the means was done using Duncan’s test and one-way ANOVA method. In order to reduce the error, all experiments were performed in triplicate.
Results and Discussion: Total phenolic content of extracts ranged between 1502.25 to 1836.69 mg GA/100g E. The results showed that the ultrasonic assisted method have highest total phenolic content and the least phenolic content was observed in extract which obtained by supercritical fluid extraction. Chlorogenic Acid, Cafeic acid and Apigenin-6-C-glucoside were the predominant fractions in Pimpinella affinis which detected by Liquid chromatography–mass spectrometry system. The least and highest amount of MIC and MBC were belonged to ultrasonic assisted and supercritical fluid extracts, respectively. Staphylococcus aureus was most sensitive and Escherichia coli and Pseudomonas aeruginosa were most resistance bacteria. Pimpinella extract due to having phenolic compounds such as Gallic acid, Cafeic acid, Chlorogenic Acid, Kaempferol and Apigenin showed antimicrobial activity and can be used as natural antimicrobial agent.
Neda Nayyeri; Mohammad Reza Edalatian Dovom; Mohammad Bagher Habibi Najafi; Masoumeh Bahreini
Abstract
Introduction : Nowadays, attention to foods free from chemical preservatives is on the rise. Recently, consumers have concerned about foods containing these preservatives in their formulation .Therefore,the use of antimicrobial peptides produced by Lactic acid bacteria (LAB) are strongly highlighted. ...
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Introduction : Nowadays, attention to foods free from chemical preservatives is on the rise. Recently, consumers have concerned about foods containing these preservatives in their formulation .Therefore,the use of antimicrobial peptides produced by Lactic acid bacteria (LAB) are strongly highlighted. Ribosomally-synthesized peptides, which possess antimicrobial properties, are produced by a vast range of organisms including prokaryotes and Eukaryotes.Yeasts are the most important microorganisms which are responsible for fruit juice and soft drink spoilage. In case of growth and production of by-products like CO2, acid and other contaminants, the spoilage will be visible.Lactic acid bacteria isolated from natural, local sources such as dairy products have presented potentially antifungal features against food spoilage fungi. Among these, Rodotorula and Penicillium are regarded as the most critical genera in fruit juice spoilage.The main objective ofthis study was the evaluation of anti-yeast activity of Lactobacillus plantarum isolates from different stages of Lighvan production against Rodotorulamucilaginosa as fruit juice spoilage indicator. In the next step, technological parameters effects were analyzed on antimicrobial potential of cell-free supernatant of these isolates. Finally, we aimed at finding the most effective isolate on aforementioned yeast.Materials and methods: NineteenLb.plantarumisolates, which were identified previously, were subjected to antifungal assay. For this purpose, RodotorulamucilaginosaPTCC 5257 was selected. Agar spot and Well Diffusion Assay (WDA) were applied for antifungal assay in solid and liquid media, respectively.Determination of yeast colony: Following the cultivation of yeasts in Potato Dextrose Broth, it was determined using Spectrophotometer.Preparation of Lb.plantarum cell-free supernatant (CFS) was carried out. In agar spot method, clear zones of inhibition around the spotted colonies were evaluated after 24-48h incubation. In WDA, CFS of Lb.plantarum isolates were poured in wells and clear zones were evaluated around each well after 24-48 h incubation.Technological properties: The influence of different levels of pH (2, 3, 4, 5, 6, and 7) was analyzed on CFS of Lb.plantarum isolates. This assay was done according to Wang et al., 2011. Finally, results were reported using the measurement of clear zone diameter in mm. All experiments were performed in duplicates.The effects of various temperatures were applied on CFS and remaining the antifungal activity was evaluated according to Rouse et al., 2008. Finally, all CFS of Lb.plantarum isolates were subjected to Proteniase K and antifungal properties of CFS were assayed by WDA according to Ghrairi et al., 2005.Results and discussion:Agar spot results showed the highest and lowest clear zone of inhibition related to C28 and LF49 with 16 and 6 mm diameter, respectively. In this method, 11 out of 19 isolates (60%) presented anti-yeast activity with clear zone formation. In comparison between two incubation temperatures (25 and 30◦C), all isolates stronger clear zone in 30◦C than in 25◦C. This was due to enhancement of yeast growth in 25C rather than in 30C. Also, with respect to the mesophilic nature of Lb.plantarum isolates, the possibility of metabolite production are more likely in 30C. It was reported that antifungal activity of LAB is mostly due to synergistic effect of lactic acid and acetic acid. In agar spot, some colony-associated antimicrobial compounds are responsible for antifungal activity. In WDA, 8 out of 19 isolates (42%) were positive for their inhibitory effects. The highest anti-yeast activity was seen at pH=2. It seems that antimicrobial compounds are likely more stable at acidic conditions than at alkaline ones. Among isolates, C28 presented the highest stability at alkaline conditions. With pH increase, the antifungal activity decreased so that no anti-yeast activity was seen at pH=7. Regarding the different temperatures, we should mention that thermal resistance of isolates' CFSwitnessed declining trend with increasing of temperature. This fact implies the presence of low- molecular weight compounds in CFS. Finally, all isolates' CFS was subjected to proteinase K. All isolates have lost their anti-yeast activity after enzyme treatment showing their proteinaceous nature.Conclusion: In WDA, the number of positive isolates showing anti-yeast activity declined in comparison with agar spot. Since some isolates retain their inhibitory activity toward food spoilage yeast at low pH, their CFS can be applied in acidic foods like fruit juice. Also, some isolates showed their antifungal activity at high temperatures (80C and 100C) which are applied for fruit juice pasteurization, so they can be applied in fruit juices as a bio-preservative.
Mahmoud Yolmeh; Mohammad Bagher Habibi Najafi; Reza Farhoosh; Fereshteh Hosseini
Abstract
IntroductionFood consumers tend to use natural products without any synthetic additives. Therefore, many studies have been conducted to investigate the possibility of replacing synthetic additives with natural substances in various food products.Annatto dye is a natural carotenoid pigment extracted from ...
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IntroductionFood consumers tend to use natural products without any synthetic additives. Therefore, many studies have been conducted to investigate the possibility of replacing synthetic additives with natural substances in various food products.Annatto dye is a natural carotenoid pigment extracted from the pericarp of BixaorellanaL. seeds. The major fraction of the annatto extract is 9´-cis-bixin that is soluble in oil and 9´-cis-norbixin is the major dye fraction of the alkaline extract that is soluble in water. Annatto dye creates orange to red color in food and to be used as a natural pigment in a variety of food materials including cheese, butter, margarine, confectionary and bakery products, different kinds of drinks, snacks and jams. In addition, annatto dye has antioxidant and antimicrobial activity.Nowadays, the extraction of natural dye from plant resources has become a common technology. However, complementary information using new methods and optimization of the extraction conditions seems to be necessary in order to accomplish the highest yield of extraction. Response surface method (RSM) is effective and efficient in optimizing color extraction conditions.In this study, the different conditions of extraction process were optimized through RSM in order to obtain maximum yield and best quality of annatto dye.Materials and methodsMaterialsAnnatto seeds were purchased from Hyderabad, India. All solvents were analytical grade, Merck, Germany.Extraction of annatto dyeA certain amount of annatto seeds was soaked in n-hexane for 6 hours in order to remove oils. After filtration, the defatted seeds were used for dye extraction. Since chloroform and acetone showed the highest yields of extraction during preliminary experiments, these two solvents and their mixtures were exploited for the final experiments assigning 0 for pure acetone and 100 for pure chloroform. The extracts were filtered through Whatman filter paper NO.1 and then vacuum-dried in the 1410D-2E vacuum oven (Shel Lab, USA) to produce dye powder. Low temperatures (40°C) were applied to prevent thermal dissociation of conjugated double bonds during drying. Dye measurementThe coloring strength was measured according to Vasu et al. method; model UV-160A spectrophotometer Shimadzu, Japan, at 502 nm in which bixin has the maximum absorbance value when it is dissolved in chloroform.Determination of extraction efficiencyThe obtained powder was weighed and the mass ratio of the powder to the weight of the seeds was taken into account as the extraction yield.Experimental designIn this study, Minitab® software version 16.1.1 (Minitab Inc. USA. 2010), was used and a five level four factor central composition design was created to investigate the effect of the independent variables such as temperature, extraction time, seed to solvent ratio and chloroform concentration on the dependent variables namely the extraction efficiency and absorbance values.Results and DiscussionThe values of R2, R2-adj and R2-pred revealed that the full quadratic models were the most adequate for the extraction efficiency and absorbance values.The all of the linear terms show a significant effect except the extraction time (P< 0.05). The quadric term of extraction time and the seed to solvent ratio also had a significant effect (P< 0.05) on the extraction efficiency, however, the effect of other two quadric terms was insignificant (P> 0.05). The interactive terms of extraction temperature* seed to solvent ratio(X1X3) and the seed to solvent ratio*Chloroform concentration (X3X4) had a significant effect on the extraction efficiency (P< 0.05); however, the other two interactive terms was insignificant (P> 0.05).For the absorbance values, the all of the linear terms show a significant effect (P < 0.05); the quadric term of extraction temperature (X12) and the seed to solvent ratio (X32) also had a significant effect (P< 0.05) on absorbance values, but, the effect of other two quadric terms (X22 and X42) did not show a significant effect (P> 0.05). The all of interactive terms was insignificant (P> 0.05).An increase in the extraction efficiency was observed with the increasing temperature. Banik and Pandey while extracting oleanolic acid from Lantana camararoots demonstrated that as temperature increases extraction efficiency improves too. However, at temperatures higher than 70 °C, the annatto seed pigments were degraded and the response was reduced so the quadratic effect of temperature was negative. The absorbance value was increased by increasing the temperature; however, the absorbance value decreased at higher temperature by thermal decomposition and damage of the conjugate double bond.The absorbance value increased by increasing the chloroform concentration and seed to solvent ratio initially, however, subsequently decreased due to the damage of the conjugate double bond in higher chloroform concentration and saturation of solvent in higher seed to solvent ratio.Temperature of 48.33 ˚C, extraction time of 2 hr, the ratio of seed to the solvent of 12.88 and chloroform concentration of 100% were found to be as the optimum conditions of the process. The extraction efficiency of 3.95 percent of annatto seed and absorbance value of 0.597 were acquired as the predicted results.
Amir Pourfarzad; Mohammad Bagher Habibi Najafi; Mohammad Hossein Hadad Khodaparast; Mohammad Hassanzadeh Khayyat
Abstract
Introduction: Fructans are an important product of the industry of prebiotics. In addition to their interesting nutritional and health benefit properties, fructans are also used in food formulations for their techno-functional properties such as fat substitute, bulk agent, water retention. Serish (Eremurus ...
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Introduction: Fructans are an important product of the industry of prebiotics. In addition to their interesting nutritional and health benefit properties, fructans are also used in food formulations for their techno-functional properties such as fat substitute, bulk agent, water retention. Serish (Eremurus spectabilis) belongs to the family of Liliaceae and geographically distributed in the region of South Asia and Central Asia. Their roots accumulate high levels of fructans during their growth and are traditionally used to cure jaundice, liver disorders, stomach irritation, pimples and bone fractures and even as a glue for industrial application. Recently fructan extraction from numerous plants and fungus has drawn the attention of researchers. Also, several methods for fructan extraction have been developed such as hot-water extraction, precipitation by alcohol and ultrasound-assisted extraction. To the best of our knowledge, there are no reports on the fructan extraction from Serish. The present study is considered the first attempt aiming to determine the optimal conditions for water extraction of Serish fructans. Materials and methods: The Serish root powders were obtained from the local medical plant market, Mashhad, Iran. Moisture, ash, fat, protein, Carbohydrate and total dietary fiber were determined according to standard AOAC methods. All variables were examined in triplicate. Conventional extraction was carried out in a water bath. Total carbohydrate was assayed colorimetrically using the phenol–sulphuric acid method. The concentrations of soluble reducing sugars were measured using a 3,5-dinitrosalicylic acid (DNS) method. The fructan content was measured by the difference between total carbohydrate and reducing sugars. The percentage of fructan yield (%) was evaluated based on equation of Lingyun, Jianhua, Xiaodong & Yalin (2007). The purity was evaluated according to the method of Paseephol, Small & Sherkat (2007). As an index of degree of polymerization, the average chain length, was calculated according to Lingyun, Jianhua, Xiaodong & Yalin (2007). A Box-Behnken design was constructed using the software Design Expert Version 6.0.10 and was used for estimating the effect of independent variables on the extraction parameters. Three extraction variables considered for this research were x1 (extraction time), x2 (extraction temperature) and x3 (water: solid) for conventional extraction method. Lack of fit, coefficients of determination (R2), adj-R2, coefficient of variation (CV) and significant probabilities were calculated to check the model adequacy. Optimization was based on generation of the best results for fructan extraction. In order to determine the validity of the model, the experimental and predicted values were compared by paired t-test. Results & discussion: It has a marked amount of protein and fats. The ash value is relatively high, suggesting an important mineral content. The composition of total fiber suggests its possible use as a source of dietary fiber for enrichment of foods. In addition, results show that Serish root powder is a polysaccharide-rich material. The results indicated that extraction temperature has the most effect on the extraction yield. Increase of time, temperature and water to solid ratio led to significantly increase in extraction yield. Considering the significant quadratic term of extraction time, it becomes clear that yield rises as extraction time increase from 0 to 22.5 min but it decreases at higher times. The yield increase between 0 to 22.5 min might be due to the time requirement for contact of fructan to the release medium where the liquid penetrated into the Serish powder, dissolved the fructan and subsequently diffused out from the root. On the other hand, the yield decrease after 22.5 min may be ascribed to degradation of fructan to free sugar and enhancement of impurities extraction at higher times. When extraction time goes by certain threshold, the yield started to decrease. The yield showed a large tendency to increase when the extraction temperature was increased. This is maybe due to the enhancement of the mass transfer resulting from the increased solubility of fructan and the decreased viscosity of the solvent. Yield was increased by portion of water to solid. This might be attributed to the availability of liquid that increases the driving force of fructan out of the root. Based on the sum of squares, temperature had the most effect on degree of polymerization. The results indicated that increase of time, temperature and W/S ratio resulted in increase of the degree of polymerization which might be due to the enhancement of overall carbohydrates extraction. On the other hand, the degree of polymerization of extracted fructan was lower than 10. This is probably because the disruption of fructan branch to reducing sugars with increasing temperature that leads to chain length decrease. Thus, the produced oligosaccharides could be used as sweetener. W/S ratio had the most effect on purity. The results showed that increase of time, temperature and W/S ratio resulted in increase of the purity which might be due to the enhancement of overall carbohydrates extraction. With the increase in extraction time, the purity of extract increased gradually, but decreased after the purity reached a maximum at 22.5 min. This decrease may be ascribed to degradation of fructan to free sugar and enhancement of impurities extraction at higher times. Multiple response optimizations were performed to measure the optimum levels of independent variables to achieve the desired response goals. Extraction yield and purity were desired maximal. Conclusion: The final results for this optimization was found to be extraction time of 28.38 min, extraction temperature of 88ºC and water to solid ratio of 50:1 v⁄w. Response surface methodology was an efficient statistical tool to model the influence of extraction conditions of fructan from Serish root powder on the extraction yield. These results also suggested that by modifying the proportion of these components, a large range of variations may be obtained. There was a good agreement between the experimental data and their predicted counterparts, showing the effectiveness of the proposed conditions and reliability of Box–Behnken analysis on fructan precipitation.
Mahmoud Yolmeh; Mohammad Bagher Habibi Najafi; Mahmoud Najafzadeh
Abstract
Introduction: One of the most important aspects of food preservation is controlling the growth of microorganisms, which if overlooked it leads to uncontrolled growth of microorganisms associated with food spoilage and food poisoning. Microbial contamination of foods is important because of pathogens ...
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Introduction: One of the most important aspects of food preservation is controlling the growth of microorganisms, which if overlooked it leads to uncontrolled growth of microorganisms associated with food spoilage and food poisoning. Microbial contamination of foods is important because of pathogens are capable to transfer to foods during the processing, distribution, and storage. Escherichia coli and Bacillus cereus can cause spoilage in food; intake food contains plenty of bacteria and toxic. Therefore it is important to eliminate or control these bacteria safely. Ultraviolet (UV) radiation is considered as non-ionizing radiation and the first time in 1940 was used as a method for infection elimination in air. This approach nowadays is widely used for controlling microbial growth and as disinfection in food industry. Wavelength range of ultraviolet radiation is approximately 328-210 nm. The beam is naturally present in the sunlight. The bactericidal effect of UV irradiation depends on the type of bacteria, the distance, and dose of radiation. The most cytotoxic effect of UV irradiation is obtained at the wavelength of 260 nm, which corresponds to the intense absorption of energy by organic bases in the nucleic acid. UV irradiation causes radicals generation, which subsequently attack the nucleic acid and develop mutations in their genomes and gene transcription and translation processes. In this study, the antibacterial effect of different exposure times of ultraviolet radiation on the growth of E. coli and B. cereus was evaluated.Materials and methods: All media used in this study was procured from Merck Company. Ultraviolet device (Camag, USA) was used at wavelength of 254 nm, Nr= 29000, Amp= 0.25. B. cereus isolation: 1 mL of different dilutions of rice (0.1, 0.01, and 0.001) was transferred to Brain-heart infusion (BHI) and it was incubated at 32 °C for 24 h. A loop containing the bacteria was then transferred to Mannitol Egg Yolk Polymyxin (MYP) agar and it was incubated at 35 °C for 24 h. B. cereus produce big and round colonies, with a halo around the colonies. Starch test was carried out as confirming test for B. cereus colonies. Briefly, some colonies of B. cereus were added to test tube with sterile distilled water containing starch and a few drops of lugol. Development of blue color indicates the presence of B. cereus due to starch hydrolysis.E. coli isolation: E. coli was isolated from raw milk following the method described by Kargar et al. (2005). Briefly, raw milk was first homogenized; 0.1 ml of each dilution of homogenized raw milk was inoculated on Escherichia coli broth medium containing 20 mg novobiocin. E. coli was then isolated after transferring the former media on EMB specific culture and incubation at 36 °C for 24 h. After confirming colonies by Durham tube and complementary tests, pure cultures were obtained from them by streak-plate method.UV irradiation: A loop of E. coli colonies was transferred to nutrient broth and it was treated with UV beam (254 nm) at three times (40, 60, and 80 s). After preparing dilution of 0.0001 for each of the treatments and incubating for 24 h, survival curve was plotted. These operations were also carried out on B. ceruse colonies. A control sample also was considered for each examined bacterium.Results and Discussion: Rate of Bacillus cereus growth was reduced under UV radiation. As it is shown, Death curve of E. coli, E. coli count was decreased by increasing the time of UV radiation, so that count of this bacteria reached to about zero after UV radiation for 80 s. However, reduction of B. cereus count was less than E. coli count at same wavelength (254 nm) and time of irradiation. This revealed that B. cereus have more resistance to UV radiation compared to E. coli. These results were consistent to observation of Sharp (1940) who evaluate the effects of UV light on bacteria suspended in air and reported that required energy for air sterilization containing B. cereus is more than twice the energy is needed to eliminate E. coli. UV light more penetrates to cell wall of Gram-negative bacteria compared to Gram-positive bacteria due to having a small amount of peptidoglycan in the cell wall and caused mutations in regulating genes of transcription and translation. Conclusion: The efficiency of the two main processes of cell is reduced in the presence of UV irradiation and leads to growth reduction and death. The more resistance of B. cereus can be for several reasons, such as having a thicker cell wall compared to E. coli, and the capability to produce spore, and the capability to proofing mutations.
Masoumeh Bahreini; Mohammad Bagher Habibi Najafi; Mohammad Reza Bassami; Eisa Jahed
Abstract
Ozone is a strong oxidant and a potent disinfecting agent. There are numerous application areas of ozone in food industry. While there are many investigations on the application of ozone in food industry, relatively little information is available on the potential of ozone to reduce microbial populations ...
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Ozone is a strong oxidant and a potent disinfecting agent. There are numerous application areas of ozone in food industry. While there are many investigations on the application of ozone in food industry, relatively little information is available on the potential of ozone to reduce microbial populations in fresh-cut fruits and vegetables and the visual quality of lettuce. In this study, ozone water was applied at five concentrations (0.6, 0.8, 1.2, 1.6 and 2 ppm) for four exposure times (1, 3, 5 and 10 min) on natural microflora and E. coli O157:H7 and Salmonella inoculated of lettuce. The reduction in the total bacterial count, yeast and mold, total coliform, as well as lactic acid bacteria counts were examined. The promising results indicated the efficacy of ozone water to reduce the microbial populations on lettuce. In the best condition, the inoculated samples of E. coli O157:H7 (ATCC 35150, NCTC 12900), Salmonella typhi morium ( ATCC 14028, NCTC 12023) and Salmonella enterica subsp, enterica (PTCC 1709) on lettuce were decreased further than 2 log10 cfu/g. The results showed the population of aerobic mesophilic bacteria, yeast/ moulds, total coliforms and lactic acid bacteria were decreased to 1.54, 0.94, 1.94 and 1.35 log10 cfu/g respectively. The method of ozone generation, type of application, as well as the optimal exposure time and concentration of ozone as an antimicrobial agent on lettuce is mentioned in detail.
Mohammad Bagher Habibi Najafi; Mohebbat Mohebbi; Fakhri Shahidi; Seyed Ali Mortazavi
Abstract
The effect of pretreatment osmotic-ultrasonic dehydration on the drying kinetic, rehydration kinetic, texture, shrinkage and color change of quince slices was investigated. Quince slices were osmotic-ultrasonic processed at 27.25 min for ultrasonic time, 120 min for osmotic dehydration and 50.52 % for ...
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The effect of pretreatment osmotic-ultrasonic dehydration on the drying kinetic, rehydration kinetic, texture, shrinkage and color change of quince slices was investigated. Quince slices were osmotic-ultrasonic processed at 27.25 min for ultrasonic time, 120 min for osmotic dehydration and 50.52 % for sucrose concentration. The un-treated and pre-treated samples were then dehydrated at80°C. The effective diffusivity calculated by applying the Fick’s diffusion model. The pretreatment caused a decrease in Deff. Application of osmotic-ultrasonic dehydration reduced the sample hardness, color changes and shrinkage while it had increased the sample springiness, and chewiness.
Mohammad Reza Edalatian Dovom; Mohammad Bagher Habibi Najafi; Seyed Ali Mortazavi; Majid Hashemi; Masoud Yavarmanesh
Abstract
The objective of this study was to evaluate lactic flora identification in fresh (one-day) and ripened (90-day) Koozeh cheese samples as one of the raw milk cheeses. In first step, in order to isolate the different genera of Lactic acid bacteria (LAB), selective and differential (corresponding) media ...
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The objective of this study was to evaluate lactic flora identification in fresh (one-day) and ripened (90-day) Koozeh cheese samples as one of the raw milk cheeses. In first step, in order to isolate the different genera of Lactic acid bacteria (LAB), selective and differential (corresponding) media were used as follow: MRS for lactobacilli and pediococci, MRS+ vancomycin for leuconostocs, M17 for lactococci and KAA for enterococci. Totally, 48 single, purified colonies were selected and identified using confirmatory, biochemical and phenotypic tests down to the genus level. Lactobacilli (33.33%), lactococci (12.5%), pediococci (2.08%), enterococci (47.91%) and aerococci (4.16%) were determined as the most abundant genera. At last, carbohydrate fermentation profile using API 50 CH and API 20 STREP kits was used for identification down to species level. Finally, following species were identified: Lactobacillus. plantarum, Lb. brevis, Lb. lindneri, Lb. helveticus, Lb. delbrueckii ssp. delbrueckii, Lb. pentosus, Lb. fermentum, Lactococcus. lactis ssp. lactis, Enterococcus. faecium, Ent. faecalis, Ent. avium, Ent. durans and Aerococcus. viridans. In fresh cheese, the Lactococci and lactobacilli genera were predominant but in ripened cheese the enterococci replaced them. Predominant species in fresh cheese were as follow: Lac. lactis ssp. lactis (44.44%) and Lb. plantarum (22.22%) but Ent. faecium (43.58%), Lb. brevis (12.82%) and Ent. faecalis (7.69%) constituted the major part in ripened cheese. We can mention that these predominant lactic acid bacteria play an important role during ripening and also flavor production in raw milk cheeses like Koozeh. So, more precise identification is very necessary using culture- based molecular and culture- independent methods down to strain level.
Masoumeh Bahreini; Mohammad Bagher Habibi Najafi; Mohammad Reza Bassami; Morteza Abbaszadegan
Abstract
We investigated the microbiological quality of raw vegetables in Mashhad, Iran. In order to document the incidence of indicator and pathogenic microorganisms in this area. ninety eghit raw vegetable samples collected during 7 months were analyzed. All samples were examined for the presence of aerobic ...
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We investigated the microbiological quality of raw vegetables in Mashhad, Iran. In order to document the incidence of indicator and pathogenic microorganisms in this area. ninety eghit raw vegetable samples collected during 7 months were analyzed. All samples were examined for the presence of aerobic mesophilic bacteria, coliforms, Enterobacteriaceae, Escherichia coli, Escherichia coli O157:H7, Salmonella spp., Staphylococcus aureus, yeast and mould. Our data showed that the incidence levels of aerobic mesophilic bacteria was less than 107 cfu/g on 83% raw vegetables and 100% of raw vegetables were contained Entrobacteriace and total coliforms, and their range varied from 1 log to 6 log cfu/g. The mean counts of Lactic acid bacteria and yeasts and moulds were 4.1 log cfu/g and 4.5 log cfu/g, respectively, and the incidence levels of yeasts and moulds in 83% of raw vegetables was less than 5 log cfu/g. Our results were similar with other studies that determined microbial levels on raw vegetables. 12.7% of samples raw vegetables contained E.coli, but only 4.1% were higher than ≥ 2 log cfu/g. The incidence levels for E.coli O157:H7 and Salmonella on raw vegetables were 6% and 12.7% respectively. 94.9% of raw vegetables were contaminated with S. aureus and 7.8% of them were coagulase positive.
Masoud Mazaheri Nasab; Mohammad Bagher Habibi Najafi; Seyed Mohammad Ali Razavi
Abstract
In this research, the effect of different levels of carrageenan gum (0.05– 0.2%) and whey protein concentrate (0.5 - 1.5%) on physical, chemical and sensory properties of low fat mozzarella cheese have been investigated. Use of these fat replacers cause significant differences (P ≤ 0.05) on chemical ...
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In this research, the effect of different levels of carrageenan gum (0.05– 0.2%) and whey protein concentrate (0.5 - 1.5%) on physical, chemical and sensory properties of low fat mozzarella cheese have been investigated. Use of these fat replacers cause significant differences (P ≤ 0.05) on chemical properties as increase in gum and WPC resulted moisture and protein content to increase but pH to decrease however carageenan was not affected. The physical properties of mozzarella cheese changed significantly (P ≤ 0.05) as increase in gum and WPC resulted meltability to increase although carrageenan had largest share of this effect. Increase of carrageenan resulted free oil formation to increase but increase of WPC was not significant. Length of stretch was not affected by carrageenan although increase of WPC decreased it. Carrageenan content did not effect on color, aroma and taste but score of texture and overall acceptance increased. WPC decreased score of color, aroma and taste but texture improved. The overall acceptance of treatments that have greatest amounts of carrageenan plus moderate amounts of WPC was higher than others. Finally the review of mixture experimental design results show that best low fat mozzarella cheese will produce with composition of 0.2% of carrageenan and up to 1% of WPC as fat replacers.
Masoumeh Bahreini; Mohammad Bagher Habibi Najafi; Mohammad Reza Bassami; Morteza Abbaszadegan; Ahmad Reza Bahrami; Hamidreza Ejtehadi
Abstract
The number of vegetable processing plants has been increased during recent years in Iran as many other countries. On the other hand, fresh vegetable products are susceptible to microbial contamination after harvest, processing, handling, packing and distribution. The aim of this study was to determine ...
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The number of vegetable processing plants has been increased during recent years in Iran as many other countries. On the other hand, fresh vegetable products are susceptible to microbial contamination after harvest, processing, handling, packing and distribution. The aim of this study was to determine and evaluate the level of microbial load of vegetables during different cleaning steps in a fresh-cut vegetable processing plant and to identify the critical points in the process lines and operating areas. Samples were taken from the plant before and after washing, disinfection, cutter, drying and packaging and kept in ice pack and delivered to the laboratory. The samples were analyzed for mesophilic aerobic count, yeasts and moulds, lactic acid bacteria, total coliforms, Enterobacteriaceae, E. coli and Staphylococcus aureous as well as for the presence of Salmonella, according to the standard guideline. The amounts of total aerobic bacteria, Enterobacteriaceae, E. coli, yeasts and moulds on surfaces and air were also determined. Results showed that bacteria as well as yeasts and moulds levels were decreased after washing and disinfectation up to 1 and 1.5 log10, respectively, but after that, the microbial load was increased due to secondary contamination. During all steps, salmonella was not detected, but E. coli detected in some of the steps and S. aureous was detected at all steps. The highest levels of total aerobic bacteria, Enterobacteriaceae, E. coli, yeasts and moulds were detected on the equipments (cutters, peeling, centrifuge machines, etc.). Different Hygienic areas should be separated enough to allow maintenance of good hygiene in cleaner areas in primary washing steps. Despite this, the results showed that there is a vital need to improve cleaning and hygienic practices in vegetable processing plants. Several practical recommendations were given for cleaning, design of production lines, training of employees and surface hygiene.
Keywords: Ready to eat vegetables, Microbial evaluation, Microbial quality, Minimal processing, Hygienic level
Fereshteh Hosseini; Mohammad Bagher Habibi Najafi; Majid Hashemi; Shadi Bolourian; Fereshteh Zaman Zade
Abstract
Macaroni is one of the favorite dishes in Iranian,s family food program. In this study, effects of using different level of curcumin as a natural and functional component extracted from Curcuma Longa plant, against total count , total coliforms, psychrotrophic bacteria, yeasts and moulds and colorimetric ...
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Macaroni is one of the favorite dishes in Iranian,s family food program. In this study, effects of using different level of curcumin as a natural and functional component extracted from Curcuma Longa plant, against total count , total coliforms, psychrotrophic bacteria, yeasts and moulds and colorimetric properties of macaroni in comparison with beta carotene and turmeric as commercial color additives has been investigated. Treatments were five different level of curcumin, C1:0/005, C2:0/01, C3:0/03, C4:0/05, C5:0/07, 0/07 turmeric and 0/01 beta carotene as positive controls and sample with no color additive as a negative control. PCA, VRBA and MEA mediums were used for microbial analysis. Colorimetric properties of macaroni in two form (powdered and non powdered ) was measured with a Hunter Lab Colorimeter and the color differences were recorded as CIE-LAB L*(lightness), a* (redness–greenness) and b* (yellowness–blueness) values and the colorimetric difference (ΔE) for each sample was calculated. Results showed that there is a linear relationship between %curcumin and total count, yeasts and moulds, so with increasing curcumin level in samples, total count, yeasts and moulds were decreased. Also, samples containing curcumin in comparison with the samples containing the same percent of beta carotene were lighter, less red and have the same yellowness. In fact, using %0/03 curcumin in macaroni formulation, produces the same ΔE as %0/07 turmeric and %0/01 beta carotene in comparison with non color additive samples. Also, by increasing the amount of curcumin in formulation, macaroni were being less light, redder and more yellow.
Keywords: Macaroni, Curcumin, Antimicrobial, Hunterlab, Turmeric
Amir Salari; Mohammad Bagher Habibi Najafi; Reza Farhoosh; Seyed Hassan Marashi
Abstract
The effect of different solvent systems on the extraction of antioxidant and anti radical agents of grape seed was studied. For this purpose 6 different solvent systems with similar polarity and different selectivity were used to prepare grape seed extract. Extraction efficiency, reducing activity, radical ...
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The effect of different solvent systems on the extraction of antioxidant and anti radical agents of grape seed was studied. For this purpose 6 different solvent systems with similar polarity and different selectivity were used to prepare grape seed extract. Extraction efficiency, reducing activity, radical scavenging property and the effect of each extract on the increase of thermal resistance (oxidative stability index) of antioxidant free soybean oil were analyzed in the form of factorial test in a totally randomized design with triplicate repetition. Reducing activity test proved that grape seed extracts (GSE) had a higher reducing strength compared with BHT and α-Tocopherol except for ethylacetat treatment which had no significant difference between the extracts. Results of radical scavenging activity were similar to reducing activity results. The evaluation of oxidative stability index showed that acetone treatment has had the maximum Carry-through properties
Keywords: grape seed extract, antioxidant, antiradical, radical scavenging activity, solvent system, reducing power, oxidative stability index.
Azam Ayoubi; Mohammad Bagher Habibi Najafi; Mahdi Karimi
Abstract
In this study, physicochemical and organoleptical properties of muffin cake prepared by substitution of egg white with different levels of whey protein concentrate (WPC) and different levels of guar and xanthan gums in the furmolation were evaluated.WPC at three levels ;25 , 50 and 75 % , guar gum at ...
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In this study, physicochemical and organoleptical properties of muffin cake prepared by substitution of egg white with different levels of whey protein concentrate (WPC) and different levels of guar and xanthan gums in the furmolation were evaluated.WPC at three levels ;25 , 50 and 75 % , guar gum at two levels ; 0.1 and 0.3 % , and xanthan gum at two levels ; 0.1 and 0.15 % , were considered as variable treatments . Data analysis showed that addition of WPC, significantly affected the physicohemical and sensory properties of the samples. Moreover guar and xathan gum affected all the physicochemical and sensory properties except for the after one and two days of storage, crust colour and taste. The results of this research showed that although WPC alone was not an appropriet substitution for egg white, the application of WPC at levels of 25 and 50% along with guar (0.3%) or xanthan gum (0.15%) could be an appropriate substitution for egg white while maintaining sensory properties and improving almost all of the physicohemical characteristices of muffin cakes.
Key words: muffin cake; whey protein concentrate; guar gum; xanthan gum; physicochemical properties; organoleptical properties.
Amir Salari; Mohammad Bagher Habibi Najafi; Reza Farhoosh; Seyed Hassan Marashi
Abstract
This study has been done to survey of solvent system effect on extraction of grape seed extract and its antimicrobial properties. For this purpose, grape seed extracts were extracted with six different solvent systems. Minimum Bactericidal Concentration (MBC) of extract on six spoilage and Food-born ...
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This study has been done to survey of solvent system effect on extraction of grape seed extract and its antimicrobial properties. For this purpose, grape seed extracts were extracted with six different solvent systems. Minimum Bactericidal Concentration (MBC) of extract on six spoilage and Food-born pathogens was determined. The results indicated that MBC of different extracts have no significant difference and its value for Salmonella enteritidis, Escherichia coli, Enterobacter aerogenes was 1000 ppm. This value for S.aureus and listeria monocitogenes was 500 ppm. Results showed that gram positive bacteria were more sensitive than gram negative ones.
Fereshteh Hosseini; Mohammad Bagher Habibi Najafi; Nasser Sedaghat
Abstract
In this study, a flexible package comprises of three layers, polyethylene (100μ), aluminium foil
(9μ) and polyester (12μ) was used for packaging blackcherry preserves. All packed preserves were
kept up to three months at 4 different storage temperatures (4, 23, 35 and 40°C). Physicochemical,
microbial ...
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In this study, a flexible package comprises of three layers, polyethylene (100μ), aluminium foil
(9μ) and polyester (12μ) was used for packaging blackcherry preserves. All packed preserves were
kept up to three months at 4 different storage temperatures (4, 23, 35 and 40°C). Physicochemical,
microbial and organoleptical properties of all trials were determined monthly. As a result, the average
pH, °Bx, acidity, Fe and Pb content were 3.99, 17.49, 0.25, 3.16ppm and 387.98ppb. All
organoleptical properties of samples were acceptable. Temperature had statistically significant effect
on the physicochemical and organoleptical properties of samples. The samples stored at 4 and 23°c
were more acceptable due to their better quality. Flexible pouches have more advantages such as good
colour and constant level of heavy metal as well as low cost and..
Keywords: blackcherry, laminated flexible pouch, packaging, preserve
Nasser Sedaghat; Mohammad Bagher Habibi Najafi
Abstract
The influence of packaging system on stability during storage of raw dried pistachio nuts was studied.
The pistachio nuts were packed in plastic multilayer pouches (PS/EVOH/PE) at different conditions
(atmosphere, vacuum and oxygen scavenger). Accelerated Shelf Life Testing (ASLT) method was
used ...
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The influence of packaging system on stability during storage of raw dried pistachio nuts was studied.
The pistachio nuts were packed in plastic multilayer pouches (PS/EVOH/PE) at different conditions
(atmosphere, vacuum and oxygen scavenger). Accelerated Shelf Life Testing (ASLT) method was
used for evaluation the storage of pistachio at 20, 35 and 50 °C. Samples were analyzed at 4, 8, 12
weeks by using of split-plot design. To follow the oxidation profile, the formation of volatile oxidized
products (Hexanal) was determined by GC-MS. Results showed that the formation of hexanal under
all conditions was significant (p
Mohammad Hossein Hadad Khodaparast; Mohammad Bagher Habibi Najafi; Amir Hossein Elhami Rad; Nasim Divandari
Abstract
Abstract
In recent years several types of protein rich products derived from sesame seeds or sesame meal such as sesame milk are found in the market and have been attracted consumers both in developed and undeveloped countries mainly due to bearing health benefits. Since Iranian consumers have not yet ...
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Abstract
In recent years several types of protein rich products derived from sesame seeds or sesame meal such as sesame milk are found in the market and have been attracted consumers both in developed and undeveloped countries mainly due to bearing health benefits. Since Iranian consumers have not yet been familiar with such healthy milk analog products, the objective of this study was to introduce the best formulation of sesame milk made from dehulled sesame seeds as well as sesame meal according to Iranian preferences. In order to make a beverage which is almost equal to composition of milk, two main factors were chosen as variable namely pH(6.5, 7.5, 8.5), and time of mixing and extraction (15 to 30 min), the ratio of sesame to water was fixed at 1:6 based on literature and our previous work. The optimum combination of those factors was then determined in a complete randomized design method with a factorial experiment. The selected sesame milk trials from both sesame seeds and sesame meal were then formulated as follow: sugar (0, 5, 6, and 7 %) and vanillin (0, 40, 60, 80 ppm) and all samples were organoleptically judged on the basis of overall acceptability. The collected data were then statistically analyzed using a nine point hedonic method. The results shown that the best sesame milk formulation is the one obtained as follow: the ratio of seed to water (1:6), natural pH (6.5), 15 min mixing time, 6% sugar and 40ppm vanillin.
Key words: sesame milk, sesame seeds, sesame meal.
Seyed Mohammad Ali Razavi; Mohammad Bagher Habibi Najafi; Zahra Alaei Roozbahani
Abstract
Abstract
Halwa-Ardeh is a traditional food in Iran and Middle East countries, which is produced by crushing the dehulled sesame seeds and then mixing with a proper sweetener such as grape concentrate, date syrup, and honey. The oil content of this product is on the average of 57-65% (w/w). In this ...
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Abstract
Halwa-Ardeh is a traditional food in Iran and Middle East countries, which is produced by crushing the dehulled sesame seeds and then mixing with a proper sweetener such as grape concentrate, date syrup, and honey. The oil content of this product is on the average of 57-65% (w/w). In this research, the effect of different levels of fat substitutes including guar gum (of 0.1, 0.15 and 0.2%), Xanthan (0.01, 0.015 and 0.02%), and modified starch (0.75, 1.25 and 1.75%) on the emulsion stability and sensory characteristics (oiliness, firmness, spreadability, adhesiveness, color, mouth coating, taste, and total acceptance) of reduced fat sesame paste/date syrup blends have been investigated. The results showed that all fat replacers at each substitution level (except for 0.02% substitution of xanthan gum) increased the emulsion stability of samples in comparison with the control. In addition, the sensory evaluation by panelists showed that the effect of fat substitutes at each level of substitution on sensory properties of many samples was not significant (α=5%), but all fat replacers improved the spreadability and firmness of samples compared to the control.
Keywords: Sesame Paste; Date Syrup; Xanthan; Modified Starch; Guar; Emulsion Stability; Sensory Properties
Ashraf Gohari Ardabili; Mohammad Bagher Habibi Najafi; Mohammad Hossein Hadad Khodaparast
Abstract
Abstract
In this study the possibility of utilizing date syrup as a sugar replacer in soft ice-cream was investigated. For this purpose control sample was formulated based on Iranian ice- cream standard. Data syrup which produced from third grade Kabkab dates, replaced sucrose in four levels (25, ...
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Abstract
In this study the possibility of utilizing date syrup as a sugar replacer in soft ice-cream was investigated. For this purpose control sample was formulated based on Iranian ice- cream standard. Data syrup which produced from third grade Kabkab dates, replaced sucrose in four levels (25, 50, 75 and 100%). Physical properties including overrun, viscosity and freezing point (drawing temperature) were measured for each treatment. Sensory properties including texture, flavor, odor and total acceptance were judged using 15 panelists. Data of physical properties were analyzed as a completely randomized design in triplicate and for analyzing sensory properties completely randomized block design was used to eliminate differences of panelists. Comparison between means was done with Duncan's test at level P=0.05. Results showed that replacement affected all above properties significantly (P
