Food Engineering
Maryam Azizkhani; Rafat Karbakhsh Ravari
Abstract
The objective of this study was to improve the survival of lactic acid bacteria (LAB) in Tarhana soup as a non-dairy matrix. Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophiles were encapsulated in electrospun nanofiber mats fabricated from corn starch (CS) and sodium alginate ...
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The objective of this study was to improve the survival of lactic acid bacteria (LAB) in Tarhana soup as a non-dairy matrix. Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophiles were encapsulated in electrospun nanofiber mats fabricated from corn starch (CS) and sodium alginate (SA) and the protective effect of the nanofibers were investigated on the cells during the preparation of Tarhana and in the gastrointestinal tract. The moisture content of the control and nanofiber- loaded dried Tarhana samples was 8.75 and 8.71%, respectively; therefore, using nanofiber mats in the formulation had no significant effect
on the moisture content of the samples. A negative zeta potential value of -15.1 mV was found for LAB- loaded nanofibers. The nanofibers mats prepared from SA and CS mix showed a bead- free and clean structure with uniformity in size. The diameter size of most of the fibers ranged from 175- 338 with an average of 265 nm. Loading nanofiber mats with L. delbrueckii subsp. bulgaricus and S. thermophilus cells led to a uniform distributed beaded structure and the average diameter enhanced to approximately 763 nm. The viability of L. delbrueckii and S. thermophilus at the end of the electrospinning process was 92.82% and 95.83%, respectively, which indicating a slight loss in their population. Survival of nanoencapsulated S. thermophilus and L. delbrueckii was 93.50% and 89.16% respectively, while for free cells it was 85.3 and 76.4% that showed considerable protective effect of CS/SA fibers on the cells against dehydration of Tarhana medium. Nanofiber mats improved the stability of the cells against ordinary heat treatment used in preparing Tarhana soup. The survival rate of S. thermophilus was higher than L. delbrueckii subsp. bulgaricus and a significant difference was observed between the viability of free and nanoencapsulated bacteria. The survival of CS/SA nanoencapsulated S. thermophilus and L. delbrueckii subsp. bulgaricus was 83.25% and 80.21%, respectively, which is indicative of the significant protective effect of fibers on the cells against the heating process. The nanofibers also provided good stability for the cells in the gastrointestinal tract as 106 to 107 CFUg-1 of the cells were survived which is within the recommended level of potential probiotic dose to be effective. There was no significant difference in the color of all samples. Nanoencapsulation in CS/ SA nanofiber mats improved the protection of both LAB strains in simulated fluids of the stomach and intestine (Table 4). After continuous exposure to simulated gastrointestinal fluid, a significant loss of viable free LAB cells (higher than 4 log CFU/ml) was found while the population of S. thermophilus and L. delbrueckii subsp. bulgaricus encapsulated in CS/ SA nanofibers decreased only 0.45 and 0.37 log CFU after 120 min (p> 0.01), 0.93 and 0.80 log CFU after 180 min (p< 0.01), respectively. Tarhana soup prepared with probiotic– loaded nanofibers gained higher scores in terms of consistency, mouth feel, odor, taste, flavor, and overall acceptability attributes. Tarhana soup with nanofibers possessed much sour taste and flavor than samples prepared with free cells of probiotics. The results of the present study indicated that the protection obtained from CS/ SA capsules secured around106 to 107 CFU/g of the probiotic cells which are within the recommended level of probiotic dose to be functional in consumers’ body. Therefore, this product can be used by the consumers like vegetarians and lactose or milk peptide intolerants who do not consume dairy products but need potential fermented probiotic food.
Maryam Azizkhani; Fatemeh Adinehpour
Abstract
In order to inhibit the oxidation of lipids, improve the oxidative stability of foods and to minimize the hazard risk to human health, antioxidants are added to food materials in industrial processing. In this work, the antioxidant potential of cinnamon (Cinnamomum zeylanicum), ajowan (Carum copticum) ...
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In order to inhibit the oxidation of lipids, improve the oxidative stability of foods and to minimize the hazard risk to human health, antioxidants are added to food materials in industrial processing. In this work, the antioxidant potential of cinnamon (Cinnamomum zeylanicum), ajowan (Carum copticum) and zataria (Zataria multiflora Boiss.) essential oils (EOs) at different concentrations (0, 1 and 1.5%) on free fatty acid content (FFA), peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) of grape seed oil stored at 60ºC was evaluated. Ajowan treated samples (1.5%) showed the lowest (1.02%) and zataria treated samples (1%) expressed the highest (1.19%) FFA value among EO-treated samples. Samples treated with 1.5% cinnamon showed the lowest PV (69.5 meq O2/ kg) at the end of the storage period. Following control, the highest PV was seen in samples treated with zataria (1%). Grape seed oil samples treated with 1 and 1.5% cinnamon showed the lowest TBARS values during the whole storage period (one month). TBARS of zataria treated samples increased slightly toward the end of storage and a similar trend in TBARS was observed for samples treated with ajowan. The antioxidant activity of EOs in grape seed oil followed in descending order was cinnamon, ajowan, and zataria.
Fahimeh Tooryan; Maryam Azizkhani
Abstract
Introduction: Nowadays, consumers are applicant to usage of natural replacements causing to side effects of synthetic preservatives such as carcinogenicity and teratogenicity. The tendency to use natural preservatives and replacing them with chemical preservatives has led to various studies of natural ...
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Introduction: Nowadays, consumers are applicant to usage of natural replacements causing to side effects of synthetic preservatives such as carcinogenicity and teratogenicity. The tendency to use natural preservatives and replacing them with chemical preservatives has led to various studies of natural compounds with antioxidant properties such as essential oils. Considering the environmental problems raised from current plastic packaging, edible and biodegradable coating could be developed and also be effective in controlling the chemical and microbial properties of food; especially if their effect be strengthened by adding natural antioxidant and antimicrobial agents like herbal essential oils. Various herbal compounds such as black pepper essential oils with antioxidant properties can be effective in combining with natural biodegradable coatings such as chitosan in oxidation control and enhance the effects or prevent or delay the chemical spoil. Safety and shelf-life of foods can be improved by using this technologies such as using natural preservatives. Adding essential oil, as a suitable source of antioxidant, for improvement the quality of the fish is the main purpose. Many fruits, especially orange, are rich in polyphenols. These materials are the most commonly existing phytochemicals in most fruits. Orange juice concentrate can be a good source of antioxidant and can be employed as a preservative in food products. Omega-3 fatty acid is used in daily healthy diet and plays an important role in prevention of disease. Being a considerably main source of Omega-3 fatty acid groups, fish preservation against oil oxidation and any other similar causatives seems quite necessary. In the present study, the effects of orange juice concentrate and chitosan coating enriched with black pepper essential oil on the chemical degradation of rainbow trout fillet stored in a refrigerator investigated.
Materials and methods: The chemical composition of black pepper essential oils were determined using a gas chromatography equipped with mass spectroscopy (GC/MS). GC-MS analysis of the essential oil was performed using Agilent-Technologies 6890N Network gas chromatographic (GC) system, equipped with Agilent Technologies 5975 inert XL Mass selective detector and Agilent-Technologies 7683 B series auto injector (Agilent-Technologies, Little Falls, CA, USA). Samples were stored at 4 ± 1 C° up to 12 days and evaluated periodically ( on days 0, 4, 8 and 12) for chemical and sensory characteristics. The samples were divided into 8 groups and assessed for PH-values, total volatile nitrogen (TVN), thiobarbituric acid (TBA), peroxide value (PV), free fatty acids (FFA) and sensory evaluation .The samples were also evaluated for antioxidant activity by measuring their scavenging abilities to DPPH radical (2,2 diphenyl-1-picril hydrazyl) and RP (Reducing power). Statistical analysis was performed using SPSS 20 software.
Results & Discussion: Results showed that More than 21 compounds were identified in oil, representing 97.75% of the total oil. The major constituents of essential oils obtained from the black pepper were β-caryophyllene (25.56%), Limonene (15.19%), Sabinene(12.2) , α-copaene(8.5) and beta –bisabolene (7.81) respectively. Results revealed that in comparison to the other treatments the control showed a significant increase in the trend of oxidative and sensory indexes and In the coated samples, the sample of fish coated with orange juice concentrate ,chitosan, and black pepper essential oil was the least amount of indexes than the rest (p<0/05) and showed lower indexes during the storage time .The radical scavenging DPPH, orange juice concentrate with a Brix 1/39 (66/9 %)and pepper essential oil 2% (64/1%) have more ability and had a greater antioxidant activity. In investigating corruption oxidation and sensory evaluation in all samples,chitosan coating with pepper essential oil and orange juice concentrate was higher(score:7/2) than other treatments and there were significant differences between treatment and control (p<0/05). Final peroxide value (meq O2/Kg oil) and tiobarbituric acid (m gr/kg oil MD) number using chitosan coating with pepper essential oil and orange juice concentrate in sample was 0.14 and 0.015, respectively. This significant deference was also observed when comparing to control sample (p<0.05)Minimum oxidative changes were observed in samples treated with orange juice concentrate,chitosan, and black pepper essential oil and had the best conditions in reduction of oxidative rancidity. The results obtained in this study showed that the chitosan coating enriched with black pepper essential oil with orange juice concentrate has a good potential to being employed as an active packaging to preserve food products. Overall, this study demonstrated that using concentrated juice incorporated with chitosan coating with pepper essential oil has a good effect on the quality of rainbow trout fillets and can keep on the sensorial attributes acceptably during 12 days storage time and present a good potential for their application in the food industry.
Fahimeh Tooryan; Maryam Azizkhani
Abstract
Introduction: Lipids are valuable foods that operate as the medium of heat transfer to the food and susceptible to oxidation on storage and frying processes. Lipid oxidation is one of the major cause of food quality deterioration during storage for vegetable oils, fats and other food systems. The free ...
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Introduction: Lipids are valuable foods that operate as the medium of heat transfer to the food and susceptible to oxidation on storage and frying processes. Lipid oxidation is one of the major cause of food quality deterioration during storage for vegetable oils, fats and other food systems. The free radical are defined as any chemical species having one or more unpaired electrons is generally responsible for the deterioration and limiting the shelf life of fatty foods. Characteristic changes associated with oxidative deterioration include development of unpleasant tastes and odors as well as changes in color, specific gravity, viscosity and solubility .Moreover, the products of lipid oxidation may be potentially toxic and may lead to adverse effects such as the production of carcinogens, mutagenesis and aging. Autoxidation occurs when molecular oxygen reacts with unsaturated lipids like canola oil. Antioxidants are a group of chemicals affect the process of lipid oxidation at different stages and capable of extending the shelf life of food that contain lipids. In general, food industry have been added and applied the synthetic antioxidants such as BHA (Butylated hydroxyl anisole), BHT (Butylated hydroxyl anisole) and TBHQ (Tert-butyl hydroquinone) during the manufacturing process to retard lipid oxidation and prevent fat oxidative and rancidity. They are used to retard the development of unpleasant flavour caused by the oxidation of unsaturated fatty acids. They retard oxidation of lipids by reacting with free radicals, chelating free catalytic metals and also by acting as oxygen scavengers. However, there is concern about the safety and toxicity of synthetic antioxidants in relation to their metabolism and accumulation in body organs and tissues. Synthetic antioxidants are known among other things to cause impairment of blood clotting, lung damage and to act as tumor promoters. Consumers acceptance of synthetic antioxidants remains negative due to their perceived detrimental effect on human health like carcinogenic effects. Consequently, This has led to an increasing trend and interest in the search for effective natural antioxidant and there has been a tendency towards natural antioxidants and replace of these synthetic antioxidants with natural ones such as phenolic compounds. Finding new resources of vegetal antioxidants in order to use them in food (as an additive or alternative with artificial antioxidants) is an important research subject in the field of food science and technology.Researches on alternative natural products such as aromatic plants extract and essential oil have been extended. Phenolic compounds are defined as substances possessing a benzene ring bearing one or more hydroxyl substituents, including their functional derivatives. There are different sources of phenols such as grapes, olive oil, sorghum, beans, spices and herbs. Aromatic plants are used traditionally in various regions of Iran for their preservation and medicinal properties, in addition to enhancing the aroma and flavor of foods. Aromatic plants components that have antiradical activities were used as natural antioxidant in food and biological products. Carum copticum (C. copticum )is well known and valuable medicinal plant that is used widely in Iranian traditional medicine. In this study C. copticum ,as natural antioxidant, was added to Canola oil for improving its oxidative stability .The aim of this research was to evaluate the antioxidant properties of C. copticum extracts (aqueous and alcoholic),and its antioxidant activity in canola oil
Materials and methods: In this study, aqueous and alcoholic extract of C. copticum fruit was extracted as a natural antioxidant. In the first stage, the amount of phenolic compounds content in extracts were measured. Then to determine antioxidant power and activity of extracts the two methods was investigated, DPPH◦ free radical scavenging and β-carotene/linoleic acid system. Each extract at three concentrations of 200 ppm ,400ppm and 600ppm added to canola oil and storage in a period of 49 days. BHT were added to Canola oil at 100 and 200ppm. Also their oxidative stability in canola oil was investigated by measuring peroxide and thiobarbituric acid values.
Results & discussion: The results showed that, C. copticum has good total phenolic content and in β-caroten bleaching assay, by concentration of 2 mg/ml BHT showed the highest inhibition effect (%96 ± 0.09) and followed CE (%76±0.0). In DPPH◦ free radical scavenging and β-carotene/linoleic acid systems, the sequence of the power of antioxidant activity was BHT then CE in concentration of 400 and 600 ppm. In oven test, all extracts inhibited primary and secondary oxidation products of canola oil. Statistical results revealed that CE in concentration of 600 ppm, did not showed significant difference for PV and TBARS comparing with 200 ppm BHT(p>0.05). But CA and CM had lower antioxidant activity in comparision with 200 ppm BHT (p<0.05). Acocording to results, C. copticum is a potent antioxidant for stabilization of canola oil and can be used as a natural antioxidant. It seems that after complementary test because of appropriate antioxidant activity, C. copticum can be used as natural antioxidant in foodstuff, especially in edible oils to improve the oxidative stability of canola oil.
Fahimeh Tooryan; Maryam Azizkhani
Abstract
Introduction: There have been great efforts to find safe and potent natural antioxidants from various plant sources. There is, at present, increasing interest both in the industry and scientific research for spices and aromatic herbs because of their strong antioxidant and antimicrobial properties, which ...
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Introduction: There have been great efforts to find safe and potent natural antioxidants from various plant sources. There is, at present, increasing interest both in the industry and scientific research for spices and aromatic herbs because of their strong antioxidant and antimicrobial properties, which exceed many currently used natural and synthetic antioxidants. Medicinal plants are complex natural mixtures which contain compounds at quite different concentrations, have antioxidant activities These properties are due to many substances, including some vitamins, flavonoids, terpenoids, carotenoids, phytoestrogens, minerals, etc. and render spices and some herbs or their antioxidant components as preservative agents in food and they were proposed as potential substitutes of synthetic antioxidants in food stuff. The number of contributions to isolation methods, techniques and activity testing of plant-origin antioxidants has significantly increased in recent years. Antioxidants are also widely used as additives in fats and oils and in food processing to prevent or delay spoilage of foods regarding to the harmful effects of synthetic preservatives on consumers’ health, there is an increasing attention, both in food industry and authorities, to medicinal and aromatic plants as natural preservatives in food products. Oxidation is one of the major causes of chemical spoilage, resulting in rancidity and deterioration of the nutritional quality, colour, flavour, texture and safety of foods .Oxidation occurrence in cheese especially full-fat types causes rancid odor and taste and loss of nutritional quality. The objectives of the present study were evaluation of aerial parts of basil (Ocimum basilicum) and clary sage (Salvia sclarea) essential oils (EOs), study their antioxidant effect on the lipid oxidation and sensorial acceptability when applied to Iranian white cheese.
Materials and methods: Investigations were carried out to assess the efficiency of two plant essential oils; clary sage and basil as natural food preservatives. In this study, the antioxidant effect of clary sage (Salvia sclarea) and basil (Ocimum basilicum) essential oils in Iranian white cheese shelf-life, at 26 ° C for 39 and 4 ° C for 90 days, were examined. Samples at three levels 0.5%, 0.75%, 1% (w/v) were treated, negative control cheese without antioxidant and positive control sample with synthetic antioxidant (BHT) 0.05% were selected. The Essential oils chemical composition were determined by gas chromatography equipped with mass spectroscopy (GC/MS). GC-MS analysis of the essential oil was performed using Agilent-Technologies 6890N Network gas chromatographic (GC) system, equipped with Agilent Technologies 5975 inert XL Mass selective detector and Agilent-Technologies 7683B series auto injector (Agilent- Technologies, Little Falls, CA, USA). The antioxidant capacity of the essential oils were assessed by measuring their scavenging abilities to 2,2 diphenyl-1-picrylhydrazyl stable radicals using DPPH method and anti-oxidative stability with peroxide value (PV) and thiobarbituric acid (TBARS) test were evaluated.
Results & discussion: Main components of clary sage EO included linalyl acetate, linalool, α-terpineol and α-pinene and the major aroma constituents of basil EO consisted of linalool and α-cadinol, eugenol ,α –Bergamotene and 1,8- Cineole. Linalyl acetate and linalool (oxygenated monoterpenes) showed stronger antioxidant activities than did the other components tested in the assays. Maximum free radical scavenging activity for clary sage and basil EOs at 1% concentration was 84.66% and 72.72% respectively that was weaker than (BHT) free radical scavenging activity (95%) by DPPH test. At 1% concentration, clary sage and basil EOs were most effective treatment at 4 and 26 C°, in free radical scavenging activity comparing to other concentrations. At 4 C° there is no any difference between all treatments up to 30th days in PV and TBARS number. The most effective treatment against lipid oxidation was at 0.75, 1% concentration basil and 1% saliva EOs at 90th days observed. Finally it seems that Basil EO was more effective than clary sage EO at both 0.75 and 1% concentration. At 1% concentration of basil EO according at 90th day storage time not observed significant difference in peroxide value and tio barbituric acid number comparing to first day. At 26 C° highest antioxidant activity was obtained at 1% concentration of basil EO. Final peroxide value (meq O2/Kg oil) and tio barbituric acid (m mol/gr oil MD) number using basil and saliva EOs was 1.379, 0.0680 and 1.817, 0.096 respectively. That significant deference was observed comparing to control sample (p
Maryam Azizkhani; Fahimeh Tooryan; Maryam Boreiry
Abstract
Introduction: Mold growth on cheese is a common problem for cheese manufacturers during ripening and curing, as well as for the retailer and consumer during refrigerated storage. Listeria monocytogenes has gained increasing attention as a pathogen of public health importance owing to large numbers of ...
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Introduction: Mold growth on cheese is a common problem for cheese manufacturers during ripening and curing, as well as for the retailer and consumer during refrigerated storage. Listeria monocytogenes has gained increasing attention as a pathogen of public health importance owing to large numbers of foodborne outbreaks of listeriosis. Ingested by mouth, Listeria is among the most virulent of foodborne pathogens with up to 20% of clinical infections resulting in death. Various types of foods, mostly dairy products such as cheese, have been associated with these outbreaks and there is considerable interest in stopping this upward trend. As a result of the negative consumer perception of chemical preservatives, attention is shifting towards natural alternatives. A technique that has been used since ancient times to prevent fungal growth on foods such as cheese involves physically rubbing the product with certain herbs or spices or their oils. Therefore, regarding to the harmful effects of synthetic preservatives on consumers’ health, there is an increasing attention, both in food industry and authorities, to medicinal and aromatic plants as natural preservatives in food products. In this research, the effect of salvia and basil essential oils (EOs) on Listeria monocytogenes and Aspergillus flavus in Iranian white cheese has been investigated. Materials and method: Commercially available EOs from basil and salvia were used in this study (Pranarôm International, Ghislenghien, Belgium). EOs were analyzed by gas chromatography mass spectrometry (GC-MS). A broth microdilution assay was employed to determine the lowest concentration (MIC) in which visible growth of the bacterium is inhibited. The concentration of EO present in those wells that yielded plates with no visible colonies was considered to be the minimum bactericidal concentration (MBC). The effects of EOs on radial growth of fungal mycelium were assayed using an agar dilution method. The lowest concentration which inhibited the growth of the fungus was considered to be the minimum inhibitory concentration (MIC) whereas the lowest concentration of EO which killed the fungus (no growth observed on fresh medium) was taken to be minimum fungicidal concentration (MFC). Iranian ultra-filtered white cheese was produced in a commercial factory with different concentrations of EOs and the effects of EOs on bacterial and fungal growth in cheese during shelf-life were determined. Also, eight trained panellists performed sensory analyses. The panellists scored for colour, odour, flavour, overall acceptability and texture using a 9-point hedonic scale (1, dislike extremely to 9, like extremely).Results and Discussion: Main components of salvia EO included linalyl acetate and linalool and of basil EO consisted of linalool and α-cadinol. The MIC and MBC of salvia were obtained %0.015 and %0.02 and of basil %0.05 and %0.06, respectively, against L. monocytogenes. In the current report, L. monocytogenes was neither eliminated nor completely inhibited by basil EO, but salvia EO was able to inhibit its proliferation in cheese. The effect was even more pronounced with 1% salvia oil compared to 0.5% or 0.75%. Basil EO at a concentration of 1% caused a 7-day delay in the growth of L. monocytogenes. A growth delay of this type is particularly useful in terms of food safety for the short-term storage of products but not on prolonged storage as Listeria may reach high levels in foods over longer periods. MIC and MFC of salvia were %0.5 and %0.65, and of basil % 0.6 and %0.8, respectively, against A. flavus. At %0.35 and %0.5 the sporulation was inhibited by salvia and basil EOs, respectively. In the present study, no growth of A. flavus was observed in the presence of 1% of salvia EO, and colony diameter attained less than 5mm by the 21st day of cold storage in cheese samples treated with 1% basil EO. Also, the bacterial growth reduced up to 6 log cfu/g of cheese. EO of basil showed weaker antimicrobial effect compared to salvia EO. Cheese samples with different concentrations of EOs were evaluated and compared to the control sample to ascertain consumer acceptability for it. Significant differences were detected among samples containing EOs and the control sample in odour, color and texture, but the samples containing 0.75% and 1% of salvia EO were significantly impaired in both odour and taste as compared with the other samples. With regard to the overall acceptability, the cheese sample containing 0.75% of basil EO was the highest acceptable sample. Generally, it is well known that in complex systems such as cheese, several ingredients interact with each other and affect the sensory properties.In conclusion, the EO of salvia showed the greatest effect on limiting microbial growth. Both EOs could have potential for commercial use in improving the preservation of these products without the need for propionates or other synthetic additives. Further research could examine the utility of the combined application of basil and salvia EOs in different dairy products such as different types of cheese, as well as the use of different quantities/ratios for optimization of their antimicrobial effects.
