Food Biotechnology
Hossein Zanganeh; Fakhri Shahidi; Seyed Ali Mortazavi; Behrooz Alizadeh Behbahani
Abstract
IntroductionOxidation reactions and microorganisms’ activity are considered as the most important factors affecting the quality of food products. Recently, in the light of the inefficiency of some chemical preservatives against microorganisms and the presence of toxic residues in food products, ...
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IntroductionOxidation reactions and microorganisms’ activity are considered as the most important factors affecting the quality of food products. Recently, in the light of the inefficiency of some chemical preservatives against microorganisms and the presence of toxic residues in food products, the use of natural antimicrobials and antioxidants has been increased. Natural antimicrobial compounds have the potential to control microbial contamination and reduce the use of antibiotics. Plant essential oils are natural compounds with the potential to be used as active ingredients in the food, pharmaceutical, and cosmetic industries. Various studies have shown that essential oils have antifungal, antibacterial, antiviral, and antioxidant activity. The essential oils are considered as superb preservatives with various biological functions. Essential oils are generally recognized as safe product (GRAS) which can be used as an alternative to synthetic additives.Grapefruit (Citrus paradisi) peel and fruit contain active ingredients such as acids, flavonoids, vitamin C, and potassium, and its essential oil is composed of terpenic hydrocarbons, such as citral, limonene, citronelal, and geraniol. Although plant essential oils have antimicrobial and antioxidant properties, one of the main problems of these natural compounds is their high volatility and instability. In this context, nanoemulsion formulations are frequently used to increase the stability and efficiency of these biologically active compounds. This study is therefore aimed to nanoemulsifying the grapefruit essential oil and evaluate its antioxidant and antimicrobial properties. Materials and Methodsβ-carotene, linoleic acid, ABTS (2,2’-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt), and DPPH (2,2-diphenly-1-picrylhydrazyl) were purchased from Sigma-Aldrich Co. (USA). Mueller Hinton Broth (MHB) and Mueller Hinton Agar (MHA) were supplied from Merck Co. (Darmstadt, Germany). Grapefruit peel was dried at ambient temperature and then powdered. The obtained powder was then transferred to a Clevenger device containing 750 ml of distilled water to perform the distillation extraction (3 h). The resulting grapefruit essential oil was stored at 4 °C until use. Grapefruit essential oil was prepared using the hydrodistillation method, and then nanoemulsified. The antioxidant activity of the nanoemulsified essential oil was investigated by DPPH and ABTS radical scavenging activity and beta-carotene/linoleic bleaching test. The nanoemulsified essential oil or methanolic (control) was mixed with DPPH solution and the mixture was then stored at ambient temperature for 30 min, in a dark place. The control sample was prepared by methanol. The absorbance of the samples was measured at 517 nm. To determine the ABTS-RS activity, the nanoemulsified essential oil was briefly charged with methanolic ABTS radical cation solution and the resulting mixture was left at room temperature for 30 min. Afterward, the absorbance was read at 734 nm. A spectrophotometric method was applied to monitor β-carotene/linoleate solution bleaching in the presence of the nanoemulsified essential oil. To do this, the absorbance of the solution was recorded at 490 nm after 120 min against the control sample at time zero and after 120 min. Antibacterial effect of the grapefruit essential oil nanoemulsion was also evaluated against Escherichia coli ATCC 25922, Salmonella typhi ATCC 6539, Pseudomonas aeruginosa ATCC 27853, Listeria innocua ATCC 33090, Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 14579, Bacillus subtilis ATCC 23857, Streptococcus pyogenes ATCC 19615, and Staphylococcus epidermidis ATCC 12228, based on disk diffusion agar, well diffusion agar, minimum inhibitory concentration, and minimum bactericidal concentration. Results and DiscussionsThe results showed that the nanoemulsion of grapefruit essential oil had a remarkable antioxidant effect of 42.27 mg/ml, 33.27 mg/ml and 54.54%, respectively, based on DPPH, ABTS, and beta-carotene-linoleic acid bleaching tests. According to disk diffusion agar and well diffusion agar results, the lowest inhibition zone was related to E. coli and the highest inhibition zone was observed in L. innocua. The minimum inhibitory concentration for L. innocua and S. aureus (the most sensitive bacteria) was 25 mg/ml, and E. coli, S. typhi, and P. aeruginosa had the highest inhibitory concentration. Also, the lowest bactericidal concentration was related to L. innocua and S. aureus bacteria and the highest concentration was observed for E. coli, S. typhi and P. aeruginosa. The nanoemulsified essential oil generally exhibited greater antibacterial activity against Gram-positive species. This could be mainly due to the difference in the cell wall composition of Gram-positive bacteria in comparison to Gram-negative; Gram-positive bacteria have a thicker mucopeptide layer in their cell wall, while Gram-negative bacteria have only a thin layer of mucopeptide and the wall structure is mainly composed of lipoprotein and lipopolysaccharide, thereby leading to a higher resistant to antibacterial agents According to the results, grapefruit essential oil nanoemulsion can be used as a natural antioxidant and antimicrobial agent to control oxidation reactions and the growth of spoilage and pathogenic microorganisms.
Food Biotechnology
Ehsan Safari; Hassan Barzegar; Hossein Jooyandeh; Behrooz Alizadeh Behbahani; Mohammad Noshad
Abstract
Introduction The addition of chemical preservatives increases the shelf life of food products, but prolonged and indiscriminate use of chemical preservatives increases the resistance of microorganisms and the health risks associated with theiruptake. Medicinal plants have a wide variety in the world ...
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Introduction The addition of chemical preservatives increases the shelf life of food products, but prolonged and indiscriminate use of chemical preservatives increases the resistance of microorganisms and the health risks associated with theiruptake. Medicinal plants have a wide variety in the world as well as in Iran. In recent years, the use of natural preservatives such as plant extracts and essential oils, due to their importance and role in controlling the growth of pathogenic microorganisms, has been proposed as an alternative to chemical preservatives. Black pepper is an aromatic medicinal plant. The specific properties of black pepper essential oil, such as its antimicrobial and antioxidant activity, have also been confirmed. Amphotericin B is one of the effective antibiotics for treating infections caused by pathogenic fungi. The mechanism of action of amphotericin B is to destroy fungal cells in such a way that by binding to ergosterol in the cell membrane of fungi, it creates pores and eventually destroys them. One of the most important and common antibiotics used in the treatment of infections caused by pathogenic bacteria is chloramphenicol. This antibiotic is effective against gram-positive and gram-negative bacteria due to its broad spectrum. The aim of this study was to identify bioactive functional groups, antioxidant potential, phenol and total flavonoid compounds and to evaluate the antimicrobial activity of black pepper extract against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus coagulans and Aspergillus niger.Materials and Methods In this study, the antimicrobial effect of black pepper aqueous extract was investigated against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus coagulans and Aspergillus niger by disc diffusion agar, well diffusion agar, minimum inhibitory concentration, and minimum bactericidal concentration methods. Total phenol and flavonoid contents of the species were determined by Folin-Ciocalteu and AlCl3 assays, respectively. Three biochemical assays, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis 3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) free radical scavenging and β- caroten/linoleic acid activity systems, were used to evaluate antioxidant activity. Identification of functional groups as well as the structure of organic compounds in black pepper extract was also performed by Fourier transform infrared spectroscopy (FTIR). To evaluate the synergistic effect of black pepper extract in combination with amphotericin B and chloramphenicol antibiotics, Sub-MIC was used. Results and Discussion The peaks observed in aqueous black pepper extract confirmed the presence of O-H (3000-3500 cm-1), C-H (2800-3000 cm-1), C=O (1613.62-1633.52 cm-1) and C-O (100.57-1038.82 cm-1) functional groups of bioactive compounds. The total phenol and flavonoids content of the extract were 45.12 mg GAE/g extract and its flavonoid content was 29.66 mg QUE/g extract which had an important role in its antioxidant activity. The aqueous black pepper extract had remarkable DPPH free radical scavenging activity (IC50=32.37 μg/ml), ABTS free radical scavenging activity (IC50=28.45 μg/ml) and beta-carotene bleaching inhibitory effect (46.45%), revealing the electron/hydrogen donating ability of the essential oil. The results of measuring the antimicrobial activity of extract by disk diffusion and agar well showed that black pepper extract showed more antimicrobial effect on gram-positive bacteria Staphylococcus aureus and Bacillus coagulans than gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. This could be due to the difference in their cell wall structure. Aspergillus niger is the most sensitive species to aqueous black pepper extract. The minimum inhibitory concentrations of extract for Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus coagulans and Aspergillus niger were equal to 32, 16, 4, 8 and 4 mg/ml, respectively. The minimum bactericidal concentration of black pepper extract for two bacterial species, Escherichia coli and Pseudomonas aeruginosa was more than 512 mg/ml. Also, the minimum bactericidal concentration for Staphylococcus aureus and Bacillus coagulans was 128 and 256 mg/ml, respectively, and 128 mg/ml for Aspergillus niger. The results of interaction of black pepper extract with chloramphenicol antibiotic showed that the Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were synergistic, but antagonism was observed for the gram-positive Bacillus coagulans.
Food Biotechnology
Sahar Roshanak; Behrooz Alizadeh Behbahani; Fakhri Shahidi; Farideh Tabatabaei Yazdi; Alireza Vasiee; Neda Norouzi
Abstract
In this research, the chlorophyll content, total flavonoid content (TFC), total phenolic content (TPC) and antioxidant activity of aqueous extract of Dandelion was determined. In addition, the effect of aqueous extract of Dandelion, obtained by maceration, was tested on various food borne and food spoilage ...
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In this research, the chlorophyll content, total flavonoid content (TFC), total phenolic content (TPC) and antioxidant activity of aqueous extract of Dandelion was determined. In addition, the effect of aqueous extract of Dandelion, obtained by maceration, was tested on various food borne and food spoilage microorganisms. Antimicrobial activity of leaf extract of Dandelion was investigated using disk agar diffusion, well agar diffusion, minimum inhibitory concentration and minimum bactericidal/fungicidal concentration methods. The values obtained for TFC, TPC, chlorophyll a and b were 22.82 (µg/mL), 116.89 (mg/mL), 0.081 (mg/l) and, 0.063 (mg/l), respectively. The result of the radical scavenging activity was IC50= 68.81µl/mL. The results showed that MIC of leaf extract of Dandelion on Aspergillus niger, Salmonella typhimurium, Bacillus subtilis and Staphylococcus epidermidis was 512, 256, 256 and 64 mg/ml respectively. MBC for Aspergillus niger was more than 512, for Salmonella typhimurium, and Bacillus subtilis was 512, and for Staphylococcus epidermidis was 128mg/ml. In addition, the diameter of inhibitory growth zone in well diffusion method was more than disk diffusion. Generally, it can be stated that the aqueous leaf extract of Dandelion on Gram-positive bacteria showed more antimicrobial activity than Gram-negative bacteria, while there is no significant inhibition on mold. Based on the results of this study, Dandelion aqueous extract might be used as a natural agent to prevent the growth of food borne microorganisms, particularly, that cause food poisoning that leading to the reduction of gastroenteritis risk.
Mohammad Hojjati; Behrooz Alizadeh Behbahani
Abstract
Introduction: There is a remarkable interest in developing natural antimicrobial compounds of essential oils and plant extracts origin, due to the increase of bacterial resistance to common antibiotics. On the other hand, lipid oxidation in raw or processed materials leads to food rancidity and deterioration. ...
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Introduction: There is a remarkable interest in developing natural antimicrobial compounds of essential oils and plant extracts origin, due to the increase of bacterial resistance to common antibiotics. On the other hand, lipid oxidation in raw or processed materials leads to food rancidity and deterioration. In this way, synthetic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) are used to prolong the storage stability of food products. Nevertheless, the toxicologists and nutritionists have documented the side effects and potential toxic effects of synthetic antioxidants. Herbs contain a wide variety of phenolic compounds such as phenolic acids, flavonoid, tannins and so forth. These bioactive compounds could be therefore used as natural antioxidants and antimicrobial agents to suppress lipid oxidation and food spoilage. In this context, Allium jesdianum extracts were obtained and their antioxidant and antimicrobial activities were investigated. Materials and methods: A. jesdianum was exposed to methanolic and aqueous maceration-based extraction methods to extract its bioactive compounds with positive biological activity. The extraction yield, total phenolic compounds, antioxidant activity (based on DPPH and ABTS radical scavenging activity), and antimicrobial activity (based on disc diffusion agar, minimum inhibitory concentration, and minimum bactericidal concentration methods) of the methanolic and aqueous extracts were evaluated and compared to each otherr. Results and discussion: The methanolic extract of A. jesdianum had higher extraction yield of 7.1±0.2% compared to the aqueous extract with 4.6±0.28% extraction yield, mainly due to the ability of methanol to extract both nonpolar and semi-polar compounds. The total phenolic compounds of the methanolic extract were also remarkably higher than the aqueous counterpart (88.28% vs. 68.29% mg gallic acid/g dried extract), indicating that the solvent type plays a significant role in extracting bioactive compounds. However, the aqueous extract was able to significantly scavenge DPPH and ABTS radicals compared to the methanolic extract. This means that the presence of phenolic compounds is not the only factor affecting the antioxidant activity of plant extracts. The bioactive extracts of A. jesdianum were able to suppress the growth of or kill the examined bacteria P. aeruginosa, E. coli, E. aerogenes, L. innocua, and S. pyogenes; and this effect was more pronounced in the methanolic extract. Therefore, A. jesdianum methanolic and aqueous extracts could be used as natural preservatives to improve the oxidative stability of food products rich in unsaturated fatty acids, and to inhibit the growth of spoilage and pathogenic microorganisms, treat infections, and increase the safety of food products.
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.
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.
Firooze Bazrafkan; Soheila Zarringhalami; Ali Ganjloo
Abstract
Introduction: In recent years special attention has been paid to the use of natural sources contain healthy bioactive compounds. Fruit and vegetable juices are a good source of many biologically active compounds, particularly vitamins, minerals and phenols. Phenolic compounds are secondary metabolites ...
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Introduction: In recent years special attention has been paid to the use of natural sources contain healthy bioactive compounds. Fruit and vegetable juices are a good source of many biologically active compounds, particularly vitamins, minerals and phenols. Phenolic compounds are secondary metabolites widely found in fruits, mostly represented by flavonoids and phenolic acids. Phenols are known for their antioxidant, anticancer and cardio-protective properties among bioactive compounds. The health benefits of these phytochemicals are directly linked to a regular intake and their bioavailability. Berries with dark blue or red colors have the highest bioactive compounds and antioxidant capacities among all common fruits and vegetables. Anthocyanins which are one of the largest and most important group of water-soluble pigments in most species in the plant kingdom are largely responsible for diverse pigmentation from orange to red, purple and blue fruits, such as: blackberry, red and black raspberries, blueberries, bilberries. White mahlab (Prunus mahaleb L.) fruits with a dark red color, which known also as English cherry, Rock cherry, St. Lucie cherry, of the Rosaceae family, subfamily Prunoidae, is a deciduous tree with 1–2 m high. Mahaleb cherry tree which grows abundantly in West Asia such as in Iran used just as basic link for cherry trees because of bitter taste of their fruits. In order to reduce the bitterness and improve the taste of mahaleb juice, a debittering process is considered as an effective solution to overcome the commercial application problem. Several debittering techniques have been used to reduce the content of bitter compounds, such as biodegradation by enzymes, addition of bitterness suppressing agents, ultrafiltration.
Material and Methods: All chemicals used were analytical grade and purchased from Merck (Darmstadt, Germany) and Sigma-Aldrich (St. Louis, MO. USA).
Selected microorganisms including Staphylococcus aureus (PTCC: 1112), Escherichia coli (PTCC: 1338), Aspergillus flavus (PTCC: 5004) and Penicillium chrysogenum (PTCC: 5037) were obtained from the Iranian Research Organization for Science and Technology (IROST), Iran.
The ripened fruits of mahaleb were collected from the orchard of Zanjan University, and transported to the laboratory. Harvest involved a random sampling from 5 trees. Stem and leaves were then discarded, and fruits stored at -18 ℃ until further use.
Frozen fruits were removed from the freezer, thawed and pitted. The fruit juice was obtained using a domestic juicer (Moulinex PC302, France). The juice was filtered through a stainless steel sieve (1 mm) to separate pomace from juice. The juice obtained was placed in dark glass bottles until further analysis.
Vitamin C content was determined using spectrophotometric method. Total phenolic content of the fruit juice was determined using Folin–Ciocalteu’s assay. Total flavonoid and anthocyanin contents of the fruit juice were determined according to the colorimetric assay at 510 and 526 nm, respectively. Antioxidant activity was determined using Diphenyl Picrylhydrazyl (DPPH) free radical scavenging and reducing power of H2O2 methods.
Antimicrobial activity of mahaleb juice against E. coli, Staphylococcus aureus, Aspergillus flavus and Penicillium chrysogenum was evaluated using agar well diffusion, and minimum inhibitory concentration and minimum bactericidal concentration was determined using broth microdilution and surface methods.
Results and Discussion: According to the result obtained, vitamin C, total phenolic, total flavonoid, total anthocyanin content was 39.26±0.01 mg/100 mL, 303.00±0.06 mg GAE/100 mL, 17.00±0.01 mg Rutin/mL and 871.63±0.93 mg Cyanidin/100 mL, respectively. Free radical scavenging activity and reducing power of H2O2 was 72.30% and 6.33%, respectively. Based on these results the white mahaleb juice had bioactive compounds such as other fruits with blue and purple color. According to other researchers there was a higher positive correlation between the amounts of carotenoids, total phenolics and anthocyanins and the antioxidant activity. Of course, it should be noted that several factors such as the plant growth region and the harvest period might have an impact on plant growth and metabolite concentration. Some studies also showed that dark red sour cherries contain higher total phenolic and total anthocyanin content compared to sour cherries with lighter red color. Therefore, mahaleb juice which was used in the current research with dark blue color and high total phenolic and anthocyanin content have high antioxidant activity.
The results also revealed that mahaleb juice had no inhibitory effect on Aspergillus flavus and Penicillium chrysogenum whereas the minimum inhibitory concentration on 102 CFU/ml of E. coli and Staphylococcus aureus was obtained at 0.9 and 0.8 % concertation of mahaleb juice. In addition, no minimum bactericidal concentration was observed. So, mahaleb juice likely has no or little antifungal activity compared to antibacterial effects. Previous studies also showed that antimicrobial activity of many extracts related to their phenolic compounds and anthocyanins. Blueberry methanol extract was shown strongly inhibit the pathogenic bacteria, such as E. coli O157:H7. The antimicrobial properties of blueberry morelikely is due to the compounds of monomeric phenolics, anthocyanins and proanthocyanidins. Therefore, mahaleb juice as a source of natural bioactive compounds such as vitamin C, phenols, carotenoids and anthocyanins is recommended as functional food in industry, especially, after debittering.
Vahid Alizade; Hassan Barzegar; Behzad Nasehi; Vahid Samavati
Abstract
Introduction: The environmental effect of synthetic plastic wastes is of increasing global concern. There is an urgent need to develop and apply renewable biopolymer materials. Development of edible and biodegradable films can help solving the waste disposal problem by partially replacing synthetic plastics ...
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Introduction: The environmental effect of synthetic plastic wastes is of increasing global concern. There is an urgent need to develop and apply renewable biopolymer materials. Development of edible and biodegradable films can help solving the waste disposal problem by partially replacing synthetic plastics (Martins et al., 2012). Chitosan; a linear polysaccharide composed of (1, 4)-linked 2-amino-deoxy-b-d-glucan, is a deacetylated (to varying degrees) product of chitin, which is the second most abundant polymer found in nature after cellulose. It has been proved to be biodegradable, biofunctional, biocompatible, nontoxic and have strong antifungal and antimicrobial properties (Aider, 2010). Thus, this work was undertaken to investigate the physical, optical, barrier, mechanical, microstructural, and antimicrobial properties of chitosan films incorporated with PEO, to examine its potential applications as a packaging material.
Materials & method: The films were prepared according to the solvent casting technique reported by (Abdollahi et al., 2012) with some modifications. Tensile strenght (TS) and elongation at break (E) of the films were measured with texture analyzer according to Barzegar et al. (2014) method. Equilibrated film strips (at 53% RH for 48 h) were fixed between the grips with an initial separation of 50 mm and the cross-head speed was set at 50 mm/min. TS was calculated by dividing the maximum force by the initial area of the film and E% was calculated through dividing the extension at the moment of specimen rupture by the initial gauge length and multiplying by 100. The WVP of the films was determined at according to the Shojaee-Aliabadi et al. (2013). The test cups containing anhydrous calcium chloride (0% RH) were sealed by the test films, then were placed inside a desiccator containing sodium-chloride-saturated solution (75% RH). Weight gain of the cups along time were recorded periodically and plotted as a function of time. Antimicrobial properties of the films were assessed using the disc-diffusion method according to Dashipour et al. (2015). Four gram-positive or gram-negative bacteria, including B. cereus, S. aureus, E. coli and S. typhimurium were used for testing.
Results and discussions: The influence of PEO incorporation on thickness, TS, EAB, WVP and water solubility of films can be seen in Table 1. The incorporation of PEO into the film-forming dispersion led to an increase in the thickness of the films, which varied between 0.131 mm and 0.185 mm. It could be due to the entrapment of PEO micro droplets by the polymer matrix (Dashipour et al. 2015). By increasing PEO concentration from 0.5 to 2 % in the film solutions, WS decreased markedly from 22.46 to 16.15 (P < 0.05). This behavior can be explained by the cross-linking effects of PEO components to esters and/or amide groups. Cross-linking in the chitosan film leads to a polymer with lower water solubility, which is useful when product integrity and water resistance are intended (Hosseini et al., 2009).
Table 1. Physical and mechanical properties of chitosan films.
PEO (% v/v) Thickness (mm)
Solubility in water (%) WVP
(g s-1 m-1 Pa-1 × 10-10) TS
(MPa) EAB
(%)
0.0 0.131 ± 0.01d 22.46 ± 0.73a 1.04 ± 0.05c 21.22 ± 1.97a 49.05 ± 1.63c
0.5 0.153± 0.01c 21.19 ± 1.22a 1.12 ± 0.06c 20.09 ± 1.40a 50.36 ± 2.98c
1 0.167 ± 0.01b 18.47 ± 0.53b 1.35 ± 0.09b 17.04 ± 1.26b 55.25 ± 2.95b
2 0.185 ± 0.01a 16.15 ± 0.54c 1.73 ± 0.09a 13.23 ± 1.35c 59.37 ± 2.49a
The incorporation of PEO into chitosan-based films leads to an increase in WVP values from 1.04 to 1.73 g s-1 m-1 Pa-1 × 10-10. A similar trend has been found by Bonilla et al., (2011) in chitosan-based films incorporated with thyme essential oil. The structural discontinuities induced in the polymer network by the addition of PEO could be the reason for the lowest resistance to breakage of the emulsified films. These discontinuities greatly reduced the film cohesion and mechanical resistance (Bonilla et al., 2012). Conversely, the EAB value of the films increased significantly (P < 0.05) from 49.05% to 59.37%, because the essential oil acted as a plasticizer even at small concentrations and enhanced the flexibility of the polymer chains.
The effects of PEO on the antimicrobial properties of the chitosan films are shown in Table 2. The films containing 1% PEO showed a certain inhibitory effect against B. cereus and S. aureus but no inhibition against S. typhimurium and E. coli. As the concentration of PEO increased, the zone of inhibition also increased significantly (P < 0.05). The films containing 2% PEO were effective against all studied bacteria and a greater inhibitory power was observed on S. aureus with the zone area of 49.67 mm2. The inhibitory effect of PEO is due to the two monoterpene hydrocarbons, α-pinene, and β-pinene (Barrero et al., 2005).
Table2. Antimicrobial activity of chitosan films.
PEO (% v/v) Inhibition zone (mm2)
S. aureus B. cereus E. coli S. typhimurium
0.0 0.00c 0.00c 0.00b 0.00b
0.5 0.00c 0.00c 0.00b 0.00b
1 22.58 ± 1.76b 15.63 ± 0.63b 0.00b 0.00b
2 49.67 ± 3.02a 41.96 ± 1.40a 21.12 ± 1.87a 12.49 ± 1.57a
Conclusion: The results obtained in this study showed that the chitosan films incorporated with PEO has a good potential to being empolyed as an active film to preserve food products. Addition of PEO decreased water solubility and tensile strength, while increased the thickness, WVP and percent elongation of the films. Overall, this study demonstrates that PEO-containing films present a good potential for their application in the food industry.
Azadeh Ranjbar Nedamani; Elham Ranjbar Nedamani
Abstract
The aim of this work was to study the antimicrobial activity of tomato skin lycopene oleoresin against Pseudomonas aeruginosa، Escherichia coli، Staphylococcus ureuse، Salmonella typh ، L. monocytogenes ، Bacillus cereus، Bacillus licheniformis. Oleoresin was extracted from tomato peel. Lycopene ...
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The aim of this work was to study the antimicrobial activity of tomato skin lycopene oleoresin against Pseudomonas aeruginosa، Escherichia coli، Staphylococcus ureuse، Salmonella typh ، L. monocytogenes ، Bacillus cereus، Bacillus licheniformis. Oleoresin was extracted from tomato peel. Lycopene content was measured by spectrophotometer. Lycopene oleoresin contained 2321mg lycopene/ 100 g oleoresin diluted in serial micro-dilution technique from 40,000 to 78.125 ppm. Microbial culturing was done in ELISA 96-well micro-titer plates in triplet and then MIC and MBC were determined. The results were shown that tomato peel oleoresin contained 2% lycopene, can inhibit and restrain the gram positive and negative bacteria.
Vida Mardani Ghahfarokhi; Mehran Alami; Saeedeh Arabshahi- Delouee; Alireza Sadeghi Mahoonak
Abstract
In this study, phenolic compounds of evening primrose leaves (Oenothera biennis) were extracted with aceton 70%, ethanol 70% and methanol 70%. Total phenolic content of aceton extract was significantly higher than the ethanolic and methanolic extracts. Extracts were tested for their antimicrobial activity ...
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In this study, phenolic compounds of evening primrose leaves (Oenothera biennis) were extracted with aceton 70%, ethanol 70% and methanol 70%. Total phenolic content of aceton extract was significantly higher than the ethanolic and methanolic extracts. Extracts were tested for their antimicrobial activity against Lactobacillis plantarum and Saccharomyces cerevisiae, using micro broth dilution method. All extracts showed good antimicrobial activity against tested microorganisms. Aceton extract had the most efficient antimicrobial activity. Lactobacillis plantarum was found to be more sensitive to aceton extract than Saccharomyces cerevisiae. The MBC values of aceton extract for Lactobacillis plantarum and Saccharomyces cerevisiae was 0.5 and 1 (μg/ml), respectively. The antimicrobial activity of aceton extract (0.25, 0.5 and 1 μg/ml) was also evaluated in apple juice inoculated using Lactobacillis plantarum and Saccharomyces cerevisiae during 35 days storage at ambinent temprature. Concerning microbial data in apple juice, the extract was able to control Lactobacillis plantarum and Saccharomyces cerevisiae growth. Aceton extract also showed higher inactivation effect on Lactobacillis plantarum in apple juice. Phenolic compounds did not change during 35 days of storage. No change in organoleptic quality of apple juice treated with aceton extract (0.25 μg/ml) was observed, according to sensory evaluation.
Vida Mardani Ghahfarokhi; Mehran Alami; Saeedeh Arabshahi- Delouee; Rasul Khoda Bakhshi; Maryam Ghaderi
Abstract
Evening primrose (Oenothera biennis) is a biennial flowering plant increasingly cultivated for medicinal use of γ-linolenic acid rich oil of its seeds. In this study, total phenolic and flavonoids content, antioxidant and antimicrobial activity of aceton, ethanolic and metanolic extracts of evening ...
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Evening primrose (Oenothera biennis) is a biennial flowering plant increasingly cultivated for medicinal use of γ-linolenic acid rich oil of its seeds. In this study, total phenolic and flavonoids content, antioxidant and antimicrobial activity of aceton, ethanolic and metanolic extracts of evening primrose flowers were evaluated. Aceton extract had the highest extraction yield, total phenol and flavonoids content. Extracts were also tested for their antioxidant activity using scavenging activity of 2,2- diphenyl-1-picrylhydrazyl and reducing power of Fe+3 in comparision with BHT. BHT was the highest in DPPH radical scavenging and reducing power followed by aceton, ethanolic and methanolic extracts. The extracts also showed good antibacterial activity against all of tested microorganism and the tested gram-negative bacteria was more resistant to inhibitory effect of extracts. Among different bacteria tested, Salmonella. typhimurium was found to be the most resistant to aceton and ethanolic extracts. The MBC values, with respect to aceton and ethanolic extracts for Salmonella. typhimurium were 10 and 20 (μg/ml), respectively
Homa Baghaei; Farimah Aghaei; Nasser Sedaghat; Mohebbat Mohebbi
Abstract
In view of the importance environmental pollution caused by plastic food packaging, in recent years there is a considerable interest in edible films and coating based on polysaccharides, proteins, lipids or combination of them. Edible coatings also serve as carriers of food additives such as anti-browning ...
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In view of the importance environmental pollution caused by plastic food packaging, in recent years there is a considerable interest in edible films and coating based on polysaccharides, proteins, lipids or combination of them. Edible coatings also serve as carriers of food additives such as anti-browning and antimicrobials agents, colorants, flavor, nutrients and spices, so act as active packaging. In this study, effect of garlic essential oil )0.5%, 1.5%, 2.5% w/w of film solution) on isolated soy protein films was investigated by measuring changes in properties including antimicrobial activity against (Escherichia coli H7:0157, Salmonella enteritidis and Staphylococcus aureus), mechanical (tensile strength, elongation at break), physical (transparency, water vapor permeability, microstructure) and sensory (chewing, apparent and odor). Incorporation garlic oil improved mechanical and water vapor permeability properties and decreased transparency, structure and organoleptic attributes (p
Zohreh Karami; Habibollah Mirzaee; Zahra Emam-Djomeh; Alireza Sadeghi Mahoonak; Morteza Khomeiri
Abstract
In this research, anti-microbial activity of ethanolic extract of licorice root against food spoilage microorganisms (Lactobacillus delbrueckii, Leuconostocmesenteroides, Candida krusei, Saccharomyces cerevisiae) in an orange flavored carbonated soft drink was investigated. The MIC and MBC of extract ...
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In this research, anti-microbial activity of ethanolic extract of licorice root against food spoilage microorganisms (Lactobacillus delbrueckii, Leuconostocmesenteroides, Candida krusei, Saccharomyces cerevisiae) in an orange flavored carbonated soft drink was investigated. The MIC and MBC of extract against Lactobacillus delbrueckii was 0.7 mg/ml and 0.8 mg/ml respectively, and against Leuconostoc mesenteroides MIC and MBC were 0.9 mg/ml. Also, MIC and MBC against Candida krusei and Saccharomyces cerevisiae using microdillution method was equal to 0.8mg/ml. In this research an orange flavored beverage preserved with natural licorice root extract was formulated and parameters such as phenolic contents, changes in population of aerobic mesophilic bacteria, yeast and acid-resistant micro-organisms during storage time were evaluated. Concentrations of 1000, 1500 and 2000 ppm of licorice root extract and samples containing 1000, 1500 and 2000 ppm of licorice root + 50% benzoate was used to control growth of food spoilage microorganisms in the beverage. Samples enriched with licorice root and a blank sample (commercial sample) were kept at room temperature and microbial counts were monitored during 1, 10, 20, 30, 40, 50, 60, 70, 80 and 90 days. Results of microbial examinations showed that the use of licorice root extract preserved the orange flavor carbonated soft drink during 90 days storage. Also, phenolic compounds showed good stability during 90 days storage time.
