Food Biotechnology
Parisa Raei; Morteza Khomeiri; Alireza Sadeghi Mahoonak; Ali Moayedi; Mahboobeh Kashiri
Abstract
IntroductionNowadays, antibiotic resistance is increasing in all parts of the world and is emerging and expanding globally. Due to their natural antimicrobial properties and low tendency to develop bacterial resistance, antimicrobial peptides can be a good candidate as an alternative to synthetic antibiotics. ...
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IntroductionNowadays, antibiotic resistance is increasing in all parts of the world and is emerging and expanding globally. Due to their natural antimicrobial properties and low tendency to develop bacterial resistance, antimicrobial peptides can be a good candidate as an alternative to synthetic antibiotics. Bioactive peptides are produced using enzymatic hydrolysis by enzymes extracted from microorganisms and plants, digestive enzymes, and fermentation by proteolytic starter cultures. Enzymatic hydrolysis of proteins is performed by commercial proteases or a combination of several proteolytic enzymes. Commercial proteases are expensive due to their specificity. Among the strategies for protein hydrolysis with the aim of obtaining bioactive peptides is microbial fermentation, which is more environmentally friendly and has a high potential for use in industry due to its relatively low cost compared to commercial enzymes. It is a suitable method for the hydrolysis of sesame meal protein. Bacillus species are bacteria that have high proteolytic activity and are able to produce different endopeptidases in the fermentation medium. The activity of endopeptidases in the environment containing proteins causes the production of peptides with small sizes and free amino acids in higher amounts compared to enzymatic hydrolysis, which is one of the advantages of using Bacillus species with high proteolytic activity compared to pure enzymes. In general, the purpose of this research was to produce sesame meal protein hydrolysate by fermentation with Bacillus subtilis and to investigate its antimicrobial and antioxidant activity. Materials and MethodsIn this study, at the first step, sesame meal was defatted with hexane at a ratio of 1:5, then it was dried and sesame meal protein isolate was extracted, and the optimization of fermentation conditions was determined by the response surface methodology (RSM). Independent variables, including temperature (30 to 45 ˚C), time (12 to 36 h), and substrate concentration (2 to 6%), were considered. The antioxidant properties of the treatments, including DPPH radical scavenging activity, ferric ion reducing power, and antimicrobial activity, were investigated, and the optimum treatment was selected. Then the protein hydrolysate was freez-dried and stored at -20 °C. Results and DiscussionAccording to the results, temperature (39.68 °C), time (30.07 h), and substrate concentration (4.85%) were selected as optimum conditions. Under these conditions, DPPH radical scavenging activity and ferric ion reducing power of hydrolysate were 63.57% and 0.9951 (absorbance at 700 nm), respectively. The inhibition percentages of Staphylococcus aureus (59.58%), Escherichia coli (6.55%), Listeria monocytogenes (62.43%), and Clostridium perfringens (50.97%) were obtained in the optimized condition. Bacillus subtilis, in the presence of sesame meal protein, showed significant (p<0.05) protease activity over time. After 48 hours, the clear zone diameter was determined to be 22 mm. The clear zone created by this strain showed that Bacillus subtilis has high proteolytic activity and can be a suitable bacterium for hydrolyzing sesame meal protein with the aim of obtaining hydrolysates with the highest antimicrobial and antioxidant activities. The antimicrobial activity of the protein hydrolysate can be due to the higher degree of hydrolysis. By increasing the hydrolysis time, peptides with low molecular weight are produced, which cause better interaction with the microbial cell membrane, disrupt the membrane, and lead to the inhibition of the microorganism. According to the results, the sesame meal protein hydrolysate showed more inhibitory effect against gram-positive bacteria than gram-negative bacteria (Escherichia coli). Researchers reported that the difference in sensitivity to antimicrobial compounds between gram-positive and gram-negative bacteria can be attributed to the structure and composition of the cell envelope (cytoplasmic membrane or outer membrane, and cell wall). In general, the bioactivity properties of protein hydrolysate depend on the amino acid composition, sequence, and molecular weight of the amino acids. The antioxidant activity can be due to the high content of polar and aromatic amino acids. By further hydrolysis of proteins, peptides and polar free amino acids are produced that interact with free radicals and converted into safe and stable intermediate products. ConclusionIn this study, Bacillus subtilis strain was used to ferment sesame meal protein, which is a rich source of protein, to produce protein hydrolysate with maximum antimicrobial and antioxidant activities. Results showed that the protein hydrolysate obtained from sesame meal protein isolate had antimicrobial and antioxidant activities. It can be used as a natural antimicrobial or antioxidant agent in the formulation of food or pharmaceutical industry to improve the health of society.
Food Biotechnology
Khadijeh Shirani Bidabadi; Shilla Safaeian; Rezvan Mousavi Nadushan; Nahid Rahimifard
Abstract
IntroductionSargassum and Padina are two genera of brown algae that are widely scattered in temperate regions. Sargassum species are categorized as tropical and sub-tropical brown seaweed which are valuable sources of bioactive compounds including dietary fibers, carotenoids, vitamins, and minerals. ...
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IntroductionSargassum and Padina are two genera of brown algae that are widely scattered in temperate regions. Sargassum species are categorized as tropical and sub-tropical brown seaweed which are valuable sources of bioactive compounds including dietary fibers, carotenoids, vitamins, and minerals. These brown algae demonstrate diverse biological activities such as antioxidant, antimicrobial, and anti‑Alzheimer, due to the presence of flavonoids, triterpenoids, flavonoids, sterols, polyphenols, and pheophytine. The genus Padina is scattered in many environmental conditions, mainly in the tropical marine waters, and belongs to the family Dictyotaceae. Some bioactive components isolated from Padina species have been demonstrated hypoglycemic, hypolipidemic, anti-obesity, hepatoprotective, cardioprotective, immunostimulatory, and antimicrobial activities., The aim of this study was to prepare an extract from two species of algae Padina and Sargsum by massaging and ultrasound assisted-methods as well as analyzing their compounds and investigating the antioxidant, antimicrobial and enzymatic properties of the extracts. According to the obtained results, ultrasound assisted method was a suitable method for extraction. This extract can be used as a combination of antioxidant, antimicrobial, anti-Alzheimer's and nitrate reducing agent in food additives. Materials and MethodsChemical materials were supplied by Sigma-Aldrich GmbH (Sternheim, Germany). The algal species utilized in the current investigation; namely, Padina distromatic and Sargassum angustifolium were collected from the coastal region of Chabahar bandar, Sistan and Baluchistan Province, Iran. To eliminate all the impurities and extraneous materials, they were washed by using distilled water and then dried at ambient temperature (24-48 h) until the constant weight. Extraction by maceration was compared with the extraction using ultrasonic assisted method. Determination of chemical compounds was parformed using GC-MS device. Investigation of antioxidant properties and total polyphenol and flavonoid content were also performed. The degree of free radical scavenging was done according to DPPH method. Evaluation of antimicrobial effect of algae extracts were the main challenges in our research. S. aureus ATCC25923, Listeria innocua ATCC 33090, E. coli ATCC 25922 and S. typhi ATCC 6539 were used for antimicrobial test. Determination of minimum growth inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were performed using wells in agar.The enzymatic activity was also determined. In this study, the activity of acetylcholinesterase was investigated using the method introduced by Ellman et al. (1961) and also the activity of nitric oxidase was determined using a kit protocol (Nvand-Iran). Factorial experiment in the form of a completely randomized design was used to analyze the data. Duncan's multiple range test was used to determine the difference between the means at the 95% confidence level, and SAS software version 2.9 will used for statistical analysis. Results and DiscussionThe current study investigated the antioxidant, antibacterial, anti-inflammatory, and anti-Alzheimer’s attributes of two brown algae namely Padina distromatic and Sargassum angustifolium which were collected from the coastal region of Chabahar Bandar, Iran. The results clearly indicated that the type of algae and extraction techniques used in this investigation highly affected phytochemical compositions, antioxidant, AChE inhibitory, scavenging, and antimicrobial activities. Considering both extraction yield and phytochemical components, extraction by ultrasound assisted method provided better results. Among all algal extracts, UPE presented the highest AChE inhibitory activity, and antibacterial activity and USE presented the highest antioxidant activities, total phenols and flavonoids, reflecting the presence of various bioactive components. The extracts of two various seaweeds utilized in the current study highlighted considerable inhibitory action against four pathogenic bacteria. According to the observations of the antibacterial assay, S. aureus was the most sensitive microorganism, while L. innocua was revealed as the most resistant bacteria to the extracts of P. distromatic and S. angustifolium. Further, the chemical components responsible for the antioxidant, AChE inhibitory, and antibacterial power were confirmed by GC-MS analysis. The findings of the current investigation confirmed the potential of the health benefits and therapeutic effect of brown marine algae. Thus, the extract of P. distromatic and S. latifolium could be an effective supplement to be incorporated into the products’ formulation in the food and pharmaceutical industries as well as in medication to alleviate several disorders such as Alzheimer.
Fakhri Shahidi; Farideh Tabatabaei Yazdi; Majid Nooshkam; Zahra Zareie; Fereshte Fallah
Abstract
Introduction: Lipid oxidation leads to the generation of off-flavors and potential toxic compounds. Synthetic antioxidants are frequently applied for inhibiting this reaction, however; there is a concern regarding to the potent toxic effects of synthetic antioxidants on human health. The non-enzymatic ...
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Introduction: Lipid oxidation leads to the generation of off-flavors and potential toxic compounds. Synthetic antioxidants are frequently applied for inhibiting this reaction, however; there is a concern regarding to the potent toxic effects of synthetic antioxidants on human health. The non-enzymatic glycosylation reaction (Maillard reaction) has been broadly used to ameliorate the biological and functional features of proteins and polysaccharides. The Maillard reaction produces products with versatile functions such as antioxidant, antimicrobial, antihypertensive, anti-browning, and prebiotic properties. In this regard, the Maillard reaction products (MRPs) can be used in the food industry to inhibit the oxidation reaction due to their superb antioxidant effect. In this study, chitosan was glycosylated with inulin, fructose, and glucose. Chitosan is a chitin derivative with cationic nature having antimicrobial, antioxidant, metal chelation, and film-forming features. Inulin is recognized as a prebiotic sugar with vast applications in food and pharmaceutical sciences. The purpose of this study was to chemically modify chitosan through the Maillard reaction in order to boost its antioxidant and antimicrobial properties. Materials and methods: Chitosan (0.5% w/v) was dissolved in 1.0% v/v acetic acid solution followed by stirring for 1.0 h at room temperature. Afterwards, sugars inulin, glucose, and fructose were separately added to the chitosan solution at final concentration of 1.0% w/v. The obtained solutions were then stirred until complete sugar dissolution. The pH of solution was adjusted to 6.07 by adding 2.0 M sodium hydroxide and then the chitosan-sugar Maillard conjugates were fabricated through autoclaving the solutions at 121 °C. Changes in pH after the reaction were measured using a pH meter. The extent of the Maillard reaction was estimated via measuring the absorbance of the conjugated solutions at 294 nm (the intermediate products) and 420 nm (final products). Fourier transform infrared (FTIR) spectroscopy at transmission mode and 400-4000 cm-1 was employed to evaluate the structural changes of chitosan upon conjugation. Antioxidant activity of the conjugates was evaluated based on the reducing power assay. One mL of the samples was charged with 1.0 mL of distilled water and 1.0 mL of potassium ferricyanide (1.0% w/v). The solution was mixed and incubated at 50 °C for 20 min. After adding 2.5 mL of tri-chloroacetic solution (10% w/v), the obtained solution was centrifuged at 5000 g for 5.0 min. Afterwards, 2.0 mL of the supernatant was mixed with 2.0 mL of distilled water and 1.0 mL of ferric chloride (0.1% w/v). The solution was stand for 10 min at ambient temperature and then its absorbance was recorded at 700 nm. Antimicrobial effect of the conjugates against pathogenic microorganisms (E. coli, S. aureus, B. subtilis, P. aeruginosa, A. niger, and C. albicans) was measured according to the minimum inhibitory (MIC) and microbiocidal (MBC) concentrations. SPSS software (version 21) and one-way ANOVA were applied for data analysis. Duncan’s multiple range test was employed to determine the differences between means. Results & discussion: The Maillard reaction led to a significant decrement in pH value of chitosan-saccharide systems, mainly due to the covalent coupling of amino groups of chitosan to carbonyl groups of reducing sugars in conjugation with the production of acetic and formic acids. The highest intermediate compounds (A 294nm) and lowest browning intensity (A 420nm) observed in chitosan-fructose conjugate, which was likely attributed to the lower reactivity of fructose. Chitosan-inulin conjugate presented the highest A 420nm and lowest intermediate-to-final ratio (A 294nm/A 420nm), probably due to the lower inulin molecules and subsequently carbonyl groups compared to fructose and glucose. These groups may react with amino groups of chitosan at initial reaction times, leading more conversion rate of the intermediate compounds to the final ones. FTIR spectra of the chitosan and conjugates revealed that absorbance peak at 1661 cm-1 in chitosan spectrum decreased and shifted to 1578 cm-1 (in chitosan-fructose conjugate), 1579 cm-1 (in chitosan-glucose conjugate), and 1580 cm-1 (in chitosan-inulin conjugate), indicating the stretching C-N group and -C=N group and the formation of Schiff base (-C=N) between reducing end of the saccharides and amino groups of chitosan. Reducing power of the chitosan-saccharide systems improved after the thermal process. Although, chitosan-glucose and chitosan-fructose conjugates had significantly higher reducing power than unconjugated counterparts, but chitosan-inulin conjugate showed non-significantly improved antioxidant activity compared to its non-heated mixture. Antioxidant activity of the Maillard conjugates was ascribed from the electron donating ability of their hydroxyl and pyrrole groups. The conjugates had lower MIC and MBC in comparison to their unconjugated pairs, except for chitosan-glucose conjugate, which showed no differences in MIC and MBC compared with its non-heated mixture. Antimicrobial property of the Maillard products, especially melanoidins has been attributed to their metal chelating features; melanoidins exert a bacteriostatic effect at low concentration and bactericidal effect at high levels through sequestering ionic iron from medium and magnesium from outer membrane, leading to the cell membranes destabilization. Additionally, antioxidant capacity, high surface activity, and inhibiting effect towards catabolic enzymes have been reported as another antimicrobial mechanisms of the Maillard products. In general, it can be concluded that chitosan-saccharide Maillard-based conjugates, particularly inulin-chitosan one could be used in the food sector as a novel prebiotic-based active bio-compound with antioxidant and antimicrobial features.
Vahid Alizadeh; Hassan Barzegar; Behzad Nasehi; Vahid Samavati
Abstract
The present work describes the physicochemical and antimicrobial properties of active films developed by incorporating different concentrations (0.5, 1, and 2% v/v) of Satureja hortensis essential oil (SEO) and 3% (w/w) nanoclay into a chitosan- montmorillonite nanocomposite film. The tensile strength ...
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The present work describes the physicochemical and antimicrobial properties of active films developed by incorporating different concentrations (0.5, 1, and 2% v/v) of Satureja hortensis essential oil (SEO) and 3% (w/w) nanoclay into a chitosan- montmorillonite nanocomposite film. The tensile strength (TS) of the films significantly decreased and elongation at break (EAB) increased with the incorporation of SEO. The control film exhibited the lowest water vapor permeability. In addition, decreases in water solubility (WS) and transparency were observed with increasing the concentration of SEO. Thermogravimetric analysis (TGA) indicated that films incorporated with SEO exhibited a higher degradation temperature compared with the control. The structural properties and morphology of the nanocomposite films were examined by X-ray diffractometry (XRD) and Scanning electron microscopy (SEM). SEO-incorporated films were more effective against gram positive bacteria (Staphylococcus aureus and Bacillus cereus) than gram negative ones (Salmonella typhimurium and Escherichia coli). The results suggested that SEO, as a natural antibacterial agent, has the potential to be applied in antimicrobial biodegradable films.
Hashem Razavi Setoti; Seyed Ali Mortazavi; Monirosadat Shakeri; Shahram Beiraghi-Toosi; Elham Asadolahi
Abstract
In this study, antimicrobial effects of Zataria Multiflora boiss added to sodium caseinate film on four bacterial species: Staphylococcus aurous, Escherichia coli, Bacillus subtilis and Salmonella intertidis was investigated. Disk diffusion method was used to study the antimicrobial activity of Zataria ...
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In this study, antimicrobial effects of Zataria Multiflora boiss added to sodium caseinate film on four bacterial species: Staphylococcus aurous, Escherichia coli, Bacillus subtilis and Salmonella intertidis was investigated. Disk diffusion method was used to study the antimicrobial activity of Zataria multiflora Boiss in sodium caseinate film. 9 mm disks were prepared from produced films with different concentrations of Zataria multiflora Boiss. with 1, 2, 3 and 4%. Surface culture was done under sterile condition using 0.1 ml of broth culture of each bacterial (106 -107 cfu/ml) on BHI agar. Then the disks were placed. Diameter of inhibition zone was considered as an index of antimicrobial activity of the film. Statistical analyses were done by means of SigmaSDAT software and mean comparison was carried out by LSD test. Results showed that disks containing essential oils of Zataria multiflora Boiss. in each concentration inhibited growth of E.coli, Sa.interitidis and B.cereus. Since there was no significant differences between 3% and 4% concentrations for these bacteria (p>0/05), concentration of 3% is the most appropriate and cost-effective concentration with the highest antimicrobial effect. Only the film containing 1% of essential oil of Zataria multiflora Boiss. Made no inhibition zone on S.aurous, in the other word had no inhibitory effect in this concentration. But inhibition zones created by 2, 3 and 4% for S.aurous were significantly different (p
