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
Shadi Atashgahi; Ali Moayedi; Alireza Sadeghi Mahoonak; Hoda Shahiri Tabarestani; Alireza Sadeghi
Abstract
Soy whey (SW) is a byproduct from tofu and soy protein isolate (SPI) production that contains various nutrients such as protein, amino acids, minerals, carbohydrates, isoflavones. In this study, SW was fermented with lactic acid bacteria (LAB) with the aim to enhance total phenolic contents (TPC), Gamma ...
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Soy whey (SW) is a byproduct from tofu and soy protein isolate (SPI) production that contains various nutrients such as protein, amino acids, minerals, carbohydrates, isoflavones. In this study, SW was fermented with lactic acid bacteria (LAB) with the aim to enhance total phenolic contents (TPC), Gamma amino butyric acid (GABA) and antioxidant activity. Eight different LAB strains were selected and the activity and cell counts of the most potent strains were investigated during fermentation. The results showed that all the isolates were able to grow in SW and the increase in incubation time led to significantly (p<0.05) decrease the pH of all samples from 5.75 to 4.5. Among eight LAB isolates, Lactiplantibacillus plantarum MCM4 and Weissella confusa MDM8 showed higher activity in terms of acid production, increase in TPC content and proteolytic activity. The sample fermented by L. plantarum MCM4 had the highest content of free amino acids (1.73 mg/ml) and the unfermented sample with 0.9 mg/ml had the lowest content. GABA concentration varied from 6.15 mg/mL (unfermented) to 24.175 mg/100 mL (SW fermented with L. plantarum MCM4). In this research, it was found that fermentation increased the antioxidant capacity of SW in such a way that the highest amount was observed in sample fermented with Lactiplantibacillus plantarum MCM4. A positive correlation (R2= +0.72) was found between viable cell counts and proteolysis. It can be concluded that, fermentation with L. plantarum MCM4 and W. confusa MDM8 can be applied as an approach to valorize SW.
Food Biotechnology
Rana Tahmasbi; Mahta Mirzaei; Mohammadreza Khani
Abstract
Introduction: Fermented foods, probiotic, prebiotics, and symbiotic, are among the most important groups of functional food that have attracted the attention of researchers during the last years. Proteolytic activity of lactic acid bacteria can lead to the production of peptides in the fermented product. ...
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Introduction: Fermented foods, probiotic, prebiotics, and symbiotic, are among the most important groups of functional food that have attracted the attention of researchers during the last years. Proteolytic activity of lactic acid bacteria can lead to the production of peptides in the fermented product. The produced peptides can exhibit different biological activities such as antioxidant, antihypertensive, etc. that are influenced by the type of protein source, type of bacteria, time and conditions of fermentation process. Fermentation of various cereals such as quinoa seeds with high sugar and protein content by lactic acid bacteria can lead to the production of antioxidant peptides and improving their nutritional properties. Materials and Methods: In this study, the role of Lactobacillus reuteri and Lactobacillus acidophilus and the combination of two bacteria on the progress of fermentation and antioxidant activity of quinoa extract was investigated. The fermentation process was started by separate and simultaneous inoculating of Lactobacillus reuteri and Lactobacillus acidophilus and continued for 72 hours at 37° C. Sampling was performed every 24 hours of fermentation and samples were kept at -20° C for further analysis. The parameters such as pH, acidity, amount of soluble protein, degree of hydrolysis, amount of phenolic compounds and DPPH and ABTS radical scavenging activity were determined. Results and Discussion: Lactobacillus acidophilus showed higher acidification capacity than Lactobacillus reuteri. The amount of acidity in the sample fermented by Lactobacillus acidophilus increased from 0.27 to 1.13 % after 72 hours, while this amount was measured as 0.80 % for sample fermented by Lactobacillus reuteri. The amount of soluble protein and the degree of hydrolysis increased in samples fermented by both species. However, the largest increase was related to the sample fermented by Lactobacillus reuteri, so that the amount of soluble protein increased from 0.72 to 0.88 mg / ml and the value of free amino groups increased from 20.28 to 58.14 µM leucin/ mg protein during 72 hours of fermentation. The DPPH and ABTS radical scavenging activity increased in all fermented samples. The highest antioxidant activity was observed in samples fermented by Lactobacillus reuteri, followed by a combination of two bacteria (50:50) and Lactobacillus acidophilus. The amounts of phenolic compounds increased in all fermented samples. However, the highest increase was related to the sample fermented by Lactobacillus reuteri, so that it increased from 0/73 to 16.21 mg Gallic acid / ml after 72 hours of fermentation. Therefore, the results showed that despite the higher acidifying power of Lactobacillus acidophilus in quinoa extract, but Lactobacillus reuteri exhibited higher proteolytic activity, more ability to produce antioxidant peptides and also release phenolic compounds during the fermentation process.Simultaneous use of the two bacteria did not intensify the proteolytic activity and antioxidant activity of peptides, and the greatest increase in acidity, proteolysis, and antioxidant activity occurred in the first 24 hours of fermentation. Fermented extracts showed higher ABTS radical inhibitory activity than DPPH radical inhibition, indicating the hydrophilic nature of most produced antioxidant compounds. The highest levels of antioxidant activity were observed in samples fermented by Lactobacillus reuteri, a combination of Lactobacillus reuteri and Lactobacillus acidophilus (50:50) and Lactobacillus acidophilus, respectively. The results showed that fermentation by Lactobacillus reutri has the greatest effect on the production of antioxidant peptides and the release of phenolic compounds. The results of this study confirm the effectiveness of fermentation methods on improving the healing properties of quinoa extract and Lactobacillus reuteri was a more effective bacterium in fermentation and production of antioxidant peptides compared to Lactobacillus acidophilus. Simultaneous use of two bacteria did not increase the intensity of fermentation and did not improve the antioxidant activity compared to single use of each bacteria. Finally, the results of this study showed that fermentation of quinoa extract improves its antioxidant properties and has the potential to be used as a fermented beverage.
Mohammad Ebrahim Goharjoo; Mohammad Reza Edalatian Dovom; Fakhri Shahidi; Farideh Tabatabaei Yazdi; Mohammad Javad Varidi
Abstract
Introduction: Carrot products such as carrot juice and fermented carrot products possess high nutritional value and they are considered as a major source of β-carotene. Carotenoids because of containing conjugated double bonds, have antioxidant properties and provide the natural yellow, orange and red ...
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Introduction: Carrot products such as carrot juice and fermented carrot products possess high nutritional value and they are considered as a major source of β-carotene. Carotenoids because of containing conjugated double bonds, have antioxidant properties and provide the natural yellow, orange and red colors in fruits and vegetables. Due to the outbreak of some problems such as lactose-intolerance and high blood cholesterol especially in dairy products’ consumption, great attention has been drawn toward fermented vegetable products. Lactic acid bacteria (LAB) including important genera: leuconostocs, lactobacilli, streptococci and pediococci are wide-spread and have been divided according to morphological features and fermentation pathway, which utilize glucose. Current knowledge regarding involved microorganisms in vegetable fermentation is still dependent on biochemical and classical data. Nowadays, application of molecular methods in the field of microbial identification has been provided better understanding from fermented foods ecology. Since local starter cultures are considered as precious genetic resources in each country and also they play an important role in production and creation of organoleptic characteristics in fermented products, therefore, the objective of present study was the isolation and identification of lactic flora from fermented carrot with the help of conventional (biochemical) and molecular methods and determination of phylogenetic relationships.
Materials and methods: Following the production of fermented carrot samples, they were packed in plastic container and stored at ambient temperatures (25-27°C). In the next step, total LAB count was performed according to Iranian standard of 5484. Isolation and selection of LAB was done during 32 days with the intervals of 0, 4, 8, 16, 24 and 32. For initial identification of LAB, isolated were subjected to gram staining and catalase tests. Also biochemical tests including growth at 15 and 45C, at NaCl 6.5% and 18%, pH=4.4 and 9.6, were done in order to identify and classify at genus level. Carbohydrate fermentation profiles were obtained for isolates with the aid of 10 sugars. Molecular identification was done with DNA extraction followed by amplification of 16S gene with universal primers (27 F and 1492 R). For sequencing of resulted PCR-products, they were sent to Macrogen Company, South Korea. Phylogenetic tree was plotted with Clustal Omega and Fig. Tree soft wares.
Results and discussion: In the first step, 144 gram positive, catalase negative isolates were screened and selected as presumptive LAB according to gram staining and catalase test and morphological characteristics. Among them, 48 representative isolates were chosen and identified up to genus level according to biochemical tests. Five distinct genera were identified as Pediococci (4.08%), homofermentative lactobacilli (34.69%), hetero fermentative lactobacilli (36.74%), Leuoconostocs (20.41%) and enterococci (4.08%). Carbohydrate fermentation profiles revealed Lactobacilli constitute the highest percent among other genera and also some species like Lb. kimchi and Lb. parakefiri were detected. Growth of lactic acid bacteria experienced increasing trend up to day-16 but thereafter showed decline trend until the end of storage time (day-32). 26 out of 48 isolates were subjected to molecular analysis. Results of sequencing revealed following species: Lb.plantarum (9), Lb. brevis (8), Leu. mesenteroides (4), Lb. casei (1), Lb. paracasei (1), and Lb, pantheris (1). Changes and variation of lactic flora during fermentation stages revealed that at initial stages of fermentation (0- day-8) Leuconostocs sp. were predominant species but disappeared then. In the next stages of fermentation Leuconostocs sp. were replaced by homo-fermentative strains such as Lb. plantarum which was present from the first day up to day-24 but constituted the majority of species on day-16. In the final stage, Lb. brevis dominated the others due to better survival and resistance of this bacterium at the increased acidity level. Phylogenetic tree results revealed three clusters including cluster I (composed of three sub-clusters), cluster II (three sub-clusters) and cluster III (two sub-clusters). Cluster I included two genera: Leuconostocs sp. (mesenteroides) and Lactobacillus (pantheris, casei and paracasei). Cluster II included Lb. brevis and finally cluster III composed of Lb. plantarum.
Reza Farhoosh; Mohammad Shahedi; Ali Sharif
Abstract
The best PH for getting Millard reaction started and Acrylamide formation ranges 7 to 8. PH below the range slows the reaction speed down and the resultant Acrylamide formation delayed. This research assess how Acetic Acid in 0.05, 0.15, 0.25% concentrations together with sourdough may promote acidity ...
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The best PH for getting Millard reaction started and Acrylamide formation ranges 7 to 8. PH below the range slows the reaction speed down and the resultant Acrylamide formation delayed. This research assess how Acetic Acid in 0.05, 0.15, 0.25% concentrations together with sourdough may promote acidity in bread dough and how they can cause a reduction of acrylamide content in Sangak bread [an Iranian traditional bread]. Here the acrylamide is assessed after it was derived and then transferring it to gaseous chromatography with ion indicator. The concentration of acrylamide in Sangak breads made of sourdough with 0.05, 0.15 and 0.25% of acid acetic showed a decrease of 73.47, 81.50 and 82.10% and also a 90.55, 92.80 and 95.96 % decrease when the bread has been made of the same compounds and yeast. The acidity of compounds with acidity rate of 0.05, 0.15 and 0.25% in Sangak bread made of yeast equates to 0.12, 0.14 and 0.17% (normal) respectively; while these values for Sangak breads made of sourdough stand at 0.16, 0.18 and 0.21% (normal). Therefore, decreased acrylamide can be attributed to increased acidity of dough.
