Applied Food Biotechnology
Year:2019 | Volume:6 | Issue:4 |Papers Count:6

Background and objective: Soybean is one of the most important grains with high proteins, good quality edible oils, appreciable amount of minerals and vitamins. Due to some disadvantages soybeans’ compounds affecting the flavor, odor and stability, different types and levels of processing are considered to make better products with healthy properties. Hypertension (high blood pressure) is one of the modern world diseases, which increases the risk of serious human health problems. There are several systems in humans’ body e. g. angiotensin converting enzyme regulator to blood pressure control. The aim of the present review is to report the effect of germination and fermentation on the concentration of bioactive compounds with angiotensin converting enzyme inhibitory properties. Results and conclusion: Many scientific research has demonstrated that germination (sprouting, also known as malting) and fermentation are two effective and inexpensive technologies improving soybean quality. During these two processes, anti-nutritional and bioactive compounds affecting human health e. g. anti-hypertension components have been removed and released, respectively. Furthermore, studies have shown effect of soybean isolated compounds to inhibit angiotensin converting enzyme. Therefore, soybean germination and fermentation could affect the concentration of bioactive compounds with angiotensin converting enzyme inhibitory properties.

Background and objective: Lactobacillus casei AP are probiotic bacteria found in the gastrointestinal tracts of Indonesian breast-fed infants. Lactobacillus casei AP can degrade inulin through metabolic pathways that involve certain proteins. However, detailed information on how inulin is metabolized by this strain is limited. The aim of this study was to identify intracellular proteins that play roles in metabolism of inulin. Material and methods: Bacteria were cultured on media containing commercial inulin or inulin extracted from dahlia tubers as the sole carbon source and protein identification was carried out using intracellular extraction. The bacterial intracellular proteins were isolated and separated using sodium dodecyl sulphate-polyacrylamide gel electrophoresis and then peptides were identified using electrospray ionization-liquid chromatography-mass spectrometry. Based on the identified proteins, corresponding genes involved in inulin metabolism were identified and their expression levels were quantified using quantitative real time-polymerase chain reactions. Results and conclusion: Comparisons of intracellular proteins from Lactobacillus casei AP cultured in inulin and MRS control media showed a different protein band at 70 kDa in bacterial cells cultured in inulin or inulin extract. This protein was identified as a glycoside hydrolase (α-2, 1 glycosidic) with a gene expression value of 1. 55 or a fructan hydrolase (β-2, 1 fructo-furanosidic) with a gene expression value of 2. 68, compared to controls.

Background and objective: Iranian mustard is cultivated in southern areas of Iran and used traditionally as natural preservative. Aims of the current study were identification and comparison of the chemical compositions and antibacterial activities of two Iranian mustard essential oils and assessment of these oils use for increasing the shelf life of turkey meats. Material and methods: Chemical compositions of two Iranian mustard essential oils were identified using gas chromatography-mass spectrometry and antibacterial activities of these oils were assessed against Salmonella typhimurium, Escherichia coli, Citrobacter freundii, Pseudomonas aeruginosa, Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus and Enterococcus faecalis using disc diffusion and broth macrodilution assays. Inhibitory effects of the essential oils were assessed on growth of mesophilic psychrotrophic bacteria, yeasts and molds and sensory evaluation was carried out for the turkey meats. Results and conclusion: Results of GC-MS showed presence of bioactive constituents, especially allyl isothiocyanate (75. 87-80. 07%). All the bacterial growth, especially for Escherichia coli, was inhibited with inhibition zones of greater than 20 mm and minimum inhibitory and bactericidal concentrations of 0. 156 mg ml-1. Treatment of turkey meat samples with the mustard essential oils significantly decreased the count of mesophilic psychrotrophic bacteria, yeasts and molds during 20 days of storage at 4° C ± 1, compared to controls (P≤ 0. 05). Over the time, the sensory score of the treated samples increased, compared to controls. Based on these findings, the Iranian mustard essential oils can be used as natural preservatives in foods.

Background and objective: Functional properties of essential oils are attributed to their components, many of which exhibit antimicrobial activity against pathogenic and spoilage microorganisms in a wide variety of foods. However, essential oils are unstable compounds; therefore, they can be encapsulated for a better protection and increase of functionality. In this work, antimicrobial activities of oregano, thyme and clove leave essential oils (non-encapsulated and nanoencapsulated) were assessed against Escherichia coli ATCC 29922, Salmonella typhimurium ATCC 14028 and Staphylococcus aureus ATCC 25923 using emulsification. Material and methods: The essential oils were characterized based on their physicochemical properties. Nanoemulsions were prepared, using 5% (w w-1) of essential oils, and then characterized based on their physical properties, stability and encapsulation efficiency. The microdilution antimicrobial assay was carried out to assess minimum inhibitory concentration and minimum bactericidal concentration of the essential oils and their nanoemulsions. Data from physical properties of the essential oils and physical properties, stability and encapsulation efficiency of the nanoemulsions were statistically analyzed. Results and conclusion: Antimicrobial activity of the essential oils showed decreases in minimum inhibitory concentration by 27-60% for the nanoencapsulated oils, compared to nonencapsulated oils. Nanoencapsulated and nonencapsulated oregano essential oils exhibited the lowest minimum inhibitory concentration and minimum bactericidal concentration values. Based on the results, nanoencapslulated essential oils may further be used in various foods to avoid microbial contaminations.

Background and objective: Non-thermal methods are suggested for decontamination of spices to preserve safety and quality of the products. In this study, effects of atmospheric pressure floating-electrode dielectric-barrier discharge plasma were investigated on red pepper powder, compared to gamma irradiation. Material and methods: To achieve the optimum time of treatment for decontamination, Escherichia coli, Bacillus cereus and Aspergillus flavus as microorganisms in red pepper were exposed to atmospheric pressure floating-electrode dielectric-barrier discharge plasma for 10, 20 and 30 min and the structural changes in microorganisms were investigated using scanning electron microscopy and DNA measurement following exposure. The red pepper was exposed to plasma for 20 min (optimum time) and 10 KGy gamma irradiation. Microbial count, color measurement and sensory evaluation of the samples were assessed before and after treatments. Results and conclusion: Results indicated that the density of surviving bacterial strains decreased when time of exposure increased and this decrease was significant after 10 min (P≤ 0. 05). The complete decontamination was carried out within 20 min. The deformation of cells and destruction of cell wall structures were seen in bacteria and mold following exposure. Data revealed that cold floating-electrode dielectric-barrier discharge plasma for 20 min inactivated red pepper microorganisms as well as gamma irradiation. As a conclusion, floating-electrode dielectric-barrier discharge plasma is an appropriate method to decontaminate the red pepper powder (regardless of color change) and can replace traditional methods without changes in the product quality and taste.

Background and objective: Pineapple peels contain significant quantities of carbohydrates, which can be used as cheap raw materials for production of commercially important products through fermentation. The aim of this study was to use this feed stock for the cultivation of Saccharomyces cerevisiae NCDC 364 and its use as single cell protein. Material and methods: The single cell protein was produced using discarded pineapple peels and Saccharomyces cerevisiae NCDC 364. Optimization of bioprocess variables (temperature, pH, incubation period, carbon source and nitrogen source) affecting single cell protein production was carried out using classical "one factor at a time" approach. The harvested cells from optimized media were screened for amino acid content using high-performance thin-layer chromatography. Results and conclusion: The Saccharomyces cerevisiae NCDC 364 produced maximum single cell protein in pineapple peel based media, compared to non-optimized media. The "one factor at a time" approach showed that the maximum biomass production was achieved at optimized levels of temperature of 25º C, pH of 5, incubation period of 120 h, carbon source of 1% sucrose and nitrogen source of 0. 5% beef extract. The amino acid profiling of the harvested biomass using high-performance thin-layer chromatography analysis revealed that tryptophan included a comparatively higher concentration of 6. 52%, followed by threonine (3. 25%). Results of this study suggest that easily available raw materials such as fruit peels offer cost-effective substrates for production of commercially important microbial proteins for alarming global issues linked to protein malnutrition.