applied food biotechnology
Volume:10 Issue: 2, Spring 2023

Postbiotics are microbial-derived soluble products, which are released during the growth and fermentation process of beneficial microorganisms in gastrointestinal tract, food and complex microbiological culture systems (cell-free supernatant or extracellular extract) or after cell lysis (intracellular extract). Colorectal cancer is one of the most common cancers within the leading causes of cancer mortality worldwide, which can be associated with a defeated gastrointestinal barrier. In this study, potential functionality of the extracellular and intracellular extracts of probiotics (Latilactobacillus sakei, LS) and protective culture (FreshQ®, FQ) on proliferation and cell survival of HCT-116 colon cancer epithelial cells was investigated.

Probiotic bacteria were cultivated in de Man, Rogosa and Sharpe broth and then postbiotics was isolated by centrifugation and sonication. The achieved solutions were lyophilized and stored until use. Moreover, HCT-116 cells were exposed to various concentrations of Latilactobacillus sakei and FreshQ® extracts (1.25-40 mg ml-1) for 24 h and then effects of these products on cell cytotoxicity, proliferation and apoptosis were investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, wound healing and AO/EB assays.

Extracellular and intracellular extracts of Latilactobacillus sakei and FreshQ the decreased in cell viability based on the postbiotic concentrations (p≤0.05), while cell proliferation was inhibited by extracellular and intracellular extracts of Latilactobacillus sakei and FreshQ® in wound healing assay. Results showed that postbiotics could induce apoptosis evidenced by acridine orange/ethidium bromide staining. In summary, Latilactobacillus sakei and FreshQ® postbiotics are able to decrease cell viability and proliferation and enhance apoptosis in HCT-116 colorectal cancer cells. In addition, FreshQ® postbiotics seemed more potent than that Latilactobacillus sakei postbiotics did.

Milk proteins are precursors of several biologically active peptides. One of the methods of producing these peptides is fermentation using lactic acid bacteria. The aim of this study was to investigate production of antioxidant and angiotensin-I converting enzyme inhibitory bioactive peptides in cow milk fermented by two strains of Levilactobacillus brevis.

Two strains of Levilactobacillus brevis KX572376 (M2) and Levilactobacillus brevis KX572382 (M8) were used in fermentation of low-fat cow milk. Moreover, pH changes, proteolytic activity, water-soluble extract biological activity (antioxidant activity and angiotensin-I converting enzyme inhibition) of the samples and peptide fraction less than 3 kDa were investigated at 24 and 48 h of fermentation (30 °C). Peptide profile of the superior sample was analyzed as well. Statistical analysis was carried out using one-way of variance, Tukey test and SPSS software v.25.

The two strains decreased milk pH to a similar level in the first 24 h. Quantities of free amine groups in the samples treated with M2 and M8 strains within 24 and 48 h of fermentation were significantly different (p≤0.05), compared to the control sample. In the first 24 h of fermentation, no difference was observed in the quantity of free amines of M2 and M8 samples. In the second 24 h, further free amine groups were produced due to the activity of M8 strain in milk. Antioxidant activity of the water-soluble extracts of M2 and M8 samples was significantly (p≤0.05) higher than that of the control sample during fermentation. Antioxidant activity in fractions less than 3 kDa did not show significant differences in M2 and M8 samples at 24 and 48 h of fermentation. In the control sample, no antioxidant activity was observed in fractions less than 3 kDa. The highest ACE inhibitory activity in fractions less than 3 kDa of M8 was observed after 48 h. No angiotensin-I converting enzyme inhibition was seen in fractions less than 3 kDa of M2 and control sample. The RP-HPLC peptide patterns of the fraction less than 3 kDa of M8 and control sample were different, which was a justification for the biological activity in this sample.

Essential oils include low solubility, poor bioavailability and rapid release, which may limit their use as bioactive compounds in foods and medicine. Nanoencapsulation can preserve inherent qualities of essential oils and improve their physicochemical characteristics and health benefits. Focus of the present study was on the loading of essential oils from Zataria multiflora in pickering nanoemulsions, nanoparticles and nanophytosome. In addition, the present study assessed how these systems affected their physicochemical characteristics and antioxidant and antimicrobial activities, compared to free-essential oils.

Encapsulation of Zataria multiflora Boiss essential oil in nanocarriers as a novel phytoconstituents delivery system was carried out using three various methods. Physicochemical characterization of nanocarriers was studied using dynamic light scattering, Fourier transform infrared spectroscopy, field emission scanning electron microscope, confocal laser scanning microscopy, optical microscope and antioxidant activity. The minimum inhibitory and bactericidal concentration assessment effects against Listeria monocytogenes at 24 h and temperatures (10, 25 and 37 °C) were investigated. Encapsulated Zataria multiflora Boiss essential oil with subinhibitory concentrations (0.25, 0.5 and 0.75) in hamburger formulation was selected as a food model for chemical, microbiological and sensory evaluation.

In general, this study compared three types of biocarriers with free essential oils. Primarily, nanophytosome showed promising results in delaying oxidation and in antimicrobial and sensory assessments, compared to two other nanocarriers. In conclusion, essential oil nanophytosomes of Zataria multiflora Boiss include the potential as an efficient natural food preservative.

Monolaurin can be produced by enzymatic glycerolysis of a palm kernel olein-stearin mixture. Monolaurin can act as an antibacterial agent against Gram-positive and Gram-negative bacteria. Few studies have investigated activity of monolaurin against Bacillus subtiliscells and spores. Therefore, the aim of this study was to investigate effects of a purified monolaurin from enzymatic glycerolysis of palm kernel olein-stearin mixture on growth, spore germination, cell surface hydrophobicity and cell structure of Bacillus subtilisFNCC 0060.

Monolaurinwas produced using palm kernel-olein mixture under the best enzymatic glycerolysis condition and purified using solvent (hydroalcoholic) method. Effects of a purified monolaurin on Bacillussubtilisgrowth and spore germination were studied using nutrientbroth. Analysis of cell surface hydrophobicity was carried out using microbial adhesion to hydrocarbons assay and cell structure was studied using transmission electron microscope.Completely randomized experimental design was used and each treatment was carried out in triplicate. Analysis of variance and Duncan multiple range tests were used to analyze data.

Results showed that purified monolaurin inhibited growth of Bacillus subtilisFNCC 0060. Moreover, development of Bacillus subtilisin nutrient broth with monolaurin of 100-5,000 μg.ml-1was slower than that without monolaurin.Higher concentration in the media decreased the microbial specific growth rate and increased doubling time. Spores of Bacillus subtilisFNCC 0060 in nutrient broth with monolaurin of 100-1,000 μg.ml-1delayed germination for up to seven days of incubation. Presence of monolaurin significantly decreased bacterial cell adherence. Furthermore, cytoplasm of Bacillus subtilisFNCC 0060 seemed shrunk significantly, causing cytoplasmic damages and disorganization of the components.

Consumers prefer not to use synthetic preservatives so, natural ones such as essential oils (in this research, garlic oil (GO) are mostly consumed in food products as an antimicrobial agents. Application of garlic oil in food industries is limited. Because of its water insolubility, volatility, pungent odour and flavor, and low stability. Encapsulation could eliminate its restrictions. In the present study, different concentrations of free and encapsulated garlic oil in ß-cyclodextrin (GO/ß-CD) were used for formulation of sausage

Five types of sausage were produced, including control (without garlic oil), containing free garlic oil (GO), and three samples containing 546, 818, and 1364 mg of encapsulated garlic oil per kg. After that, changes of pH, color, oxidation indices (PV and TBARs(, monitoring of B. cereus, S. aureus, E. coli, and S. enterica, and sensory (taste, color, odor, and acceptability by 8-point hedonic test) properties were studied during 29 days storage at 4oC.

By increasing the GO/ß-CD content of samples, the overall color changes decreased. The pH of all produced sausages remained constant. At the end of storage, PV was not significantly changed, and TBARs changing was very low. S. aureus was the most susceptible, followed by S. enterica, E. coli, and B. cereus. In sensory evaluation, the panelists did not distinguish between the control and the samples containing GO/ß-CD. Encapsulation of garlic oil with beta-cyclodextrin did not affect the taste of the produced sausages. Due to good antimicrobial properties of garlic oil, it can be used in meat products as a natural preservative.