نشریه بهداشت مواد غذایی
سال یازدهم شماره 3 (پیاپی 43، پاییز 1400)

Due to the widespread production and supply of synbiotic or functional foods, it is necessary to study and study the various sources of supplement extraction to produce these products. Various studies have shown the positive effect of these supplements on human health and the prevention and treatment of a variety of diseases such as diabetes, cancer, gastrointestinal disorders, liver problems, etc. Research into the production and supply of commercial supplements such as inulin has been underway for many years and now has a significant share of the synbiotic food market. But new supplements such as the use of bacterial polysaccharides, yeasts, edible fungi, and algae are a new area of ​​research in synbiotic supplements due to their economic benefits and numerous proven benefits to human health. Changes in the gut microbiome affect the number and function of the microbiome in other parts of the body, leading to disease or health promotion. In the present article, in addition to an overview of probiotics and prebiotics and synbiotics, a comprehensive overview of various prebiotic supplements with different biological origins has been provided.

Mycobacterium avium subspecies paratuberculosis (MAP), the causative agent of Johne’s disease, is a very slow-growing bacterium that imposes heavy costs on livestock-related industries. Due to the similar clinical and pathological symptoms in Johne’s and Crohn’s diseases, MAP is likely to play a role in the development and progression of Crohn’s disease. Hence, the possibility of transferring MAP through milk has created many concerns. To investigate the status of MAP contamination in raw and pasteurized milk samples in Kerman province, three diagnostic methods, including culture, IS900 PCR, and IS900 nested PCR was used. The results showed that the level of contamination with MAP in raw milk was relatively high in the studied herds. Based on culture, PCR, and nested PCR assays, 4.38%, 9.16%, and 13.55% were found positive, respectively. In pasteurized milk samples, 1.12%, 3.93%, and 6.18% were found positive for MAP by culture, PCR, and nested PCR, respectively. Comparing the methods used in this study demonstrated the best capability of nested PCR to detect MAP contamination. High levels of MAP contamination in raw milk on the one hand and relatively high resistance to thermal treatments, along with its intracellular characteristics, cause more survival of this bacterium, especially in the milk pasteurization process. Therefore, food hygiene researchers should pay more attention to the public health hazard caused by this bacterium.

Staphylococcus aureus beyond the cause of food poisoning, can cause wide spectrum of infections in human and is a serious threat in food industry. This study was conducted to evaluate antibacterial effect of alcoholic extract of garlic (Allium sativum) alone and in combination with nisin on inhibition of Staphylococcus aureus in minced meat of the tilapia fish. Garlic Extract was prepared by vacuum evaporation method using the rotary device. The effects of different concentrations of garlic alcoholic extract (0, 1, 2.5, 3.5, 5%) and nisin (0, 0.5 and 2.5 μg / g) and the combinations of nisin (micrograms per gram) and Extract (%) (0.25+3.5), (0.25+5), (0.5+1), (0.5+2.5), (2.5+1), (2.5+2.5) were studied on the growth of the S. aureus at 4 ° C for 21 days. The results showed that the bacterial growth was stopped at 3.5% and 5% concentrations of garlic extract from days 12 and 9 respectively, and It was stopped at 0.5, 2.5 μg/g of nisin from days 9 and 6 respectively. Low concentrations of garlic extract (1 and 2.5%) did not inhibit the growth of bacteria. Combined treatments of extract and nisin were able to stop bacterial growth from day 6 onwards. According to this study, garlic extract and nisin have inhibitory effect on growth of bacteria and they are introduced as a natural preservative of food instead of chemical preservative. This research approved the synergistic effect of nisin and alcoholic extract on the inhibition of the S. aureus growth.

Shrimp is a highly perishable product with limited shelf life due to melanosis and biological composition. Controlling the destructive effects of melanosis is one of the major challenges for the industry. Melanosis in crustaceans is usually controlled by inhibitors such as sodium metabisulfite. However, the use of synthetic inhibitors for melanosis and antioxidants in food processing is usually limited by considerations related to safety and impact on food quality. Thus, over the last decade, the trend towards studies on the use of natural extracts to control shrimp melanosis has increased. Data from some articles published by ScienceDirect, PubMed, Scopus, SpringerLink, and Scopus databases on the occurrence of melanin black pigment in shrimp skin were used. The shrimps were dipped in extracts and stored in ice or refrigerator. In Iran, only the effects of grape seed extract to prevent melanosis have been studied. Some studies have reported higher effects of plant extracts such as Garcinia cowa Roxb, Persicaria Odorata, rosemary, green tea, avocado, Arabic coffee grounds, and chamomile than sodium bisulfite. Some researchers have described the effects of extracts such as olive, rosemary, and thyme along with metabisulfite in preventing melanosis more than metabisulfite alone. Plant extracts were effective in reducing black spots in shrimp for 2-28 days. Studies have shown that plant extracts can act as antioxidants and be an effective natural alternative to inhibit melanosis after shrimp death.

The study of the yeasts isolated from the least studied fermented sources may have the potential to deal with the unique isolates. In this study, one of the predominant yeasts was isolated from fermented buckwheat. The isolate was identified by amplifying the target sequence of 650 bp of its ITS gene and sequencing PCR products. Afterward, some potential probiotic features of the isolates, including survival in simulated gastrointestinal conditions, antibacterial effect, auto-aggregation, antibiotic resistance, antimycotic and hemolysis ability, as well as antifungal activity against Aspergillus niger and Aspergillus flavus were studied. Based on sequencing results of the PCR products, Rhodotorula mucilaginosa was identified as the yeast isolate. The isolate had 85.07% viability in simulated gastrointestinal conditions. The inhibitory effect of the isolate on Escherichia coli was significantly (P<0.05) higher than the other foodborne bacteria. The yeast isolate had 84.60% auto-aggregation and 60.10% hydrophobicity capabilities. However, no hemolytic activity was observed. The yeast isolate was resistant to all of the studied antibiotics, and it was sensitive towards Ketoconazole among the common antifungal agents. In conclusion, the yeast isolate had appropriate potential to be used as a probiotic culture to produce fermented food products.

The growth of contaminating microorganisms in food products causes serious diseases in humans, and the use of lactic acid bacteria to control these contaminants is a promising and developing method. In this study, lactic acid bacteria were isolated from traditional yogurts and a total of 140 isolates were isolated. The probiotic potential of these lactic acid bacteria including resistance to acidic conditions, resistance to bile salts and sensitivity to ten important antibiotics were investigated and then bacteria with probiotic potential were used to inhibit food pathogens. The measured halo diameters of the bacterial medium were measured and recorded, and the antimicrobial properties of the strains were compared. ARDRA technique was also used to identify the strains. The results showed that all strains have excellent tolerance to pH 2.5 and bile salt of 0.3% and isolates Numbers 12, 100 and 102 are recognized as the most resistant strains against studied food pathogens. Findings from this study showed that yogurt samples are an important source for the production of bacteria with probiotic potential with antimicrobial activity and can be used against food pathogens.

As a natural bioproduct obtained from beekeeping, propolis with its antimicrobial and antioxidative properties can be used in food production. The purpose of this study is to evaluate the application of propolis as a preservative in food. After preparation of propolis, the physicochemical properties of raw propolis and extract were evaluated with three repetitions. the results showed that amount of waxes, moisture, fat, protein, ash and pH of raw propolis were 35.10±0.89%, 4.2±0.14%, 64.78± 0.22%, 2.30± 0.13%, 1.25± 0.25%, 4.89 ± 0.06 respectively. Obtained results of propolis extract analysis indicated that antioxidant activity, turbidity, pH, brix, total phenolic and flavonoids content of the prepared propolis ethanolic extract were 94.5±0.02%, 1.091±0.03%a.u., 5.9±0/12 and 18.5±0.07 Bx°, 91.12±0.09 mg/g (gallic acid) and 87.94±0.03 mg/g (quercetin), respectively. The extracted propolis extract was evaluated by Gas chromatography / mass spectrometry to identify chemical compounds. The results showed that the main constituents of propolis extract were included Pinostrobinchalcone (22.90%), Pinocembrin (6.14%), 2,1,3-Benzothiadiazole (5.76%), Tectochrycin (4.83%), Phenethylalcohol (4.25%), Oleic acid (3.10%). Evaluation of antimicrobial activity of propolis extract showed that the prepared extract had high antibacterial activity against Staphylococcus aureus while it was ineffective on Escherichia coli. The extract also inhibited the growth of Aspergillus fluvus fungus, unlike the control sample, so that its mycelia diameter was reached 7 mm after 8 days incubation. In general, the results showed that the produced propolis extract can be used as an effective natural preservative in foods.

One of the best ways to preserve meat is to freeze it, which can keep the meat in a natural state without significant spoilage. In this regard, this study aimed to investigate the effect of storage time (1, 7, 14, 21 and 28 days) in freezing (temperature -18 ° C) on chemical properties (humidity, ash, fat and protein), oxidation indices (peroxide, Conjugated diene and thiobarbituric acid), number of psychrophilic bacteria and structure of minced and non-minced beef fatty acids. The results showed that with increasing storage time, the amount of humidity and protein decreased, but the peroxide index, conjugated diene and thiobarbituric acid increased and there was no significant change in the amount of fat and ash in the samples. However, oxidation indexes of peroxide, conjugated diene and thiobarbituric acid in minced beef were not higher than minced meat. The maximum amount of peroxide (1.2 meqO2/kg) was related to the minced meat sample during 28 days of storage at freezing temperature. Based on gas chromatographic findings, there is no difference between minced meat and minced meat in terms of short chain fatty acids C10 to C20, and the amount of n-3 and n-6 fatty acids in minced meat is higher than minced meat. The results of bacterial count showed that the number of psychrophilic bacteria in meat samples did not increase during storage of meat at freezing temperature.