Effect of carboxymethyl cellulose-based coatings incorporated with Zataria multiflora Boiss. essential oil and grape seed extract on the shelf life of rainbow trout fillets

To prolong the shelf life of seafood products, lipid oxidation and growth of microorganisms should be retarded. The objective of the current study was evaluating the potential application of carboxymethyl cellulose (CMC) coatings incorporated with Zataria multiflora Boiss. essential oil (ZMEO) and grape seed extract (GSE) on chemical (thiobarbituric acid reactive substances (TBARS) and total volatile basic nitrogen (TVB-N)), microbial (total viable count, lactic acid bacteria and Pseudomonas spp.) and organoleptic attributes of rainbow trout fillets during refrigerated storage for twenty days. GCeMS analysis showed that ZMEO is rich in monoterpene phenols such as thymol and carvacrol. The following results were obtained after 20 days of storage: The minimum level of TVB-N was measured in the fillets coated with CMC + 2 v/v ZMEO + 0.5 v/v GSE. The minimum number of total viable bacteria, lactic acid bacteria and Pseudomonas spp. were determined in the fillets coated with CMC + 2 v/v ZMEO + 1 v/v GSE. The fillets coated with CMC + 1 v/v ZMEO + 1 v/v GSE showed the best organoleptic properties. Our results revealed that CMC-based coatings incorporated with ZMEO and GSE could improve chemical, microbial and sensorial characteristics of rainbow trout fillets during cold storage. © 2015 Elsevier Ltd

Antibacterial activity of acetic and lactic acid against Listeria monocytogenes and their effect on the intracellular constituent release

Background: Organic acids (e.g. acetic and lactic acid) have been used in foods as natural preservatives. Acetic acid and its salts are used in foods as antimicrobial and acidulant agents. The aim of this study was to evaluate the antibacterial activity of acetic and lactic acids against the Listeria monocytogenes. Materials and Methods: This experimental study was conducted at the Department of Food Hygiene (Faculty of Veterinary Medicine, Urmia University) during autumn 2015. The antibacterial effects of acetic and lactic acid against Listeria monocytogenes were determined using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and cell constituents release methods. The concentration ranges of acetic and lactic acid (0.0195-10 and 0.043-22.2 μl/ml, respectively) were used to determine the MIC of acids. Results: Based on the results, acetic and lactic acid inhibited the growth of Listeria monocytogenes and acetic acid had stronger effect against the the bacterium. The MIC values for acetic acid and lactic acid were 2.5 and 5 μl/ml, respectively. Cell constituents release showed that acetic and lactic acids are able to lyze the bacterial cell. Conclusion: Acetic and lactic acids were effective in inhibiting the growth of Listeria monocytogenes and the antibacterial effect of acetic acid was stronger than that lactic acid. These acids can be used in foods in combination with other preservatives to inhibit the food borne pathogens and food spoilage microorganisms

Effects of Thymus vulgaris and Mentha pulegium on colour, nutrients and peroxidation of meat in heat-stressed broilers

This study was designed to investigate the effects of Thymus vulgaris (thyme) and Mentha pulegium (mentha) powders on meat colour, nutrient composition and malondialdehyde (MDA) where broiler chickens were under heat stress. Two hundred one-day-old male chicks were used in a completely randomized design with four treatments and five replicates each (10 birds per replication). Treatments were the control diet, 0.5% mentha, 0.5% thyme and 0.5% mixture of the two plants. The results showed no effect of dietary supplements on thigh meat redness and yellowness. Both plant products diminished the thigh lightness significantly compared with the control. No significant differences between treatments were observed for the ash, ether extract and crude protein content of the thigh muscle. Supplementation of thyme and mentha separately or together increased the moisture of the thigh muscle significantly, compared with the control. The combination of the plant products resulted in a higher thigh pH and significantly lower malondialdehyde (MDA) concentration in the thigh muscle compared with the control. In conclusion, dietary supplementation of thyme and mentha separately or in combination improved the meat quality of broiler chickens under heat stress through decreasing the MDA concentration and increasing the pH and moisture content of the thigh muscl

Histamine determination in Koopeh cheese in West-Azerbaijan province by HPLC

Histamine as a primary heterocyclic amine has an important role in human physiology particularly in nervous system as a chemical mediator and neurotransmitter that was found in many foods such as cheese, milk, meat, fish, beer, wine and vegetables. Increasing of histamine concentration in foods is often related to low quality of raw materials, contamination, improper food processing or storage. Therefore, the amount of histamine content is used as a good indicator of hygienic quality in foods and the degree of freshness or spoilage of foods. Histamine can cause symptoms in sensitive consumers such as: redness of face, sweating, palpitations, headache, oral burning and bright red rashes. Cheese provides an ideal environment for the production of proteolytic releases of free amino acids and biogenic amines such as histamine. The aim of this study was to evaluate the amount of histamine in Koopeh cheese as one of the most popular types of traditional cheeses made from raw sheep milk or sometimes cow milk in West-Azerbaijan province, Iran. Experiments conducted by HPLC method on 70 samples of traditional Koopeh cheese revealed that the least amount of histamine was 2.43 ppm and the highest value was estimated at 1102.24 ppm. The average amount of histamine in cheese samples was 304.23 ± 150.89 ppm. Histamine production in cheese and other foods is based on the presence and growth of decarboxylase-positive microorganisms. Therefore, providing guidelines that reduce the population of these types of microorganisms will be effective on decreasing the amount of biogenic amines and histamine in particular

Effects of Rhus coriaria on nutrient composition, thiobarbituric acid reactive substances and colour of thigh meat in heat-stressed broilers

Heat stress negatively affects the meat quality in broiler chickens, as indicated by lipid peroxidation. The aim of this study was to investigate the effects of 0.0, 2.5, 5.0 and 10 g sumac fruit powder/kg of the diet, along with 100 mg α-tocopherol acetate (AT)/kg as antioxidants, on meat characteristics of broilers under heat stress conditions. Consumption of 5.0 g sumac/kg decreased the thiobarbituric acid reactive substance (TBARS) concentration in thigh meat. The thigh meat pH increased only as a result of AT consumption. Dietary inclusion of both AT and 10 g sumac/kg decreased the fat content of the meat. None of the meat colour indices, lightness (L*), redness (a*) and yellowness (b*), was affected by dietary treatments. It was concluded that dietary sumac consumption improved the TBARS and pH, and decreased thigh meat fat in broilers under heat stress.Keywords: Alpha tocopherol acetate, chicken meat quality, intramuscular fat, pH, sumac, lipid oxidatio

Effect of cinnamon essential oil and grape seed extract as functional-natural additives in the production of cooked sausage-impact on microbiological, physicochemical, lipid oxidation and sensory aspects, and fate of inoculated Clostridium perfringens

The present study was conducted to extend the shelf life of Lyoner-type sausages during 40 days of storage at 4 °C with individual and combinational use of natural preservatives including cinnamon essential oil (CEO) and grape seed extract (GSE). The samples were analyzed for physicochemical properties (pH, aw, and color changes), lipid oxidation (thiobarbituric acid reactive substances TBARS), microbial quality (Lactic acid bacteria count, total viable count, psychrotrophic count, mold and yeast count, and fate of inoculated Clostridium perfringens), and sensorial characteristics (taste, odor, color, texture, and overall acceptability) at 10-day intervals. Results indicated that using GSE and CEO had higher ΔE (.55–1.56), a* (13.03–13.91), and lower L* (65.10–66.82), b* (15.40–16.65), whiteness index (59.45–60.60), TBARS values (2.91–3.28), and microbial counts than control at the end of storage time. Samples containing CEO.04%+ GSE.16% showed the best antimicrobial activity against C. perfringens (reduction of 1.72 log10 CFU/g at the end of storage time). Results also indicated that CEO addition and GSE addition improved odor and color scores of the samples, respectively. Therefore, use of CEO and GSE, especially in combination, is recommended to be applied in meat products. Practical applications: Nowadays, because of the adverse effects of chemical preservatives, application of multipurpose natural preservatives in small quantities is a more preferred approach. Therefore, to increase the shelf-life and quality characteristics of meat products, new ingredient systems that are associated with natural and organic foods, are applied. The results of the present study showed the synergistic effects of combined use of CEO and GSE in maintaining the quality of fresh meat products as well as preventing their undesirable impacts on sensory attributes and physicochemical properties. Thus, combinational use of CEO and GSE due to extending the shelf life and safety of meat products can practically profit both producers and consumers. © 2018 Wiley Periodicals, Inc