نشریه بهداشت مواد غذایی
سال دهم شماره 4 (پیاپی 40، زمستان 1399)

The coating is one of the methods to extend the chicken fillet shelf life. The present study was conducted to evaluate the effect of carrageenan edible coating (1%) containing (Mentha longifolia) essential oil (1.5%) on the quality of chicken fillet during refrigerated storage. Samples were separated into three groups: uncoated (control), coated with carrageenan and coated with carrageenan contained essential oil (Mentha longifolia) were stored at refrigerator temperature for 21 days and were evaluated for microbial (psychrotrophic and mesophilic) counts, chemical properties [pH, total volatile nitrogen (TVN) and thiobarbituric acid (TBA)] and sensory characteristics (appearance, muscles elasticity, odor, and color). The results of the bacterial analysis showed that coating with carrageenan and carrageenan- essential oil coatings had significant effects on delaying the increasing trend of psychrophilic and mesophilic bacterial counts as compared to control. Chemically, carrageenan-essential oil treatment showed lower TBA, TVN, and pH values ​​than the other two groups during storage (p < 0.01). Moreover, the carrageenan and carrageenan contained essential oil treatments maintained sensorial factors at acceptable levels for 3 and 9 days respectively. Based on the results of the present study, carrageenan coating did not have the ability to extend the shelf life of chicken fillets but, the carrageenan-essential oil coating could extend the shelf life of chicken fillets for 9 days.

< p >Regards the economic potential in extensive rearing of Narrow-clawed crayfish (Astacus leptodactylus) in Haft Barm lakes, Fars Province (Iran), and considering the chain value and global marketing, we need to monitoring programs on hygienic quality of this export product in terms of heavy metal accumulation. For this purpose, crayfish specimens were captured with 45 total samples from three permanent lakes and transported to the laboratory. Preparing of their tail meat as the edible parts and measuring of heavy metals (Cd, Cu, Ni, Pb, and Zn) have been accomplished via the wet digestion method and atomic absorption spectroscopy (AAS), respectively. Results showed that Cd (0.004±0.003) and Zn (2.61±0.747 µg/g DW) were the minima and maximum concentrations in the tail meat of Haft Barm’s crayfish. Since the concentrations of all measured trace elements were within the permissible limits of hygienic standards (WHO and FAO) and based on health risk assessment (daily intake index), Haft Barm’s crayfish have admissible health in terms of their accumulation. Hence, daily and continuous consumption of these aquatic products by consumers has been thoroughly safe, and there is no risk for them in this regard.

Listeria monocytogenes (Lm) is an important foodborne pathogen that is of great importance in milk and its products. Despite the measures taken to eliminate and control Lm contamination in pasteurized milk products, but due to its high spread in the environment, there is a possibility of secondary contamination in products such as Ultra-filtered (UF) white cheese. This study aimed to investigate the inhibitory effect of nisin-producing Lactococcus lactis on Lm in Ultra-filtered white cheese. Ultra-filtrated and pasteurized cow's milk was inoculated with 3 Log CFU/g of standard or native strains of Lm and control and treatment (containing nisin-producing L. lactis) cheese samples were manufactured. Changes in the population of Lm and nisin concentration were estimated throughout the storage period. According to the results, in all groups, the population of Lm began to decrease from day five onwards. Nonetheless, the decreasing trend in the treatment samples and in parallel with the production of nisin was significant (p < 0.01). The native strain of Lm was significantly (p < 0.01) more resistant than the standard one. Since the nisin-producing L. lactis, despite inhibiting Lm, did not negatively affect the growth of starter bacteria and the resulting pH decline of the cheese samples. Consequently, nisin-producing L. lactis can be used to control some bacterial contamination of the UF white cheese. It is also necessary to study the behavior of native strains isolated from food samples along with laboratory strains in inoculation studies.

Shrimp is one of the seafood that its wholesomeness plays a major role in human health. Shrimp spoils very quickly due to having unsaturated fatty acids. However, with timely and early detection, many economic losses can be avoided. For this purpose, various methods are used to detect healthy shrimp from spoiled ones. The most common methods are the sensory and physical examination of shrimp, chemical and microbial tests. In this study, a colorimetric indicator was fabricated using biodegradable polyvinyl alcohol/Chitosan film based on the color changes of hematoxylin at different pH values. Changes in pH, total volatile basic nitrogen contents (TVBN), and colorimetric characteristics of shrimp specimens were examined by contact with this color indicator. The suggested indicator in response to pH shows a variety of colors ranging from light yellow to dark purple in mildly acidic to strong alkaline environments. The performance of the proposed indicator in the detection of shrimp freshness by contact and non-contact methods confirmed that does not necessarily need to be in direct contact with the shrimp and has the ability to show its reaction to the shrimp freshness even in the presence of shrimp. In addition, there is a strong correlation between the total volatile basic nitrogen contents due to shrimp spoilage and the color characteristics of the indicator. The results showed that the proposed indicator is good sensitive to pH changes and shows shrimp spoilage through color changes. Therefore, this colorimetric indicator can be easily used in smart packaging.

In water applications, improper drainage systems increase the pollution of water resources. This study aimed to find an eco-friendly water disinfectant in the coagulation stage of drinking water treatment plants. In this study, iron oxide nanoparticles were synthesized by the co-precipitation method. The antibacterial activity of iron oxide nanoparticles was assessed on six important water-polluting bacteria (Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus cereus, and Staphylococcus aureus). The results showed that the highest effect of synthesized iron oxide nanoparticles with MIC< 0.07 μg/ml is against B. cereus and E. faecalis. In addition, iron oxide nanoparticles had antibacterial activity against Staphylococcus aureus with MIC= 0.3 μg/ml and in K. pneumoniae with MIC= 1.25 and P. aeruginosa and E. coli with MIC= 0.6 μg/ml. MBC results showed that iron oxide nanoparticles were to eliminate 99.9% of E. coli and S. aureus bacteria at a concentration of 1.25 μg/ml and K. pneumoniae at a concentration of 2.5 μg/ml. The obtained results show the antibacterial potential of nanoparticles for use in water treatment. It seems that the use of Fe3O4 nanoparticles as adsorbents in the water treatment process can be an efficient and economical alternative to disinfect water in the early stages of water treatment.

Rice is one of the world's most commonly consumed cereals. Consequently, its contamination by food contaminants, including heavy metals, should be taken into consideration. The purpose of this study was to determine the level of heavy metal contamination in rice samples of Hashemi cultivar harvested randomly from three areas of Masal, Shanderman, and Soomehsara in the west of Gilan province. In the second stage, the effect of two factors of soaking time of rice before cooking and cooking method (drained and boiled) on changes of heavy metals in consumed rice was evaluated. Following the preparation and digestion steps, the concentration of heavy metals (lead, cadmium, chromium and nickel) was determined using induced plasma mass spectrometry (ICP-MS). The results showed that in comparison with the other two regions and the standard limit, the concentrations of Cr and Ni in rice harvested from the Shanderman region (with 2.1 and 1.35 ppm, respectively), were significantly higher contamination. The results showed that washing and soaking the rice were very effective in reducing the heavy metal content. Moreover, cooking rice using the drainage method was more effective in reducing the concentration of heavy metals than the boiled method. Due to the difference in the effect of soaking treatments and different sintering methods in reducing the concentration of metals, using a combination of 3 consecutive washes and 6 hours of soaking and cooking in both methods is introduced as the most effective treatment in reducing the concentration of heavy metals.