Shelf-Life Extension of Fish Samples by Using Enriched Chitosan Coating with Thyme Essential Oil

Bilayer coatings for extension of the shelf life of fish fillets: Incorporating seaweed sulfated polysaccharides in chitosan-alginate LbL structures

The aim of this study was to develop a new active coating of layer-by-layer (LbL) structure composed of alginate (as polyanions) and chitosan (as a polycation) containing sulfated polysaccharide (fucoidan) from Sargassum angustifolium, to protect rainbow trout fillets during refrigerated storage. Chitosan and alginate do not combine with each other as a homogeneous solution, so they are suitable for multilayer coatings. The results demonstrated that coating samples with chitosan and fucoidan significantly improved the quality of fish fillets and extended their shelf life from 6 to 16 days. The chemical values (TBARS and TVB-N) and bacterial growth (total viable count (TVC), total psychrophilic count (PTC), and lactic acid bacteria (LAB)) indicated lower levels in the LbL coating samples containing fucoidan compared to the alginate and control samples. Among the different coating samples, the LbL coating with fucoidan (AChF1) exhibited lower weight loss, improved chromaticity (L*, a*, and b*), and minimal changes in mechanical and sensory evaluations. Based on the findings, AChF1 was the most effective treatment for increasing the shelf life of rainbow trout fillets during refrigerated storage. Therefore, it has potential applications in the food packaging industry.

Investigation of physio-mechanical, antioxidant and antimicrobial properties of starch-zinc oxide nanoparticles active films reinforced with Ferula gummosa Boiss essential oil

The production of surface compounds coated with active substances has gained significant attention in recent years. This study investigated the physical, mechanical, antioxidant, and antimicrobial properties of a composite made of starch and zinc oxide nanoparticles (ZnO NPs) containing various concentrations of Ferula gummosa essential oil (0.5%, 1%, and 1.5%). The addition of ZnO NPs improved the thickness, mechanical and microbial properties, and reduced the water vapor permeability of the starch active film. The addition of F. gummosa essential oil to the starch nanocomposite decreased the water vapor permeability from 6.25 to 5.63 g mm-2 d-1 kPa-1, but this decrease was significant only at the concentration of 1.5% of essential oils (p < 0.05). Adding 1.5% of F. gummosa essential oil to starch nanocomposite led to a decrease in Tensile Strength value, while an increase in Elongation at Break values was observed. The results of the antimicrobial activity of the nanocomposite revealed that the pure starch film did not show any lack of growth zone. The addition of ZnO NPs to the starch matrix resulted in antimicrobial activity on both studied bacteria (Staphylococcus aureus and Escherichia coli). The highest antimicrobial activity was observed in the starch/ZnO NPs film containing 1.5% essential oil with an inhibition zone of 340 mm2 on S. aureus. Antioxidant activity increased significantly with increasing concentration of F. gummosa essential oil (P < 0.05). The film containing 1.5% essential oil had the highest (50.5%) antioxidant activity. Coating also improved the chemical characteristics of fish fillet. In conclusion, the starch nanocomposite containing ZnO NPs and F. gummosa essential oil has the potential to be used in the aquatic packaging industry.

Studying the microbial, chemical, and sensory characteristics of shrimp coated with alginate sodium nanoparticles containing Zataria multiflora and Cuminum cyminum essential oils

Retardation of quality loss of seafood has been a new concept in recent years. This study's main objective was to evaluate the microbial, chemical, and sensory attributes of shrimp coated with alginate sodium nanoparticles containing Zataria multiflora and Cuminum cyminum essential oils (EOs) during refrigerated storage. At the end of storage time (15 days storage at 4°C), the pH, thiobarbituric acid reactive substances (TBARS), and total volatile basic nitrogen (TVBN) amounts in shrimps coated with the alginate nanoparticles were 7.62, 1.14 mg MDA/kg, and 117 mg/100 g which were significantly (p < .05) lower than the control groups. The count of all bacteria groups was also lower in this treatment, which was 2-2.74 Log CFU/mL on day 15 of cold storage. This combined treatment also obtained the highest sensory scores (around 7) and the lowest melanosis score (2.67) due to the effective delaying microbial and oxidation activities. Therefore, this edible coating could substantially retard microbial and chemical changes and improve the organoleptic properties of shrimp under refrigerated storage.

Impacts of Nano-Gelatin Coating Containing Thymol and Nisin on Chemical Quality Indices of Rainbow Trout Fillets Stored at 4°C

Background: Seafood such as fish is an integral part of human nutrition and an excellent source of protein. However, their short shelf life is quite challenging for the food industry. Objectives: This study was carried out to investigate the effects of nano-gelatin coating embedded with thymol and nisin on the chemical quality indices of rainbow trout fillets during 16 days of storage at 4°C. Methods: The fillets were randomly divided into six groups, including control (C), gelatin (G), nano-gelatin (NG), nano-gelatin + thymol (NG-T), nano-gelatin + nisin (NG-N), and nano-gelatin + nisin and thymol (NG-T-N). The chemical quality of fish samples was assessed by performing pH, thiobarbituric acid reactive substance (TBARS), peroxide value (PV), free fatty acid (FFA), and total volatile basic nitrogen (TVB-N) analyses every four days. Results: The results revealed the stunning effect of nisin and thymol addition to the nano-gelatin coating on all chemical quality indices. Besides, PV, TBARS, and FFA analyses showed that nano-gelatin containing thymol significantly decreased lipid oxidation in fish fillet samples (P < 0.05). The lowest amounts of PV (8.33 meq oxygen/kg oil), TBARS, and FFA were recorded for NG-T-N. The best results in the TBARS test (P < 0.05) were observed in NG-T-N, followed by NG-T (1.45 and 1.69 mg of malonaldehyde/kg of tissue, respectively), and similar results were recorded for FFA analysis. On day 16, the lowest amounts of TVB-N were measured for NG-T-N, followed by NG-N and NG-T (26.13, 29.86, and 38.26 mg N/100 g, respectively). Both nisin and thymol reduced the TVB-N and increased the shelf life, and the best results were observed in groups treated with nisin and thymol simultaneously. However, the application of gelatin and nano-gelatin coating without nisin and thymol was ineffective in improving the chemical quality of samples, and they must be used with nisin and/or thymol. Conclusions: Gelatin nanogel embedded with thymol and nisin can be utilized to enhance the chemical quality and shelf life of fish fillets.

Recent developments of natural antimicrobials and antioxidants on fish and fishery food products

Fish and fishery products (FFP) are highly perishable due to their high nutritional value and moisture content. The spoilage is mainly caused by microorganisms and chemical reactions, especially lipid oxidation, leading to losses in quality and market value. Microbiological and lipid deteriorations of fishery-derived products directly lower their nutritive value and pose the risk of toxicity for human health. Increasing demand for safe FFP brings about the preservation using additives from natural origins without chemical additives due to their safety and strict regulation. Antimicrobials and antioxidants from natural sources have exhibited an excellent control over the growth of microorganisms causing fish spoilage via different mechanisms. They also play a major role in retarding lipid oxidation by acting at various stages of oxidation. Antimicrobials and antioxidants from natural sources are usually regarded as safe with no detrimental effects on the quality attributes of FFP. This review provides recent literature on the different antioxidant and antimicrobial agents from natural sources, focusing on microbial and oxidative spoilage mechanisms, their inhibition system, and their applications to retard spoilage, maintain safety, and extend the shelf life of FFP. Their applications and benefits have been revisited.

Antioxidant and antibacterial properties of coating with chitosan-citrus essential oil and effect on the quality of Pacific mackerel during chilled storage

The goal of the study was to investigate whether chitosan-citrus essential oil composite works as an efficient preservative in Pacific mackerel (Pneumatophorus japonicus) during chilling storage. FT-IR analysis showed that chitosan-citrus essential oil coating was successfully prepared. Our results demonstrated that chitosan-citrus essential oil coating possessed significantly higher capability of scavenging reactive oxygen species ( O 2 - and OH-) than chitosan. Furthermore, Pacific mackerel coated with chitosan-citrus essential oil composite could significantly reduce parameters of corruption including physicochemical (drop loss, biogenic amine, and thiobarbituric acid-reactive substances) and microbiological parameters (total viable count), as compared with untreated and chitosan groups after 12 days of storage at -3°C. These results indicated that CS-CEOs could work as efficient preservative for Pacific mackerel storage through ameliorating redox state and inhibiting microbial growth and suggested that chitosan-citrus essential oil composite has great potential in preservation of aquatic products during superchilled storage.

Effect of anchovy by-product protein coating incorporated with thyme essential oil on the shelf life of anchovy (Engraulis encrasicolus L.) fillets

The effects of anchovy by-product protein coatings incorporated with thyme essential oil (TEO) on the shelf life of anchovy (Engraulis encrasicolus L.) fillets stored at 4 ± 1 °C were investigated. We grouped fillets in three categories: untreated fillets, fillets treated in coating solution alone, and fillets treated in coating solution containing 1.5% TEO and analyzed on 0, 3, 6, and 9 days of storage. It was observed that the total volatile basic nitrogen (TVB-N) and pH of all the fillet groups increased under cold storage conditions; however, this increase was much slow in both the coated anchovy fillets. Both coating applications slowed down the lipid oxidation but the coating containing TEO exhibited better effect than coating alone. The coating application alone or with essential oil had limited effect on microbial growth but positively affected the sensory quality. These results revealed that anchovy by-product protein coating mixed with TEO may prolong anchovy fillets' shelf life stored under cold condition.