Effect of alginate-gallic acid coating on freshness and flavor properties of Mackerel (Scomberomorus commerson) fillets under refrigerated storage.

This study investigates the effect of sodium alginate-gallic acid (ALG-GAL) coating on mackerel's flavor compounds and quality properties during cold storage at 4 °C for 12 days. To this end, freshness quality indicators, including biogenic amines (BAs), volatile organic compounds (VOCs), ATP-related compounds, K value, total viable counts (TVC), thiobarbituric acid (TBA), and sensory assessment, were measured. During storage, eight BAs, i.e., histamine (HIS), tyramine (TYR), putrescine (PUT), cadaverine (CAD), 2-phenylethylamine (2-PHE), agimation, spermine (SPM), and spermidine (SPD) were identified in control and treated samples. The biogenic amine index (BAI) for control samples was 56.25 at the time of sensory rejection (day 6). BAI for samples coated with ALG-GAL did not exceed 20 mg/100 g at the time of sensory rejection (day 12). The fillets treated with the ALG alone or incorporated with GAL possessed a different trend in the retardation of VOCs, including aldehydes, ketones, alcohols, and hydrocarbons. Seven key flavors VOCs, including 3-methylbutanal, phenylacetaldehyde, E-2-hexanal, 1-hexanol, 1-octen-3-ol, 2,3 pentanedione, and hydroxyl-2-butanone, were identified in control and coated samples. Samples coated with ALG and GAL were of significantly higher quality (p < 0.05) throughout storage, which could result in lower Inosine (HxR) concentrations and K values. The results of TVC showed that use ALG-GAL had lower bacterial counts compared to control (p < 0.05). The ALG-GAL-coated samples retarded the increase in the contents of TBA during storage. In addition, significant differences in sensory scores between ALG and ALG-GAL were observed (p < 0.05). In this study, aldehydes and hypoxanthine (Hx) were the main compounds in the formation of off-flavor. These results revealed that ALG coating combined with GAL improved the quality of refrigerated mackerel fillets by decreasing off-flavor compounds and TVC population.

Effect of a chitosan-based nanocomposite containing ZnO and Zataria multiflora essential oil on quality properties of Asian sea bass (Lates calcarifer) fillet.

This research aimed to estimate the effects of chitosan (CH) coating in combination with zinc oxide nanoparticles (ZnONPS) and Zataria multiflora essential oil (ZEO) on the bacterial and biochemical properties of the Asian sea bass (Lates calcarifer) fillets during refrigeration storage (4 ± 1 °C). The fillets were randomly divided into five treatments (CH, CH-ZnONPS, CH-ZEO, CH-ZnONPs-ZEO, and control). Then, the treated fillets were kept at 4 °C and quality analysis was performed on days 0, 4, 8, 12, and 16. The results revealed that the combination of ZnONPs and ZEO with CH coating is an active coating with antimicrobial effects. Also, the coated fillets improved the biochemical properties (such as FFA, TBA, TVBN, pH) as well as color properties during refrigeration storage. The highest rate of FFA (3.59 ± 0.08%oleic acid), TBA (1.43 ± 0.00 mg MDA/kg), TVBN (30.82 ± 0.30 mg/N100g), and pH (7.38 ± 0.03) was recorded in control fillets while the lowest rate of FFA (2.19 ± 0.00%oleic acid), TBA (0.61 ± 0.00 mg MDA/kg), TVBN (19.60 ± 0.20 mg/N100g), and pH (6.99 ± 0.04) was recorded in CH-ZnONPs-ZEO coated fillets (p < 0.05) on day 16. The sensory acceptance score was better than that of the control treatment on days 8 and 12 in Sea bass fillet coated with CH-ZnONPs, and CH-ZnONPS/CH-ZEO, respectively, and it was lower the critical score for fishery products. The combination of nanoparticles or essential oils (individually or in combination together) with edible coatings (chitosan) could increase and optimize the storage time of refrigerated seafood.

Effect of chitosan-whey protein isolated coatings incorporated with tarragon Artemisia dracunculus essential oil on the quality of Scomberoides commersonnianus fillets at refrigerated condition.

The purpose of present work was to assess the effects of chitosan (CH) coating in combination with whey protein isolated (WPI) and tarragon essential oil (TEO) on the bacterial (total mesophilic (TMC) bacteria and psychrotrophic (PTC) bacteria), physicochemical (total volatile bases- nitrogen (TVB-N), pH, thiobarbituric acid reactive substances (TBARS), free fatty acid (FFA)) and sensory properties of Scomberoides commersonnianus muscle during storage at refrigerator (4 ± 1 °C). The fillet were randomly divided into seven lots and subjected to the following treatments by immersion: chitosan (CH), whey protein isolate (WPI), whey protein isolate- TEO (WPI-TEO), chitosan-TEO (CH-TEO), chitosan-whey protein isolated (CH-WPI), chitosan/whey protwin isolated+ TEO (CH/WPI + TEO) and controls, then stored at 4 °C. Results indicated that incorporation of WPI and TEO into the material coating developed active coatings with good antimicrobial agent growth inhibition activity against TMC and PTC bacteria. The coated samples also retarded the increase in the contents of TVB-N, pH, TBARS and FFA during storage. The score less than critical score of 3 was made at day 8 and 12 for fillet coated with control and coated samples except of fillets coated with chitosan, respectively. These results confirmed that the incorporation of essential oils or other biopolymers into edible coatings may improve the deterioration of chilled seafood.

The shelf life extension of refrigerated Nemipterus japonicus fillets by chitosan coating incorporated with propolis extract.

In this study, chitosan coatings incorporated with propolis extract (PE) were utilized to extend the shelf-life of refrigerated Nemipterus japonicus fillets. Microbiological (total mesophilic bacteria (TMB) and total psychrotrophic count (TPC)), physicochemical (pH, total volatile bases nitrogen (TVB-N), 2-thiobarbituric acid reactive substances (TBARS), free fatty acid (FFA)) and sensory (color, odor and preference) characteristics of coated fillets were evaluated during 12days. The results showed that incorporating PE into chitosan solution could significantly (P<0.05) improve the quality of fish fillets. The results showed that the chitosan+PE samples reduced the extent of lipid oxidation, as judged by TBARS and FFA, suggesting that there is a synergistic effect between chitosan coating and propolis. Moreover, the application of chitosan coatings with PE improved the TVB-N and pH values of the Nemipterus japonicus samples significantly compared to untreated sample, thus extending the shelf life of Nemipterus japonicus fillet approximately >10days. All wrapped fillets in treatment samples incorporated with PE had lower bacterial counts compared to control (P<0.05). However, the bacterial counts of chitosan coating combined with PE were lower than those treated by chitosan or PE alone during the storage. The fillets treated with chitosan and PE had the best sensory properties. The increase (>10days) in the shelf-life was attributed to the antioxidant and antimicrobial characteristics of chitosan and PE. These results confirmed that chitosan coating enriched with PE can be an improving method to reducing deterioration of refrigerated Nemipterus japonicus fillets.