This study was investigated the effects of some oils on chemical, microbiological and sensory quality in vacuum packed smoked rainbow trout (Oncorhynchus mykiss W.1792) fillets. Acceptability scores for appearance, taste and odour of untreated and treated smoked trout decreased with storage time. The limit of sensory acceptance was reached after 56 days for the untreated samples, after 84 days for with rosemary and thyme oil-treated samples after 98 days for with sage oil-treated and after 112 days for with clove oil-treated samples. Significant differences were not found between groups as microbiological (p > 0.05). However, significant differences were found both among groups and during the storage in term of TBA (thiobarbituric acid) and PV (peroxide value), FFA (free fatty acid) values (p < 0.05). Essential oils as natural antioxidant can be used in conjunction with vacuum packed to enhance hot smoked fish quality.
Effects of chitosan coating combined with sumac on the quality of rainbow trout (Oncorhynchus mykiss) fillets stored in refrigerated condition (4°C) for 12 days were evaluated. The treatments in this study were—T1, control; T2, chitosan: 2% w/v; T3, chitosan: 2% w/v and sumac: 1% w/v; and T4, chitosan: 2% w/v and sumac: 2% w/v. The shelf life of the samples were determined periodically using physicochemical (pH, peroxide value [PV], thiobarbituric acid [TBA], and total volatile basic nitrogen [TVB‐N]), microbiological (total viable counts [TVCs] and psychrotrophic bacteria), and sensory analyzes. During the storage period, T3 and T4 groups showed lower pH, PV, TBA, and TVB‐N values than T1 and T2 groups. The sensory results are in line with chemical and microbiological results. Treatment with 2% chitosan + 1% sumac and 2% chitosan + 2% sumac increased the shelf life of rainbow trout fillets by 6 days as compared to the control samples.
Practical applications
To avoid the adverse effects of chemical preservatives and to answer natural and reliable product demands of the consumers, plant extracts and edible coatings are applied to increase the shelf life and to prevent the spoilage of fresh fish. The results of this study reported the efficacy of chitosan edible coating combined with sumac as a new natural preservative for improving the shelf life of rainbow trout fillets. The findings revealed that sumac extract combined with chitosan coating can be an alternative method to extend the shelf life, to preserve the quality and safety of fish, as a result of their good antioxidant and antimicrobial activity.
In this study, the effects of the different concentrations of rosemary (Rosmarinus officinalis) extract on the shelf life of hot-smoked and vacuum-packed Luciobarbus esocinus fillets were investigated in terms of its microbiological, chemical and sensory quality. The results showed that rosemary extract had a significant effect on lactic acid bacteria, psychrophile bacteria, yeast-mold, thiobarbituric acid and peroxide value during storage (P < 0.05). The shelf lives of smoked L. esocinus fillets to which rosemary extract was added were determined to be 42 days for 400 mL/L, 84 days for 600 mL/L and 800 mL/L brine. Also, that in the control group (without rosemary extract) was determined to be 42 days. Rosemary extract was effective in controlling the growth of bacteria and chemical indices.
PRACTICAL APPLICATIONSHot smoked fish stored in anaerobic conditions is very sensitive to deterioration and, based on sensory evaluation, has a limited shelf life ranging from 3 to 4 weeks at refrigerator temperature. Natural extracts have proven to be an effective preservation method for the extension of shelf life of foods. Our study has clearly shown that addition of rosemary extract in smoked fish resulted in longer shelf life, and this method could be commercially used.
Guran H.S., Oksuztepe G., Coban O.E., Incili G.K. (2015): Influence of different essential oils on refrigerated fish patties produced from bonito fish (Sarda sarda Bloch, 1793). Czech J. Food Sci., 33: 37-44.The effects of different concentrations of thyme (group T), clove (group Cl), and rosemary (group R) extracts on the microbiological, chemical, and sensory attributes of fish patty made from the bonito fish (Sarda sarda Bloch, 1793) were investigated. The numbers of total mesophilic aerobic bacteria, coliform bacteria, Staphylococcus-Micrococcus spp. and yeasts and moulds in group R were lower than those of the other groups during storage (P < 0.05). During the storage period, total volatile basic nitrogen (TVB-N), thiobarbituric acid index (TBA-i), peroxide values, and free fatty acid content gradually increased in all groups, and significant differences were found between the groups (P < 0.05). The results of sensory evaluation showed that the shelf life of fish patties was 4 days for the control group, and 8, 10, and 14 days for the groups treated with thyme, clove and rosemary essential oil, respectively (P < 0.05). In conclusion, the addition of essential oils showed a positive effect on the product shelf-life; and in particular, rosemary essential oil produced a remarkable effect.
Consumer demand for food of high quality has driven research for alternative methods of food preservation on the one hand, and the development of new and rapid quality assessment techniques on the other hand. Recently, there has been a growing need and interest in healthier food products, which has led to an increased interest in natural preservatives, such as essential oils, plant extracts, and edible films and coatings. Several studies have shown the potential of using biopreservation, natural antimicrobials, and antioxidant agents in place of other processing and preservation techniques (e.g., thermal and non-thermal treatments, freezing, or synthetic chemicals). Changes in food quality induced by the application of natural preservatives have been commonly evaluated using a range of traditional methods, including microbiology, sensory, and physicochemical measurements. Several spectroscopic techniques have been proposed as promising alternatives to the traditional time-consuming and destructive methods. This review will provide an overview of recent studies and highlight the potential of spectroscopic techniques to evaluate quality changes in food products following the application of natural preservatives.
In this study, sage, thyme and clove oils were evaluated as a glazing material for rainbow trout (Oncorhynchus mykiss) frozen. One percent sage, thyme and clove oil solutions were used for glazing. Water‐glazed (WG) and nonglazed (NG) rainbow trout fillets were used as controls. Fish fillets were glazed and were stored in a freezer at −18C for 6 months. Samples were analyzed at 1, 2, 3, 4, 5 and 6 months for moisture content, total volatile basic nitrogen, thiobarbituric acid, peroxide value, free fatty acids and sensorial quality. It was determined that glazed samples had higher moisture content compared to NG trout fillet after 6 months storage. Essential oils were effective in controlling lipid oxidation in rainbow trout fillet (P < 0.05).
PRACTICAL APPLICATIONS
Freezing is one of the most employed methods used for preserving fresh fish and other seafood products. However, frozen storage does not completely inhibit chemical reactions (e.g., lipid oxidation) that lead to quality deterioration of fish and fish product. The antioxidant property of some essential oils may make it ideal for use as a glazing solution for suppressing lipid oxidation in rainbow trout fillet during frozen storage.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.