Investigation of the inhibitory effect of some reducing agents on enzymatic browning ( melanosis ) in different shrimp species

In the shellfish sector, black spot formation called melanosis affects the appearance of the products negatively. This browning is harmless in terms of quality, but it significantly reduces its acceptability by the consumer and therefore causes economic loss. To prevent this problem, sulfides have been used as major inhibitors of melanosis worldwide. However, because of the frequent allergic reactions that cause health problems in humans, it is being investigated whether there are natural alternatives to the chemical compounds used to prevent melanosis. Various techniques and mechanisms have been developed for this purpose for many years. Most of the methods have focused on the inhibition of the activity of the polyphenol oxidase (PPO). There are studies on the use of ascorbic acid and erythorbic acid on fruits and vegetables to prevent the browning. Ascorbic acid and its isomer erythorbic acid are the best alternative reducing agents to sulphite. It is generally used as an anti-melanotic agent in fruit juices, purees, sliced, fruit, canned fruits and vegetables. However, there have been no studies on the use of them for shrimps. On the other hand, it is reported that the development of melanosis in shrimps differs among species and this difference is caused by differences in substrate level, enzyme concentration and enzyme activity. Therefore, in this study, it was aimed to investigate the effect of ascorbic acid and erythorbic acid which are from reducing agents, on the development of melanosis in different shrimp species. For this purpose, the combination of sulphide application, known as the best melanosis inhibiting agent and the effects of combinations of reducing agents and sulphate have been tried. Three shrimp species (Aristomorpho foliacea, Pleosonica edwardsi and Melicertus hathor) have been used as research material. 10 different groups have been formed in the experiment. In these groups, both ascorbic acid and erythorbic acid have been applied in combination with sodium metabisulphite as well as by themselves. In addition, sodium metabisulfite has been applied alone for comparison. A group of shrimps that untreated has been also considered a control. Erythorbic acid, ascorbic acid and sodium metabisulphate solutions have been prepared with distilled water. Immediately after catching, 10 shrimps have been separated and stored at + 4 ° C after being immersed in the solutions. During the storage, the development of melanosis in shrimp has been examined daily and other quality control analyzes have been conducted. Total volatile basic nitrogen (TVB-N), trimethylamine (TMA-N) and pH values increased during the storage period in treated groups. Although the difference between the application groups in terms of TVB-N, TMA-N and pH values was not statistically significant, when compared with the control group. It was observed that the use go of ascorbic acid and erythorbic acid alone or combinations with sulfide were effective in protecting the quality.When the shrimp species were compared, the highest TVB-N value was determined in P. edwardsi species.The TVB-N values of A. foliacea and M. hathor species were found to be lower. The lowest TMA-N value was determined in M. hathor species. The TMA-N values of A. foliacea and P. edwardsi species were found to be higher. The highest pH value was determined in P. edwardsi species. The pH values of A. foliacea and M. hathor species were found to be lower. Although L *, a * and b * values were not statistically different between the application groups, it was observed that the application of ascorbic acid and erythorbic acid affects the color values when applied with sodium metabisulphite. When the shrimp species were compared, the highest L * value was determined in P. edwardsi species. The L * values of A. foliacea and M. hathor species were found to be lower. The highest a * value was determined in A. foliacea species. The lowest a * value was found in P. edwardsi and M. hathor species. The highest b * value was determined in A. foliacea species. The next highest value was P. edwardsi and the lowest value was M. hathor species. Although there was no statistically significant difference between the treatment groups in terms of melanosis values, it was determined that ascorbic acid and erythorbic acid and their combinations were effective in retarding the melanosis when compared with the control group. When the shrimp species were compared, the highest melanosis value was determined in M. hathor species, and the highest value of A. foliacea and P. edwardsi species was found to be lowest. When examined in terms of storage days, melanosis values increased due to storage and reached the highest value on 96 hours