Effect of adjustable parallel high voltage on biochemical indicators and actomyosin Ca2+-ATPase from tilapia (Orechromis niloticus)

Oxidation of proteins in fish meat products leads to reduced water-retention capacity, protein solubility and actomyosin Ca2+-ATPase activity, followed by the loss the freshness and processing suitability. In this study, we investigate the effect of protein denaturation indicators such as water-retention capacity, protein solubility, actomyosin Ca2+-ATPase activity and appearance assessment on tilapia (Orechromis rtiloticus) meat stored in a refrigerator (4 degrees C, 75% RH) treated with various high-voltage electrostatic fields (HVEF) (300, 600 and 900 kV/m) continuously over a period of eight days. The moisture content of tilapia decreased from 78.6% to 74.0% after 8 days, and the HVEF (300, 600 and 900 kV/m) could retain the moisture content above 76.0% after 8 days. Besides, HVEF can delay tilapia protein water-retention loss at least 1.01 times longer than without HVEF treatment. Furthermore, HVEF can delay the water- and salt soluble proteins solubility increase by about 0.8-1.1 times and 0.95 times, respectively. Moreover, HVEF (300 kV/m) can more effectively inhibit actomyosin Ca2+-ATPase activity decrease at least 0.9 times longer than without HVEF treatment; in addition, increasing the electric field strength (600-900 kV/m) does not destroy enzyme activity. Above all, the biochemical indicators, sensory and appearance assessment also show that HVEF (900 kV/m) treatment can maintain the freshness and extend the shelf life 1.6 times longer than without HVEF treatment during the storage period at 4 degrees C, 75% RH. Besides, the HVEF (900 kV/m) treatment not only does not destroy the Ca2+-ATPase activity but also maintains actomyosin Ca2+-ATPase activity in application to the fish preservation industry. (C) 2016 Elsevier Ltd. All rights reserved.