Improvement of Vitis amurensis Rupr.grape quality by using fish protein hydrolysates as fertilizer

High quality wine grape is the first factor to satisfy the wine-maker to produce superior quality wines.In this work,a fish protein hydrolysates derived from deep-sea salmon or cod,was used as fertilizer to improve Shuanghong(Vitis amurensis Rupr.)grape quality.Application of powder fish protein hydrolysates fertilizer by spraying directly to foliar(4.5 kg/ha),to root(4.5 kg/ha)or to the both foliar(4.5 kg/ha)and root(4.5 kg/ha)were carried out respectively,during the period from 2–3 weeks before flowering until 2–3 weeks before harvest.Grape sampling was made at both veraison and harvest.Different classes of phenolic compounds,including 10 phenolic acids and 11 proanthocyanidins in grape seeds and 10 anthocyanins in grape skins were determined by UHPLC or HPLC;total anthocyanins and total polyphenols in grape skins were determined by spectrophotometric method.Antioxidant activities of the phenolic compounds were evaluated by ABTS and FRAP methods.The results showed that the application of fish protein hydrolysates fertilizer to both root and foliar led to a significant improvement of berry quality at harvest/maturity,i.e.,increasing 12.13%total polyphenols(TP),8.3%total anthocyanins 11.03%ABTS and 45.81%FRAP compared with control.Besides,both root and foliar application resulted in the highest individual anthocyanins and proanthocyanidins in grapes.These results suggest that the both root and foliar application could be of great interest for the viticulturists to produce grapes with higher polyphenolic content and antioxidant activity.Although this work was experimented with Vitis amurensis Rupr.grapes,the proposed methods would also be applicable to other grape varieties for the purposes of increasing anthocyanin or polyphenol contents.

Optimization of hydrolysis conditions for the production of protein hydrolysates from fish wastes using response surface methodology

The recycling of waste from food processing is an important industrial procedure for obtaining protein sources with high added value.In this study,trout(Onchorynchus mykiss),anchovy(Engraulis encrasicolus),and whiting(Merlangius merlangus)wastes were hydrolyzed.The hydrolyzation procedure was investigated under the optimum predicted conditions defined by time,temperature,and enzyme ratio(E/S)using alkaline protease(pH 8),Protamex(pH 7),and Flavourzyme(pH 7).The hydrolysis conditions that showed the best degree of hydrolysis(DH%)were optimized using response surface methodology(RSM)with the central composite design(CCD)and Box-Behnken design(BBD)models.The effects of three independent variables,temperature(40-60℃),time(1-8 h),and enzyme concentrations(1-2%),were examined for model optimization.It was determined that the DH%varies between 50.92%and 74.30% according to the type of fish waste and enzyme.The highest degree of hydrolysis was observed from trout waste(74.30%)and the lowest degree from whiting waste(50.92%)with Flavourenzyme.From this study,it has been shown that different degrees of hydrolysis and protein recovery can be obtained,depending on fish species,waste composition,enzyme type,and hydrolysis method.