Study On The Process Technology Of Purple Breaded Shrimps By Vacuum Fried

Breaded shrimp is the main product of deep processing of shrimp because of its unique flavor and taste which is widely popular among global consumers and sells well in domestic and foreign markets.The sophisticated batter formulation and processed way always determine all the final quality performance of the breaded shrimps.At present,breaded shrimp always made in traditional fried with higher oil content which could be up to 50% of the total weight of the fried food.Higher oil absorption particularly leads to several serious health problems and the oil in breaded shrimps is easily prone to deteriorate during storage.In order to satisfy the higher requirements of consumers for the food nutrition and health,therefore,it is necessary to create a healthy breaded shrimp with lower fat,better quality and longer shelf life.This study firstly evaluate the characteristics and quality of a batter system with PSPF,soy protein isolate(SPI)and xanthan gum and develop for vacuum fried breaded shrimp,and then optimized the vacuum fried parameter of breaded shrimps with purple sweet potato flour in batter system.Finally,the quality changes and moisture migration of vacuum fired shrimps stored at different temperature were researched and built shelf life of vacuum fried purple breaded shrimps.Purple sweet potato flour(PSPF),soy protein isolate(SPI),and xanthan gum were used as coating materials.The effect of citric acid concentration on the color of batter system and vacuum fried purple breaded shrimps were investigated.In addition,the ratio of SPI and xanthan gum on the quality of vacuum fried purple breaded shrimps including the rheological properties,coating pick-up,color,moisture content,oil content,texture,anthocyanin content and antioxidant activity were studied.The result showed that when citric acid concentration of 0.3%,batter system and vacuum fried purple breaded shrimps have the best color.Compared with the control group,it was observed that the batter system with PSPF,SPI and xanthan gum had better rheological properties,and a ratio of2:1 for SPI to xanthan gum had the highest coating pick-up value(49.83%),the more attractive purple(a* = 3.07),less oil content(20.55%),retained higher anthocyanin content(51.71 mg/100 g)and PSPF vacuum fried shrimps showed high free-radical scavenging activity(60.19% for DPPH· and 35.97% for ·OH).Therefore,the batter system with PSPF,SPI and xanthan gum is widely used for vacuum fried breaded products.To optimize the vacuum fried parameter of breaded shrimps with purple sweet potato flour in batter system.Firstly,the effect of frying temperature,frying time and vacuum degree on the quality of vacuum fried breaded shrimps,such as: color,texture,moisture content,oil content,and anthocyanin content were investigated.As the result of the single-factor experiment and Box-Bohnken experimental design of response surface methodology,it was found that frying temperature,frying time and vacuum degree have significant effects on the quality of vacuum fried breaded shrimps(frying temperature >frying time > vacuum degree,P < 0.05).When vacuum frying temperature at 80 ℃,vacuum frying time at 18 min and vacuum degree on 0.08 MPa,the vacuum fried breaded shrimps had uniform and attractive color,crispy taste and complete shape with the sensory score of 85.19 ± 0.57,which was close to the predictive value(88.63).In order to study the quality changes of vacuum fired purple breaded shrimps stored at-16 ℃(frozen storage),0 ℃(ice storage),4 ℃(cold storage),25 ℃(room temperature)and 37 ℃(high temperature),the effect of storage temperature on several evaluation indicators in terms of color,total anthocyanin content(TAC),total viable count(TVC),acid value,peroxide value(POV)and moisture migration were investigated,and then predicting shelf life.The results showed that TVC,acid value and POV of vacuum fried purple breaded shrimp increased with the increase of storage time and temperature,which is obviously slower than vacuum fried traditional breaded shrimp.But TAC and the sensory score showed a decreasing trend.The change of the relative contents of bound water,immobilized water and free water of vacuum-fried purple breaded shrimp were studied by low-field nuclear magnetic resonance(LF-NMR)and imaging techniques(MRI).The result of LF-NMR showed a significant decreasing trend and migration in water with the change of storage time.TVC,acid value and POV were significantly correlated with the sensory score through Pearson correlation analysis.The results of the shelf life of vacuum fried breaded shrimps was 341,94,73,20 and 10 days stored at-18,0,4,25 and 37 ℃,which were all longer than the traditional fried breaded shrimp.