Study On The Effects Of Bromelain On The Quality Of Smoked Salted-duck

Smoked salted-duck is one of the typical representatives of Chinese traditional meat products.However,the traditional processing method of smoked salted-duck has a long production cycle and low efficiency.Due to the high processing temperature,the modern processing method results in serious oxidation and unsatisfactory flavor.It seriously restricts the healthy development of the smoked salted-duck industry.It has been found that exogenous proteases could promote protein degradation,increase tenderness,improve flavor of meat products during the processing.However,there is no report on the effects of bromelain on the quality of smoked salted-duck.Therefore,applying bromelain to the processing of smoked salted-duck has important application potential and value for improving product quality and flavor.This thesis systematically studied the qualities of smoked salted-duck treated with bromelain,such as cooking loss,p H,texture characteristics and myofibril properties.Based on this research,the changes in salt and moisture content during the production process of smoked salted-duck were measured.In order to analyze the effect of bromelain on the structure of smoked salted-duck,transmission electron microscopy observation was measured.In terms of protein oxidation,the contents of carbonyl group and sulfhydryl group,and the surface hydrophobicity of myofibril protein were measured.In addition,this subject further studied the flavor substances during the processing of smoked salted-duck treated with bromelain.Free amino acids,free fatty acids and nucleotides,combined with volatile flavor substances were measured to explore the effects of bromelain on smoked salted-duck during processing.The main findings are as follows:1.Effect of bromelain on the eating quality of smoked salted-duckThis chapter investigated the effects of different concentrations of bromelain on the eating quality of smoked salted-duck.The results showed that treatment with bromelain could significantly reduce the p H value and the cooking loss of smoked salted-duck,and inhibit the lipid oxidation(P <0.05).At the same time,through SDS-PAGE and mass spectrometry analysis,the myosin and actin in smoked salted-duck were also extensively degraded due to the enzymatic hydrolysis of bromelain.Thereby,these changes reduced hardness and improved springiness and cohesiveness of smoked salted-duck(P <0.05).Electronic tongue analysis showed that when the concentration of bromelain was 900 U/g,the umami and richness of smoked salted-duck were increased,and the bitterness was reduced(P <0.05).Combined with sensory evaluation,it could be concluded that bromelain treatment could improve the eating quality of smoked salted-duck in paritular at the addition level of 900 U/g.2.Effect of bromelain treatment on cathepsin activity and myofibrillar protein properties of smoked salted-duck during processingThis chapter determined the effect of bromelain treatment on the quality of smoked salted-duck from the aspects of cathepsin activity and protein properties.The results showed that bromelain treatment had no significant effects on salt content,moisture content and activities of cathepsin B and L of smoked salted-duck(P>0.05).The transmission electron microscopy showed that the structure of myofibril was destroyed due to the treatment of bromelain,thereby improving its texture properties of smoked salted-duck.During the processing of smoked salted-duck,the carbonyl content was gradually increased and the sulfhydryl content was gradually decreased(P <0.05).The treatment of bromelain could significantly reduce the carbonyl content and increase the sulfhydryl content of smoked salted-ducks(P <0.05).It showed that bromelain treatmet could significantly reduce the protein oxidation level of smoked salted-duck during processing.3.Effect of bromelain treatment on the substance of taste and flavor of smoked salted-duck during processingThis chapter studied the effect of bromelain on the substance of flavor and taste quality of smoked salted-duck during processing.The results showed that free amino acids were gradually accumulated during processing.Bromelain treatment could increase the content of free amino acids,especially essential amino acids(P <0.05).At the same time,bromelain treatment increased the content of monounsaturated fatty acids,specifically oleic acid and palmitoleic acid(P <0.05).Bromelain treatment also significantly increased the content of inosine 5’-monophosphate and cytidine 5’-monophosphate,and decreased the content of inosine(P <0.05).It indicated that the treatment of bromelain could affect the accumulation of flavor substances during the production of smoked salted-duck.GC-MS results showed that the bromelain treatment could produce more types of flavor substances.The content of phenols,acids and ketones were increased(P < 0.05),indicating that bromelain could increase the volatile flavor substances of smoked salted-duck.