Control Methods Of The Quality Distortion Of Salted Radish And Their Mechanism Analysis

Salted radish is one of the main products of salted products.It has bright colors,unique flavor and texture,and has been interested by consumers.However,the traditional salting process(such as dry salting)that most food factories still use today will cause severe color,flavor,and texture deterioration during the long-term salting of radish,which will affect the entire product.The result causes huge economy loss every year.Therefore,the change mechanism of color,flavor and other quality indicators in the process of salting radish is explored,and research a new type of salting processing technology of improving the quality of radish in the salting process is proposed,which has great practical significance,and it can provide an effective reference for the salting of other vegetables too.In this paper,we used white radish as salting materials,citric acid as acidifying agent,to study the effect of different acid treatment on the quality of radish in the salting process,including different pH acid salting,traditional salting combined with follow-up long-term acid salting,traditional salting before acid treatment.The results of different pH acid salting showed that long-term salting at pH 2 and pH 3 groups maintained the best radish color,but the texture were destroyed more seriously.For flavor,gas chromatography-mass spectrometry(GC-MS)results showed that the content of sulfur compounds and esters in the volatile substances of salted radish accounted for the absolute proportion of flavor substances,and which were the main flavor of salted radish.The pH of the salting solution has a great influence on the flavor of salted radish.With the decrease of salting solution's pH,the content of the salted radish's flavoring material decreases rapidly.The partial least squares regression(PLSR)was used to analyze the flavor and sensory results of the salted radish,and dimethyl disulfide,dimethyl trisulfide,4-methylthio-3-butenyl isothiocyanate,glutaric acid dimethyl ester and methyl furandicarboxylate were determined have a significant correlation with the flavor of salted radish.There has a significant positive correlation between dimethyl trisulfide and the color of salted radish(p < 0.05).The color,texture and flavor of radish salted by traditional salting combined with follow-up long-term acid salting are not good,which shows this method is not conducive for long-term salting of radish.Based on the above experimental results,the changes in the color of salted radish were used as an indicator,the enzyme activities of polyphenol oxidase(PPO)and glucosinolates(glucosidase)were used as the basis for the acid treatment of salted radish,which were salted by the traditional salting process after acid treatment.The correlation between the color of the salted radish and the two enzyme activities were analyzed by SPSS,and the results showed that the activities of the two enzymes had extremely significant correlation with the color of the salted radish(p < 0.01);GC-MS analysis showed radish's flavor compounds were closely related to the pH of the previous acid treatment,and which have little to do with the initial pH of the later salting.On this basis,further accurate acid treatment was used,while the determination of PPO enzyme activity,glucosidase activity,total phenol,protopectin content and other indicators of salted radish were measured and used SPSS for correlation analysis.The color of salted radish was significantly correlated with the enzyme activity(p < 0.05),demonstrating the reliability of these two enzyme activities as acid treatment basis;the crispness of salted radish and the content of protopectin had significantlly Positive correlation(p < 0.01).The results of salting showed that the pH 2.2 and pH 2.4 groups could inhibit the deterioration of radish color well.Adding 0.4% CaCl2 can maintain crispness of radish effectively.According to the results above,the salted radish with traditional salting process were used short-term acid processing,the determination of color difference display pH 2.2 acid solution can better inhibit the traditional salting process radish color deterioration during processing.The formulation and stability of salted radish liquids were verified and improved,and according to the problem of browning and flaking of preserved radishes during shelf life,the additives were selected to improve the radish's quality: For crispening agents,0.2% calcium lactate was added in the liquid,it has a good protective effect on radish texture.For color protection,five different color-retaining agents were selected for color protection,and accelerated experiments were performed in 35°C incubator.The results showed that citric acid and EDTA-2Na can provide effective protection for radish color.