Study On Quality Change And Color Protection Of Pickled Vegetables During Preservation

Pickled vegetable is a traditional fermented vegetable product and has a long history. Pickled vegetables is a kind of indispensable accompaniments,which is rich in amino acids and lactate acid,it has many advantages:rich nutrition,delicious and crisp,light and refreshing,promote digestion which was deeply loved by Chinese people, especially in the northeast of China.In this paper,the problems of preservatives abuse and microbial spoilage during production,distribution and sale were studied.We studied the change of quality during pickled vegetables storage.the development of the compound preservatives and color-protecting methods,the results were as followes:(1) In this studied,we found that the nitrite content in the pickled vegetables was6.03±0.15mg/kg before packaging.the content decreased to Omg/kg after the pickled vegetables preserved33d at37±,and decreased to0.77±0.09mg/kg after the pickled vegetables preserved33d at7℃,which indicated that the higher temperature of the preservation was,the faster the degredation of the nitrite;The total acid content was8.43±0.04g/kg during preservation.As the extension of time of the preservation, the total acid content increased to the maximum at first,and then decreased,when the conditions of preservation were at7℃and37℃,the maximum total acid contents were12.18±0.01g/kg and12.51±0.02g/kg respectively,the total acid content of the pickled vegetables preserved at7℃(8.91±0.02g/kg)was significantly higher than the total acid content of the pickled vegetables preserved at37℃(6.96±0.0] g/kg)after the pickled vegetables preserved33d (P<0.05).Therefore the total acid content of the pickled vegetables preserved at37℃decreased more rapidly.The amino nitrogen content showed the trend that decreaed at first and then increased,during the initial preservation,the content was0.79±0.01g/kg.The amino nitrogen content gradually increased to1.76±0.03g/kg when the pickled vegetables were preserved at37℃, and the amino nitrogen content was1.66±0.06g/kg when the pickled vegetables were preserved at7℃, the difference was not significant (P>0.05); the NaCl contents decreased to0.09±0.13g/kg and2.98±0.16g/kg respectively when the pickled vegetables were preserved at7℃and37℃,the difference was significant (P<0.05);The total sugar content was9.24±1.46g/kg at first,then decreased to0.59±0.15g/kg and0.76g/kg respectively,and the reducing sugar content was2.77±0.05g/kg at first,then decreased to0.13g/kg and0.77±0.04g/kg respectively, decreased by21.31times and3.60times respectively.(2) Dehydrogenation sodium acetate, sodium diacetate and potassium sorbate were used as factors and quadratic polynomial regression model equation was builded by multivariate regression fitting,Y=53.8218-17.7865X1—33.0102X2—52.3543X3+22.4388X12+121851X22+15.7213X32+14.2500X1X2—12.7500X1X3—0.7500X2X3,and the composite preservative regression model which was builded P<0.0001,which indicated that the regression model was highly significant;lack of fit P=0.143>0.05showed that lost item was not significant(.P>0.05), and in line with the model requirements.The best preservative formulations optimization:amount of sodium dehydroacetate was0.016%(g/g),sodium diacetate was0.266%(g/g) and potassium sorbate was0.032%(g/g).The variance analysis results showed that potassium sorbate had the strongest bacteriostatic effect,sodium diacetate was second which was followed by dehydrogenation sodium acetate.According to formulation optimization compound preservative formula was obtained and verification test was processed,the total number of colonies was5.63×102cfu/mL and less than the predicted value.which showed a good anticorrosive effect in preservation.(3) This study found that the L*value of pickled vegetables which added sodium erythorbate were preserved at37℃for30days was significantly higher than the control groups (P<0.05),but the L*value differences between which added0.06%(g/g)and0.08%(g/g)sodium erythorbate were not significant(P>0.05), the optimal supplementation of sodium erythorbate was0.1%(g/g);the L*value of pickled vegetables which added0.004%(g/g)and0.005%(g/g)sodium pyrosulfite were significantly increased(P<0.05). While the L*value of the pickled vegetables which added0.004%(g/g)and0.005%(g/g)sodium pyrosulfite were not significant differences(P>0.05),when the pickled vegetables were preserved after30d and45d. Therefore, the optimal supplementation of sodium pyrosulfite was0.004%(g/g).(4) In the same packaging conditions we found that L*value of pickled vegetables which preserved in different temperatures were significantly different (P<0.01). The Aluminum foil bags and PE bags in two different packaging and refrigeration conditions, the L*value of pickled vegetables which preserved after30d and60d almost unchanged;L*value of pickled vegetables which preserved in the foil pouch packag after30d and60d were significantly higher than which packed in PE bags(P<0.01).(5) This study found that the pickled vegetables were soaked for2h in preservatives without sterilization were better in these experiments,L*values of these pickled vegetables were higher than spray groups and the control groups (P<0.05).