Study On Processing Technology Of Raspberry Juice And Pomace Jam

In this paper,the nutrition composition and juice yield of raspberries with different maturity were compared.Based on the above investigation,raspberries with maturity of 80%to 90%were chosen as material for juice making.The effects of pectinase on juice yield,and the processing technology and storage stability of raspberry juice were studied.The processing technology and storage stability of jam,which was made from raspberry pomace,was also studied.The main results were as follows:1.Nutritional components of raspberry with two different maturitiesThe contents of the main nutrients of raspberry with two different maturities(maturity of 60%to 70%and 80%to 90%)were compared.The results showed that except for the water and pectin contents,the contents of total sugar,total acid,protein,vitamin C,total phenol,anthocyanins,ellagic acid,raspberry ketone of raspberry with maturity of 80%to 90%were higher than that of raspberry with maturity of 60%to 70%.2.Technological parameters and storage stability of raspberry juiceTreatment with pectinase could increase the juice yield of raspberry significantly,and the juice yield of raspberry with maturity of 80%to 90%is higher than that of raspberry with maturity of 60%to 70%.The enzymolysis conditions optimized by orthogonal experiment were as follows:pectase addition 0.05%(w/w),enzymolysis temperature 45?,enzymolysis time 1.75 h.Under these conditions,the juice yield of raspberry was 80.63%.Citric acid can improve the stability of raspberry juice color,and the effect was better than other organic acids.Quercetin and rutin have little protective effect on raspberry juice color.Using sensory evaluation and anthocyanin retention as indicators,the formula of raspberry juice optimized by orthogonal experiment were as follows:juice to water 1:3,sugar 8 g/100mL,aspartame 0.015 g/100mL,citric acid 4.5 mmol/100mL.There was no significant change in soluble solids,pH,total sugar and total acid(P<0.05)of the raspberry juice during the storage process,and the contents of total phenolics,Vc,anthocyanins and fruit juice absorbance decreased significantly.The quality of the juice was stable when stored at 4?,the pH value,the absorbance and the content of the main nutrients in the juice were more stable than that at 37?,indicating that low temperature was beneficial to the preservation of fruit juice,and the shelf life of the juice can be extended through a low temperature storage.3.Technological parameters and storage stability of raspberry pomace jamRaspberry pomace also contains rich nutritient,with the content of total phenol and anthocyanin of 461.81 mg/100g,and 47.42 mg/100g,separately.The optimal production process of raspberry pomace jam was optimized by orthogonal experiment.As follows:the ratio of pomace to water 4:5,pectin 4.5 g/100 g,sugar 25 g/100 g,brew time 3 min.After stored at 37? for 60 days,the contents of soluble solids,total soluble and total acid of the jam were not significantly changed(p<0.05).The contents of total phenol and Vc decreased significantly by 39.31%and 46.41%,separately.