Study On The Quality Of Hanfu Apple-sweet Potato Compound Juice

Apples are rich in carbohydrates,vitamins and trace elements."Hanfu Apple" cultivated by Shenyang Agricultural University has good flavor and good quality,its growing area has been increasing in recent years.Processing Hanfu apple into beverage can not only improve the taste of the drink but also increase the income of farmers.Sweet potato,distributed in most areas of China,contains large amounts of nutrients,including polysaccharides,proteins,carotenoids,vitamins,as well as flavonoids,anthocyanins and other polyphenols with a lot of functions such as lowing blood fat,anti-tumor,scavenging free radicals,anti-aging.At present,the research on compound fruit and vegetable juice is scared.In this paper,preparation and the quality of compound juice made of Hanfu apple and two varieties of sweet potatos(YAN25and L20)were studied.The results are as follows:1.The effects of the addition of sweet potato powder and apple on the quality of the composite juice were determined through sensory evaluation,the determination of phenolic substance,antioxidant activity,rheology,stability and other chemical indexes.The results showed that with the increase of addition of sweet potato powder and apple,the content of the pectin,dietary fiber and carotenoid in the compound juice were increased,while the content of phenolics,ABTS and DPPH free radicals scavenging activities increased first then downward.When their additions added to an extent,the fluidity and flavor become unfavorable for consuming.when the addition of sweet potato powder was 10% and the addition of apple was 25%,the quality of compound juice made of Hanfu apple and two kinds of sweet potato were best.2.The effects of sucrose,citric acid,xanthan gum,sodium methylcellulose sodium,and sterilization on the quality of composite juice were studied.The optimal formula for the composite juice of the Hanfu apple and YAN25 was: 10% of sweet potato powder,25% of apple,adding 8% of sucrose and 0.15% of citric acid,0.15% of xanthan gum,and 0.15% of methyl cellulose sodium;The optimal formula for Hanfu apple and L20 composite juice was:10% of sweet potato powder,25% of apple,adding 9% of sucrose,0.10% of citric acid,0.15% of xanthan gum and 0.15% of methyl cellulose sodium.After sterilization,the content of polyphenols and antioxidant activity of the two composite juices decreased,so long-term thermal treatment should be avoided during processing.3.The effect of compounding on the content of polyphenols,flavonoids,dietary fiber,pectin,and the scavenging activities on DPPH and ABTS free radicals were studied.The results showed that the bioactive components and antioxidant activities of composite juice were higher than the materials.The content of polyphenol,flavonoids,carotenoid,dietaryfiber and pectin of Hanfu apple-YAN25 composite juice was 8.68mg/100 g,5.66mg/100 g,5.97g/100 g and 8.65g/100 g respectively.The content of polyphenol,flavonoids,dietary fiber and pectin of Hanfu apple-L20 compostie juice was 23.15 mg /100 g,19.17mg/100 g,7.0g/100 g and 10.25g/100 g respectively,The scavenging activities on DPPH and ABTS free radicals of the two composite juice were 59.35% and 73.81%,77.37% and78.87% respectively.The contents of phenol,pectin,dietary fiber and carotenoid in the compound juice were significantly higher than those in the corresponding pulp.The results showed that the compound could increase the content of nutrients and functional components in single raw material pulp.Spss software was used to study the relationship between nutritional composition and antioxidant activity in YAN25-and L20-Hanfu apple juice.The results showed that polyphenols,flavonoids and anthocyanins in YAN25-Hanfu apple composite juice were found to be very important.The effects of dietary fiber,carotenoid and compound juice on antioxidant activity were significant(p<0.01).L20-Hanfu The effects of polyphenols,flavonoids,anthocyanins,dietary fiber and pectin on antioxidant activity of composite juice were significant(p<0.01).Through the calculation of the synergistic antioxidant coefficient,the synergistic effect between polyphenols of Hanfu apple and sweet potato was studied.The results showed that there was synergistic antioxidant effects between the polyphenols of the materials.Besides,polyphenols in composite juice also had synergistic antioxidant effects with cellulose,carotenoid.