Litchi Flavor Analysis And The Development Of Lactic Acid Bacteria Fermented Litchi Beverage

Litchi beverage had three major technical problems during sterilization and storage, the loss of aromatic substances, browning, precipitation, which determine its quality. To solve the above problem, this paper analyzed the volatile flavor compounds in different varieties of fresh litchi juice and commercial litchi beverage; the fermentation process of lactic acid bacteriawere optimized,and the quality changes during processing and shelf lifewere also studied. The main conclusions are as follows:1. There was a significant difference between volatile components of fresh litchi juice and litchi drinks, the common component only had D-limonene and ethanol. Characteristic volatile substances of fresh litchi were mainly acetic acid, myrcene, terpinolene, trans-1-methoxy-3-methyl-1-butene, ethanol, 1-butanol, 3-methyl-, acetate, hexanal, acetaldehyde, 3-methyl-3-buten-1-ol, D-limonene,(+)-4-carene, D-citronellol, ethyl acetate.2. The influences of pectin, Sodium carboxymethyl cellulose(CMC), sodium alginate and xanthan gum on the stability of fermented/non-fermented litchi juice beverage were carried outaccording to the single factor assay. The results showed that viscosity and turbidity of litchi juice beverage increased when the amount of stabilizer increased. Add the same amount of a stabilizer, stability of fermented juice is better than fresh lychee juice. Pectin and CMC had great effect on the stability of the fermented litchi juice.3. Increase the amount of sugar, the viscosity and turbidity of lactic acid bacteria fermented lychee beverages were increased. In order to obtain consistency of the juice within the acceptable range of the senses, the final amount of sugar was 1.5%. Response surface design optimizes the kind and amount of stabilizer, the results showed that lactic acid fermented litchi beverage added stabilizer pectin 0.2%, 0.12% sodium alginate, litchi juice diluted with 99.68%, lychee drinks reached a relatively good result for stability.4. UHP treatment had a good effect on retention of flavor,color and nutrients for litchi juice beverage. During storage, The browning of UHP litchi juice beverage was lower, the content of vitamin C was higher, total phenol and antioxidant capacity were also higher than those of heat treatment. The small change of b* value was also observed in UHP treated juice.Comparing to the heat treatment of litchi juice, the turbidity of lactic acid fermented litchi beverage was bigger, and the browning was lower, extracellular polysaccharides content was higher, the consumption of glucose and fructose was slower. The treatment of UHPand fermentation has good effect onretentioncolor of litchi juice.Lactic acid bacteria fermentationcould make the litchi juice stable. The browning degree, b* value, total color difference and color changes of UHP fermentation litchi juice were minimum. The color of fermented litchi juice treated by UHP was most close to the fresh juice.