Study On Browning And Flavor Control Of Rosa Roxburghii Juice

Rosa roxburghii Tratt were rich in various of nutrients, which can be easily changed or lost during processing and storage. It caused the juice browning, texture deterioration, flavor dispersion, and other phenomena. Result in the volatile quality of Roxburghii juice products and effects commercial value. This study on the by using path coefficient analysis on major factors that cause browning, and inhibiting browning turn out the best manner; Research the aroma precursors and characteristics of Rosa roxburghii juice, and try using flavor enzymes to improve the aroma quality; Using the electronic nose, the electronic tongue and sensory evaluation, further explore the optimization process to improve product quality. The main conclusions of the papers are as follows:1. Use of electronic tongue technology combined with sensory method to determine the removal of bitter taste in Roxburghii juice. Result as, the best way to apart rosa roxburghii juice from the taste of astringent is adding 0.12% Tannase, during 45℃ heating 100 min, then add 0.015% sucralose.2. Ascorbic acid oxidative degradation and Maillard reaction was the main reason lead to non-enzymatic browning in Roxburghii juice during heating and storage.Researched the effected of Roxburghii juice browning inhibition by used different additives. Founded that glucose oxidase have the best effect to inhibitory browning in Roxburghii juice. Used Box-Behnken response surface experimental design to optimize glucose oxidase inhibition optimum conditions with three factors(enzyme amount, enzymatic hydrolysis time and temperature) in Roxburghii juice browning, obtained when glucose oxidase amount was 28U/L, reaction time was 38 min, reaction temperature at 37 ℃, Roxburghii juice browning inhibition best.3. Used Amberlite XAD-2 resin adsorbed flavor compounds of Roxburghii juice, free aroma compounds had the best elution when ether/pentane(1:1). By GC/MS analysis, it detected 49 kinds of free aroma compounds, mainly phenolic and esters. Used methanol adsorbed bound aroma compounds of Roxburghii juice in resin, by GC/MS analysis, it contain 30 kinds bound aroma compounds, was based on ketones and aldehydes, which has hexanol, geraniol, ionenes, acetophenone, ketoisophorone, hexanal, nonanal, benzaldehyde, etc. Those can enhance the aroma intensity in Roxburghii juice. While only 8 kinds of flavors detected at free and bound aroma compounds.After orthogonal optimization, the optimal enzymatic manner of Roxburghii juice was enzyme dosage 20U/L, reaction temperature 45℃, hydrolysis time 60 min. There was a significant enhanced of flavor after enzymatic. Used GC/MS analysis and sensory evaluation, found almond β- glucosidase enzyme better than Trichoderma β-glucosidase enzyme.Compared with flavor compounds of Roxburghii juice for enzymatic and non-enzymatic. Result as, Enzymatic treatment showed an increase of the type and content rosa roxburghii juice flavor, played the role of natural flavoring. It drawing 46 kinds of flavor compounds were detected in non-enzymatic Roxburghii juice, mainly in alcohols and aldehydes, the aroma components relative content was 45.055%; 56 kinds of flavor compounds were detected in enzymatic Roxburghii juice, mainly in alcohols and esters, the aroma components relative content was 72.127%. After digestion Roxburghii juice which leaves alcohol, ethyl carbonate, methyl heptenone, isovaleraldehyde, fragrant leaf alcohol and active amyl alcohol, etc., the relative content of those olfactory sense substances were improved. also adds a variety of aroma components, mainly esters and hydrocarbons, such as hexyl acetate, basil allyl acetate, ethyl benzene, β- caryophyllene, according to Duran, ethyl butyrate amyl acetate, etc., are to enhance the aroma rosa roxburghii juice contribute.4. Electronic nose and electronic tongue can better distinguish between the different treatment processes in Roxburghii juice. Combined with electronic nose, electronic tongue and sensory evaluation, it founded in accordance with add 0.12% Tannase at first, heating 100 min at 45℃; then add 20U/L β-glucosidase, heating 60 min at 45℃; then adding 28U/L glucose oxidase, heating 38 min at 37 ℃, and finally add 0.015% sucralose, resulting Roxburghii juice browning slowly, naturally rich aroma and tastes, bitter taste was almost removed, easily to be accepted.