The Study Of Blueberry Vinegar Processing Under The Condition Of Immobilized Fermentation

Blueberry also named Vaccinium, has rich nutrition with sour and sweet flavor. Fresh blueberry fruit are full of special nutrients like SOD, arbutin as well as anthocyania and have many health care effects. Our country has a great number of blueberry sources, most of which are fresh fruits. Blueberry is not easy to preserve and has low industrialization and usage efficiency. Thus, we studied blueberry processing technics using fresh blueberries based on blueberry product exploitation, improved blueberry vinegar flavor by introducing lactic acid fermentation and increased vinegar fermentation efficiency via using natural materials to immobilize acetification. We hope this can lay the foundation of blueberry product exploitation and offer theoretic basis as well as practice guide for its factory production.This project used vanillic aldehyde-sulfuric acid colorimetry to get the anthocyania concentrations in home-made blueberry juice, blueberry wine, blueberry vinegar as well as multi-strains fermented blueberry vinegar are58.15mg/mL,43.19mg/mL,36.18mg/mL and34.70mg/mL. During alcoholic fermentation the loss of anthocyania is comparatively large while during acetification and lactic acid fermentation the loss is small. Via HPLC method five organic acids including oxalic acid, tartaric acid, malic acid, shikimic acid and citric acid were detected in blueberry juice while the concentration of citric acid was up to90.41%of the total organic acid concentration; All different organic acids were detected in blueberry wine and blueberry vinegar and the concentrations of lactic acid, acetic acid, citric acid and succinic acid were over98%of the total concentration of organic acids. After the introduction of lactic acid fermentation, the concentration of lactic acid increased by1.8g/100mLUsing blueberry as raw material, with the help of Angle fruit wine yeast and Acteobacter Shanghai brewing1.01, after alcoholic fermentation and acetification blueberry vinegar can be produced. Via studying the processes of alcoholic fermentation as well as acetification, we get the applicable fermentation conditions are:For alcoholic fermentation pH is4～5, fermentation temperature is28℃, total carbohydrate concentration is20Bx°, inoculum size of yeasts is1X107/mL, fermentation time is5days; For acetification pH is3, fermentation temperature is30℃, initial alcohol content is6%Vol, inoculum size is10%, fermentation time is7days.By introducing acetic acid fermentation during the process of blueberry vinegar fennentation, we studied the fermentation order, inoculation time as well as inoculation ratio the three aspects of lactic acid fermentation. The results show that when blueberry vinegar alcoholic fermentation and lactic acid fermentation process at the same time, then introduce acetification with the inoculation ratio is1:2(the inoculum size of Yeast and Lactic acid bacteria are1×107/mL and0.5×107/mL). The produced the nonvolatile acids is2.25g/100mL which is1.77g/100mL more than blueberry vinegar of traditional process. The sensory assessments of the blueberry vinegar with multi-strains fennentation are also better than the traditional one. Based on the studies above, using bagasse, wood shavings, corncob, peanut shell and rice husk to study immobilized fermentation, the results show that after7days of acetification the concentration of total acids of mobilized acetic fermentation is4.32g/100mL, and that of the immobilized fermentation with bagasse, wood shavings, corncob, peanut shell and rice husk are6.04g/100mL,5.48g/100mL,4.79g/100mL,4.95g/100mL and4.62g/100mL; After evaluating the fermentation effects, products sensor assessment, performance of immobilization as well as stability of continuous fermentation of all kinds of materials, the results indicate that bagasse has the best products sensor assessment, the best ability and speed of immobilize acetic acid bacteria, the most stable fermentation curve as well as total acids product, and the most complete tissue condition preserved after continuous fermentation. Thus bagasse is the best immobilized carrier of immobilized acetification. Using bagasse as the immobilized carrier to ferment blueberry vinegar and studying the process of acetification indicate that immobilized acetic acid bacteria has the best performance of producing acids when the fermentation pH is3.5, temperature is30℃, initial alcohol content is6%Vol, media amount is200mL, the pouring frequency of2-3times a day. According to Box-Behnken central composite design, we optimize fermentation temperature, initial alcoholic content and volume the three processing conditions which have obvious effects on total acids concentration and get the best conditions for immobilized acetic fermentation is that fermentation temperature30.52℃, initial alcoholic content6.06%Vol and media amount196.47mL. Under these conditions, the predicting total acids concentration of samples after fermentation is7.46g/100mL; In the proof test, we measured the real total acids concentration is7.41±0.72g/100mL which has no significant difference with the predicting value of response surface.