| Blueberry,because of its high nutritional value and health promotion,is being welcomed by consumers,and new products made from this berry appear qucikly in domestic market.This study presents a technology for wine product brewed from wild blueberry juice.In this case,soda was added to adjust the acidity of blueberry juice,and two nitrogen sources were supplemented to enhance the activity of yeasts.The quality of blueberry-based wine was evaluated by physicochemical indexes,color and aroma components during the whole of fermentation process.Specifically,effects of yeast species plus nitrogen sources as well as pH plus aging on the quality of blueberry wine were discussed.The following are main results.1.Effects of yeast species plus nitrogen sources on the quality of blueberry wine.Firstly,blueberry wines supplemented with two types of nitrogen sources were fermented by two commercial yeasts.Physico-chemical indexes were tested,and the aromatic compounds of blueberry wine were analyzed by headspace solid-phase microextraction(HS-SPME)coupled to gas chromatograph-Mass spectrometer(GC-MS).As a result,the yeast "red fruit" in combination with the nitrogen "DAP" favored the fermentation of blueberry wine.The types and relative contents of aromatic compounds from the blueberry wine were richer than those of the controls.The major aroma components which contribute to the wine flavor,including isopentanol,isobutanol,ethyl acetate and acetoin were detected2.Effects of pH plus aging on the quality of blueberry wine.Physicochemical indexes,colors and aromatic compounds of the blueberry wines at pH 3.1,pH 3.3 and pH 3.5 were used to explore the effects of pH on the quality of blueberry wine.Changes in colors and aromatic compounds of the blueberry wine which was stored in bottles for 5-month aging were evauated.The results showed that lower pH was beneficial to the color-keeping of wine.During the whole period of aging,the content of anthocyanins in blueberry wine gradually decreased,and resultantly leaded to the red tone to decrease,the yellow tone to increase and the lightness to go up gradually.Aromatic compounds did not show a correlation to pH.Types of aromatic compounds did not change obviously during wine aging,but the levels of some aromatic compounds like alcohols,acids and terpenes decreased,especially dropped faster in the first two months.The levels of some esters,aldehydes and ketones showed an increase or unchanged throughout 5-month aging.3.Development of a blueberry wine brewing process.The present study suggests that an appropriate technology for blueberry wine production is initial pH-controlled to 3.3 by adding soda,in combination with the yeast "red fruit" and the nitrogen "DAP".In this way,the good fermentation of blueberry juice as raw material to wine product will takes place. |
