Study On Fermentation Process Of Monascus Pitaya Wine

Fruit wine has been developed rapidly due to its great flavor and excellent healthcare function.As a consequence,the study on novel fruit wine has become a new research hotspot these days.Pitaya wine was considered as one of emerging fruit wine products.However,it was urgent to improve the quality of pitaya wine mainly because its flavor was not pleasant enough to be favored by all customers.Therefore,an innovative type of monascus pitaya wine was developed using yeast and monascus during the primary and the secondary fermentation process,respectively.In order to obtain monascus pitaya wine with pleasant flavor,coordinate taste and stable quality,three aspects was studied in the present work:(1)An innovative type of fermentation process of monascus pitaya wine was established.The primary and the secondary fermentation process were analyzed on the basis of box-behnken central composite design.And response surface method(RSM)was used to establish a mathematical model so as to optimize the corresponding fermentation process.The conditions of primary fermentation were obtained as follows: fermentation time(5.3 d),fermentation temperature(29.3 °C),inoculum concentration of yeast(0.024%),and sucrose addition(17.4%).The score of sensory valuation for the wine after the primary fermentation was 86.8.And the conditions of secondary fermentation were follows: fermentation time(62 h),3fermentation temperature(30.2 °C),and inoculum concentration of red kojic rice(9.2%).Based on the above-mentioned optimal condition,the total ester content in pitaya wine was significantly improved to 15.415 g/L with a high sensory valuation score at 91.1.(2)Based on the headspace solid-phase microextraction-gas chromatography-mass spectromete(HS-SPME-GC-MS)technique,the internal standard method was employed to measure 8 kinds of important ester components in monascus pitaya wine.The results were obtained with low detection and quantitative limits,showing that this method was appropriate for detecting ester components in fruit wine.The content of ester components in pitaya wine was compared,including the monascus wine samples obtained after the primary and the secondary fermentation process,and also the pitaya wine prepared by traditional method.The results showed that the ester content in the monascus pitaya wine sample after the secondary fermentation process were significantly higher than the traditional pitaya wine.Besides,the aroma components,namely ethyl acetate,isoamyl acetate,ethyl hexanoate,isoamyl acetate,and phenethyl acetate,had important effect on forming typical flavor of monascus pitaya wine.In addition,the aroma contents and score of sensory evaluation were basically stable during the earlier storage stage,but decreased rapidly after that.For more clarification,the ester content in monascus pitaya wine greatly decreased during the whole storage time.The decomposed fruit aroma were mainly attributed to the decrease of ethyl acetate and ethyl hexanoate.Besides,the negative effect on wine flavor was mainly due to the increased contents of ethyl lactate,ethyl butyrate,and phenethy.However,the low-temperature storage technique had great benefits on improving the quality of monascus pitaya wine.(3)The color of monascus pitaya wine significantly changed during the storage process.For more clarification,the brightness value(L*)and yellow blue value(b*)increased,but the red and green value(a*)decreased.The color of wine sample deteriorated to salmon pink after a short time storage,and then dark brown after the long time storage.Thus,6 kinds of additives were used to inhibit the color changes.The results indicated that D-sodium isoascorbiate,citric acid,and potassium sorbatehave good effect on protecting the color.In order to improve the color protection effect,D-Sodium isoascorbiate and citric acid were used as a compound color fixative.Based on the total addition of 0.3%,the radio between D-Sodium isoascorbiate and citric acid at 2:1 was benefit for storage.Compared with the traditional pitaya wine,this innovative monascus pitaya wine was significantly better in both flavor and color aspects.It is a clear indication that our study on fermentation process of monascus pitaya wine could bring real benefits to quality enhancement,which would further provide a good reference for developing other innovative kinds of fruit wine.