Research On The Processing Technology And Storage Characteristics Of Xiangxi Ponkan Glutinous Rice Wine And Crisp Cake

Xiangxi Ponkan（Citrus reticulata Blanco cv.Ponkan） is a local citrus hybrid,native to Hunan Province,and characteristically produces large yields of high quality and very nutritious fruits.At present,the Xiangxi Ponkan fruits are mainly sold fresh with very limited processing into other products.This makes the industry prone to fluctuations in market prices and inability to sell due to large number of fruits in the market,resulting in huge losses to both the fruit growers and the business people.In view of the above problems,this paper aimed at exploring new processing technologies for Xiangxi Ponkan fruits,using the fruits as the main raw material to produce green,healthy and nutritious low-alcohol Ponkan glutinous rice wine,and using Ponkan pomace as the filling of Chinese shortcake to produce Ponkan pomace shortcake with unique flavor.The comprehensive utilization of Xiangxi Ponkan fruit was studied through the above two processing methods.The main results were as follows;（1）Study on the preparation technology and quality of Ponkan glutinous rice wineIn this study,Angel liquor-flavor sweet wine starter(saccharifying enzyme activity was about 141±2.31 mg·g^-1·h^-1)was selected as the fermentation starter of Ponkan glutinous rice wine.Through single factor and orthogonal experiments,the optimal fermentation conditions of Ponkan glutinous rice wine were obtained as follows:after primary fermentation for 54 h,30%Ponkan juice and 0.4 g/L fruit wine yeast were added for secondary fermentation for 24 h.The obtained Ponkan glutinous rice wine had rich flavor,mellow taste and moderate sweet and sour taste.In order to further improve the taste and flavor of the wine,the wine was blended,and the optimal blending technology was obtained by orthogonal optimization as follows:15%Ponkan juice,0.06%citric acid and 0.1 g/L xylitol were added,and the dilution ratio was 40%.The blended Ponkan glutinous rice wine had mild fragrance and refreshing taste.The nutritional quality and antioxidant properties of pure glutinous rice wine（PN₁）,blended wine of glutinous rice and Ponkan juice（PN₂）,original wine of Ponkan glutinous rice（PN₃）and blended wine（PN₄）were analyzed.The results showed that the contents of V_C（168.97±3.65 mg/L）,carotenoids（3.60±0.00μg/100 m L）and total phenols（49.01±0.13 mg/100 m L）in PN₄were significantly higher than those in the other three types of rice wine（P<0.05）.The results of antioxidant experiment showed that the[DPPH·]scavenging rate of PN₄was significantly higher than that of PN₁and PN₂（63.19±1.59%,P<0.05）,and the hydroxyl radical scavenging rate of PN₄was significantly higher than that of PN₂and PN₃（95.88±0.43%,P<0.05）.The Aroma components of PN₄and PN₁were analyzed by GC-MS,and the results showed that PN₄contained 32 kinds of aroma components,such as ethanol,isoamyl alcohol,d-terpene diene,phenylethyl alcohol,etc.PN₁contain 18 compounds such as ethanol,isoamyl alcohol,phenylethyl alcohol,ethyl octanoate and so on.12 of them such as D-terpene diene,linalool and so on were peculiar to PN₄.That characteristic aroma of PN₄was attribute to D-terpene diene and terpinene,while that of PN₁was attributed to ethyl palmitate,phenylethyl alcohol,phenylacetaldehyde and so on.In summary,PN₄not only had better nutrition and quality indicators than other groups,but also had the characteristic aroma of citrus.（2）Study on the stability,sterilization methods and storage characteristics of Ponkan glutinous rice wine（PN₄）.The effects of sodium alginate,xanthan gum,pectin and sodium carboxymethyl cellulose on the stability of PN₄were investigated.The results showed that the precipitation rate of PN₄decreased from 2.29±0.15%to 1.47±0.23%when 0.04g/100 g sodium carboxymethyl cellulose was added,which was significantly lower than 2/5 of the control group（P<0.05）.The germicidal efficacy and quality of PN₄under different sterilization conditions were studied.The results showed that PN₄could achieve commercial sterility after sterilization at 70°C for 30 min,but the soluble solids content and non-enzymatic browning index increased significantly.The storage experiment showed that the total number of colonies increased in varying degrees during storage,but did not exceed the value required by the national standard.The total phenolic content of the product was basically stable at 4°C,and the shelf life of the product at 4°C and 25°C was 206.83 d and 48.24 d,respectively,according to the ASLT accelerated test.The aroma components of PN₄were analyzed by GC-MS.The results showed that alcohols and esters were the main flavor compounds of PN₄during storage,and 10 new compounds such as serinol and acetone alcohol（with mint aroma）were added,while isoamyl alcohol（with unpleasant odor）was not detected at the 50th day.The decrease of various fatty acid esters led to the gradual softening of the odor of rice wine,and the gradual weakening of the odor and grease;The contents of D-terpene and terpinene did not change significantly during storage,and the characteristic aroma of Ponkan could be maintained during storage.（3）Study on processing technology and shelf life of Ponkan pomace shortcake.With Ponkan pomace and glutinous rice flour as stuffing materials,the optimal processing technology of Ponkan pomace shortcake was obtained by single factor and orthogonal experiments as follows:the ratio of glutinous rice flour to Ponkan pomace was 1:2.5,the addition of white granulated sugar was 65%,the addition of salt was1.2%,and the ratio of stuffing to skin was 1:1.The prepared Ponkan pomace shortcake has crisp skins and sweet and soft fillings.The results showed that the total sugar content（22.29±2.66%）,crude fat content（28.82±0.72%）and crude fiber content（0.64±0.15%）of the product were significantly higher than those of the crisp cake without Ponkan pomace（P<0.05）.The physicochemical and microbiological indexes were in line with the national standards.The storage experiment at room temperature showed that the acid value and peroxide value of Ponkan pomace shortcake increased during storage at 25°C,peroxide value was the main index to measure the deterioration of Ponkan pomace shortcake,and the fitted regression equation was y=0.01666 x-2.66911 with storage time t as abscissa and ln（POV）as ordinate.The results showed that the shelf life of Ponkan pomace shortcake was 76.99d with peroxide value as index at room temperature.The Ponkan glutinous rice wine had soft taste,rich nutrition and good antioxidant properties,and the Ponkan pomace shortcake had crisp taste,unique flavor and rich dietary fiber.The production process,nutritional characteristics and storage properties of the product were studied,which could provide technical and theoretical reference for the development and processing of Xiangxi Ponkan.