Preliminary Study On The Effects Of Ultra-high Pressure On The Quality Of Gunanfeng Rice Wine

The taste of new brewing Gunanfeng rice wine is strange and spicy because of its larger numerator degree of freedom and disorder arrangement. So it is necessary to storage rice wine for a period of time, which could stabilize the components through a series of physical and chemical interactions, to improve its quality. However, the natural aging of rice wine is a long procedure, and requires a lot of wine containers and large storage areas, which restrict the production and development of the enterprise. Therefore, it makes a significant difference to develop an artificial aging method which could reduce the aging time and maintain the natural quality of rice wine, as well as be applied in the practical production. Ultrahigh pressure (UHP) aging treatment could promote the molecular rearrangement and its association through changing the distance between the molecules, and at the same time high pressure can be converted into the activation energy needed in the intermolecular reaction, thereby shortening the aging time of rice wine and improving its quality.In this study, ultrahigh pressure technology was used to treat Gunanfeng rice wine, and the effects of this on the sensory quality, volatile substances and physicochemical characteristics of Gunanfeng rice wine were investigated; Besides, the simulation system of alkyd esterification reaction was built to research the effect of UHP treatment on it, which could provide the basis for improving the quality of rice wine and its industrial application.Research conclusion was as follows:1. The results of sensory evaluation showed that the sensory quality of rice wine would be optimal under the conditions that the level of ultrahigh pressure was 300 MPa, the holding time was 30 min, and medium temperature was 20℃. And the significance of sensory qualities of rice wine samples with different producing time and ultrahigh pressure conditions was analysed, which exhibited that there was no significant differences among the optimal ultrahigh pressure treated rice wine, general ultrahigh pressure treated rice wine and natural aging rice wine. So it suggested that the ultrahigh pressure treatment could improve the sensory quality of rice wine, and there was no retrogradation phenomenon.2. HS-SPME-GC-MS method was used to test the volatile substances in rice wine. Optimum extraction conditions of solid phase microextraction was sample amount of 5 ml, extraction temperature of 50℃, extraction time of 40 min, salt of 1 g. The result showed that there were 10 kinds of alcohols,5 kinds of aldehydes,5 kinds of acid, and 18 kinds of ester. It also suggested that the oxidations of alcohols and aldehydes, and the esterification reaction between alcohols and acids in rice wine were promoted through ultrahigh pressure treatment, which could lead to the reduction of the amounts of the volatile alcohols, aldehydes and acids, and the increase in the content of volatile esters. The amounts of volatile alcohol, aldehyde, acids, esters in optimum ultrahigh pressure treated rice wine were almost equal to those of regular aging one. Besides, there was no retrogradation phenomenon among the volatile substances in the treated rice wine in spite of prolonging storage time.3. The physicochemical characteristics of the optimal ultrahigh pressure treated rice wine exhibited changes. Compared with the new one, its levels of alcohol content, total acid and non-sugar solids were decreased slightly. its amount of amino nitrogen, total sugar and pH increased slightly. And there was no significant differences between physicochemical characteristics of optimum ultra-high pressure treated rice wine and that of ultra-high pressure storage rice wine. These suggested that ultrahigh pressure treatment could not lead to the retrogradation phenomenon of physicochemical characteristics.4. The seven kinds of organic acids in the new rice wine, optimum ultra-high pressure treated one, ultra-high pressure storage one and the natural aging ones with different years were tested. The total concentrations of these acids among these samples were 11.18g/L, 10.10g/L,9.98g/L,9.85g/L,8.58g/L,9.85g/L, respectively. Compared with the new rice wine, the amounts of acids in ultrahigh pressure treated one decreased except for that of the tartaric acid which increased slightly. With the storage time prolonging, the amounts of acids decreased except for that of the malic acid which increased slightly. And there was no significant differences between the amounts of organic acids of optimum ultra-high pressure treated rice wine and that of ultra-high pressure storage rice wine. These suggested that ultrahigh pressure treatment could not lead to the retrogradation phenomenon of organic acids.5. The in the new rice wine, optimum ultra-high pressure treated one, ultra-high pressure storage one and the natural aging ones with different years were tested and analysed. The result showed that there were 15 kinds of free amino acids, and the concentrations of total free amino acids in different samples were 2238.67mg/L, 2274.57mg/L,2244.28 mg/L,2290.39 mg/L,2274.12 mg/L,2277.76 mg/L, respectively. Compared with the ultrahigh pressure treated rice wine, there were no change in the kind of amino acid, and slight changes in the concentration of individual amino acid and the total amount of amino acids with the prolonging storage time. These suggested that ultrahigh pressure treatment could not lead to the retrogradation phenomenon of amino acids.6. The effect of ultrahigh pressure treatment on alkyd esterification showed that ultra-high pressure treatment had positive impacts on the esterification reactions in alkyd systems. And ultrahigh pressure treatment had little effect on the hydrolysis of ethyl acetate.