| In this paper,purple peel passion fruit was used as raw material.The optimum brewing process of whole passion fruit wine was combined with response surface method,and passed through four antioxidant systems(DPPH,ABTS~+,·OH,reducing ability)to evaluate its antioxidant activity with passion fruit juice and raw juice;The aroma characteristics of the row juice,juice wine and whole fruit wine were evaluated by using HS-SPME-GC-MS,GC-O and electronic nose technology;p H-differential method and fully automatic colorimeter combined with degradation kinetics model were used to study the effects of low acyl(LA)and high acyl(HA)gellan gum on the thermal stability of anthocyanins from passion fruit peel(PFP)in model beverages with the presence of ascorbic acid,which were heat-treated at 85℃for 0,1,2,3,4 and 5 hours.The components of anthocyanins of passion fruit peel were identified by UPLC/Q-TOF-MS,and the content of each component in PFP was detected by HPLC;Taking sensory score as the index,response surface methodology was used to optimize the process of low sugar passion fruit peel preserved fruit,and the sensory,physicochemical and health indexes were determined.The main results are as follows:(1)The optimum conditions for the whole passion fruit wine were initial sugar content19%,yeast inoculum 0.04%,fermentation temperature 29°C,fermentation 5 d.Under the optimized conditions,the alcohol content of whole fruit wine was 12.9%Vol,the light transmittance was 85.6%,the total sugar(measured by glucose)was 7.5g/L,the total acid(measured by tartaric acid)was 6.2g/L,and it belonged to the semi-dry fruit wine;In four antioxidant systems,the rate of free radical scavenging and reducing ability increased with the increase of sample volume.The order of antioxidant activity was whole fruit wine>juice wine>raw juice.(2)78 aroma components were identified in the raw juice,juice wine and whole fruit wine,including 21 alcohols,21 esters,10 terpenes,7 ketones,4 aldehydes,3 ether acids and12 other substances;27 characteristic aroma components were identified by GC-O combined with aroma intensity method,including 12 alcohols,7 esters,4 terpenes,2 ketones,1 acid and 1 aldehyde.There were significant differences in aroma intensity among row juice,juice wine and whole fruit wine(P<0.05);There are 15,18 and 19 aroma components with OAV greater than Linalool,β-violone and ethyl hexanoate are the most important aroma components;PCA showed that there were obvious differences among the three.LDA showed that there were overlaps in flavor between juice wine and whole fruit wine,but there was a big difference between them and the raw juice.(3)During the heat treatment,the anthocyanin content in the four model beverage systems,PFP,PFP+VC,PFP+VC+LA and PFP+VC+HA,showed a downward trend,and the degradation of anthocyanins conformed to the first-order kinetic model.The half-lives were 308.44 min,155.09 min,189.69 min and 217.92 min respectively;low concentration(0.2%-0.5%)of gellan gum could improve the stability of anthocyanins,and the interaction between HA and anthocyanin was stronger than LA;During the heating period of 1-5 h,the L*value increased significantly,the a*and b*values decreased significantly(P<0.05),anthocyanins showed the phenomenon of extensive fading,but it is slower than the fading reaction of 0-1h.That is,the four model beverage systems showed brightening,reddish,and yellow deepening,and anthocyanins from passion fruit peel showed extensive discoloration;Four anthocyanins were identified from the passion fruit peel,namely cyanidin-3-glucoside,cyanidin-3-glucoside,cyanidin-3-rutinoside and paeoniflorin-3-glucoside,of which cyanidin-3-sophoroside was first found in the passion fruit peel.With cyanidin-3-glucoside as external standard,the content of total anthocyanin was 75.67 mg/g,cyanidin-3-glucoside was the most,the content was 45.13 mg/g,followed by cyanidin-3-rutinoside,the content was 23.88 mg/g,and finally cyanidin-3-sophoroside and paeoniflorin-3-glucoside,the contents were respectively 4.45 mg/g and 2.20 mg/g.(4)The best processing technology of low sugar Passion fruit peel preserved fruit was pickling time 6.0 h,compound sugar alcohol content 16.5 g,anthocyanin addition 0.05 g,Passion fruit juice adding 11.8 m L,Soaking times twice.Under these conditions,the sensory score of preserved fruit was 86.5,and the physical and chemical and health indexes were qualified.The results showed that xylitol and maltitol were used to replace white granulated sugar.The total sugar content was 12.86%,and the sugar content was reduced by 53.48%under the same sweetness conditions,so as to provide theoretical basis for the comprehensive utilization of passion peel and the development of low sugar preserved fruit. |
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