| Roselle is a traditional medicinal and edible plants,its calyx rich in nutrition and has many special functions,so it has a promising application prospects in the food sector.The water extraction process of roselle has the advantages of convenience and economic,and is used in food development widely.In this study,the dry roselle calyx from different regions of China was studied,and the water extraction technology and the fermentation process of the wine were optimized by response surface methodology.The difference of the main components in roselle water extract from different regions and their fermented wines were analyzed.The active ingredients and flavor components in roselle wine and the dynamic changes of the active ingredients in the fermentation process of roselle wine were studied,which provided theoretical basis for the development and utilization of roselle resources.The results were as follows:1.The optimum extraction conditions of roselle by the response surface method were as follows: the ratio of material to wate was 1:28,the extraction temperature was 84.0 ℃,the extraction time was 78 min.Under the optimal condition,the extraction rate of anthocyanin was(0.060 ± 0.009)% and the extraction rate of polyphenols was(0.201 ± 0.05)%.The results showed that the total phenolic content was between 535.57 to 873.43 mg/L,among them,the content of total phenols was the lowest in the roselle water extract of Danzhou,Hainan,and was highest in Longyan,Fujian;The total anthocyanin content showed a great difference among roselle water extract from different regions,the content was between 32.56 mg/L to 210.57 mg/L;The total flavonoids content range from 124.09 mg/L to 457.04 mg/L;The total acid content ranged from 3.4 g/L to 7.9 g/L,The total organic acid content ranged from 4.73 g/L to 8.61 g/L,the main organic acid species varied according to the region.Among them,tartaric acid,acetone Acids,lactic acid,citric acid,hibiscus acid and hydroxycitric acid are the common organic acids in the roselle water extract from different regions;The total phenolic acids content ranged from 207.84 mg/L to 415.95 mg/L.The content of protocatechuic acid in roselle water extract was higher than other phenolic acids except the roselle water extract from Zhaoqing,Guangdong;The content of flavonoids varied from 10.67 mg/L to 18.29 mg/L.Only four flavonoids were detected among the seven flavonoids detected,they were rutin,quercetin glucoside,myricetin and luteolin respectively,and the content of myricetin and luteolin was higher among the four flavonoids.;Seventeen kinds of amino acids were detected in the roselle water extract from different regions,and aspartic acid was the major amino acids in all roselle water extract except the rose water extract from Baoshan,Yunnan,its relative content was between 43.65% ~ 95.66%,while the content of serine was only detected in the roselle water extract of Longyan,Fujian.There is a correlation between the contents of roselle water extract from different areas,of which the total content of anthocyanins and total anthocyanin content,total content of anthocyanins and total acids,total content of organic acids and total acid content showed a significant positive correlation(P <0.01),and there was a significant negative correlation between total content of organic acids and total flavonoids content(P <0.01).The correlation between total flavonoids content and total phenols content,total flavonoids content and total content of phenolic acids,total phenols content and total content of flavonoids showed a significant positive correlation(P <0.05).2.The fermentation process was optimized by response surface methodology,the optimum fermentation conditions were as follows: fermentation temperature was 24.5 ℃,the dosage of S4 yeast was 1.6 g/L,sugar content was 22.5%,fermentation time was 10 d.The alcohol content of roselle wine was between 9.1 to 11.6%(v/v),the content of reducing sugar was between 1.40 to 25.32 g/L and the total acid content was between 5.48 to 9.00 g/L,The total ester content was between 1.26 to 1.97 g/L,the roselle wine had a bright red color,clear and transparent,the physical and chemical indicators were within the standard of wine.The principal component analysis of the main quality indicators of roselle wine was used to establish the quality evaluation model of roselle wine,obtained the equation: F = 0.4362F1 + 0.2985F2 + 0.2652F3,the results showed that the roselle wine from Wuding in Yunnan,Baoshan in Yunnan,Dali in Yunnan,Longyan in Fujian,Lincang in Yunnan,Meizhou in Guangdong,Huizhou in Guangdong and Guilin in Guangxi had a better quality,which was consistent with sensory evaluationand results.3.The results of the analysis of the flavor components(organic acids,amino acids and volatile components)in the roselle wine with good quality from 8 origins were as follows : The organic acid species was same in each roselle wine,but there was a significant difference(P <0.05)in the content and composition ratio.Eight kinds of organic acids such as tartaric acid,pyruvic acid,malic acid,lactic acid,citric acid,succinic acid,hibiscus acid and hydroxycitric acid were detected in each roselle wine.Among them,lactic acid was the main organic acid in each roselle wine.The relative content of total amino acids ranged from 23.86% to 31.38%,and its content was between 1.89 to 2.89 g / L,Sixteen kinds of amino acids were detected in each rose wine,and the total amount of amino acids was between 59.19 to 314.49 mg/L,Among them,aspartic acid is the most abundant amino acid in each roselle wine.In addition to tryptophan,the seven kinds of essential amino acids accounted for 6.11~61.47% of the total amino acids,the ratio of essential amino acids to nonessential amino acids was between 0.08~1.6,the amino acid composition in roselle wine from Baoshan in Yunnan,Huizhou in Guangdong,Longyan in Fujian,and Meizhou in Guangdong were closest to protein model of human body according to the protein ideal model proposed by FAO/WHO;The relative content of sweet amino acids was between 9.64% to 19.73%.Except roselle wine originating from Lincang in Yunnan Province,The relative content of umami amino acids was between 15.01% to 74.03%,Aspartic acid was the major umami amino acid in each roselle wine;The relative content of aromatic amino acids was between 0.39% to 9.42%.A total of 115 kinds of volatile components were detected in each roselle wine,Among them,isoamyl alcohol,phenethyl alcohol and ortho-acid were the main characteristic aroma components of roselle wine.Alcohols ingredients were the main volatile components of roselle wine,accounting for 43.49% to 75.79%;Ester substances are the largest variety of volatile components in each roselle wine,the percentage was between 5.84% to 22.08%.The proportion of acids compositionin in each roselle wine was between 7.71% to 29.18%.The aldehydes and ketones were trace substances in roselle wine,among which Aldehydes accounted for 0.30% to 1.85% of roselle wine,while the percentages of ketones in each roselle wine were below 0.8%.4.The results of changes of the active ingredients in the fermentation process of roselle wine were as follows: The total anthocyanin content decreased in the fermentation process,and the rate of decline was between 4.56% to 30.32% during the main fermentation stage,and during the post-fermentation stage the rate of decline was between 22.71% to 49.73%.,and the rate of decrease of total anthocyanin in the post-fermentation period was higher than that in the main fermentation period.;The total content of anthocyanin in the fermentation process was similar to that of the total anthocyanin content,but its rate of decrease in the main fermentation stage was greater than that in the post-fermentation stage.The content of D-3-S was slowly decreased in the fermentation process,the rate of decrease was between 63.58% to 81.58%,and the rate of decrease in the post-fermentation stage was lower than that in the main fermentation stage,while the rate of decrease of the content of C-3-S in the post-fermentation stage was higher than that in the main fermentation stage;The total phenolic content in all roselle wine showed a trend that increase first and then decreased,and then increased slowly and tends to be stable,the total phenolic content before fermentation was between 531.74 mg/L to 880.57 mg/L,and was between 498.34 mg/L to 838.43 mg/L after the main fermentation period,and after 40 days of post-fermentation period total phenolic content was between 470.91 mg/L to 867.71 mg/L;total flavonoids in the roselle wine fermentation process showed a decrease trend,and the rate of decrease in the post-fermentation stage was higher than the main fermentation stage;The trend of the content of phenolic acids monomer and total phenolic acids content in each roselle wine were roughly same during the fermentation process,at the end of the main fermentation,the total phenolic acid amount was between 147.90 mg/L to 21.89 mg/L,and after 40 days of post-fermentation,the total phenolic acids amount in each roselle wine ranged from 128.14 mg/L to 254.59 mg/L,the content decreased compared with that before fermentation.The content of hibiscus acid decreased in the initial stage of main fermentation,then increased or decreased within a certain range.,At the end of the main fermentation period,the content of hibiscus acid in each roselle wine was between 0.83 g/L to1.99 g/L,which was 63.13% to 88.46% of the content of hibiscus before fermentation,After 40 days of post-fermentation,the content of hibiscus acid in each roselle wine was between 1.12 g/L to 1.63 g/L;The main change trend of HCA in the main fermentation stage was to reduce and then increase and then decreased until the end of the main fermentation,the content of HCA in each roselle wine was between 0.12 g/L to 0.37 g/L,which was 50.00% to 80.65% of the HCA content of each roselle wine before fermentation,In the post-fermentation process,the HCA content tended to decreased in the first ten days,after which the content was stable within a certain range of 0.09 g/L to 0.26 g/L.The active ingredients in roselle wine had a complex change in the fermentation process and stabilized within a certain content eventually,and obtained its unique functional ingredients.So the roselle wine hold a health care function and has a good prospect in food field. |
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