Microflora Analysis And Effects On BC Fermentation Of Pre-fermented Broth Of Coconut Water From Indonesia And Vietnam

At present,coconut water is the main raw material for industrial production of BC,both at home and abroad,especially in Southeast Asia.Previous study and experience had proven that coconut water can be used for frementating BC after being taken out of the shell and then naturally fermentated in the environment,which production of BC is better than fresh coconut water.In recent years,due to the supply of coconut fruits in Hainan Island is falling short of supply with the tourism boom,most of the coconut used in HanNan's coconut processing industry which are imported from Southeast Asian countries such as Vietnam and Indonesia.The early stage of the laboratory research showed that the yield of BC is notably effected by different producing areas,pre-fermentating time and pre-fermentating area.So it looks significant to analyze the influence of Climate and geography environment on coconut water pre-fermentation,even BC fermentation,the microflora in fermented processing,which can provide theoretical basis for the problem of instability and insecurity in the production process of the BC industry.This study compared the effects of pre-fermented coconut water in Vietnam factory environment and the Indonesia pre-fermented coconut water in HaiNan factory environment on BC fermentation,combined with the composition analysis,the composition change of perfermentation would have effects on the yield of BC.At the same time,high throughput sequencing was used to compared the composition and variation and bacteria in two environments,analyzing the difference between the two places and their possible reflection.In addition,the traditional methods were used to isolate the dominant microorganism to obtain single strain,which will be used to study the influence on BC synthesis of single strain pre-fermentation.The main results are as follows:(1)Effects on BC production of pre-fermented coconut water with different treatmentsThere are nine groups of pre-fermented coconut water with different treatments in view of Vietnam and Indonesia,coconut processing plant and laboratory.The test results all proved that the it can promote BC production,but the effects are not uniform.The group IN2 from Indonesia shows the highest increase in BC production at the third day,reaching 6.02 g/L which is the 7.5 times of the control group(fresh coconut water).Sample YV4,YV5 from Vietnam are the least to increase BC production,only 3 g/L.The sample HN1?HN2 from Haikou and IN1 from Indonesia show the highest BC production which are 5.1 g/L,5.87 g/L,5.44 g/L,and 5.12,5.8,6.5 times of the control group at forth day,respectively.The sample YV1,YV2,YV3 from Vietnam respectively show the highest BC production which are 5.65 g/L(3d),5.05 g/L(4d),4.90 g/L(4d)and 7.3,6.6,6.4 times of the control group.In conclusion,the production of BC is notably influenced by pre-fermentation environment.It also can be seen that different pre-fermenting environment,climate of coconut origin environment and pre-fermenting time could affect the degree of promoting synthesis.(2)Analysis of Microflora in Pre-fermented Coconut WaterThe core bacterial genus is mainly Lactobacillus in the sample IN2 from Indonesia,and following is Acetobacter.After 12H fermentation,the Lactobacillus content was 32%while the Acetobacter was only 0.03%.After a day of fermentation,the content of Acetobacter increased rapidly,and the total proportion of Acetobacter and Lactobacillus is up to 98%.The core fungus genus is Candida,which is the main fungus in Indonesian sample fermentation.And in the whole fermentation process,the proportion of Candida is above 85%.In Vietnamese sample YV1,the core bacterial genus is mainly Lactobacillus followed by Acetobacter and Lactococcus when fermented for 12 h.In the process of fermentation 1-6d,the dominant genus are Acetobacter and Lactobacillus,which total proportion are 98%.For Vietnam fungus genus,there is a high proportion for candida at 12 h,which is 51%.However,in the sample fermented for 1-6 d,there is a kind of fungu which is up to 98%and failed to identify.According to the analysis of the beta diversity,there is a significant difference in the microbial structure between the Indonesian sample IN2 and the Vietnamese sample YV1.According to the analysis of the alpha diversity,the fungi flora in Indonesian samples are more abundant,while the bacterial flora is more abundant in Vietnamese sample YV1.(3)Analysis the composition of pre-fermented coconutThe total acid content,reducing sugar content,soluble solid content,and pH are measured of nine groups IN1,IN2,HN1,HN2,YV1,YV2,YV3,YV4,and YV5.Compared with the corresponding four indicators of the natural pre-fermented coconut water,the trend is basically the same.The contents of the organic acid in all groups are determined,and the reasults showed that 5 kinds of organic acids were all detected,and the lactic acid content is the highest in each group of samples,which was positively correlated with BC yield.Followed by D-galacturonic acid,acetic acid,glucuronic acid,and D-galacturonic acid are negatively correlated with BC yield.(4)The effect on BC production of single strain for coconut water pre-fermentation.Screening bacteria from the most high-yielding pre-fermented coconut water by the traditional method of isolation and purification,according to the general characteristics,we selected 1-2 strains from each category to study the effects of their fermentation broth on BC fermentation.The promoting effects are difference for yeast,lactic acid bacteria and acetic acid bacteria.Yeast shows the best effect on BC production which up to 6 g/L.Then followed by lactic acid bacteria,the BC production is 3 g/L,but acetic acid bacteria promoting effect is not obvious.Among all strains,Y20 and 84-3 show the best effect on BC yield,respectively 6.01 g/L and 6.3 g/L.Y20 has been identified as Saccharomyces paradoxus,which is closely related to saccharomyces cerevisiae,and 84-3 is saccharomyces cerevisiae.In conclusion,the role of fermented coconut water for BC synthesis is related to the icrobiological effect during fermentation.It is prominent for yeast,and the role of saccharomyces cerevisiae is better than candida.