Analasis Of Microbial Diversity And Quality Of Northeast Fermented Vegetables Foods

Northeast Sauerkraut and Kimchi are traditional vegetable fermented foods with Chinese cabbage as the main raw material.Because of different processing techniques,the microbial community structure of the fermentation system is different,and its flavor characteristics and texture are also changed.Therefore,this project mainly uses cabbage as the main raw material to prepare the northeast sauerkraut and korean radish cabbage respectively,to study the dynamic changes of microorganisms and quality during the fermentation process,and comprehensively analyze the influence of different processing technologies on the quality characteristics of fermented food.(1)The number of lactic acid bacteria in the early stage of fermentation of Northeast Sauerkraut increased to 1.1 ×108cfu/mL,and then fluctuate within a certain range.The number of lactic acid bacteria fermented to 28 days was 6.1 X 106cfu/mL.The number of lactic acid bacteria in the early stage of fermentation of Kimchi increased to 2.1 ×1010cfu/mL when it was fermented to 28 days,and then decreased.Due to the high total acid content in the Kimchi,the lactic acid bacteria could not be detected in the fermentation until 20 days,and the difference in the lactic acid bacteria between the two fermentation systems was significant(p<0.01);The number of Leuconostoc in northeast sauerkraut increased to 6.1 ×107cfu/mL at the beginning of fermentation,and then decreased gradually.The number was 3.5 ×102cfu/mL at 28 days of fermentation.The number of leuconostoc in Kimchi increased to 8.3 × 109cfu/mL in the early stage,and then decreased.Since Leuconostoc is not resistant to acid,the total acid content in Kimchi is high,and when it is fermented to 28 days,Leuconostoc is not detected.The change of Leuconostoc in both systems was significant(p<0.01);The total number of bacterial populations in the system of Northeast Sauerkraut and Kimchi was basically the same,with an upward trend with the growth of lactic acid bacteria in the initial period,and then there was no major change and fluctuate within a certain range.Bacterial diversity was analyzed by PCR-DGGE technique.Eleven specific bands were found on the DGGE profiles of Northeast Sauerkraut and Kimchi,and the most homologous strains were found in Genbank by Blast program.The results showed that Lactobacillus plantarum,Leuconostoc mesenteroides,and Enterobacter were dominant bacteria in the fermentation process of Northeast Sauerkraut fermentation system.Lactobacillus sakei and Leuconostoc are the predominant microflora in different stages of fermentation during the fermentation process of Kimchi.(2)The pH of Northeast Sauerkrau dropped from 5.46 to 3.61 during the fermentation process.The total acid has been growing slowly,and the total acid reached 1.58%by the 28th day of fermentation.The pH of Kimchi decreased from 5.73 to 3.74,and the total acid content increased significantly from day 0.It reached 7.41%at 28 days.Because the contents of ingredients and nutrients in the fermented broth of Northeast Sauerkrau and Kimchi were different,the total acid concentration of the Kimchi during the fermentation was significantly higher than the total acid concentration in the Northeast Sauerkrau(p<0.01).(3)The sucrose content in the fermented system of Northeast Sauerkraut is less,and when it is fermented to 20 days,the sucrose is fully utilized.The glucose content is also less and is completely consumed during the fermentation process.Although the content of fructose is less,it still exists,and the content is 0.10 mg/mL when it is fermented to 28 days;The content of sucrose in Kimchi fermentation system was high,and the sucrose content in the early stage of fermentation was significantly reduced.The sucrose content was 3.69 mg/mL when the fermentation was carried out to 28 days.The glucose content is high,the glucose content increases at the initial stage of fermentation,and glucose is fully utilized when it is fermented to 20 days.The fructose content was high at the beginning of fermentation and was consumed.The fructose content increased from 12 to 16 days.After 16 days,the fructose content decreased,and the content was 20.93 mg/mL at 28 days.Due to the different ingredients of Northeast Sauerkraut and Kimchi,Kimchi was supplemented with ingredients such as white sugar,so the sugar content of Kimchi during fermentation was higher than that of Northeast Sauerkraut.(4)The content of lactic acid in the fermentation process of Northeast Sauerkraut increased,and the content was 6.80 mg/mL when it was fermented to 28 days.During the fermentation process of Kimchi,the lactic acid also showed an upward trend,and the content was 20.67 mg/mL when it was fermented to 28 days.The content of lactic acid during the fermentation process of Kimchi was significantly higher than that of Northeast Sauerkraut(p<0.01).The content of acetic acid in Northeast Sauerkraut increased first and then decreased.The content was 0.42 mg/mL when it was fermented to 16 days,and the acetic acid content was 0.03 mg/mL when it was fermented to 28 days.The content of acetic acid in Kimchi is high,and the content is 13.63 mg/mL when it is fermented to 28 days.The content of acetic acid in Kimchi during the fermentation process was significantly higher than that in Northeast Sauerkraut(p<0.01).Because the ingredients of the Northeast Sauerkraut and Kimchi fermentation broth are not different from the nutrient content,the organic acid content is significantly different.(5)The results of testing and analyzing the texture changes of Northeast Sauerkraut and Kimchi with different texture stages using texture analyzer showed that hardness 1,cohesiveness,elasticity,and chewiness all showed a downward trend during the fermentation process.