Effect Of Lactic Acid Bacteria Fermentation On The Quality Of Hawthorn Pulp

If the unreasonable use of a large number of by-products produced by the processing of hawthorn will not only cause great waste,but also cause environmental pollution.The research work on the deep processing products of hawthorn by-products can be used to find new ways for the utilization of hawthorn by-products.The fermented fruit and vegetable juice can integrate the raw material flavor of the fruits and vegetables and the fermented flavor of the probiotic fermentation,which not only can better retain the nutrients in the fruits and vegetables,but also increase the health function of the probiotics.However,the traditional fruit and vegetable juice fermentation process has problems such as low fermentation efficiency,long fermentation time,low activity of lactic acid bacteria,and low quality requirements.As a marginal and cross-cutting science and technology,ultrasound technology can not only promote the proliferation of microorganisms,increase the activity of microorganisms,but also improve the quality of products.This paper systematically studied the acclimation of lactic acid bacteria,the fermentation process of lactic acid bacteria fermented hawthorn pulp,the effect of lactic acid bacteria fermentation on the function and quality of hawthorn pulp,and the effect of ultrasonic treatment on the fermentation of hawthorn lactic acid bacteria.The main findings are as follows:1.Domestication of Lactobacillus plantarum,Lactobacillus acidophilus and Lactobacillus casei by stepwise domestication.Finally,the viable count of Lactobacillus plantarum could reach 7.25 lg(cfu/mL)in pure hawthorn pulp,the viable count of Lactobacillus acidophilus was 7.90 lg(cfu/mL)and the viable count of Lactobacillus casei was 7.45 lg(cfu/mL).The acclimation standard of lactic acid bacteria(?7.00 lg(cfu/mL))could be achieved.2.The optimal fermentation process of fermented hawthornpulp was determined by single factor experiment and Response surface experiment: fermentation time was 12 h,material-water ratio was 1:15,fermentation temperature was 37 ?,inoculum volume was 12%.The acid production of lactic acid bacteria was 2.87 g/kg.3.The effects of lactic acid bacteria fermentation on the physicochemical properties,antioxidant capacity,active ingredients,organic acids,volatile aroma components and sensory properties of hawthorn pulp were studied.The results showed that the total acid,amino nitrogen and conductivity in the hawthorn pulp after fermentation increased significantly,and the reducing sugar content,soluble solids and centrifugal sedimentation rate decreased significantly.The L* value of fermented hawthorn pulp increased compared with the pre-fermentation hawthorn pulp.The a* value and b* value decreased compared with the pre-fermentation hawthorn pulp,indicating that the hawthorn pulp was biased bright yellow after fermentation.The ?E after fermentation decreased compared with that before fermentation,indicating that the total color difference of the yam pulp decreased after fermentation by lactic acid bacteria.The in vitro antioxidant capacity and active ingredients(free phenol and flavonoids,total phenols and total ketones)of fermented hawthorn pulp increased significantly.The organic acid content of the fermented hawthorn pulp increased significantly,and a new organic acid,lactic acid,was formed.The volatile aroma components of the hawthorn pulp after fermentation had significant changes.The sensory score of the fermented hawthorn pulp was significantly increased.4.The effects of ultrasonic treatment on the fermentation performance and morphology of lactic acid bacteria in fermented hawthorn pulp,the physicochemical properties,antioxidant capacity,active ingredients,organic acids,volatile aroma components and sensory of fermented hawthorn pulp were systematically studied.The results showed that the biomass of lactic acid bacteria increased by 23.51% under the condition of ultrasonic condition of 360 W for 5 min;the fermentation performance of lactic acid bacteria was significantly higher than that of unsonicated fermented hawthorn pulp;the cell membrane of lactic acid bacteria produced repairable damage and the morphology did not change significantly;the total acid,soluble solids,amino nitrogen,and conductivity in the fermented hawthorn pulp reached the highest,and the reducing sugar content and centrifugal sedimentation rate reached the lowest.Under the ultrasonic condition of 360 W,5 min,there was no significant difference between the L* value and the ?E value compared with the unsonicated fermented mountain syrup,indicating that the color of the fermented hawthorn pulp did not appear obvious under this ultrasonic condition;the in vitro antioxidant capacity of the fermented hawthorn pulp was significantly increased,and the active ingredients(free phenol and flavonoids,total phenols and total ketones)were significantly increased.Under the ultrasonic condition of 360 W and 5 min,the content of organic acids in the fermented yam pulp was the highest,and the types of volatile aroma components were also the most.Fermentation of lactic acid bacteria produces new components such as ketones with creamy aroma,acid-like substances of acetic acid odor,alcohols and phenolic substances with floral and fruity odor.On the basis of the main aroma components of lactic acid bacteria fermented hawthorn pulp,under the ultrasonic condition of 360 W,5 min,an ester compound with similar nutty and strong floral aroma was newly produced.The fermented hawthorn pulp had the highest sensory score at 360 W for 5 min.