Optimization of Fermentation Process of Ginger-Apple Complex Juice by Lactic Acid Bacteria and Difference of Flavor Substances Before and After Fermentation
The fermentation conditions for the production of fermented ginger-apple juice with lactic acid bacteria were optimized,using apple juice and ginger juice as raw materials,and the difference of volatile substances before and after fermentation was studied.Fermentation of ginger-apple complex juice was conducted using commercially available mixed lactic acid bacteria.The effects of inoculum amount,fermentation time,amount of ginger juice and fermentation temperature on the quality of fermented complex juice was evaluated by viable bacterial count and sensory score.The fermentation conditions were optimized by single factor experiment and orthogonal design.Head-space gas chromatography ion migration spectrum(HS-GC-IMS)was used to analyze the volatile flavor components.The result showed that the optimum fermentation conditions were as follows:0.7％of inoculum amount,60 h in fermentation time,10％ginger juice content,40 ℃ in fermentation temperature.The flavor of the fermented ginger-apple juice under the optimized conditions was very well,and the viable bacterial count reached 8.87 Ig CFU/mL.A total of 76 volatile substances were detected in the fermented ginger-apple juice,including 24 esters,18 alcohols,11 aldehydes,6 ketones,6 acids,5 alkenes and 6 other substances.The relative contents of esters and alcohols decreased after fermentation,while aldehydes,ketones and hydrocarbons showed a increasing trend.Lactic acid bacteria fermentation obviously changed the volatile composition of ginger-apple juice.
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