发酵条件对酸樱桃发酵汁挥发性风味物质的影响探究

Study on the effect of fermentation conditions on volatile flavor substances of sour cherry fermentation juice

目的 考察发酵条件对酸樱桃发酵汁中风味物质的影响。方法 利用3株乳酸菌发酵酸樱桃汁,以pH为指标明确最佳发酵菌种和稀释比例。随后利用气相色谱-离子迁移谱法(gas chromatography-ion mobility spectrometry,GC-IMS)探究糖添加量、pH、氮源、稀释比例对发酵挥发性风味物质的影响。结果 最佳发酵菌为鼠李糖乳杆菌(Lactobacillus GG,LGG),最佳稀释比例为1:3,氮源对挥发性风味物质几乎没有影响;而不同添加量的碳源(葡萄糖)导致发酵液乙偶姻、双乙酰等含量差异;随着pH增加,乙偶姻、双乙酰、2-戊酮等含量显著升高;稀释比例通过影响发酵原汁的浓度导致发酵后风味物质乙偶姻含量显著增加、2-戊酮含量显著降低。进一步差异比对3株乳酸菌酸樱桃发酵汁的风味,发现LGG代谢脂肪酸可产生较多的2-庚酮及2-戊酮。结论 菌种、糖添加量、稀释比例、起始pH均可导致发酵液中乙偶姻、2-庚酮及2-戊酮等挥发性风味物质产生显著影响,本研究为酸樱桃的加工利用提供理论指导。

Objective To investigate the effects of fermentation conditions on volatile flavor substances of sour cherry fermentation juice. Methods Three lactic acid bacteria were used to ferment sour cherry juices, the optimal fermentation strain and dilution ratio were determined with pH as index, then gas chromatography-ion mobility spectrometry(GC-IMS) was used to investigate the effects of sugar addition, pH, nitrogen source and dilution ratio on fermentation flavor substances. Results The best fermentation bacteria was Lactobacillus GG(LGG), and the best dilution ratio was 1:3. Nitrogen source had little effect on volatile flavor substances;the content of acetoin and diacetyl in fermentation broth was different with the carbon source(glucose);with the increase of pH, the content of acetoin,diacetyl and 2-pentanone in fermentation liquid significantly increased;the dilution ratio resulted in significant increment in the content of acetoin and significant reduction in the content of 2-pentanone after fermentation by affecting the concentration of fermentation juice;the volatile flavor of sour cherry fermentation broth of 3 lactic acid bacteria were further compared by GC-IMS, it was found LGG could produce more 2-heptanone and 2-pentanone by lactic acid bacteria fatty acids metabolic. Conclusion The bacteria species, amount of sugar addition, dilution ratio and the initial pH can all lead to the significant difference of flavor substances such as acetoin, 2-heptanone and 2-pentanone in fermentation broth, which will provide theoretical guidance for the processing and utilization of sour cherry.