蜜生假丝酵母LGL-2发酵油菜蜂花粉酵素工艺优化及品质评价

Optimization and Quality Evaluation of Rape Bee Pollen Jiaosu Fermentation by Candida apicola LGL-2

以油菜蜂花粉为主要原料,以蜂蜜中选育出的蜜生假丝酵母LGL-2为试验菌株,研究不同发酵时间、发酵温度、接种量和底物含量对油菜蜂花粉酵素总酚含量的影响。以总酚含量为指标,采用响应面法优化油菜蜂花粉酵素发酵工艺条件。在此条件下,进一步比较分析油菜蜂花粉及其酵素的酚类化合物、挥发性风味成分和抗氧化活性。结果表明:油菜蜂花粉酵素的最佳发酵工艺参数为发酵时间48 h、发酵温度30℃、接种量20%、底物含量30%,此时油菜蜂花粉酵素总酚含量可达11.48 mg GAE/g。采用高效液相色谱(HPLC)分析酚类化合物,发现其内包含没食子酸、对香豆酸、芦丁、鞣花酸和槲皮素,各酚类化合物含量经蜜生假丝酵母LGL-2发酵后均有所提高。采用相对气味活度值法(ROAV)结合顶空固相微萃取-气相色谱-质谱技术(HS-SPME-GC-MS)对油菜蜂花粉及其酵素的挥发性香气成分进行测定分析,共检测出26种挥发性香气成分,其中7种被鉴定为油菜蜂花粉酵素关键性挥发性香气成分,部分醇类和酯类物质含量提升为产品带来优良风味。抗氧化活性试验表明,相比于发酵前,油菜蜂花粉酵素具有更强的DPPH自由基清除能力(DPPH·)、ABTS^(+)自由基清除能力(ABTS^(+)·)以及铁离子还原能力(FRAP)。综上,经蜜生假丝酵母LGL-2发酵能有效提高油菜蜂花粉的酚类物质含量、风味品质及抗氧化活性。

Using rape bee pollen as raw material,the Candida apicola LGL-2 selected from honey was used to investigate the effect of fermentation factors including fermentation time,fermentation temperature,inoculum amount and substrate content on the total phenolic content of rape bee pollen jiaosu.The fermentation process of rape bee pollen jiaosu was optimized by response surface methodology(RSM)using total phenolic content as the response variable.Based on these conditions,the phenolic compounds,volatile aroma components and antioxidant activities of rape bee pollen and jiaosu were further compared.The results showed that the optimal conditions for rape bee pollen jiaosu by Candida apicola LGL-2 were fermentation time 48 h,fermentation temperature 30℃,inoculum amount 20%and substrate content 30%,and the total phenolic content of rape bee pollen jiaosu was 11.48 mg GAE/g after fermentation.Phenolic compounds including gallic acid,p-coumaric acid,rutin,ellagic acid and quercetin were detected in rape bee pollen and jiaosu by high performance liquid chromatography(HPLC),and the contents of all the phenolic compounds above were increased after the fermentation by Candida apicola LGL-2.The volatile aroma compounds of rape bee pollen and jiaosu were analyzed by headspace solidphase microextraction and gas chromatography-mass spectrometry(HS-SPME-GC-MS)combined with the relative odor activity value(ROAV).Twenty-six volatile aroma compounds were detected,7 of which were identified as key aroma components of rape bee pollen jiaosu,and the contents of some alcohols and esters were enhanced to bring excellent flavor to jiaosu.Compared with rape bee pollen,rape bee pollen jiaosu exhibited stronger antioxidant activities as determined by DPPH·,ABTS^(+)·and FRAP assay.These results indicated that fermentation by Candida apicola LGL-2 could effectively improve the phenolic content,flavor and antioxidant power of rape bee pollen.