毛酸浆发酵过程中的非酶褐变原因解析

以毛酸浆为原料，同时接入酵母菌和乳酸菌，在25、30 ℃和37 ℃条件下对其进行发酵。以褐变度（browning degree，BD）为指标，检测其在发酵过程中引起非酶褐变的抗坏血酸（VC）、5-羟甲基糠醛（5-hydroxymethyl furfural，5-HMF）、多酚、还原糖、氨基酸态氮等化学组分的变化。采用通径系数分析方法，解析毛酸浆发酵过程中非酶褐变的主要原因。结果表明，在25、30 ℃和37 ℃等不同发酵条件下，毛酸浆发酵液中5-HMF含量、还原糖含量、氨基酸态氮含量等变化与褐变度的变化密切相关。在25 ℃发酵条件下，5-HMF含量对褐变度起到的直接作用最强，5-HMF含量和还原糖含量的交互作用是决定褐变度的首要因素；在30 ℃发酵条件下，氨基酸态氮含量对褐变度起到的直接作用最强，5-HMF含量和氨基酸态氮含量的交互作用是决定褐变度的首要因素；在37 ℃发酵条件下，5-HMF含量对褐变度起到的直接作用最强，同时，也是决定褐变度的首要因素。美拉德反应（Maillard reaction）是毛酸浆发酵过程中非酶褐变的主要原因。

Analysis of Mechanism of Non-Enzymatic Browning of Physalis pubescens L. during Fermentation

The mixed culture fermentation of the fruit juice of Physalis pubescens L. with yeast and lactic acid bacteria
was carried out at 25, 30 and 37 ℃, respectively. Changes in the contents of vitamin C, total phenols, 5-hydroxymethyl
furfural (5-HMF), reducing sugar and amino acid nitrogen, associated with non-enzymatic browning occurring during the
fermentation process, were examined in order to explore the mechanism of non-enzymatic browning through path coefficient
analysis. The results indicated that the change of browning degree (BD) was closely related to 5-HMF, reducing sugar,
and amino acid nitrogen in the fruit juice of Physalis pubescens L. fermented at three temperatures. In addition, 5-HMF
had the strongest direct impact on BD, while interaction between 5-HMF and reducing sugar was the chief determinant of
non-enzymatic browning during fermentation at 25 ℃. When fermentation was done at 30 ℃, amino acid nitrogen had the
strongest direct impact on BD and the major cause of non-enzymatic browning was interaction between 5-HMF and amino
acid nitrogen. During fermentation at 37 ℃, the non-enzymatic browning of Physalis pubescens L. was mainly caused by
5-HMF as the principal determinant of BD. Therefore, Maillard reaction is the major cause of the non-enzymatic browning
of Physalis pubescens L. during the fermentation process.