Correlation Between Protein Hydrolysates and Color During Fermentation ofMucor-TypeDouchi

Abstract

The correlations between the color of douchi and different protein hydrolysates from the post-fermentation period were analyzed. The results showed that peptides had the highest correlation with the color change, while free amino acids were second, which indicated that peptides and free amino acids were more involved in the Maillard reaction. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the 7S component may be more involved in the Maillard reaction during the pre-fermentation of douchi, and that 11S subunits may be more involved in the formation of melanin in the initial stage of post-fermentation. The water-soluble extracts of two douchi samples in the most rapid formation stage of melanin were analyzed by reversed phase-high performance liquid chromatography. The results showed that the hydrophilicity of hydrolysates decreased depending on color. Meanwhile, the amino acid analyses demonstrated that the four amino acids with the maximum loss ratios were all hydrophilic in this stage, which indicated a loss in the hydrophilic components due to their involvement in the Maillard reaction.

Fermentation of texturized vegetable proteins extruded at different moisture contents: effect on physicochemical, structural, and microbial properties

“…Hydrolysates of protein and sugar hydrolyzed from carbohydrates are important sources for Millard Reaction (MR) which occurs between reducing sugars and amino compounds (Langer and Rzeski, 2014;Wang et al, 2013). Therefore, as described by Zhang et al (2015), the degree of protein hydrolysis during fermentation might be associated with the significant color change of the fermented TVP products in our experiment. TVP extruded at lower MC (40%) exhibited significantly higher total color change (DE) and redness (a) than those of TVP extruded at higher MC (50%) during fermentation.…”

Comparing the differences of characteristic flavour between natural maturation and starter culture for Mucor‐type Douchi

“…Mucor ‐ type Douchi was prepared according to the process (Zhang et al ., ) with slight modifications. The processes were as follows: first step was soya bean steaming, in which soya bean was washed, soaked, drained and then steamed at 100 °C for 120 min; second step was prefermentation process in which the streamed soya bean was cooled to below 40 °C, inoculated with the A .…”

“…() investigated the effect of fermented rice culture on the quality of low‐salt Aspergillus ‐ type Douchi , and the results showed that it could promote a rapid growth of yeasts and lactic acid bacteria and improved sensory characteristics when supplemented with 10% and 15% fermented rice culture. Characteristic colour of Mucor ‐ type Douchi also depended on the parameters of postfermentation, such as peptides and free amino acids, which may be involved in the Maillard reaction (Zhang et al ., ).…”

Changes of Composition and Angiotensin I-Converting Enzyme-Inhibitory Activity During Douchi Fermentation

“…Proteins were broken down into polypeptides and amino acids by microbial enzymes during Douchi fermentation. [24,25] Our previous study results shows that the peptide content of Douchi fermented with Mucor wutungkiao had been increasing during the fermentation [26] . Consequently, we can concluded that Douchi ripening accompanied with nutrient decomposition under the action of microbial enzyme, and the increase of peptide and amino acid content contributed to protein digestibility [27] .…”