Correlation Between Protein Hydrolysates and Color During Fermentation of Mucor-Type Douchi

Figures & data

TABLE 1 Sample codes and fermentation times of douchi

Code	Fermentation time	Code	Ferment time
Pe0	Boiled soybean	Po60	Post-fermentation for 60 d
Pe8	Pre-fermentation for 8 d	Po70	Post-fermentation for 70 d
Po5	Post-fermentation for 5 d	Po80	Post-fermentation for 80 d
Po10	Post-fermentation for 10 d	Po90	Post-fermentation for 90 d
Po20	Post-fermentation for 20 d	Po100	Post-fermentation for 100 d
Po40	Post-fermentation for 40 d	Po150	Post-fermentation for 150 d
Po50	Post-fermentation for 50 d

FIGURE 1 The color change of douchi during the fermentation process.

FIGURE 2 The contents of different protein hydrolysates in douchi during the fermentation process.

TABLE 2 Correlation analyses between protein hydrolysates and the color change during the post-fermentation stage of douchi

Analysis project	Soluble protein	Peptide	Free amino acid	Macromolecular soluble protein
Pearson’s correlation coefficient	0.494	0.521	0.457	0.382

FIGURE 3 SDS-PAGE of samples from the rapid melanin formation stage.

FIGURE 4 The RP-HPLC profiles of hydrolysates from the Pe 8 and Po 5 stages.

TABLE 3 The changes in total amino acids of douchi from the 8th day of pre-fermentation to the 5th day of post-fermentation

Amino acid	Total amino acids of Pe8 (g/100 g)	Total amino acids of Po5 (g/100 g)	Loss of amino acids between Pe8 and Po5	Ratio of loss (%)
Asp	2.95	2.27	0.68	22.79
Thr	0.89	0.71	0.18	20.24
Ser	0.61	0.49	0.12	19.72
Glu	3.89	3.07	0.82	20.93
Gly	1.30	1.03	0.27	20.52
Ala	1.61	1.32	0.29	18.21
Cys	0.44	0.38	0.06	13.40
Val	1.64	1.34	0.30	18.48
Met	0.52	0.45	0.07	14.04
Ile	1.39	1.12	0.27	19.50
Leu	2.42	1.90	0.52	21.46
Tyr	0.96	0.77	0.19	20.29
Phe	1.85	1.48	0.37	20.04
Lys	1.35	1.05	0.30	22.61
His	0.94	0.72	0.22	23.20
Arg	1.49	1.04	0.45	29.87
Pro	1.27	1.02	0.25	19.62
Total	25.53	20.17	5.36	20.99