Table 1.

Change in phenolic compounds content in soybeans during the 30-day pickling process (μg g⁻¹, dry basis, P < 0.05, n = 6)

	Untreated soybean (control)	Pickled soybean					LSD (0.05)
		Day 1	Day 5	Day 10	Day 20	Day 30
Phenolic acid
PR	12.1 ± 1.5d	11.7 ± 1.2d	14.6 ± 1.9c	15.3 ± 2.3c	19.4 ± 1.3a	17.6 ± 2.5b	1.6
mC	1.9 ± 0.2a	1.5 ± 0.2c	1.7 ± 0.2b	1.5 ± 0.1c	1.4 ± 0.1cd	1.3 ± 0.2d	0.1
tC	2.1 ± 0.3f	3.5 ± 0.5e	4.7 ± 0.6d	5.5 ± 0.5c	6.9 ± 0.9b	7.9 ± 0.9a	0.6
VA	144.3 ± 6.4a	94.6 ± 9.7b	90.0 ± 6.0bc	86.4 ± 3.3c	73.2 ± 10.8d	72.3 ± 7.5d	6.5
Flavonoid
CA	53.0 ± 1.7a	39.6 ± 3.5b	37.3 ± 18.7b	36.2 ± 5.1b	48.5 ± 14.0a	49.3 ± 3.7a	8.5
NA	38.6 ± 2.4a	35.3 ± 2.2ab	32.5 ± 4.3bc	31.3 ± 2.5 cd	27.9 ± 4.2d	26.3 ± 5.2d	4.0
QU	7.2 ± 1.6b	7.6 ± 1.4ab	7.4 ± 1.7b	7.3 ± 2.1b	8.9 ± 1.0a	8.0 ± 2.3ab	1.5
NG	2.5 ± 0.5f	10.3 ± 0.9e	18.1 ± 1.3d	25.0 ± 2.3c	41.4 ± 2.6b	60.3 ± 5.8a	2.4
Total phenolics
	261.7 ± 8.1a	204.1 ± 10.0d	206.2 ± 24.2d	208.4 ± 4.4d	227.5 ± 19.2c	242.8 ± 17.5b	13.3

	Vinegar (control)	Pickling solution
		Day 1	Day 5	Day 10	Day 20	Day 30	LSD (0.05)
Phenolic acid
PR	ND	13.1 ± 1.6bc	15.3 ± 1.2ab	14.3 ± 2.4ab	17.3 ± 4.5a	11.8 ± 2.3c	1.7
mC	ND	0.9 ± 0.0c	1.1 ± 0.2b	1.2 ± 0.3ab	1.3 ± 0.2a	1.3 ± 0.3a	0.1
tC	ND	1.8 ± 0.1c	1.9 ± 0.2bc	2.0 ± 0.2b	2.3 ± 0.3a	2.3 ± 0.3a	0.1
VA	ND	14.8 ± 3.6b	18.7 ± 4.2a	16.7 ± 2.1ab	17.6 ± 3.0a	14.5 ± 2.7b	2.0
Flavonoid
CA	ND	62.4 ± 9.4 cd	66.3 ± 3.7c	60.1 ± 8.5d	82.5 ± 8.4b	93.4 ± 4.8a	4.7
NA	ND	4.1 ± 0.4b	4.8 ± 1.1a	4.7 ± 0.6a	5.1 ± 0.5a	5.0 ± 0.4a	0.4
QU	ND	TR	TR	4.3 ± 0.2	5.6 ± 0.7	5.9 ± 0.2	–
NG	ND	1.8 ± 0.9c	1.8 ± 0.1c	2.0 ± 0.2c	3.0 ± 0.1b	3.6 ± 0.2a	0.3
Total phenolics
	ND	102.2 ± 11.3c	110.6 ± 6.4b	108.9 ± 12.6bc	135.6 ± 5.0a	140.9 ± 9.2a	6.0

ND not detected, TR trace level concentrations, PA phenolic acid, F flavonoid, PR protocatechuic acid, mC m-coumaric acid, tC t-cinnamic acid, CA catechin, NA naringin, QU quercetin, NG naringenin, VA vanillin

^a–f Values with different superscripts differ significantly according to pickling period (P< 0.05)