. 2022 Feb 9;9:833906. doi: 10.3389/fnut.2022.833906

Table 1.

Changes in the contents of free amino acids (mg/L) of apple juice during lactic acid fermentation and the subsequent refrigerated storage period (4°C, 30 days).

Amino	Strains	Time
acid
		Fermentation for 0 h	Fermentation for 12 h	Fermentation for 24 h	Fermentation for 48 h	Fermentation for 72 h (Storage for 0 d)	Storage for 10 d	Storage for 20 d	Storage for 30 d
Asp	L. acidophilus	678.8 ± 31.8^Ad	662.3 ± 1.9^Bd	834.4 ± 15.7^Ac	974.1 ± 14.2^Ab	979.4 ± 1.0^Ab	1,529.7 ± 12.5^Aa	1522.8 ± 1.6^Aa	1512 ± 4.5^Aa
	L. casei	678.8 ± 31.8^Ad	672.4 ± 7.3^ABd	835.3 ± 17^Ac	933.4 ± 5.7^Bb	969.3 ± 16.8^Ab	1,443 ± 20.9^Ba	1460.3 ± 6.2^Ba	1,458.2 ± 2.5^Ca
	L. plantarum	678.8 ± 31.8^Ad	676.6 ± 1.5^Ad	852.9 ± 33.6^Ac	926.7 ± 7.2^Bb	972.9 ± 1.0^Ab	1,496.4 ± 20.2^ABa	1492.7 ± 17.4^ABa	1,489.3 ± 9.8^Ba
Thr	L. acidophilus	695.3 ± 13.2^Aa	522.7 ± 2.7^Ab	404.3 ± 6.2^Ac	385.5 ± 1.8^Ad	373.9 ± 2.6^Ad	ND	ND	ND
	L. casei	695.3 ± 13.2^Aa	521.5 ± 4.6^Ab	400.2 ± 0.3^Ac	379.4 ± 2.3^Ad	371.4 ± 2.9^Ad	ND	ND	ND
	L. plantarum	695.3 ± 13.2^Aa	533.6 ± 8.2^Ab	412.9 ± 8.6^Ac	378.2 ± 5.3^Ad	370.6 ± 6.8^Ad	ND	ND	ND
Ser	L. acidophilus	ND	ND	ND	ND	ND	ND	ND	ND
	L. casei	ND	ND	ND	ND	ND	ND	ND	ND
	L. plantarum	ND	ND	ND	ND	ND	ND	ND	ND
Glu	L. acidophilus	200.9 ± 3.2^Ad	213.4 ± 2.5^Ac	184.6 ± 0.8^Ae	205.3 ± 1.5^Bd	218.4 ± 1.6^Bb	292.2 ± 3.1^Aa	294.7 ± 1.3^Ba	294.1 ± 0.4^Ba
	L. casei	200.9 ± 3.2^Ad	211.2 ± 1.1^Ac	185 ± 2.3^Ae	212 ± 0.6^Ac	227.7 ± 1.7^Ab	293.7 ± 6.1^Aa	300.5 ± 2.2^Aa	299.9 ± 2.4^Aa
	L. plantarum	200.9 ± 3.2^Ad	210.1 ± 1.8^Ac	189.6 ± 4.8^Ae	206.1 ± 2.8^Bcd	224.3 ± 0.5^Ab	298.9 ± 1.1^Aa	300.1 ± 0.5^Aa	301.1 ± 1.1^Aa
Gly	L. acidophilus	4 ± 0.1^Af	47 ± 0^Be	72.5 ± 0.9^Bd	77.8 ± 1.6^Bc	80.3 ± 1.2^Bb	100.2 ± 0.6^Ba	100.1 ± 1.3^Ba	101.3 ± 1.2^Ba
	L. casei	4 ± 0.1^Ae	46.9 ± 0.2^Bd	76.8 ± 1.8^ABc	83 ± 1.4^Ab	85.3 ± 1.2^Ab	104.9 ± 2^ABa	106.2 ± 1.9^Aa	106.5 ± 1.2^Aa
	L. plantarum	4 ± 0.1^Ae	48.2 ± 0.1^Ad	77.6 ± 1.7^Ac	84.8 ± 1.4^Ab	86.9 ± 1.7^Ab	106.8 ± 1.6^Aa	107.7 ± 1.7^Aa	108.9 ± 1.8^Aa
Ala	L. acidophilus	33.3 ± 0.1^Ab	37.8 ± 0.9^Aa	8.3 ± 0.8^Ac	1.9 ± 0.2^Ad	1.9 ± 0^Ad	ND	ND	ND
	L. casei	33.3 ± 0.1^Ab	36.8 ± 0.9^Aa	7.7 ± 0.4^Ac	1.9 ± 0^Ad	1.9 ± 0.2^Ad	ND	ND	ND
	L. plantarum	33.3 ± 0.1^Ab	39 ± 1.1^Aa	9.9 ± 1^Ac	2 ± 0.2^Ad	1.9 ± 0.1^Ad	ND	ND	ND
Cys	L. acidophilus	3.1 ± 0.1^Ad	5.1 ± 0^Ac	6.5 ± 0.3^Aab	6.5 ± 0^Aa	6.2 ± 0^Ab	ND	ND	ND
	L. casei	3.1 ± 0.1^Ad	5 ± 0^Ac	6 ± 0.1^Aa	5.9 ± 0^Bab	5.8 ± 0.1^Bb	ND	ND	ND
	L. plantarum	3.1 ± 0.1^Ac	5.2 ± 0^Ab	6.4 ± 0.4^Aa	6.4 ± 0.2^Aa	6.2 ± 0.2^Aa	ND	ND	ND
Val	L. acidophilus	31.5 ± 0.1^Ab	35.3 ± 0.3^Aa	8.7 ± 0.9^Ac	2.1 ± 0.2^Ad	2.7 ± 0.2^Ad	8.4 ± 0.4^Ac	6.9 ± 3.5^Ac	8.2 ± 0.7^Ac
	L. casei	31.5 ± 0.1^Ab	34.2 ± 0.4^Aa	6 ± 0.3^Bd	1.5 ± 0.1^Be	2.2 ± 0.2^Ae	7.5 ± 0.4^Ac	8 ± 0.4^Ac	7.7 ± 0.7^Ac
	L. plantarum	31.5 ± 0.1^Ab	34.8 ± 0.5^Aa	7.7 ± 0.8^ABc	1.7 ± 0^Be	2.3 ± 0.2^Ae	4.1 ± 0.3^Bde	6.3 ± 3.4^Acd	8.3 ± 0.5^Ac
Met	L. acidophilus	10.4 ± 0.5^Aa	8 ± 0^Aab	2.9 ± 1^Abc	1.1 ± 0.5^Ac	1.2 ± 0.3^ABc	4.3 ± 1.1^Abc	4.7 ± 1.3^Abc	11.4 ± 6.4^Aa
	L. casei	10.4 ± 0.5^Aab	7.7 ± 0^Bb	0.9 ± 0.5^Ac	0.6 ± 0^Ac	0.9 ± 0^Bc	9.7 ± 3.8^Aab	13 ± 1.1^Aa	10.3 ± 5^Aab
	L. plantarum	10.4 ± 0.5^Aab	7.9 ± 0.2^ABabc	1.3 ± 0^Ac	1.1 ± 0.5^Ac	1.5 ± 0^Ac	3.5 ± 0.1^Abc	9.6 ± 8.8^Aab	13.8 ± 2.2^Aa
Ile	L. acidophilus	59.6 ± 1.6^Aa	49.1 ± 0.5^Ab	7.4 ± 0.3^Ac	1.4 ± 0.1^Ad	1.8 ± 0.2^Ad	2.4 ± 0.6^Ad	3.9 ± 3.1^Acd	4 ± 2.6^Acd
	L. casei	59.6 ± 1.6^Aa	46.9 ± 0.6^Ab	3.9 ± 0.2^Bc	0.7 ± 0.1^Bd	1.2 ± 0.1^Ad	0.9 ± 0.2^Bd	1.6 ± 1^Ad	1.8 ± 0.6^Ad
	L. plantarum	59.6 ± 1.6^Aa	48.4 ± 1.1^Ab	5.9 ± 0.9^Ac	0.9 ± 0.3^ABd	1.5 ± 0.3^Ad	1.3 ± 0.3^ABd	3.4 ± 3.2^Acd	3.4 ± 3.2^Acd
Leu	L. acidophilus	16.7 ± 0.3^Ab	22.6 ± 0.4^Aa	4.1 ± 0.1^Acd	1.8 ± 0.3^Ad	2.6 ± 0.3^Ad	3.9 ± 0.4^Acd	7.1 ± 2.8^Ac	6.5 ± 3.1^Ac
	L. casei	16.7 ± 0.3^Ab	21.8 ± 0.5^Aa	3.1 ± 0.2^Bc	0 ± 0^Bf	1.2 ± 0.6^Ae	2.2 ± 0.5^Ad	2.2 ± 0.5^Ad	2.4 ± 0.1^Acd
	L. plantarum	16.7 ± 0.3^Ab	22.4 ± 0.2^Aa	3.9 ± 0.3^Acde	1.4 ± 0.5^Ae	2.1 ± 0.6^Ade	3.4 ± 0.7^Acde	5.8 ± 4.1^Acd	6.7 ± 2.9^Ac
Tyr	L. acidophilus	ND	3.2 ± 0.1^Aa	3.5 ± 0.2^Aa	3.9 ± 0.1^Aa	4 ± 0^Aa	ND	3.6 ± 0.6^Aa	2 ± 2.8^Aab
	L. casei	ND	3 ± 0^Ad	3.7 ± 0.1^Ab	3.4 ± 0.1^Bc	4.1 ± 0.2^Aa	ND	ND	ND
	L. plantarum	ND	7.9 ± 7^Aa	3.3 ± 0^Aab	3.9 ± 0.1^Aab	3.9 ± 0^Aab	ND	2 ± 2.9^Aab	3.7 ± 0.4^Aab
Phe	L. acidophilus	12.9 ± 0.1^Aa	8.9 ± 0.3^Ac	7.1 ± 0^Ad	7.1 ± 0.1^Ad	7.2 ± 0.1^Ad	12 ± 0.3^Ab	12.1 ± 0.1^Ab	11.8 ± 0^Bb
	L. casei	12.9 ± 0.1^Aa	8.9 ± 0.3^Ac	7.2 ± 0.1^Ad	6.8 ± 0.1^Be	7.1 ± 0.2^Ade	11.7 ± 0.1^Ab	11.8 ± 0.1^ABb	11.9 ± 0^Ab
	L. plantarum	12.9 ± 0.1^Aa	9 ± 0.4^Ac	7.2 ± 0^Ad	7 ± 0^Ad	7.2 ± 0.1^Ad	11.7 ± 0.1^Ab	11.7 ± 0.1^Bb	11.9 ± 0.1^ABb
Lys	L. acidophilus	25.4 ± 0.1^Ad	51 ± 0.7^Ab	51.8 ± 0.6^Ab	46.9 ± 0.1^ABc	46 ± 0.1^Ac	60.9 ± 0.8^Aa	61.1 ± 0.5^Aa	60.6 ± 0.2^Aa
	L. casei	25.4 ± 0.1^Ad	49.9 ± 0.7^Ab	49.6 ± 0.1^Ab	44.8 ± 0.4^Bc	44 ± 0.5^Ac	57.8 ± 0.6^Aa	58.2 ± 1^Aa	58 ± 0.1^Aa
	L. plantarum	25.4 ± 0.1^Ac	50.1 ± 0.5^Ab	49.4 ± 3.9^Ab	47.4 ± 1.3^Ab	46.5 ± 1.4^Ab	60.9 ± 1.7^Aa	61.1 ± 1.5^Aa	60.7 ± 1.9^Aa
His	L. acidophilus	26 ± 0.1^Aa	25.5 ± 0.2^Ab	21.1 ± 0.1^Ad	19.4 ± 0^Ae	19.5 ± 0^Ae	24 ± 0.3^Ac	24.1 ± 0.1^Ac	24 ± 0.1^Ac
	L. casei	26 ± 0.1^Aa	25 ± 0.2^Ab	20.5 ± 0.2^Ad	18.8 ± 0.1^Be	19 ± 0.1^Be	23 ± 0.2^Bc	23.3 ± 0.4^Bc	23.3 ± 0.2^Bc
	L. plantarum	26 ± 0.1^Aa	25.4 ± 0.2^Ab	20.8 ± 0.5^Ad	19.3 ± 0.1^Ae	19.4 ± 0.2^ABe	23.6 ± 0.2^ABc	23.6 ± 0.1^ABc	23.6 ± 0.1^ABc
Arg	L. acidophilus	10.8 ± 0.1^Ae	45.3 ± 0.7^Aa	36.3 ± 0.4^Ac	33.5 ± 0.3^Ad	34.2 ± 0.5^Ad	40.7 ± 0.8^Ab	41.6 ± 0.5^Ab	41.2 ± 0.2^Ab
	L. casei	10.8 ± 0.1^Ae	44.4 ± 0.7^Aa	34.9 ± 0.2^Ac	32.3 ± 0.5^Ad	32.9 ± 0.4^Ad	38.9 ± 0.6^Ab	39.5 ± 1^Ab	39.5 ± 0.4^Bb
	L. plantarum	10.8 ± 0.1^Ae	44.4 ± 0.6^Aa	35.4 ± 1^Ac	32.9 ± 0.4^Ad	33.3 ± 0.7^Ad	39.9 ± 0.5^Ab	40.1 ± 0.5^Ab	39.8 ± 0.8^ABb
Pro	L. acidophilus	ND	6.3 ± 0.6^Ac	6.7 ± 0.1^Ac	9.9 ± 0.6^Ab	11.1 ± 0.6^Ab	53.7 ± 0.1^Aa	54.8 ± 2.8^Aa	55.1 ± 0.4^Aa
	L. casei	ND	5.8 ± 0.3^Acd	2.6 ± 3.7^Ade	9 ± 0.2^Abc	10.7 ± 0.5^Ab	55.5 ± 2.2^Aa	56 ± 0.4^Aa	56 ± 0.3^Aa
	L. plantarum	ND	5.8 ± 0.7^Ac	6.9 ± 0.3^Ac	8.9 ± 0.9^Ab	10.4 ± 0.9^Ab	53.5 ± 1.7^Aa	53.9 ± 0.7^Aa	53.4 ± 0.4^Ba

Results are expressed as mean ± standard deviation from the three replicates. ND refers to not detected. Values with different letters indicated a significant difference (p < 0.05).