J Food Bioact

Journal of Food Bioactives, ISSN 2637-8752 print, 2637-8779 online

Journal website www.isnff-jfb.com

Original Research

Volume 14, June 2021, pages 81-93

Qualitative and quantitative changes of nonvolatile compounds and taste profiles in Wuyi rock tea during the manufacturing processes

Figure 1. The contents of polyphenols and caffeine during Wuyi rock tea manufacturing processes. (a) EGCG; (b) C; (c) ECG; (d) EC; (e) EGC; (f) GA; (g) GCG; (h) GC; (i) CAFF.

Figure 2. The contents of L-theanine and total sugar during Wuyi rock tea manufacturing processes. (a) L-Theanine. (b) Total sugar.

Figure 3. The concentrations of free amino acids during Wuyi rock tea manufacturing processes. (I) Bitter-tasting amino acids, (a) Val; (b) Ile; (c) Leu; (d) Tyr; (e) Phe; (f) Trp; (g) Lys; (h) His; (i) Arg. (II) Sweet-tasting amino acids, (j) Thr; (k) Ser; (l) Gln; (m) Gly; (n) Ala; (o) Met; (p) Pro. (III) Umami-tasting amino acids, (q) Asp; (r) Glu. (IV) Other amino acid, (s) Cys.

Figure 5. The taste profiles of Wuyi rock tea during manufacturing processes. (a) The tasty series of taste chemical compounds form Wuyi rock tea during manufacturing processes based on Dose-over-threshold factors with natural logarithms computation. The data from FF-WRT in ‘Umami’ attribute had significant difference (p<0.05) from the other samples (‘*’ labeled). (b) Radar of sensory taste attributes profile duing Wuyi rock tea manufacturing processes (SRt-OT & FF-WRT). The taste attributes labeled with ‘a’, ‘b’ had significantly difference (p<0.05) for the two samples.

**Table 1.** Taste qualities, thresholds and dose-over-threshold factors of Wuyi rock tea
Tastant	Threshold (μmol/L)	FTL	Wi-OT	1S-OT	2S-OT	3S-OT	4S-OT	5S-OT	Fx-OT	Ro-OT	FRt-OT	SRt-OT	FF-WRT
nd, not detectable. FTL, fresh tea leaves; Wi-OT, withering; 1S-OT, first shaking; 2S-OT, second shaking; 3S-OT, third shaking; 4S-OT, fourth shaking; 5S-OT, fifth shaking; Fx-OT, fixing; Ro-OT, rolling; FRt-OT, first roasting; SRt-OT, second roasting; FF-WRT, Wuyi rock tea after full fire processing treatment. GC, (−)-Gallocatechin; EGC, (−)-Epigallocatechin; C, (+)-Catechin; EGCG, (−)-Epigallocatechin gallate; EC, (−)-Epicatechin; GCG, (−)-Gallocatechin gallate; ECG, (−)-Epicatechin gallate; CAFF, caffeine. Val, Valine; Ile, Isoleucine; Leu, Leucine; Tyr, Tyrosine; Phe, Phenylalanine; Trp, Tryptophan; Lys, Lysine; His, Histidine; Arg, Arginine; Thr, Threonine; Ser, Serine; Gln, Glutamine; Gly, Glycine; Ala, Alanine; Hypro, Hydroxyproline; Met, Methionine; Pro, Proline; Asp, Aspartic acid.
Group I: Astringent-tasting compounds
GC	540	28.30	29.51	28.60	33.32	33.50	33.68	34.53	33.92	32.17	36.70	42.51	47.83
EGC	520	45.46	118.49	127.40	128.28	128.28	129.41	124.70	84.52	70.95	102.98	117.54	65.11
C	410	6.30	13.19	13.61	12.60	12.77	12.94	13.36	10.50	10.25	11.01	11.26	10.34
EGCG	190	325.85	557.78	559.61	528.73	519.54	511.73	480.05	348.35	337.33	396.92	455.82	380.61
EC	930	22.56	32.08	31.56	34.01	34.38	34.56	33.97	26.71	26.38	29.12	29.63	19.74
GCG	390	3.19	3.58	3.41	3.24	3.24	3.47	3.64	3.36	3.41	3.19	3.41	5.82
ECG	260	77.55	80.25	81.64	83.20	80.77	80.77	81.38	71.90	73.21	78.51	83.38	66.68
Total		509.21 ± 14.66	834.87 ± 54.98	845.84 ± 25.52	823.38 ± 27.53	812.48 ± 19.55	806.56 ± 25.64	771.62 ± 40.95	579.26 ± 46.45	553.69 ± 17.29	658.42 ± 49.04	743.55 ± 22.09	596.14 ± 19.79
Group II: Bitter-tasting compounds
CAFF	500	206.40	215.77	212.47	212.99	214.74	214.02	217.42	215.67	229.67	214.33	219.06	216.80
Val	21,000	0.02	0.04	0.05	0.07	0.09	0.11	0.11	0.12	0.11	0.11	0.10	0.03
Ile	11,000	0.01	0.03	0.04	0.06	0.07	0.09	0.10	0.10	0.10	0.09	0.09	0.02
Leu	12,000	0.02	0.05	0.06	0.07	0.08	0.10	0.10	0.11	0.11	0.09	0.09	0.02
Tyr	5,000	0.05	0.22	0.27	0.35	0.42	0.57	0.58	0.54	0.53	0.45	0.46	0.13
Phe	58,000	nd	0.01	0.01	0.02	0.04	0.05	0.05	0.06	0.05	0.05	0.05	0.01
Trp	18,000	0.12	0.25	0.28	0.27	0.27	0.30	0.33	nd	nd	nd	0.18	nd
Lys	3,400	0.03	0.13	0.17	0.24	0.30	0.39	0.40	0.41	0.39	0.32	0.32	0.07
His	1,500	nd	nd	nd	0.24	0.32	0.41	0.43	0.43	0.40	0.22	0.24	nd
Arg	2,800	nd	nd	nd	0.16	0.08	0.22	0.19	0.20	0.21	0.16	0.18	nd
Total		206.64 ± 0.22	216.49 ± 8.86	213.37 ± 4.33	214.47 ± 18.55	216.40 ± 2.43	216.26 ± 10.38	219.70 ± 6.92	217.63 ± 8.72	231.57 ± 3.44	215.83 ± 5.49	220.77 ± 0.66	217.06 ± 3.51
Group III: Sweet-tasting compounds
Total sugar	9,000	7.14	6.14	7.06	7.36	7.38	7.25	6.65	6.02	6.47	5.51	5.14	5.00
Thr	40,000	0.01	0.03	0.03	0.04	0.04	0.05	0.05	0.05	0.05	0.05	0.04	0.01
Ser	30,000	0.04	0.07	0.08	0.09	0.11	0.11	0.12	0.12	0.11	0.10	0.10	0.02
Gln	17,000	0.14	0.33	0.31	0.33	0.30	0.36	0.34	0.46	0.43	0.40	0.39	nd
Gly	30,000	0.01	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.02	0.01
Ala	8,000	0.17	0.42	0.38	0.35	0.38	0.47	0.38	0.47	0.45	0.43	0.43	0.11
Hypro	4,000	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd
Met	2,000	nd	nd	nd	nd	0.05	0.11	0.06	0.01	0.01	nd	nd	nd
Pro	26,000	nd	0.00	0.01	0.01	0.04	0.04	0.04	0.03	0.01	0.01	0.03	nd
Total		7.51 ± 0.02	7.01 ± 0.02	7.89 ± 0.07	8.21 ± 0.08	8.33 ± 0.09	8.41 ± 0.04	7.66 ± 0.09	7.18 ± 0.05	7.56 ± 0.05	6.51 ± 0.06	6.16 ± 0.04	5.16 ± 0.03
Group IV: Umami-like taste compounds
Theanine	3.44	6.77	9.28	8.70	9.83	8.93	10.55	8.35	8.13	8.15	5.82	5.32	0.42
Asp	4,000	1.02	1.69	1.71	1.90	1.76	1.72	1.96	1.87	1.80	1.68	1.49	0.57
Glu	3,000	2.47	2.33	2.30	2.33	2.10	1.98	1.90	0.46	0.44	0.35	0.37	nd
Total		10.26 ± 0.22	13.30 ± 0.11	12.71 ± 0.12	14.07 ± 0.87	12.79 ± 0.36	14.24 ± 1.28	12.21 ± 0.44	10.47 ± 0.57	10.39 ± 0.14	7.85 ± 0.17	7.18 ± 0.34	0.99 ± 0.04

Table 1. Taste qualities, thresholds and dose-over-threshold factors of Wuyi rock tea

Tastant

Threshold (μmol/L)

FTL

Wi-OT

1S-OT

2S-OT

3S-OT

4S-OT

5S-OT

Fx-OT

Ro-OT

FRt-OT

SRt-OT

FF-WRT

nd, not detectable. FTL, fresh tea leaves; Wi-OT, withering; 1S-OT, first shaking; 2S-OT, second shaking; 3S-OT, third shaking; 4S-OT, fourth shaking; 5S-OT, fifth shaking; Fx-OT, fixing; Ro-OT, rolling; FRt-OT, first roasting; SRt-OT, second roasting; FF-WRT, Wuyi rock tea after full fire processing treatment. GC, (−)-Gallocatechin; EGC, (−)-Epigallocatechin; C, (+)-Catechin; EGCG, (−)-Epigallocatechin gallate; EC, (−)-Epicatechin; GCG, (−)-Gallocatechin gallate; ECG, (−)-Epicatechin gallate; CAFF, caffeine. Val, Valine; Ile, Isoleucine; Leu, Leucine; Tyr, Tyrosine; Phe, Phenylalanine; Trp, Tryptophan; Lys, Lysine; His, Histidine; Arg, Arginine; Thr, Threonine; Ser, Serine; Gln, Glutamine; Gly, Glycine; Ala, Alanine; Hypro, Hydroxyproline; Met, Methionine; Pro, Proline; Asp, Aspartic acid.

Group I: Astringent-tasting compounds

540

28.30

29.51

28.60

33.32

33.50

33.68

34.53

33.92

32.17

36.70

42.51

47.83

EGC

520

45.46

118.49

127.40

128.28

129.41

124.70

84.52

70.95

102.98

117.54

65.11

410

6.30

13.19

13.61

12.60

12.77

12.94

13.36

10.50

10.25

11.01

11.26

10.34

EGCG

190

325.85

557.78

559.61

528.73

519.54

511.73

480.05

348.35

337.33

396.92

455.82

380.61

930

22.56

32.08

31.56

34.01

34.38

34.56

33.97

26.71

26.38

29.12

29.63

19.74

GCG

390

3.19

3.58

3.41

3.24

3.47

3.64

3.36

3.41

3.19

3.41

5.82

ECG

260

77.55

80.25

81.64

83.20

80.77

81.38

71.90

73.21

78.51

83.38

66.68

Total

509.21 ± 14.66

834.87 ± 54.98

845.84 ± 25.52

823.38 ± 27.53

812.48 ± 19.55

806.56 ± 25.64

771.62 ± 40.95

579.26 ± 46.45

553.69 ± 17.29

658.42 ± 49.04

743.55 ± 22.09

596.14 ± 19.79

Group II: Bitter-tasting compounds

CAFF

500

206.40

215.77

212.47

212.99

214.74

214.02

217.42

215.67

229.67

214.33

219.06

216.80

Val

21,000

0.02

0.04

0.05

0.07

0.09

0.11

0.12

0.11

0.10

0.03

Ile

11,000

0.01

0.03

0.04

0.06

0.07

0.09

0.10

0.09

0.02

Leu

12,000

0.02

0.05

0.06

0.07

0.08

0.10

0.11

0.09

0.02

Tyr

5,000

0.05

0.22

0.27

0.35

0.42

0.57

0.58

0.54

0.53

0.45

0.46

0.13

Phe

58,000

0.01

0.02

0.04

0.05

0.06

0.05

0.01

Trp

18,000

0.12

0.25

0.28

0.27

0.30

0.33

0.18

Lys

3,400

0.03

0.13

0.17

0.24

0.30

0.39

0.40

0.41

0.39

0.32

0.07

His

1,500

0.24

0.32

0.41

0.43

0.40

0.22

0.24

Arg

2,800

0.16

0.08

0.22

0.19

0.20

0.21

0.16

0.18

Total

206.64 ± 0.22

216.49 ± 8.86

213.37 ± 4.33

214.47 ± 18.55

216.40 ± 2.43

216.26 ± 10.38

219.70 ± 6.92

217.63 ± 8.72

231.57 ± 3.44

215.83 ± 5.49

220.77 ± 0.66

217.06 ± 3.51

Group III: Sweet-tasting compounds

Total sugar

9,000

7.14

6.14

7.06

7.36

7.38

7.25

6.65

6.02

6.47

5.51

5.14

5.00

Thr

40,000

0.01

0.03

0.04

0.05

0.04

0.01

Ser

30,000

0.04

0.07

0.08

0.09

0.11

0.12

0.11

0.10

0.02

Gln

17,000

0.14

0.33

0.31

0.33

0.30

0.36

0.34

0.46

0.43

0.40

0.39

Gly

30,000

0.01

0.02

0.01

Ala

8,000

0.17

0.42

0.38

0.35

0.38

0.47

0.38

0.47

0.45

0.43

0.11

Hypro

4,000

Met

2,000

0.05

0.11

0.06

0.01

Pro

26,000

0.00

0.01

0.04

0.03

0.01

0.03

Total

7.51 ± 0.02

7.01 ± 0.02

7.89 ± 0.07

8.21 ± 0.08

8.33 ± 0.09

8.41 ± 0.04

7.66 ± 0.09

7.18 ± 0.05

7.56 ± 0.05

6.51 ± 0.06

6.16 ± 0.04

5.16 ± 0.03

Group IV: Umami-like taste compounds

Theanine

3.44

6.77

9.28

8.70

9.83

8.93

10.55

8.35

8.13

8.15

5.82

5.32

0.42

Asp

4,000

1.02

1.69

1.71

1.90

1.76

1.72

1.96

1.87

1.80

1.68

1.49

0.57

Glu

3,000

2.47

2.33

2.30

2.33

2.10

1.98

1.90

0.46

0.44

0.35

0.37

Total

10.26 ± 0.22

13.30 ± 0.11

12.71 ± 0.12

14.07 ± 0.87

12.79 ± 0.36

14.24 ± 1.28

12.21 ± 0.44

10.47 ± 0.57

10.39 ± 0.14

7.85 ± 0.17

7.18 ± 0.34

0.99 ± 0.04