Effects of microwave heating on physicochemical properties, microstructure and volatile profiles of yak meat

Figures & data

Figure 1. Distribution of heating sites in microwave chamber.

Figure 2. (a) Heating efficiency of different sites determined one by one in microwave chamber. (b) Heating efficiency of different sites determined at the same time in microwave chamber. Values are presented as mean ± SD of at least triplicate measurement. Bars with different lowercase indicate significant differences among the heating sites (p <.05).

Figure 3. (a) SDS-PAGE patterns of yak meat during cooking by boiling water. (b) SDS-PAGE patterns of yak meat cooked by different microwave treatments.

Figure 4. Effects of microwave treatments on organoleptic quality of yak meat.

Table 1. Effects of microwave treatments on cooking loss and shear force of cooked yak meat.

Treatment condition		Cooking loss(%)	Shear force(N)
Boiled in water		35.98 ± 0.00^g	316.85 ± 3.40^a
High (700 W; 100%)	30 s	37.03 ± 0.67^fg	259.73 ± 0.13^fg
	40 s	38.75 ± 0.16^ef	259.83 ± 5.29^fg
	50 s	40.09 ± 0.22^de	265.69 ± 4.56^efg
	60 s	40.66 ± 0.00^cde	276.03 ± 6.62^d
Medium (560 W; 80%)	50 s	39.82 ± 0.85^de	265.42 ± 1.87^efg
	60 s	40.48 ± 0.00^de	257.20 ± 11.85^g
	70 s	43.51 ± 1.41^b	268.04 ± 6.46^def
	80 s	45.92 ± 2.39^a	287.04 ± 6.08^c
Low (420 W; 60%)	70 s	38.91 ± 1.14^ef	274.64 ± 0.00^efg
	80 s	41.01 ± 1.71^cd	274.06 ± 0.80^de
	90 s	44.08 ± 1.51^de	304.20 ± 7.01^b
	100 s	42.58 ± 0.37^bc	315.57 ± 0.64^a

Note: Values are presented as mean ± SD of at least triplicate measurement. Data followed by different superscript letters within a column indicate significant differences among treatments (p <.05).

Table 2. Effects of microwave treatments on colour values of cooked yak meat.

Treatment condition		L*	a*	b*
Boiled in water		57.95 ± 0.29^a	6.56 ± 0.18^h	12.04 ± 0.20^e
High (700 W; 100%)	30 s	55.79 ± 0.91^ab	6.74 ± 0.15^gh	13.64 ± 0.55^cd
	40 s	53.03 ± 1.13^c	6.94 ± 0.38^gh	13.77 ± 0.33^bcd
	50 s	51.70 ± 0.61^cd	7.19 ± 0.09^fg	13.66 ± 0.17^cd
	60 s	49.36 ± 2.28^de	7.64 ± 0.13^ef	14.62 ± 0.79^a
Medium (560 W; 80%)	50 s	53.39 ± 1.51^bc	7.24 ± 0.61^fg	13.35 ± 0.18^d
	60 s	50.85 ± 2.39^cd	7.67 ± 0.39^ef	13.81 ± 0.50^bcd
	70 s	49.82 ± 0.99^de	7.94 ± 0.02^de	14.07 ± 0.35^abcd
	80 s	48.92 ± 0.72^de	8.40 ± 0.44^bcd	14.26 ± 0.71^abc
Low (420 W; 60%)	70 s	53.24 ± 1.61^bc	7.99 ± 0.36^cde	14.36 ± 0.53^abc
	80 s	49.47 ± 1.43^de	8.52 ± 0.29^bc	14.39 ± 0.12^abc
	90 s	48.03 ± 1.91^e	8.70 ± 0.15^ab	14.49 ± 0.06^ab
	100 s	47.77 ± 1.89^e	9.11 ± 0.09^a	14.68 ± 0.12^a

Note: Values are presented as mean ± SD of at least triplicate measurement. Data followed by different superscript letters within a column indicate significant differences among treatments (p <.05).

Figure 5. Microstructure of yak meat cooked by microwave treatments (10×).

Table 3. Relative percentages of flavour compounds in cooked yak meat identified by GC-MS.

Number	Compounds by class		Boiling water	700W				560W				420 W
				30s	40s	50s	60s	50s	60 s	70 s	80 s	70 s	80 s	90 s	100 s
1	Alkanes	Trichloromethane	0.54	–	–	–	–	–	–	–	–	–	–	–	–
2		Propylene Oxid	4.02	4.68	–	–	–	–	–	–	–	–	–	–	–
3		N-heptane	–	–	–	–	1.07	0.93	0.5	–	0.61	0.78	1.29	0.54	0.69
4		Octane	–	–	–	–	10.35	11.91	14.71	6.44	21.80	27.02	25.74	36.43	45.18
5		Pentylcyclopropane	–	0.98	–	–	–	–	–	–	–	–	–	–	–
6		Nonane	0.54	–	–	–	0.31	0.43	0.32	0.21	1.08	0.63	0.64	1.12	0.84
7		2-methyloctane	–	–	–	–	–	0.14	–	–	0.23	0.15	0.16	0.17	–
8		2-methyl-5-ethylheptane	–	–	0.09	–	–	–	–	–	–	–	–	–	–
9		N-tridecane	0.29	0.24	0.47	0.36	0.35	0.25	0.24	0.08	0.17	0.17	0.25	0.17	0.12
10		N-dodecane	–	–	0.39	0.27	0.12	0.14	0.09	0.24	0.40	0.11	0.16	0.16	0.13
11		N-tetradecane	–	–	0.24	0.2	0.22	0.19	0.16	0.08	0.17	0.17	0.17	0.2	0.13
12		4,6-dimethyldodecane	–	–	–	–	–	–	–	–	0.15	–	–	–	–
13		2,7,10-trimethyl dodecane	–	–	0.42	0.66	–	–	–	–	–	–	–	–	–
14		N-pentadecane	–	–	–	0.21	–	0.13	–	–	–	–	–	–	–
15		Hexadecane	–	–	–	–	–	–	–	–	0.17	0.08	–	–	–
16		N-octadecane	–	–	–	0.1	–	–	–	–	–	–	–	–	–
17		1-nitrohexane	–	–	–	–	–	–	–	–	0.15	0.17	0.21	0.27	0.18
18	Aldehydes	2-methylpropanal	0.54	–	–	–	–	–	–	–	–	–	–	–	–
19		Pentanaldehyde	–	2.39	2.36	1.59	–	–	–	–	–	–	–	–	–
20		3-methyl butyraldehyde	–	–	0.55	0.59	–	–	–	–	–	–	–	–	–
21		2-methyl butyraldehyde	–	–	0.44	–	–	–	–	–	–	–	–	–	–
22		N-hexanaldehyde	11.51	19.4	22.31	17.74	4.20	–	–	–	–	–	–	–	–
23		N-heptaldehyde	1.84	3.37	3.22	2.76	0.46	0.42	0.2	0.14	–	0.16	0.21	–	–
24		Benzaldehyde	1.67	1.91	2.47	2.49	–	–	–	–	–	–	–	–	–
25		Octanal	–	4.26	5.02	5.06	–	–	–	–	–	–	–	–	–
26		Nonanal	7.51	11.63	12.62	12.79	2.3	2.83	2.02	1.88	5.82	2.29	2.76	2.86	2
27		Decanal	0.86	1.07	0.78	0.59	0.14	0.13	0.07	0.12	0.12	0.11	0.1	0.09	0.06
28		Undecanal	–	–	0.12	0.1	–	–	–	–	–	–	–	–	–
29		Hexadecanal (palmitaldehyde)	0.64	0.26	0.44	0.6	0.99	0.33	0.76	0.18	0.21	0.38	0.27	0.27	0.26
30		Tetradecanal	–	–	0.16	0.49	0.08	–	0.1	–	–	–	–	–	–
31	Alcohols	Methyl mercaptan	1.99	1.83	1.88	1.86	–	–	–	–	–	–	–	–	–
32		2,3-butanediol	–	–	–	–	4.16	9.74	–	3.57	19.07	–	16.92	14.97	–
33		Isoamyl alcohol	–	–	–	–	4.81	6.15	6.04	–	4.04	4.23	3.18	2.3	4.86
34		N-hexanol	–	–	1.45	2.16	1.81	1.78	1.39	0.54	1.21	1.96	2.08	1.59
35		1-heptanol	–	–	–	–	–	0.41	0.36	–	0.41	0.63	0.68	0.63	0.48
36		1-octanol	0.91	–	0.94	0.94	0.77	0.9	0.78	0.57	1.15	1.77	1.93	1.78	0.24
37		2-ethylhexanol	0.79	0.48	–	–	0.14	0.16	–	–	0.24	0.28	0.34	0.37	0.87
38		1-octen-3-ol	0.54	0.67	0.98	1	0.99	1.03	0.81	0.31	0.71	0.98	1.05	1.08	–
39		(E) -2-octen-1-ol	–	–	–	–	0.09	–	–	–	–	–	–	–	1.39
40		1-nonyl alcohol	–	–	–	–	0.64	–	–	–	–	–	–	–	1.21
41		Linalool	0.42	0.3	0.25	0.09	0.12	–	–	–	–	–	–	–	–
42		Lauryl alcohol	–	–	–	–	–	–	–	–	–	0.16	–	0.18	–
43	Acids	Acetic acid	0.86	2.13	1.24	1.11	6.28	17.19	2.57	2.71	3.08	3.66	3.71	2.64	2.83
44		Oxalic acid	–	–	–	–	0.31	–	0.37	0.22	–	0.48	–	–	–
45		4-hydroxybutyric acid	–	0.43	–	–	–	–	–	–	–	–	–	–	–
46		Isovaleric acid	–	–	–	–	0.23	0.16	–	0.03	–	–	–	–	–
47		Caprylic acid	1.06	–	0.47	0.54	0.4	0.32	–	–	–	–	–	–	–
48		Capric acid	1.23	0.37	0.59	0.71	0.94	0.68	–	0.33	0.19	0.36	0.26	0.26	0.12
49		Lauric acid	–	–	0.19	0.23	0.39	0.19	–	0.13	–	0.15	0.1	0.18	–
50		Myristic acid	–	–	–	0.09	0.23	0.09	–	0.05	–	0.09	0.1	0.06	0.04
51		Propanoic acid	2.70	3.94	2.75	2.77	3.91	3.97	3.06	3.42	1.2	0.19	0.72	0.68	0.18
52		3-aminobutyric acid	–	–	–	–	–	0.3	–	–	–	–	0.55	0.33	0.54
53		DL-β-aminobutyric acid	–	–	–	–	–	–	–	–	0.41	–	–	–	–
54	Ketones	acetone	–	–	5.8	4.9	6.02	4.97	5.17	5.79	8.01	6.22	6.89	5.25	4.75
55		2-butanone	3.83	4.24	3.72	2.86	–	–	–	–	–	–	–	–	–
56		3-hydroxy-2-butanone	–	–	6.76	14.1	27.77	11.78	37.54	51.95	7.4	2.71	1.88	1.98	0.75
57		2-heptanone	–	–	–	–	0.34	0.3	0.27	–	0.26	0.32	0.34	0.3	0.28
58		6-methyl-5-hepten-2-one	–	0.85	–	–	–	–	–	0.18	0.37	–	–	–	–
59		2-methyl-3-octanone	–	–	1.34	1.43	0.44	0.39	0.2	–	–	–	–	–	–
60	Esters	Vinyl acetate	–	–	0.83	2.19	–	–	–	–	–	–	–	–	–
61		Butyric acid monoglyceride	0.69	–	–	–	–	–	–	–	–	–	–	–	–
62		Isoamyl acetate	–	–	–	–	0.37	0.54	0.3	0.07	0.77	0.28	0.26	0.25	0.28
63		Heptyl formate	–	–	–	–	0.37	–	–	0.13	–	–	–	–	–
64		Phthalic acid, hex-3-yl isobutyl ester	–	–	0.09	–	–	–	–	–	–	–	–	–	–
65		Isobutyl phthalate-5-methylhex-2-ester	–	0.22	–	–	–	–	–	–	–	–	–	–	–
66	Amino acids	Glycylglycine	–	–	0.39	0.27	–	–	–	–	–	–	–	–	–
67		Alanylglycine	4.91	3.96	3.41	4.59	0.34	0.34	0.3	0.28	0.18	0.3	0.39	0.25	0.41
68		N-acetyl-l-alanine	–	–	–	–	–	–	–	0.07	–	0.23	–	–	–
69		Alanyl-leucine	–	–	–	–	0.08	–	–	–	–	0.3	–	–	–
70	Aromatics	Toluene	2.03	–	–	–	–	–	0.66	–	–	–	–	–	–
71		Ethyl benzene	–	–	–	0.13	–	–	–	0.09	–	–	–	–	–
72		O-xylene	–	–	–	–	–	–	–	0.15	–	–	–	–	–
73		2,6-di-tert-butyl-4-sec-butylphenol	–	0.11	–	–	–	–	–	–	–	–	–	–	–
74	Alkenes	2-octene	–	–	–	0.23	–	–	–	–	–	–	–	–	–
75	Others	Carbon dioxide	–	–	–	–	–	–	16.59	16.22	–	24.24	–	14.08	24.64
76		Carbon disulphide	0.79	0.78	–	–	–	–	–	–	–	–	–	–	–
77		Dimethyl sulphide	0.64	–	–	–	–	–	–	–	–	–	–	–	–
78		Dimethyl sulphone	–	–	0.22	0.17	–	–	–	–	–	–	–	–	–
79		Dimethyl disulphide	–	–	–	0.24	–	–	–	–	–	–	–	–	–
80		Urea	–	–	–	–	–	–	–	0.09	–	0.05	–	–	–
81		Ethanolamine	–	–	–	–	–	0.08	0.14	–	0.18	–	–	0.07	0.15
82		Ammonium carbamate	–	–	–	–	13	15.97	–	–	16.21	–	18.86	–	–
83		Methoxyphenyloxime	32.42	14.3	6.08	3.52	0.78	1.26	1.39	1.22	1.67	1.21	1.65	1.49	0.94
84		Tetramethylpyrazine	–	–	–	–	–	–	–	0.24	–	–	–	–	–
85		2-phenylfuran	–	–	0.47	0.67	0.43	0.38	0.4	–	0.31	0.39	0.4	0.39	0.32
86		Cis-Anethol	–	–	–	–	–	–	–	–	–	0.07	–	0.09	–
87		N6-(4-methoxybenzoyl) adenosine	3.19	1.7	0.83	0.51	0.1	0.06	0.05	0.05	0.37	–	0.05	0.25	–

Figure 6. Results of PCA of volatiles of microwave treatment detected by GC-MS showing the first 2 principal components (PC1 and PC2).