Optimization of the production of roasted-nutty aroma by a newly isolated fungus Tolypocladium inflatum SRH81 and impact of encapsulation on its quality

Journal of Genetic Engineering and Biotechnology

Table 1 Volatile compounds identified in headspace of Tolypocladium inflatum SRH81 culture during incubation

Peak no.	KI^a	Volatile compounds^b	Incubation time (days) Peak area^c × 10⁶				Description^d
Peak no.	KI^a	Volatile compounds^b	6	9	12	15	Description^d
1	762	Acetoin	1.82^a ± 0.23	0.90^b ± 0.11	0.44^c ± 0.06	–	Buttry¹
2	825	2-Methylpyrazine	10.99^c ± 1.28	14.36^b ± 1.81	19.20^a ± 2.43	2.65^d ± 0.33	Nutty green²
3	908	2,5-Dimethylpyrazine	0.02^d ± 0.00	0.11^c ± 0.02	0.78^b ± 0.10	2.06^a ± 0.26	Nutty²
4	918	2,6-Dimethylpyrazine	0.01^c ± 0.00	0.04^c ± 0.01	0.58^b ± 0.07	1.06^a ± 0.13	Nutty, roasted³
5	993	2-Ethyl-3-methylpyrazine	0.06^c ± 0.01	4.88^b ± 0.616	6.27^a ± 0.79	0.92^c ± 0.12	Nutty, earthy⁴
6	1000	2,3,5-Trimethylpyrazine	0.07^c ± 0.01	3.86^b ± 0.49	7.30^a ± 0.92	0.70^c ± 0.09	Chocolate²
7	1032	2-Acetylpyrazine	0.77^b ± 0.10	3.85^a ± 0.08	0.36^c ± 0.05	0.30^d ± 0.04	Popcorn⁵
8	1077	2-Ethyl-3,5-dimethylpyrazine	0.34^b ± 0.04	0.48^b ± 0.06	0.66^a ± 0.08	0.40^b ± 0.05	Roasty⁶
9	1080	3-Ethyl-2,5-dimethylpyrazine	0.01^c ± 0.00	0.04^b ± 0.01	0.14^a ± 0.02	–	Earthy-roasty²
10	1084	2,3,5,6-Tetramethylpyrazine	0.20^c ± 0.03	0.61^c ± 0.08	2.48^a ± 0.31	0.80^b ± 0.10	Roasted nutty⁷
		Total	14.29^c ± 1.81	29.13^b ± 3.68	38.21^a ± 4.83	8.89^c ± 1.12

^aRetention indices of volatile compounds on DB-5 column
^bCompounds listed according to their elution on DB-5 column
^cValues × 10⁶, expressed as total ion chromatograms(TIC) of GC-MS (n = 3) ± standard deviation
^dVolatile compound description was performed according to¹ Forster et al. [25], ²Adams and De-Kimpe [2], ³Bonvechi [26],⁴ Frederick et al. [1], ⁵Muller and Rappert [24], ⁶Yan et a1 [27]., ⁷Afoakwa et al. [28]. Mean values in the same row for each culture followed by different superscript lower case letters are significantly different at P < 0.05