Customized heating treatments variably affect the biological activities and chemical compositions of three indigenous culinary herbs

Figures & data

Table 1. Acronyms used for the selected culinary herbs at different time intervals of heat-treatments.

		Acronyms used for selected culinary herbs
		T. foenum-graecum		C. citratus		P. crispum
Heating methods	Time intervals (min)	Fresh	Processed	Fresh	Processed	Fresh	Processed
Untreated	Control	FTU	PTU	FCU	PCU	FPU	PPU
Roasting	10	FTR10	PTR10	FCR10	PCR10	FPR10	PPR10
	20	FTR20	PTR20	FCR20	PCR20	FPR20	PPR20
	30	FTR30	PTR30	FCR30	PCR30	FPR30	PPR30
Baking	10	FTBk10	PTBk10	FCBk10	PCBk10	FPBk10	PPBk10
	20	FTBk20	PTBk20	FCBk20	PCBk20	FPBk20	PPBk20
	30	FTBk30	PTBk30	FCBk30	PCBk30	FPBk30	PPBk30
Boiling	10	FTB10	PTB10	FCB10	PCB10	FPB10	PPB10
	20	FTB20	PTB20	FCB20	PCB20	FPB20	PPB20
	30	FTB30	PTB30	FCB30	PCB30	FPB30	PPB30

F = Fresh samples; P = Processed samples; U = Untreated samples; R = Roasted samples; Bk = Baked samples; B = Boiled samples.

Figure 1. Effect of different heating methods and time on antioxidant activity of selected culinary herbs. (a) DPPH scavenging assay (b) Total reducing power assay. Data represent the mean of three replicates, and the standard deviation is represented by the error bars.

Table 2. Antibacterial activity indices of selected fresh and processed culinary herbs.

	Fresh herbs			Processed herbs
Treatments	Escherichia coli	Klebsiella pneumoniae	Enterococcus faecalis	Escherichia coli	Bacillus subtilis
UT	–	1.3*	–	–	–
10 R	–	–	0.85**	–	–
20 R	–	–	0.66**	–	1*
30 R	0.5*	–	–	–	–
10 Bk	–	–	–	–	–
20 Bk	–	–	–	0.5***	1.15*
30 Bk	–	–	–	–
10 B	–	1.15*	–	–	1.3*
20 B	–	1*	–	–	–
30 B	–	0.84*	–	–	–

UT = untreated sample (control); R = Roasted, Bk = Baked, B = Boiled; 10, 20 and 30 indicates time interval in minutes; * indicates P. crispum; ** indicates T. foenum-graecum; *** indicates C. citratus.

Figure 2. Patterns of antidiabetic activity in untreated and heat-treated samples of fresh and processed selected herbs. UT: Untreated; R: Roasted. Data represent the mean of two replicates.

Table 3. Antihemolytic activity of fresh and processed samples of P. crispum observed at different concentrations.

	Activity observed at 1000 ppm		Activity observed at 10,000 ppm
Plant samples	Absorbance	% inhibition	Absorbance	% inhibition
Untreated fresh sample	0.299	1.760	0.302	0.880
Treated fresh sample	0.300	1.510	0.304	0.505
Untreated processed sample	0.288	4.410	0.295	2.770
Treated processed sample*	0.293	3.280	0.298	1.890

*Absorbance was measured at 540 nm and treated sample indicates 10 min roasting of selected herb.

Figure 3. Total phenolic, flavonoid and alkaloid contents detected in the untreated and treated samples of fresh and processed selected culinary herbs.

Figure 4. Correlation analysis of bioassays and phytochemicals (a) DPPH activity of untreated herbs (b) TRP of untreated herbs (c) α-amylase activity of untreated herbs (d) DPPH activity of roasted herbs (e) TRP of roasted herbs (f) α-amylase activity of roasted herbs (r = Correlation Coefficient).

Table 4. Compounds identified at respective retention times in selected P. crispum samples using the GCMS method.

				Concentration (%)
Names of compounds*	CC	RT	MW	Untreated fresh herb	Treated fresh herb	Untreated processed herb	Treated processed herb
Cyclohexanone	C2	5.08	98	–	–	–	1.18
2-bromotetradecane	C8	21.84	276	–	–	2.14	–
9-methyl-nonadecane	C8	22.88	282	–	–	1.04	–
3-decyn-2-ol	C4	25.62	154	–	–	1.90	–
1,2-benzenedicarboxylic acid	C5	27.14	278	–	10.75	–	15.85
Butyl octyl ester-1, 2 – benzenedicarboxylic acid	C5	27.15	334	8.66	–	–	–
Eicosane	C1	28.13	282	24.25	–	–	–
Ethyl-2-methyl-3-nitrobenzyl ester glutaric acid	C5	28.44	309	–	–	1.34	–
Silver decanoate	C8	28.94	278	–	–	–	1.57
2-methyl dodecane	C8	29.27	184	–	–	–	12.11
2-methyl octacosane	C8	29.42	408	–	–	–	24.52
3-methyl-4-(phenylthio)-2-prop-2-enyl-2,5-dihydrothiophene-1,1-dioxide	C3	30.39	280	–	–	2.15	–
Oxirane	C3	31.18	240	–	–	3.41	–
Trifluoroacetate-oleyl alcohol	C4	31.99	364	–	–	29.43	–
Hexadecanoic acid	C8	32.40	330	5.08	1.97	7.69	–
3-methyl-2-phenyl-5-oxa-1-azaspiro(bicycle-hexane-6,1-cyclohexane)	C3	32.42	243	–	–	6.57	–
Diisooctyl ester-1, 2 – benzenedicarboxylic acid	C5	33.21	390	48.08	81.66	38.13	42.01
Tert-hexadecanethiol	C4	33.31	258	–	–	3.82	–
Eicosyl isopropyl ether	C6	33.49	340	1.78	–	–	–
2-methyl-Z-4-tetradecene	C8	33.74	210	–	–	1.51	–
Cis-9-hexadecenal	C7	33.79	238	–	–	–	2.26
2-methyl tetracosane	C1	33.81	352	–	5.14	–	–
Di-bromotriacontane	C1	33.93	578	2.14	–	–	–
Total Identified Compounds (TIC)				89.99	99.52	99.13	99.50

CC: Chemical class; C1: Acyclic alkane; C2: Monocyclic hydrocarbon; C3: Heterocyclic compound; C4: Alcohol; C5: Aromatic dicarboxylic acid; C6: Ether; C7: Aldehyde; C8: Fatty acid; RT: Retention time; MW: Molecular weight.

*Names of compounds are mentioned as detected from the lowest to the highest retention time.