Nutraceuticals and antioxidant properties of Lonicera japonica Thunb. as affected by heating time

Figures & data

Table 1. Effect of different heating times on pH and soluble solid contents of Lonicera japonica Thunb. at 100°C

Heating time (min)	pH	Soluble solid contents (%)
0	5.43 ± 0.01^a	5.7 ± 0.1^a
30	5.44 ± 0.01^a	5.8 ± 0.1^a
60	5.44 ± 0.01^a	5.7 ± 0.1^a
90	5.35 ± 0.02^b	5.7 ± 0.1^a
120	5.29 ± 0.02^c	5.8 ± 0.1^a
150	5.25 ± 0.00^d	5.8 ± 0.0^a

^a-dValues with different letters within the same column differ significantly (p<0.05).

Table 2. Effect of different heating times on chlorophyll content in Lonicera japonica Thunb. at 100°C

Heating time (min)	Chlorophyll a (ug/g)	Chlorophyll b (ug/g)	Total chlorophyll (ug/g)
0	4.52 ± 0.04^a	2.4 ± 0.1^a	6.9 ± 0.1^a
30	3.49 ± 0.09^b	2.1 ± 0.1^b	5.7 ± 0.1^b
60	2.90 ± 0.03^c	2.0 ± 0.1^c	4.9 ± 0.1^c
90	2.58 ± 0.06^d	1.9 ± 0.0^d	4.4 ± 0.1^d
120	2.67 ± 0.06^d	1.8 ± 0.1^de	4.5 ± 0.1^d
150	2.48 ± 0.05^e	1.7 ± 0.0^e	4.2 ± 0.1^e

^a-dValues with different letters within the same column differ significantly (p<0.05).

Table 3. Effect of different heating times on color values of Lonicera japonica Thunb. at 100°C

	Color values
Heating time (min)	L*	a*	b*	ΔE	H°	C*
0	39 ± 1^a	2.6 ± 0.0^f	19.5 ± 0.2^c	-	82.4 ± 0.1^a	19.6 ± 0.2^c
30	37 ± 1^b	4.0 ± 0.1^e	22.4 ± 0.2^b	3.6 ± 0.2^d	79.8 ± 0.2^b	22.7 ± 0.2^b
60	37 ± 0^b	4.6 ± 0.0^d	23.2 ± 0.1^a	4.5 ± 0.1^c	78.9 ± 0.1^c	23.6 ± 0.1^a
90	37 ± 1^b	5.0 ± 0.1^c	23.0 ± 0.3^a	4.8 ± 0.2^bc	77.9 ± 0.2^d	23.6 ± 0.3^a
120	37 ± 1^b	5.2 ± 0.1^b	23.3 ± 0.3^a	5.0 ± 0.1^b	77.6 ± 0.1^d	23.9 ± 0.3^a
150	36 ± 2^b	5.5 ± 0.1^a	23.4 ± 0.8^a	5.7 ± 0.2^a	76.8 ± 0.5^e	24.0 ± 0.8^a

^a-fValues with different letters within the same column differ significantly (p<0.05).

Table 4. Effect of different heating times on total phenolic and total flavonoid contents in Lonicera japonica Thunb. at 100°C

Heating time (min)	Total phenolic contents (ug GAE^1/100 mg)	Total flavonoid contents (ug RE^2/100 mg)
0	2013 ± 23^d	4495 ± 99^d
30	2423 ± 66^b	5502 ± 39^b
60	2594 ± 73^a	5644 ± 57^a
90	2582 ± 11^a	5432 ± 52^b
120	2303 ± 80^c	4995 ± 73^c
150	2297 ± 30^c	4957 ± 53^c

¹ GAE: gallic acid equivalent.

² RE: rutin equivalent.

^a-dValues with different letters within the same column differ significantly (p<0.05).

Table 5. Quantification of individual phenolic acids and flavonoids in Lonicera japonica Thunb. after heating at 100°C with different heating time

	Phenolic acids contents (ug/100 mg)				Flavonoids contents (ug/100 mg)
Heating time (min)	Chlorogenic acid	Caffeic acid	4,5-dicaffeoylquinic acid	3,5-dicaffeoylquinic acid	Rutin	Quercetin	Luteolin
0	1007 ± 37^d	1.9 ± 0.1^d	13.4 ± 0.4^f	649 ± 21^c	36 ± 3^b	6.5 ± 0.3^c	0.09 ± 0.02^d
30	1261 ± 11^b	2.6 ± 0.0^b	18.9 ± 0.6^e	800 ± 2^a	42 ± 0^a	7.3 ± 0.3^b	0.15 ± 0.02^c
60	1367 ± 2^a	3.0 ± 0.0^a	25.3 ± 0.3^d	791 ± 1^a	42 ± 1^a	8.1 ± 0.1^a	0.16 ± 0.03^bc
90	1390 ± 30^a	3.0 ± 0.1^a	30.3 ± 0.3^a	740 ± 20^b	41 ± 1^a	8.4 ± 0.2^a	0.21 ± 0.02^a
120	1215 ± 26^c	2.4 ± 0.1^c	28.5 ± 0.5^b	614 ± 14^d	37 ± 0^b	7.1 ± 0.4^b	0.20 ± 0.01^ab
150	1030 ± 12^d	2.0 ± 0.1^d	26.8 ± 0.6^c	462 ± 8^e	31 ± 0^c	5.6 ± 0.4^d	0.10 ± 0.03^d

^a-fValues with different letters within the same column differ significantly (p<0.05).

Table 6. Quantification of individual organic acids in Lonicera japonica Thunb. after heating at 100°C with different heating time

	Organic acid contents (ug/100 mg)
Heating time (min)	Quinic acid	Malic acid	Shikimic acid	Citric acid	Succinic acid
0	2488 ± 4^d	511 ± 15^ab	15.4 ± 0.3^d	170 ± 10^f	663 ± 8^ab
30	2563 ± 8^c	515 ± 7^a	15.5 ± 0.1^d	231 ± 16^e	617 ± 16^c
60	2676 ± 26^b	480 ± 18^c	16.1 ± 0.1^c	543 ± 20^d	592 ± 60^c
90	2699 ± 23^b	484 ± 3^c	16.2 ± 0.4^c	754 ± 13^c	670 ± 15^ab
120	2704 ± 5^b	489 ± 13^bc	17.3 ± 0.2^b	855 ± 14^b	685 ± 29^a
150	2777 ± 15^a	478 ± 18^c	18.1 ± 0.1^a	956 ± 22^a	630 ± 4^bc

^a-fValues with different letters within the same column differ significantly (p<0.05).

Figure 1. Effect of different heating times on antioxidant properties of Lonicera japonica Thunb. at 100°C. Different letters on the bars indicate significant differences (p < 0.05)

Table 7. Pearson correlations between nutraceuticals (total phenolic, total flavonoid, chlorogenic acid, caffeic acid, 4,5-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid, rutin, quercetin, and luteolin) and antioxidant properties (DPPH radical scavenging activity, ABTS radical scavenging activity, FRAP, and reducing power) of heat-treated Lonicera japonica Thunb

Variables	1	2	3	4	5	6	7	8	9	10	11	12	13
1. Total phenolic	1
2. Total flavonoid	0.95**	1
3. Chlorogenic acid	0.91*	0.89*	1
4. Caffeic acid	0.93**	0.91*	0.99***	1
5. 4,5-dicaffeoylquinic acid	0.66	0.46	0.52	0.48	1
6. 3,5-dicaffeoylquinic acid	0.54	0.67	0.76	0.78	−0.16	1
7. Rutin	0.63	0.74	0.84*	0.85*	−0.02	0.99***	1
8. Quercetin	0.75	0.72	0.94**	0.94**	0.34	0.83	0.88*	1
9. Luteolin	0.68	0.59	0.83*	0.77	0.70	0.45	0.56	0.78	1
10. DPPH radical scavenging activity	0.99**	0.94**	0.94**	0.96**	0.60	0.63	0.71	0.83*	0.69	1
11. ABTS radical scavenging activity	0.96**	0.86*	0.88*	0.89*	0.74	0.45	0.54	0.75	0.68	0.96**	1
12. FRAP	0.96**	0.91*	0.94**	0.97**	0.54	0.67	0.74	0.87*	0.66	0.99***	0.95**	1
13. Reducing power	0.99***	0.95**	0.95**	0.96**	0.63	0.61	0.70	0.82*	0.71	1***	0.96**	0.98***	1

^aOnly significantly correlated variables and coefficients are shown.

*p < 0.05; **p < 0.01; ***p < 0.001.