Oxidative Stability of Cooking Oil Blend Stabilized with Leaf Extract of Eucalyptus citriodora

Figures & data

TABLE 1 E. citriodora leaf extract antioxidative properties and changes in color of vegetable oil stabilized with the leaves extract (mean ± SD)

Leaf extract properties
Yield of leaf extracts (g/100 g d. wt.)	TPC (g/100 g d. wt. as GAE)	TFC (g/100 g d. wt. as CE)	Inhibition of linoleic acid peroxidation (%)	DPPH scavenging activity (%)
10.88 ± 0.45	5.23 ± 0.186	1.18 ± 0.035	66.66 ± 1.99	70.56 ± 1.56
Induction period (days)	Color
	Sample		Control
	R-unit	Y-unit	R-unit	Y-unit
00	1.00 ± 0.01^c	10.00 ± 0.02^a	1.00 ± 0.01^c	10.00 ± 0.01^a
10	1.00 ± 0.02^c	10.00 ± 0.02^a	1.00 ± 0.02^c	10.00 ± 0.01^a
20	1.00 ± 0.01^c	10.00 ± 0.01^a	1.00 ± 0.01^c	10.00 ± 0.02^a
30	1.00 ± 0.01^c	10.00 ± 0.01^a	1.00 ± 0.02^c	10.00 ± 0.01^a
40	1.00 ± 0.01^c	10.00 ± 0.02^a	1.00 ± 0.01^c	10.00 ± 0.01^a
50	0.90 ± 0.02^a	9.00 ± 0.01^ab	0.90 ± 0.02^a	9.00 ± 0.01^ab
60	0.90 ± 0.02^a	9.00 ± 0.02^ab	0.90 ± 0.01^a	9.00 ± 0.01^ab
70	0.80 ± 0.01^a	8.00 ± 0.02^bc	0.80 ± 0.02^a	8.00 ± 0.01^bc
80	0.70 ± 0.02^ab	7.00 ± 0.01^cd	0.70 ± 0.01^ab	7.00 ± 0.02^cd
90	0.70 ± 0.01^ab	7.00 ± 0.01^cd	0.70 ± 0.02^ab	7.00 ± 0.01^cd
100	0.60 ± 0.01^b	6.00 ± 0.02^d	0.60 ± 0.01^b	6.00 ± 0.02^d
Decrease from day 0	0.4	4.0	0.4	4.0

TABLE 2 Different physical and oxidative stability attributes of vegetable oils stabilized with E. citriodora leaves extract (mean ± SD)

	CP (°C)		RI		FFA (percent as oleic acid)		PV (meq/kg of oil)		SV (mg of KOH/g of oil)		IV (g of iodine/100 g of oil)
Induction period (days)	Sample	Control	Sample	Sample	Control	Sample	Control	Control	Sample	Control	Sample	Control
00	7.6 ± 0.3^a	7.6 ± 0.3^b	1.4655 ± 0.002^a	1.4655 ± 0.002^a	0.15 ± 0.03^db	0.15 ± 0.03^hi	0.13 ± 0.00^k	0.13 ± 0.00^k	191.11 ± 0.61^a	191.11 ± 0.12^a	116.3 ± 1.1^a	116.3 ± 1.1^a
10	7.5 ± 0.2^b	7.6 ± 0.4^b	1.4655 ± 0.001^a	1.4656 ± 0.001^a	0.15 ± 0.03^db	0.19 ± 0.02^hi	1.45 ± 0.01^j	2.47 ± 0.06^j	191.18 ± 0.63^a	191.44 ± 0.11^a	114.1 ± 0.5^b	113.5 ± 0.8^b
20	7.6 ± 0.3^a	7.6 ± 0.2^b	1.4656 ± 0.002^a	1.4657 ± 0.001^a	0.16 ± 0.03^dcb	0.24 ± 0.04^gh	5.93 ± 0.03^i	7.73 ± 0.19^i	191.83 ± 0.45^a	192.79 ± 0.25^a	113.1 ± 0.7^bc	112.5 ± 0.4^bc
30	7.6 ± 0.2^a	7.7 ± 0.4^a	1.4656 ± 0.001^a	1.4658 ± 0.002^a	0.16 ± 0.02^dcb	0.38 ± 0.03^g	7.63 ± 0.28^h	8.94 ± 0.40^h	192.94 ± 0.37^a	192.62 ± 0.35^a	112.3 ± 0.5^cd	111.2 ± 0.8^c
40	7.6 ± 0.1^a	7.5 ± 0.2^c	1.4658 ± 0.001^a	1.4660 ± 0.002^a	0.17 ± 0.02^dcb	0.59 ± 0.01^fg	8.15 ± 0.32^g	9.32 ± 0.04^g	193.01 ± 0.91^a	194.73 ± 0.41^a	111.7 ± 1.1^d	109.5 ± 0.6^d
50	7.6 ± 0.2^a	7.7 ± 0.3^a	1.4661 ± 0.002^a	1.4664 ± 0.002^a	0.22 ± 0.03^da	0.74 ± 0.04^f	8.63 ± 0.05^f	9.65 ± 0.05^f	195.05 ± 0.67^a	196.61 ± 0.48^a	110.9 ± 0.9^de	107.3 ± 0.7^e
60	7.5 ± 0.2^b	7.6 ± 0.5^b	1.4665 ± 0.005^a	1.4669 ± 0.003^a	0.23 ± 0.04^da	1.03 ± 0.02^e	9.15 ± 0.07^e	11.06 ± 0.11^e	195.86 ± 0.37^a	198.34 ± 0.51^a	110.5 ± 0.3^de	106.1 ± 0.4^ef
70	7.4 ± 0.3^a	7.5 ± 0.3^c	1.4669 ± 0.002^a	1.4675 ± 0.002^a	0.25 ± 0.05^da	1.29 ± 0.03^d	10.24 ± 0.14^d	14.03 ± 0.52^d	197.03 ± 0.58^a	200.42 ± 0.46^a	109.4 ± 0.4^e	105.4 ± 0.7^f
80	7.6 ± 0.4^a	7.6 ± 0.7^b	1.4673 ± 0.003^a	1.4683 ± 0.004^a	0.27 ± 0.04^da	1.83 ± 0.09^c	11.31 ± 0.34^c	16.52 ± 0.38^c	197.90 ± 0.82^a	201.84 ± 0.57^a	107.5 ± 0.8^f	104.3 ± 0.9^f
90	7.5 ± 0.3^b	7.7 ± 0.4^a	1.4677 ± 0.005^a	1.4690 ± 0.002^a	0.31 ± 0.09^ca	2.19 ± 0.05^b	11.96 ± 0.24^b	18.73 ± 0.13^b	199.74 ± 0.56^a	204.76 ± 0.34^a	107.1 ± 0.6^f	102.5 ± 1.2^g
100	7.6 ± 0.1^a	7.5 ± 0.3^c	1.4683 ± 0.003^a	1.4702 ± 0.002^a	0.35 ± 0.08^a	2.52 ± 0.04^a	12.67 ± 0.19^a	21.25 ± 0.27^a	201.15 ± 0.48^a	208.12 ± 0.27^a	106.3 ± 0.2^f	99.4 ± 0.7^h
Decrease/ increase	0	–0.1	0.0028	0.0047	0.20	2.37	12.54	21.12	10.04	17.01	–10.0	–16.9

Values in columns with same alphabets in superscript do not differ significantly.

TABLE 3 Correlation coefficients (R²) among physio-chemical properties of cooking oil stabilized with E. citriodora leaves extract (mean ± SD)

	FFA	PV	SV	IV	CP	RI	R	Y
FFA	1
PV	0.799***	1
SV	0.252^ns	0.399*	1
IV	–0.801***	–0.921***	–0.370^ns	1
CP	0.179^ns	0.079^ns	–0.030^ns	–0.111^ns	1
RI	0.087^ns	0.044^ns	0.025^ns	–0.092^ns	0.046^ns	1
Color (R)	–0.598***	–0.829***	–0.295^ns	0.823***	–0.043^ns	0.024^ns	1
Color (Y)	–0.598***	–0.823***	–0.295^ns	0.823***	–0.043^ns	0.024^ns	1.00***	1

*significant at 0.05 levels;

**significant at 0.01 levels;

***significant at 0.001 levels.