Utilization of Jujube Fruit (Ziziphus mauritiana Lam.) Extracts as Natural Antioxidants in Stability of Frying Oil

Figures & data

FIGURE 1 (a) Extraction yield (%) of jujube extracts; (b) Total phenolic contents of jujube extracts. Solvent extracts of jujube by ethanol (SJE), water (SJW) and ethanol-water (SJEW). Ultrasound-assisted extracts of jujube by ethanol (UJE), water (UJW), and ethanol-water (UJEW). Supercritical CO₂ extracts of jujube by ethanol (CJE), water (CJW), and ethanol-water (CJEW).

FIGURE 2 (a) Scavenging activities of jujube extracts against DPPH^• radicals; (b) Antioxidant activities of jujube extracts in β-carotene/linoleic acid system. Solvent extracts of jujube by ethanol (SJE), water (SJW) and ethanol-water (SJEW). Ultrasound-assisted extracts of jujube by ethanol (UJE), water (UJW), and ethanol-water (UJEW). Supercritical CO₂ extracts of jujube by ethanol (CJE), water (CJW), and ethanol-water (CJEW).

TABLE 1 Changes in total polar compounds (TPC) content, carbonyl value (CV), and peroxide value (PV) of soybean oil with and without jujube fruit antioxidant during deep frying at 180°C

	TPC (w/w %)
	UJEW	UJEW	BHT	BHA	TBHQ
Time (h)	600 ppm	800 ppm	100 ppm	100 ppm	100 ppm	SBO
0	5.62 ± 0.87a	5.62 ± 0.87a	5.62 ± 0.87a	5.62 ± 0.87a	5.62 ± 0.87a	5.62 ± 0.87a
4	11.62 ± 0.71b	9.53 ± 0.64a	12.87 ± 0.58c	11.65 ± 0.55b	10.34 ± 0.70a	16.24 ± 0.27d
8	12.71 ± 1.01a	14.18 ± 0.37bc	15.22 ± 0.33c	15.08 ± 0.48bc	14.11 ± 0.41b	22.47 ± 0.55d
12	19.15 ± 0.12a	21.45 ± 0.64b	24.46 ± 0.76c	23.62 ± 0.56c	18.25 ± 0.65a	30.67 ± 0.65d
16	24.55 ± 0.68a	26.33 ± 0.86b	29.17 ± 0.40c	27.43 ± 0.93b	27.51 ± 0.89b	38.25 ± 0.58d
20	30.03 ± 0.35a	32.15 ± 0.47b	37.29 ± 0.83d	35.41 ± 0.57c	36.48 ± 0.80d	45.52 ± 0.54e
24	42.02 ± 0.38a	44.31 ± 0.22b	47.47 ± 0.53d	45.53 ± 0.51c	42.10 ± 0.62a	56.59 ± 0.50e
			CV (µmol/g)
0	13.75 ± 0.49a	13.75 ± 0.49a	13.75 ± 0.49a	13.75 ± 0.49a	13.75 ± 0.49a	13.75 ± 0.49a
4	19.23 ± 0.25b	17.68 ± 0.68a	22.56 ± 0.69c	21.45 ± 0.97c	19.06 ± 0.33b	25.68 ± 0.88d
8	25.14 ± 0.26a	25.73 ± 0.60a	29.36 ± 0.30c	27.48 ± 0.59b	27.55 ± 0.49b	38.66 ± 0.63d
12	30.44 ± 0.29a	33.61 ± 0.46c	35.58 ± 0.44d	37.14 ± 0.44e	32.25 ± 0.61b	49.54 ± 0.54f
16	34.95 ± 0.30c	36.73 ± 0.57d	42.34 ± 0.42e	33.27 ± 0.21b	31.48 ± 0.45a	47.29 ± 0.36f
20	38.14 ± 0.52a	46.50 ± 0.36c	49.68 ± 0.43e	44.72 ± 0.49b	48.19 ± 0.54d	55.33 ± 0.41f
24	42.73 ± 0.14a	44.41 ± 0.70b	55.21 ± 0.14d	52.08 ± 0.47c	51.70 ± 0.26c	64.72 ± 0.30e
			PV(meq/kg)
0	0.55 ± 0.03a	0.55 ± 0.03a	0.55 ± 0.03a	0.55 ± 0.03a	0.55 ± 0.03a	0.55 ± 0.03a
4	2.15 ± 0.12b	1.87 ± 0.06a	2.21 ± 0.06d	2.27 ± 0.11b	1.73 ± 0.06a	3.54 ± 0.05c
8	2.68 ± 0.06ab	2.75 ± 0.04b	3.75 ± 0.06d	3.24 ± 0.05c	2.62 ± 0.06a	4.26 ± 0.07e
12	3.46 ± 0.06a	3.98 ± 0.06b	4.32 ± 0.06c	4.47 ± 0.10d	4.01 ± 0.07b	5.73 ± 0.49e
16	4.22 ± 0.06a	4.70 ± 0.06b	5.01 ± 0.09d	4.21 ± 0.10c	4.72 ± 0.07b	5.54 ± 0.09e
20	5.02 ± 0.08b	5.38 ± 0.07c	4.42 ± 0.04a	5.65 ± 0.04d	5.62 ± 0.05d	7.44 ± 0.03e
24	5.01 ± 0.10c	5.12 ± 0.10d	4.02 ± 0.08a	5.16 ± 0.05d	4.70 ± 0.06b	6.25 ± 0.04e

Means ± SD; Significant differences in a same row are shown by different letters (p < 0.05); UJEW: ultrasound-assisted extract of jujube by ethanol-water (1:1), SBO: soybean oil with no added antioxidant.

TABLE 2 Changes in conjugated diene (CD) and triene (CT) values of soybean oil with and without jujube fruit antioxidant during deep frying at 180°C

	CD (mmol/L)
	UJEW	UJEW	BHT	BHA	TBHQ
Time (h)	600 ppm	800 ppm	100 ppm	100 ppm	100 ppm	SBO
0	3.20 ± 0.02a	3.21 ± 0.02a	3.21 ± 0.02a	3.22 ± 0.02a	3.22 ± 0.02a	3.20 ± 0.02a
4	7.51 ± 0.06c	6.44 ± 0.12a	7.35 ± 0.03b	7.48 ± 0.04c	6.35 ± 0.05a	10.55 ± 0.05d
8	9.42 ± 0.07a	10.07 ± 0.05c	10.57 ± 0.05e	10.33 ± 0.03d	9.84 ± 0.06b	12.36 ± 0.05f
12	10.43 ± 0.05a	11.7 ± 0.04b	12.02 ± 0.07d	11.84 ± 0.06c	11.66 ± 0.12b	15.87 ± 0.08e
16	12.71 ± 0.06a	13.84 ± 0.02c	14.35 ± 0.07e	14.18 ± 0.03d	13.45 ± 0.04b	17.44 ± 0.08f
20	14.32 ± 0.04a	15.75 ± 0.05c	16.83 ± 0.07e	16.25 ± 0.07d	15.26 ± 0.04b	20.81 ± 0.06f
24	15.67 ± 0.05a	17.08 ± 0.04c	17.77 ± 0.05e	17.46 ± 0.04d	16.53 ± 0.02b	23.47 ± 0.07f
			CT (mmol/L)
0	0.74 ± 0.03a	0.75 ± 0.03a	0.74 ± 0.03a	0.75 ± 0.03a	0.76 ± 0.03a	0.75 ± 0.03a
4	2.75 ± 0.03c	2.43 ± 0.03a	2.83 ± 0.04d	2.90 ± 0.04d	2.53 ± 0.06b	4.28 ± 0.04e
8	3.17 ± 0.05a	3.45 ± 0.05b	4.67 ± 0.05d	4.58 ± 0.06c	3.46 ± 0.05b	5.60 ± 0.04e
12	4.84 ± 0.06a	5.25 ± 0.03b	6.73 ± 0.03e	6.42 ± 0.04d	5.57 ± 0.05c	8.40 ± 0.06f
16	5.44 ± 0.03a	6.83 ± 0.08c	7.31 ± 0.03e	7.02 ± 0.13d	6.22 ± 0.04b	9.15 ± 0.08f
20	6.77 ± 0.12a	8.14 ± 0.08c	8.65 ± 0.04e	8.39 ± 0.08d	7.83 ± 0.05b	11.47 ± 0.05f
24	8.54 ± 0.06b	9.36 ± 0.05c	9.76 ± 0.04e	9.53 ± 0.05d	8.40 ± 0.04a	13.23 ± 0.02f

Means ± SD; Significant differences in a same row are shown by different letters (p < 0.05); UJEW: ultrasound-assisted extract of jujube by ethanol-water (1:1), SBO: soybean oil with no added antioxidant.

TABLE 3 Changes in free fatty acids (FFA) content and oxidative stability index (OSI) of soybean oil with and without jujube fruit antioxidant during deep frying at 180°C

	FFA (%)
	UJEW	UJEW	BHT	BHA	TBHQ
Time (h)	600 ppm	800 ppm	100 ppm	100 ppm	100 ppm	SBO
0	0.05 ± 0.00a	0.05 ± 0.00a	0.05 ± 0.00a	0.05 ± 0.00a	0.05 ± 0.00a	0.05 ± 0.00a
4	0.85 ± 0.01a	0.85 ± 0.01a	1.18 ± 0.02d	1.05 ± 0.04c	0.94 ± 0.01b	1.22 ± 0.01e
8	1.52 ± 0.03b	1.22 ± 0.03a	1.98 ± 0.03d	1.74 ± 0.04c	1.22 ± 0.03a	2.04 ± 0.04e
12	1.95 ± 0.05a	2.20 ± 0.05c	2.84 ± 0.03e	2.46 ± 0.04d	2.11 ± 0.04b	3.51 ± 0.06f
16	2.55 ± 0.05a	2.73 ± 0.02b	3.25 ± 0.06e	2.94 ± 0.03d	2.84 ± 0.06c	4.26 ± 0.04f
20	3.17 ± 0.03a	3.44 ± 0.06b	4.32 ± 0.08c	3.28 ± 0.04a	3.21 ± 0.08a	5.35 ± 0.03d
24	3.52 ± 0.02a	4.22 ± 0.04d	4.02 ± 0.04c	3.66 ± 0.06b	3.73 ± 0.03b	6.41 ± 0.09e
			OSI (h)
0	4.92 ± 0.04a	4.83 ± 0.07ab	4.65 ± 0.11b	4.65 ± 0.13bc	4.59 ± 0.13bc	4.44 ± 0.18c
4	4.72 ± 0.07a	4.68 ± 0.12a	4.42 ± 0.80b	4.37 ± 0.05b	4.36 ± 0.04b	2.25 ± 0.03c
8	4.47 ± 0.05a	4.45 ± 0.06a	4.28 ± 0.07b	4.22 ± 0.06b	4.18 ± 0.06b	1.52 ± 0.04c
12	4.26 ± 0.06a	4.23 ± 0.05a	4.01 ± 0.06c	4.01 ± 0.05b	3.85 ± 0.06b	1.20 ± 0.06d
16	3.95 ± 0.08a	3.87 ± 0.05a	3.36 ± 0.06d	3.48 ± 0.04c	3.24 ± 0.06b	0.98 ± 0.07e
20	3.68 ± 0.09a	3.55 ± 0.07b	2.05 ± 0.06c	2.87 ± 0.10d	2.92 ± 0.05c	0.72 ± 0.05e
24	3.50 ± 0.09a	3.22 ± 0.04b	2.11 ± 0.07c	2.24 ± 0.05e	2.35 ± 0.06d	0.48 ± 0.03f

Means ± SD; Significant differences in a same row are shown by different letters (p < 0.05); UJEW: ultrasound-assisted extract of jujube by ethanol-water (1:1), SBO: soybean oil with no added antioxidant.