Effect of Natural Extracted Antioxidants from Eriobotrya japonica (Lindl.) Fruit Skin on Thermo Oxidative Stability of Soybean Oil During Deep Frying

Figures & data

TABLE 1 Extraction yield, total phenolic and tocopherol compounds of loquat fruit skin extracts

Sample	Yield (%)	Total phenolic (µg/g)	Total tocopherol (µg/g)
SE	14.75 ± 0.43^a	664.53 ± 1.06^a	486.53 ± 0.67^a
UAE	10.5 ± 0.72^c	394.67 ± 1.21^c	388.58 ± 0.25^b
SCE	12.5 ± 0.72^b	425.02 ± 1.01^b	228.41 ± 0.15^c

Values (mean ± SD; n = 3) in the same column with different letters are significantly different (p < 0.05);

SE: solvent extracts of loquat skin; UAE: ultrasound-assisted extract of loquat skin; SCE: supercritical CO₂ extract of loquat skin.

FIGURE 1 Comparison of the capacity of loquat skin extracts to scavenge DPPH^• radicals. SE: solvent extract of loquat skin; UAE: ultrasound-assisted extract of loquat skin; SCE: supercritical CO₂ extract of loquat skin.

FIGURE 2 Antioxidant activities of loquat skin extracts in a β-carotene/linoleate method system. SE: solvent extract of loquat skin; UAE: ultrasound-assisted extract of loquat skin; SCE: supercritical CO₂ extract of loquat skin.

FIGURE 3 Antioxidant activities of loquat skin extracts analyzed by Rancimat method. SE: solvent extract of loquat skin; UAE: ultrasound-assisted extract of loquat skin; SCE: supercritical CO₂ extract of loquat skin; Blank: soybean oil without additives.

TABLE 2 Changes in peroxide value (PV) and total polar compounds (TPC) of the oil samples

Time (h)	SOEA	SOEB	SOSA	SOSB	SOUA	SOUB	SO-TBHQ	SBO
PV(meq/kg)
0	0.65 ± 0.01^a	0.65 ± 0.01^a	0.65 ± 0.01^a	0.65 ± 0.01^a	0.65 ± 0.01^a	0.65 ± 0.01^a	0.65 ± 0.01^a	0.65 ± 0.01^a
4	1.64 ± 0.03^ab	2.04 ± 0.05^c	2.22 ± 0.03^d	1.65 ± 0.07^ab	2.24 ± 0.04^d	1.72 ± 0.06^b	1.58 ± 0.14^a	3.82 ± 0.08^e
8	2.56 ± 0.04^e	2.52 ± 0.07^de	2.34 ± 0.04^b	2.44 ± 0.07^cd	2.53 ± 0.03^e	2.11 ± 0.07^a	2.43 ± 0.02^c	4.54 ± 0.02^f
12	3.58 ± 0.06^a	3.74 ± 0.05^b	4.15 ± 0.05^c	4.24 ± 0.02^d	3.75 ± 0.03^b	4.42 ± 0.03^e	4.12 ± 0.04^c	5.76 ± 0.04^f
16	4.32 ± 0.04^b	4.51 ± 0.03^c	5.27 ± 0.02^e	5.66 ± 0.04^f	4.72 ± 0.03^d	4.05 ± 0.07^a	4.75 ± 0.02^d	6.58 ± 0.04^g
20	4.55 ± 0.03^b	5.43 ± 0.03^e	5.84 ± 0.02^f	5.06 ± 0.03^d	4.68 ± 0.06^c	5.42 ± 0.02^e	4.04 ± 0.02^a	5.88 ± 0.03^f
24	4.06 ± 0.02^a	5.12 ± 0.03^c	5.23 ± 0.02^d	5.48 ± 0.04^e	4.05 ± 0.01^a	4.76 ± 0.04^b	5.11 ± 0.05^c	6.34 ± 0.02^f
TPC(w/w%)
0	5.84 ± 0.01^a	5.84 ± 0.01^a	5.84 ± 0.01^a	5.84 ± 0.01^a	5.84 ± 0.01^a	5.84 ± 0.01^a	5.84 ± 0.01^a	5.84 ± 0.01^a
4	11.56 ± 0.02^a	12.08 ± 0.04^c	12.29 ± 0.04^d	12.52 ± 0.04^f	11.68 ± 0.03^b	12.42 ± 0.02^e	11.55 ± 0.03^a	16.52 ± 0.04^g
8	13.52 ± 0.03^a	14.06 ± 0.03^b	14.28 ± 0.03^c	14.43 ± 0.03^d	14.56 ± 0.04^e	14.25 ± 0.03^d	13.49 ± 0.03^a	23.04 ± 0.04^f
12	18.63 ± 0.02^d	17.52 ± 0.03^a	18.06 ± 0.05^b	19.44 ± 0.02^f	18.56 ± 0.04^c	19.32 ± 0.02^e	19.65 ± 0.03^g	32.65 ± 0.03^h
16	25.48 ± 0.02^a	27.62 ± 0.03^c	27.50 ± 0.02^b	28.15 ± 0.03^d	27.52 ± 0.03^b	28.11 ± 0.04^d	27.48 ± 0.04^b	39.74 ± 0.02^e
20	34.58 ± 0.06^a	35.66 ± 0.04^c	36.55 ± 0.04^e	36.87 ± 0.06^f	35.32 ± 0.05^b	35.74 ± 0.03^d	36.88 ± 0.04^f	46.28 ± 0.04^g
24	44.74 ± 0.03^a	45.82 ± 0.02^d	47.21 ± 0.04^f	47.75 ± 0.03^g	45.51 ± 0.05^b	46.33 ± 0.04^e	45.74 ± 0.03^c	55.63 ± 0.02^h

Means ± SD within each row followed by different letters (a, b, c, etc.) are significantly different (p < 0.05); Soybean oil with 400 (SOEA) and 1000 ppm (SOEB) of solvent extracts of skin, soybean oil with 400 (SOSA) and 1000 ppm (SOSB) of skin extracts by supercritical CO₂ method, soybean oil with 400 (SOUA) and 1000 ppm (SOUB) of skin extracts by sonication method, soybean oil with 100 ppm of TBHQ (SO-TBHQ), soybean oil with no antioxidant added (SBO).

TABLE 3 Changes in carbonyl value (CV) and free fatty acids content (FFA) of the oil samples

Time (h)	SOEA	SOEB	SOSA	SOSB	SOUA	SOUB	SO-TBHQ	SBO
CV (µmol/g)
0	12.46 ± 0.02^ab	12.42 ± 0.02^a	12.48 ± 0.03^bc	12.52 ± 0.02^c	12.46 ± 0.04^ab	12.48 ± 0.03^bc	12.42 ± 0.02^a	12.5 ± 0.02^bc
4	17.43 ± 0.03^e	16.62 ± 0.04^b	17.51 ± 0.05^f	17.48 ± 0.06^ef	16.54 ± 0.02^a	17.35 ± 0.02^d	17.22 ± 0.06^c	27.44 ± 0.04^g
8	24.47 ± 0.03^a	24.52 ± 0.04^a	25.08 ± 0.03^c	25.17 ± 0.09^g	25.32 ± 0.04^e	24.63 ± 0.03^b	25.72 ± 0.04^f	39.53 ± 0.01^g
12	28.83 ± 0.03^a	29.32 ± 0.03^c	29.15 ± 0.01^b	30.42 ± 0.02^f	29.74 ± 0.02^d	30.17 ± 0.04^e	30.88 ± 0.03^g	47.26 ± 0.04^h
16	34.54 ± 0.02^a	34.92 ± 0.04^b	35.82 ± 0.02^e	38.42 ± 0.02^g	35.18 ± 0.04^c	36.53 ± 0.02^f	35.74 ± 0.02^d	54.47 ± 0.03^h
20	40.11 ± 0.04^b	40.53 ± 0.01^c	40.72 ± 0.02^d	42.50 ± 0.01^e	44.78 ± 0.03^g	35.74 ± 0.02^a	44.05 ± 0.03^f	50.25 ± 0.03^h
24	46.25 ± 0.01^a	48.17 ± 0.03^b	50.66 ± 0.04^d	53.09 ± 0.03^g	52.06 ± 0.02^e	48.26 ± 0.02^c	52.46 ± 0.05^f	58.11 ± 0.03^h
FFA (%)
0	0.05 ± 0.01^a	0.05 ± 0.01^a	0.05 ± 0.01^a	0.05 ± 0.01^a	0.05 ± 0.01^a	0.05 ± 0.01^a	0.05 ± 0.01^a	0.05 ± 0.01^a
4	1.22 ± 0.06^b	1.18 ± 0.03^b	1.22 ± 0.06^b	1.05 ± 0.04^a	1.22 ± 0.06^b	1.05 ± 0.04^a	1.05 ± 0.04^a	1.44 ± 0.02^c
8	1.44 ± 0.02^a	1.58 ± 0.03^c	1.74 ± 0.02^d	1.74 ± 0.02^d	1.52 ± 0.04^b	1.44 ± 0.02^a	1.44 ± 0.02^a	2.52 ± 0.04^e
12	1.88 ± 0.03^a	2.08 ± 0.03^b	2.45 ± 0.03^e	2.58 ± 0.03^f	2.45 ± 0.03^e	2.34 ± 0.03^d	2.28 ± 0.06^c	3.64 ± 0.02^g
16	2.44 ± 0.02^a	3.05 ± 0.04^d	3.24 ± 0.04^e	3.44 ± 0.02^f	2.98 ± 0.03^c	3.05 ± 3.04^d	2.85 ± 0.03^b	4.67 ± 0.06^g
20	3.05 ± 0.04^a	3.32 ± 0.04^b	3.52 ± 0.03^d	4.32 ± 0.04^e	3.48 ± 0.04^cd	4.45 ± 0.03^f	3.44 ± 0.02^c	6.72 ± 0.03^g
24	3.55 ± 0.03^a	4.35 ± 0.03^d	4.22 ± 0.06^c	4.44 ± 0.02^e	4.22 ± 0.06^c	4.52 ± 0.03^f	3.85 ± 0.03^b	7.44 ± 0.02^g

Means ± SD within each row followed by different letters (a, b, c, etc.) are significantly different (p < 0.05); Soybean oil with 400 (SOEA) and 1000 ppm (SOEB) of solvent extracts of skin, soybean oil with 400 (SOSA) and 1000 ppm (SOSB) of skin extracts by supercritical CO₂ method, soybean oil with 400 (SOUA) and 1000 ppm (SOUB) of skin extracts by sonication method, soybean oil with 100 ppm of TBHQ (SO-TBHQ), soybean oil with no antioxidant added (SBO).

FIGURE 4 Effect of deep frying conditions on conjugated dienes and trienes of oil samples. Soybean oil with 400 (SOEA) and 1000 ppm (SOEB) of solvent extract of skin, soybean oil with 400 (SOSA) and 1000 ppm (SOSB) of supercritical CO₂ extract of skin, soybean oil with 400 (SOUA) and 1000 ppm (SOUB) of ultrasound-assisted extract of skin, soybean oil with 100 ppm of TBHQ (SO-TBHQ), soybean oil with no antioxidant added (SBO).