Chemical compositions and antioxidant capacity of by-products generated during the apricot kernels processing

Figures & data

Table 1. Chemical compositions of BWC and DWC.

Tabla 1. Composiciones químicas de BWC y DWC.

	Protein	Reducing sugar	Polysaccharides	Total phenolics	Flavonoids	Amygdalin
BWC	4.17 ± 0.01^a	4.59 ± 0.05^a	23.55 ± 0.73^a	1.38 ± 0.04^a	2.48 ± 0.05^a	33.48 ± 0.04^a
DWC	10.32 ± 0.09^b	7.14 ± 1.01^b	14.34 ± 0.02^b	0.84 ± 0.03^a	0.52 ± 0.26^b	23.89 ± 0.03^b

Values are expressed as means ± SD. Different letters in the same column indicate significant differences at p < 0.05. The unit is g/100 g dry base weight.

Table 2. Regression equation, coefficient and linear range for the standard compounds of protocatechuic acid, procyanidin B_1, EGC, protocatechuic aldehyde, catechin, chlorogenic acid by HPLC.

Tabla 2. Ecuación de regresión, coeficiente y rango lineal de los compuestos estándar de ácido protocatecuico, procianidina B_1, EGC, aldehído protocatecuico, catequina, ácido clorogénico a partir de HPLC.

Compounds	Regression equation	Correlation coefficient	Linear range (μg/mL)
Protocatechuic acid	y = 0.5587x − 7.6476	0.9993	15.6–70
Procyanidin B1	y = 0.4538x − 3.2754	0.9981	11.11–40
EGC	y = 0.1097x − 0.482	0.9992	12.5–50
Protocatechuic aldehyde	y = 0.9709x − 8.5358	0.9991	40–200
Catechin	y = 0.6233x − 5.7241	0.9989	11.9–42
Chlorogenic acid	y = 0.3783x − 5.3841	0.9996	33–100

Figure 1. Combined HPLC chromatogram of phenolic compounds in the samples. Peak number: 1. protocatechuic acid, 2. procyanidin B₁, 3. EGC, 4. protocatechuic aldehyde, 5. catechin 6. chlorogenic acid.

Figura 1. Cromatograma combinado HPLC de los compuestos fenólicos en las muestras. Número pico: 1. ácido protocatecuico; 2. procianidina B₁; 3. EGC; 4. aldehído protocatecuico; 5. catequina; 6. ácido clorogénico.

Figure 2. Antioxidant capacity evaluation of BWC and DWC, (a) reducing power, (b) scavenging effect of DPPH free radical, (c) scavenging effect of OH free radical.

Figura 2. Evaluación de la capacidad antioxidante de BWC y DWC, (a) Poder reductor, (b) Efecto de eliminar el radical libre DPPH, (c) Efecto de eliminar el radical libre OH.

Figure 3. Scanned spectral about the effect of amygdalin (0.1, 0.25, 0.5, 0.75, 1 mg/mL) on the DPPH˙ scavenging capacity.

Figura 3. Espectral escaneado en torno al efecto de la amigdalina (0.1, 0.25, 0.5, 0.75, 1 mg/mL) en la capacidad de eliminar el radical DPPH.

Table 3. The correlation coefficient of antioxidant capacity and identified phenolic compounds.

Tabla 3. Coeficiente de correlación de la capacidad antioxidante y los compuestos fenólicos identificados.

	DPPH	Reducing power	OH
Protocatechuic aldehyde	0.6594	0.9819	0.9048
Chlorogenic acid	0.8939	0.4701	0.4803
Protocatechuic acid	0.8939	0.4701	0.4803
Catechin	0.4233	0.9034	0.8167
Procyanidin B1	0.4666	0.8767	0.7890
EGC	0.9021	0.4940	0.4957
TPH	0.2292	0.7112	0.6384
TPC	0.2921	0.7743	0.6861

Figure 4. Scores plot (a) and Correlation loading plot (b) from PCA of the samples between the individual phenolic and antioxidant activity.

Figura 4. Diagrama de puntos (a) y Diagrama de correlación de cantidades (b) de PCA de las muestras entre la actividad fenólica individual y antioxidante.