Comparative study of potato protein concentrates extracted using ammonium sulfate and isoelectric precipitation

Figures & data

Table 1. The proximate composition of potato protein (g/100 g sample).

Sample	Protein	Moisture	Starch	Fat	Ash
ASPP	83.20 ± 0.42^b	2.55 ± 0.00^b	1.84 ± 0.00^a	1.06 ± 0.03^a	4.80 ± 0.32^a
IEPP	85.80 ± 0.37^a	3.34 ± 0.16^a	1.73 ± 0.00^b	0.20 ± 0.02^b	5.16 ± 0.12^a

Values in the same column with the same letter are not significantly different (P < 0.05).

Figure 1. SDS–PAGE patterns of ASPP and IEPP. Lanes 1–5 were marker, ASPP, IEPP, ASPP in present of β-mercaptoethanol, and IEPP in present of β-mercaptoethanol, respectively.

Table 2. Color values and total polyphenol content of ASPP and IEPP.

Sample	L*	a*	b*	Total polyphenol content (CAE mg/g DW)
ASPP	60.20 ± 0.02^a	1.49 ± 0.00^a	1.16 ± 0.01^a	1.12 ± 0.25^b
IEPP	56.60 ± 0.01^b	0.53 ± 0.01^b	-0.03 ± 0.00^b	2.97 ± 0.52^a

Values in the same column with the same letter are not significantly different (P < 0.05).

Figure 2. Effect of NaCl concentration (M) (A) and pH (B) on the solubility (%) of ASPP and IEPP. Values in the same graph with the different letter are significantly different (p < 0.05).

Figure 3. Effect of NaCl concentration (M) and pH on the emulsifying properties of ASPP and IEPP. Effect of NaCl concentration (M) (A) and pH (B) on the EAI (m²/g). Effect of NaCl concentration (M) (C) and pH (D) on the ESI (m²/g). Values in the same graph with the different letter are significantly different (p < 0.05).

Table 3. Effect of NaCl concentration (M) (A) and pH (B) on the foaming stability of ASPP and IEPP.

(A)
		NaCl concentration (M)
Sample	Time (min)	0	0.2	0.4	0.6	0.8	1.0
	30	56.3 ± 9.6^c	68.8 ± 5.9^bc	69.0 ± 9.9^bc	78.2 ± 5.9^ab	85.7 ± 6.1^a	80.0 ± 5.8^ab
ASPP	60	46.7 ± 3.9^d	56.3 ± 7.9^c	62.1 ± 8.9^bc	78.1 ± 10.9^a	74.3 ± 9.3^ab	80.0 ± 7.1^a
	90	33.3 ± 2.0^e	47.5 ± 5.2^de	52.1 ± 9.2^cd	62.5 ± 12.1^bc	74.3 ± 8.9^ab	80.0 ± 6.9^a
	30	47.8 ± 7.7^c	52.3 ± 3.9^c	56.7 ± 8.6^bc	68.7 ± 6.7^ab	78.4 ± 9.6^a	66.7 ± 5.1^ab
IEPP	60	36.7 ± 3.0^d	48.9 ± 5.5^cd	51.8 ± 4.9^c	59.0 ± 9.9^bc	74.3 ± 8.4^a	66.7 ± 6.3^ab
	90	23.3 ± 4.9^d	35.0 ± 3.8^c	51.8 ± 5.6^b	59.0 ± 6.7^ab	74.3 ± 8.3^a	66.7 ± 7.8^a
(B)
		pH
Sample	Time (min)	3.0	5.0	7.0	8.0
	30	98.5 ± 1.0^a	95.2 ± 2.8^a	96.0 ± 2.0^a	89.3 ± 1.6^b
ASPP	60	98.5 ± 1.0^a	95.2 ± 2.7^a	96.0 ± 1.7^a	80.4 ± 3.3^b
	90	91.2 ± 2.8^a	92.3 ± 3.8^a	92.0 ± 1.6^a	75.9 ± 4.2^b
	30	92.9 ± 3.5^a	76.7 ± 4.0^b	80.0 ± 3.2^b	90.6 ± 1.5^a
IEPP	60	92.9 ± 4.6^a	66.7 ± 5.1^c	80.0 ± 2.0^b	90.6 ± 4.4^a
	90	84.4 ± 4.9^b	66.7 ± 3.3^c	80.0 ± 4.8^b	90.6 ± 4.6^a

Values in the same row with the same letter are not significantly different (P < 0.05).

Table 4. Amimo acid composition and nutritional value of ASPP and IEPP.

Amino acid	Mass concentration (g/100g pro)^a
	ASPP	IEPP
Non-essential amino acids
Aspartic acid	9.34	9.19
Glutamic acid	10.56	8.94
Serine	4.46	4.28
Glycine	3.70	3.65
Arginine	4.13	3.46
Alanine	4.57	3.71
Proline	4.41	3.82
Essential and semi-essential amino acids
Threonine	4.77	4.61
Cysteine	2.79	2.89
Valine	4.83	4.78
Methionine	2.54	2.23
Isoleucine	4.13	3.71
Leucine	8.20	7.84
Tyrosine	3.98	3.94
Phenylalanine	5.13	5.00
Lysine	6.36	5.89
Histidine	1.80	1.44
Total EAA	35.96	34.06
Nutritional values
EAAIadult	119.43	111.56
EAAIegg	88.28	82.23
EAA/AA (%)	41.69	42.91

^aThe results were expressed as mean value of three replicates.

Figure 4. Effect of NaCl concentration (M) (A) and pH (B) on the foaming ability (%) of ASPP and IEPP. Values in the same graph with the different letter are significantly different (p< 0.05).

Figure 5. Effect of NaCl concentration (M) (A) and pH (B) on the endothermic peak of ASPP. Effect of NaCl concentration (M) (C) and pH (D) on the endothermic peak of IEPP. Arrows point to the heat absorption peak.

Seo, S.; Karboune, S.; Archelas, A. Production and Characterisation of Potato Patatin-Galactose, Galactooligosaccharides, and Galactan Conjugates of Great Potential as Functional Ingredients. Food chemistry 2014, 158, 480–489.

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