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

Abstract

In this study, effects of NaCl concentrations (0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 M) and pH (3.0, 5.0, 7.0, and 8.0) on the physico-chemical and functional properties of potato protein concentrates extracted from potato fruit juice (PFJ) using ammonium sulfate precipitation (ASP) and isoelectric precipitation (IEP) were investigated. The total polyphenol content of potato protein concentrates extracted by IEP (IEPP) was 2.5 times of that of potato protein concentrates extracted by ASP (ASPP), which resulted in the color of IEPP darker than that of ASPP. More protein fractions (74, 62, and 35 kDa) were found in IEPP compared to ASPP. ASPP exhibited higher solubility than IEPP. The emulsifying properties of ASPP and IEPP increased along with the increasing NaCl concentration. ASPP and IEPP showed the lowest emulsifying properties and foaming ability at pH 5.0. While the foaming stability of ASPP and IEPP achieved the maximum and minimum at pH 5.0, respectively. Two endothermic peaks were observed in ASPP at pH 3.0, 8.0, and higher NaCl concentration (≥0.6 M), while more than two endothermic peaks were observed in IEPP at all NaCl concentrations (0.2-1.0 M) and pH values (3.0, 5.0, 7.0, and 8.0). The glutamic acid concentration of ASPP and aspartic acid concentration of IEPP were the highest, while histidine was the lowest according to the amino acid profile of both ASPP and IEPP. In terms of an essential amino acid index with respect to a reference protein of FAO/WHO, the nutritional values of IEPP were higher than those of ASPP.

Use of precision-fed cecectomized rooster assay and digestible indispensable amino acid scores to characterize plant- and yeast-concentrated proteins for inclusion in canine and feline diets1,2

“…Although the analyzed samples are from a single harvest, which can be considered a limitation of the study, the chemical composition of these ingredients was consistent with previously reported values. A study evaluating POP concentrates processed using ammonium sulfate precipitation or isoelectric precipitation reported higher CP values of 85.4% and 88.8% (DMB), respectively ( Zhang et al, 2017 ). The CP content of POP is higher than what is typically observed in protein concentrates.…”

A Screening Method for the Isolation of Bacteria Capable of Degrading Toxic Steroidal Glycoalkaloids Present in Potato

“…In addition to serving as a major nutrient source, potato starch is also an important industrial food ingredient. A by-product of the potato starch industry is potato fruit juice (PFJ) which contains proteins, amino acids and peptides ( Zhang et al, 2017 ). While PFJ has a high nutritional value, vegetable proteins, including potato, contain many anti-nutritional components and thus must be refined prior to human consumption ( Steinhof et al, 2005 ).…”

Techno-Economic and Life Cycle Assessment of Wastewater Management from Potato Starch Production: Present Status and Alternative Biotreatments

“…Drying the biomass was achieved using a direct contact rotary dryer. The compressor used to provide air to the bioreactor was designed to provide an aeration of 0.04 vvm, and was calculated using Equation (4). The costs of the equipment are presented in Table 6.…”

“…They include thermal coagulation, acid precipitation, salting out, isoelectric precipitation, complexing with carboxymethylcellulose or bentonite, ultrafiltration, expanded bed adsorption and dry separation [3][4][5][6]. However, the only method that is presently being used for industrial recovery of protein from PL is heat coagulation [3][4][5][6][7]. In this method, steam is injected into the liquor at a pH of 5.5 to increase the temperature to 99 • C. This coagulates the proteins, which are then precipitated and collected [8].…”