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Recovery of Proteins from Sweet Potato Cell Liquid by Acidification via Inoculation-Enhanced Fermentation and Determination of Functional Properties of Protein Products
Jing Ma 1,2
Mo Han 1,2
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Shandong Food Ferment Industry Research & Design Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250013, China, China
School of Food Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China, China
Submission date: 2023-07-23
Acceptance date: 2024-01-19
Online publication date: 2024-02-09
Publication date: 2024-02-09
Corresponding author
Jiaxiang Zhang   

Shandong Food Ferment Industry Research & Design Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250013, China, China
Starch production from fresh sweet potatoes generates process wastewater called sweet potato cell liquid (SPCL), which is rich in sweet potato protein (SPP). Currently, the commonly used protein recovery methods, such as isoelectric point precipitation and ultrafiltration, were not suitable for SPP recovery due to the low protein content of SPCL and the high cost of recovery. The feasibility of recovering SPP by SPCL acidification via inoculation-assisted fermentation was investigated in this study. The results indicated that the pH of SPCL could be reduced to approximately 4.0 within 6 h of fermentation with inoculation, resulting in an SPP extraction yield of 55.45% and purity of 66.23 g protein/100 g. With the addition of heating treatment, the extraction yield of SPP increased to 76.97–95.34%, while it maintained the purity of 66.36–70.12 g protein/100 g. The composition analysis revealed that SPP products contained sugars (below 11.5 g/100 g) in addition to protein and trace amounts of lignin and phenolics. Functional properties analysis showed that the SPP recovered by inoculation-enhanced fermentation exhibited better emulsifying and foaming properties, and higher digestibility compared to the SPP precipitated using hydrochloric acid. The method of extracting SPP from SPCL by inoculation-enhanced fermentation, as developed in this study, was a straightforward and cost-effective process that fosters significant potential for industrial applications.
This work was supported by Key R&D Program of Shandong Province, China (2023TZXD024), the development of plant protein preparation technology and new equipment (2020CXGC010604) and Major Innovation Pilot Project of Integration of Science, Education and Industry of Qilu University of Technology (Shandong Academy of Science) (No. 2022JBZ01-08).
We confirm that there are no any conflicts of interest for this article that could influence the outcome.
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