Impact of nanofiltration pre-concentration prior to a combination of electrodialytic processes on the extraction of proteins from tofu whey

Abstract

Tofu whey is a by-product of tofu production which represents a major challenge in the industry, considering treatments that must be applied before its disposal to reduce its environmental impact. Rich in nutrients, such as protein and minerals, tofu whey valorization represents an interesting alternative. In this study, the impact of a pre-concentration step by nanofiltration prior to coupled electrodialysis and electrodialysis with bipolar membrane (ED+EDBM) treatments on protein recovery was investigated. Tofu whey without concentration (1X) and volume concentration factors of 2X and 3X were used. The 3X condition allowed a protein recovery about 20 % higher than the 1X. Also, protein purity of the recovered fraction was similar for these three conditions, with an average value of 44.8 % (dry basis). The lowest relative energy consumption of 2.7 Wh/g of protein recovered was achieved with the 3X VCF; as the VCF increased, up to 3.5 times less energy was required to isolate the same amount of protein. The NF+ED+EDBM was efficient to recover the proteins with the highest molecular weights. Although the pre-concentration step improved protein recovery, yields are still low and should be increased by further optimization step.

Keywords

• Electrodialysis
• Electro-acidification
• Bipolar membrane
• Nanofiltration
• Protein
• Tofu whey