Abstract

The objective of this study was to investigate methods for improving the yield of acid soluble mustard protein isolate (SPI) by solubilizing isoelectrically precipitated protein isolate (PPI). The SPI is more valuable, as it can be used in unique food applications. Four treatments were tested in the acidic pH range: Alcalase hydrolysis; transglutaminase cross-linking; salting in with NaCl, Na₅P₃O₁₀, and (NaPO₃)₆; and protective colloid formation with pectin. The effectiveness of each treatment was determined by measuring the increase in nitrogen solubility (AOCS-Ba11-65). Alcalase hydrolysis improved PPI solubility evenly in the 2.5-3.5 pH range, effectively eliminating the solubility minimum near the isoelectric point. At pH 3, the hydrolysis treatment increased solubility from ~20% to a maximum of ~70% (0.04 g of enzyme preparation / g PPI, 2 h, pH 8.5, 50-55^oC). Protein hydrolysis during isolate production could increase the yield of SPI from 0.16 to 0.75 kg per kilogram of mustard protein.

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