Submitted to: Institute of Food Technology
Publication Type: Abstract Only
Publication Acceptance Date: 1/9/2012
Publication Date: N/A
Technical Abstract: Justification: Interest in protein hydrolysates is increasing because of their improved functionality and health benefits, particularly angiotensin-converting enzyme (ACE) inhibition, compared to their parent proteins. Large-scale production of hydrolysates is expensive, and one way to minimize costs is to use cheap, high- protein by-products. Peanut meal (PM), which is a non-food grade by-product of oil production, could be an appropriate substrate for hydrolysate production; however, aflatoxin contamination must be alleviated. Objective: Our lab has developed a process to hydrolyze protein and sequester aflatoxin from contaminated PM using commercial clays. The objective of this project was to further purify and characterize PM hydrolysates and evaluate their bioactive properties. Methods: PM dispersions (15% w/w) were adjusted to pH 9.0 and hydrolyzed with Alcalase in the presence of Novasil clay (4% w/w) at 50°C for 60 min and further clarified by centrifugation and ultrafiltration (UF) through a 10 kDa molecular weight cutoff membrane. Hydrolysates and fractions were evaluated for soluble protein, aflatoxin concentration, amino acid composition, MW distribution by SDS-PAGE and size-exclusion chromatography (SEC), and ACE-inhibitory activity. Results: Enzymatic hydrolysis increased (~22%) soluble nitrogen, and most peptides in the hydrolysates were <7 kDa, whereas the UF filtrates were enriched in peptides <1.3 kDa. Novasil addition effectively reduced aflatoxin concentrations of hydrolysates to non-detectable levels. Amino acid distributions of hydrolysates were similar to unprocessed PM. Further purification by UF and SEC improved the ACE-inhibitory activity of the hydrolysates. Fraction IV from SEC (IC50=38.8 µg/mL) was a more potent ACE inhibitor compared to the crude hydrolysate (IC50=295.1 µg/mL) and the UF filtrate (IC50=140.7 µg/mL). Significance: Results indicate that aflatoxin-free hydrolysates with ACE-inhibitory properties can be produced from contaminated PM. UF of hydrolysates enhanced this bioactivity. These data suggest further research is warranted to develop processing strategies that could ultimately allow food applications for PM.