Soluble protein isolate from brewing by-product (trub) using the Box-Behnken design

Brewing by-products, as trub, can be exploited as new nutrients sources, especially proteins. The objective of this study was to optimize the protein extraction from trub using the Box-Behnken design and response surface methodology to obtain a protein isolate and verify its antioxidants properties and phenolic compounds. Optimal extraction condition was at a pH of 12.31, concentration of 5.37 g/L, with 51.78 min of extraction at 80celcius (fixed temperature). Under these conditions, a protein isolate from trub was obtained (94.56% protein; 19.89% yield), its presented high water solubility (63.09 to 93.22%) over a wide pH range (6 to 12), high free radical scavenging capacity (63.03 and 186.07 TEAC mu mol/100 g for DPPH and ABTS, respectively) and 35.36 mg gallic acid equivalents (GAE)/g of phenolic compounds. These results brings new information about a vegetable protein from a by-product enabling its extraction and applicability in different food matrices. Novelty impact statement Alkaline solution was efficient to extract the proteins from the trub, a beer production by-product that has been little reused. Vegetable protein isolate showed phenolic compounds, antioxidant activity and solubility in water over a wide pH range; and can be used as new protein source.

Automated summary

This study successfully optimized the extraction process to obtain a high-purity protein isolate from trub, a brewing by-product, with high antioxidant properties and water solubility. The isolate showed potential for application as a new protein source in various food matrices.