Recovery of protein hydrolysates from brewer’s spent grain using enzyme and ultrasonication

Abstract

The aim of this study was to develop a green ultrasound-assisted enzymatic process to separate protein from brewer's spent grain (BSG) to produce protein hydrolysates and determine the physicochemical properties of produced protein hydrolysates. When the enzyme (Alcalase) loading increased from 1 to 20 lL g À1 BSG, the protein separation efficiency increased from 34.0% to 61.6%. The application of ultrasound pretreatment further increased protein separation efficiency to 69.8%. More promisingly, the ultrasound pretreatment was able to reduce enzyme loading by 73% and decrease enzyme incubation time by 56%. The produced protein hydrolysates had molecular weights lower than 15 kDa and high protein solubilities at the pH of 1.0-11.0. The ultrasound pretreatment improved the protein solubility to above 90%. Glutamic acid and proline were the most abundant amino acids in produced protein hydrolysates. This study demonstrated that enzymatic hydrolysis along with ultrasound pretreatment is an effective way to separate protein from BSG.

Effects of Brewers’ Spent Grain Protein Hydrolysates on Gas Production, Ruminal Fermentation Characteristics, Microbial Protein Synthesis and Microbial Community in an Artificial Rumen Fed a High Grain Diet

“…The protein content of BSG protein extract was 70%, which was much higher than that of the original BSG substrate ( Table 1). The present value was comparable to a recent study that combination of enzyme and ultrasonication, resulting in 69.8% of BSG protein content [29]; whereas, it was greater than pre-treated BSG with carbohydrases followed by direct hydrolysis using proteolytic enzymes (63.1%) [30]. The Degree of hydrolysis (DH) of the protein extracted from BSG was greater (P < 0.01) when it was treated with alcalase (34.7%) than with avourzyme (11.9%) and both protein hydrolysates showed good solubility in water.…”

Effects of brewers’ spent grain protein hydrolysates on gas production, ruminal fermentation characteristics, microbial protein synthesis and microbial community in an artificial rumen fed a high grain diet

“…The protein content of BSG protein extract was 70%, which was much higher than that of the original BSG substrate (31.7%; Table 1). The present value was comparable to a recent study that utilized a combination of enzyme and ultrasonication extraction, resulting in 69.8% of BSG protein content [35]; whereas, it was greater than BSG pre-treated with carbohydrases followed by direct hydrolysis using proteolytic enzymes (63.1%) [36]. The degree of hydrolysis (DH) of the BSG protein was higher (P < 0.01) when treated with alcalase (34.7%) than with flavourzyme (11.9%), with both protein hydrolysates showing high solubility in water.…”

Effects of brewers’ spent grain protein hydrolysates on gas production, ruminal fermentation characteristics, microbial protein synthesis and microbial community in an artificial rumen fed a high grain diet

“…The protein content of BSG protein extract was 70%, which was much higher than that of the original BSG substrate (31.7%; Table 1). The present value was comparable to a recent study that utilized a combination of enzyme and ultrasonication extraction, resulting in 69.8% of BSG protein content [35]; whereas, it was greater than BSG pre-treated with carbohydrases followed by direct hydrolysis using proteolytic enzymes (63.1%) [36]. The degree of hydrolysis (DH) of the BSG protein was higher (P < 0.01) when treated with alcalase (34.7%) than with avourzyme (11.9%), with both protein hydrolysates showing high solubility in water.…”