Abstract:

The neutral protease-assisted extraction of highland barley starch was optimized using response surface
methodology. The effects of several operating parameters, namely solid to liquid ratio, enzyme dosage, hydrolysis time,
temperature and pH, on the residual protein content of highland barley starch were studied. Three main factors including
enzyme dosage, hydrolysis time and temperature were chosen to design response surface experiments using residual protein
content and starch yield as the responses. The results showed that the three selected factors as well as the interaction between
enzyme dosage and either hydrolysis time or temperature all had significant effects on residual protein content, but had no
significant effects on starch yield. The optimal extraction conditions in the selected experimental ranges were determined as
follows: enzyme dosage, 140.79 U/g; temperature, 45.01 ℃; and hydrolysis time, 2.57 h, leading to a starch yield of 60.36%
and a residual protein content of 1.31%.

Key words: highland barley starch, neutral protease, residual protein, response surface methodology