Extraction of polyphenols and hydrolysis of birdproof sorghum starch

The presence of polyphenols in the testa and pericarp of birdproof sorghum has an inhibitory effect on enzyme activity during hydrolysis of sorghum starch. In this communication the effect of different NaOH concentrations at various temperatures on the extraction of polyphenols from birdproof sorghum is described. It was found that a 0.25 M NaOH solution extracted all the polyphenols within 75 min at 22°C. The enzymic hydrolysis of birdproof sorghum starch (without polyphenols) was also investigated. A recovery of up to 92±0.6% glucose from the available starch was obtained. The change in sugar composition during hydrolysis was monitored by h.p.l.c.