Abstract: In order to find optimal conditions for the malting of naked oats, the effects of steeping temperature (11–19 ℃), germination temperature (11–19 ℃) and germination time (2–6 d) on β-glucan and phytic acid contents and protein digestibility in vitro of oat malts were studied by one-factor-at-a-time and orthogonal array design methods. β-glucan and phytic acid contents and protein digestibility in vitro were not substantially affected by steeping temperature. β-glucan and phytic acid contents decreased with increasing germination temperature and germination time. Protein digestibility in vitro increased with prolonged germination time but was only minorly affected by germination temperature. The optimal conditions for the malting of naked oats were determined as follows: the steeping procedure was performed at 14 ℃ and followed a pattern of steeping for 6 h, relaxation for 10 h, steeping for 4 h, relaxation for 7 h, steeping for 3 h, and relaxation for 1 h before germination at 15 ℃ for 4 d. Under these conditions, oat malts revealed a 42.8% decrease in phytic acid content and a 142.1% increase in protein digestibility in vitro. Therefore, the nutritional quality was improved.

Key words: oat, malting, phytic acid, β-glucan, protein digestibility