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Development of Predictive Models for Optimization of Phytate Degradation in Wheat and Rye During Hydrothermal Processing

¹Dept. Food Science, Chalmers University of Technology, Göteborg, Sweden. ²Corresponding author. Telephone: +46 31 3355626. Fax: +46 31 833782. Email: eva-lotta.bergman@fsc.chalmers.se ³Oy Lahden Polttimo AB, Lahti, Finland.

Whole kernels of wheat (Triticum aestivum ‘Kosack’), rye (Secale cereale ‘Motto’) and rice (Oryza sativa) were hydrothermally treated to reduce the phytate content. The hydrothermal processes used in this study included alternating wet and dry steeping periods. Two hydrothermal processes were used for wheat and rye with two and three wet and dry steeping steps, respectively. The process using two wet and dry steeping steps (process 1) was optimized for phytate reduction with respect to temperature during the process and lactic acid concentration used in the wet steeping steps. Optimal conditions for phytate breakdown in wheat and rye in process 1 were 55°C during the whole process and 1.3–1.5% lactic acid solution as the soaking agent in the wet steeping periods for wheat and 1.3% for rye. The hydrothermal process with three wet and dry steeping periods for wheat and rye (process 2) showed that the temperature used in the third wet and dry steeps did not significantly influence (P > 0.05) the phytate reduction in wheat and rye during these steps. The maximal phytate reduction was 94.4–95.6% in wheat and 99.0–99.5% in rye during hydrothermal processing. In rice, hydrothermal processing resulted, at best, in a 99.8% phytate reduction.