Modelling of the Soaking and Drying Stages for Senia-type Pre-cooked Rice

Abstract

[EN] Background and objectives The production of precooked rice has mainly been applied to long rice varieties, while japonica varieties are significantly less represented, especially Spanish varieties. The aim of this paper was to model the water mass flow process in precooked round-shaped rice (Bahia-Senia) for the soaking (Peleg model) and drying phases (drying by hot air and by combined hot air and microwaves, Fick, Midili, and Page models). Optical and mechanical properties after drying were recorded. Cooking tests were also performed.

Findings The results show that optimum soaking process was achieved at 35 degrees C during 20 min. For the drying stage, water loss increases using microwave energy at 2.45 GHz and no variations with air temperature were registered. Thus, the optimal drying conditions were achieved at 40 degrees C combined with microwave during 42 min.

Conclusions Precooked round rice processing conditions have been established. This treatment would reduce the final cooking time (96 oC) for the user by 94%, which implies that in only 3 min, the precooked rice would reach the same level of moisture as the control rice after 20 min of cooking.

Significance and novelty These findings can be used by food industry in selecting the proper soaking and drying conditions that favors the production of precooked round-shaped rice.