Mechanistic modelling and simulation of instant decompression assisted novel steaming treatment for the characterization of no cooking rice-a new insight

Abstract

Instant controlled pressure drop (ICPD) treatment is an emerging technology involving high-pressure saturated steam treatment in combination with instant vacuum decompression. The treatment reactions were simulated based on mechanistic modelling approach for the characterization of novel no cooking rice. The process involves treating post-harvested or soaked post-dried paddy with saturated steam (0.1–0.5 MPa for 150–100 s), and drying at 40–60 °C temperature. Standardized process conditions as obtained from the optimization were treatment pressure of 0.5 MPa, treatment time of 150 s, and degree of polishing of 12 % with maximum rehydration ratio of 4.16 and minimum cooking time of 5 min. The rice underwent gelatinization during ICPD treatment, exhibiting first-order kinetics and a progressive increase in gelatinization values as the treatment pressure varied. Further indications of enhanced quality attributes, such as cooking and rehydration, were discernible from the results of scanning electron microscopy (SEM) and X-ray diffraction (XRD) data and also based on the interpretation of hydration, drying, and rehydration kinetics. From the results of XRD, V and B-type peaks could be observed and interpreted in ICPD-treated rice due to the formation of amylose–lipid complex and retrogradation of starch molecules during parboiling. Besides, ICPD-treatment filled rice cracks progressively owing to starch gelatinization, according to SEM data. Soaking leaches starch out and plugs all the pores and fractures in the kernel, while steaming causes it to swell and expand, creating a smooth surface and filling gaps.