Background

Paddy is one of the most important food crops in the world. The major operations of paddy processing are soaking, parboiling/steaming, drying and milling. The paddy processing is an energy-intensive process with the substantial wastewater generation.

Scope and approach

The knowledge of mathematical modeling in different stages of paddy processing helps to improve the final rice quality and reduce the energy consumption. The present article analyzes the results of the recently published research work on different models used in paddy soaking, parboiling and drying operations. In addition, the article discusses the effects of modern methods of parboiling and drying operations on the process kinetics, microstructural changes and rice quality.

Key findings and conclusions

Hot water soaking (40–80 °C), single steaming, double steaming, pressure cooking and microwave heating are used to parboil or gelatinize the starch in rice. Also, acids/alkaline solutions can gelatinize the rice starch. The open sun (2–4 days), hot air (50–80 °C), superheated steam, vacuum, infrared (0·167-0·625 W cm⁻²), and microwave drying (2.45 GHz) are employed to dry the parboiled paddy up to 12–14% moisture content (db). Modelling and simulation tools have been used to study these complex processes during paddy hydration, starch gelatinization and drying. Fick's law of diffusion, Peleg model, and exponential equation are used to describe the water sorption in paddy. Arrhenius equation, Ozawa Model and Kissinger equation are useful in understanding the starch gelatinization kinetics. Several empirical and semi-empirical models are used to study the drying kinetics of gelatinized paddy. In drying, the models given by Page, Henderson and Pabis and Newton describe the drying kinetics better than other models. The effects of modern methods of the parboiling and drying can be understood from the kinetics and other constants of the models as well as from the change in the microstructure of starch that takes place in the process of gelatinization. The recent developments on the effects of modern methods of hydration, parboiling and drying with limitations have also been focussed in the manuscript. Because of the concerns of wastewater generation during paddy hydration and parboiling, new techniques need to be developed for reducing wastewater generation and its treatment.

中文翻译：

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水稻煮沸和干燥数学模型的全面综述：现代技术对过程动力学和稻米品质的影响

背景

水稻是世界上最重要的粮食作物之一。稻谷加工的主要操作是浸泡，煮沸/蒸煮，干燥和研磨。稻谷加工是一种能源密集型过程，会产生大量废水。

范围和方法

在稻米加工不同阶段的数学建模知识有助于提高稻米的最终品质并减少能耗。本文分析了最近发表的关于在稻田浸泡，预煮和干燥操作中使用的不同模型的研究工作的结果。此外，本文还讨论了现代煮沸和干燥操作方法对过程动力学，微观结构变化和大米品质的影响。

主要发现和结论

热水浸泡（40–80°C），单次蒸煮，两次蒸煮，加压蒸煮和微波加热可用于煮沸或糊化大米中的淀粉。同样，酸/碱溶液可以使大米淀粉糊化。晴天（2-4天），热空气（50-80°C），过热蒸汽，真空，红外线（0·167-0·625 W cm ^-2），然后使用微波干燥（2.45 GHz）将半熟的稻米干燥至水分含量（db）高达12–14％。建模和仿真工具已用于研究水稻水合，淀粉糊化和干燥过程中的这些复杂过程。用菲克扩散定律，佩莱格模型和指数方程式描述了水稻对水的吸收。Arrhenius方程，Ozawa模型和Kissinger方程有助于理解淀粉糊化动力学。几种经验和半经验模型用于研究糊化水稻的干燥动力学。在干燥过程中，Page，Henderson和Pabis和Newton给出的模型比其他模型更好地描述了干燥动力学。从模型的动力学和其他常数以及糊化过程中发生的淀粉微观结构变化，可以了解现代煮沸和干燥方法的效果。手稿中还重点关注了现代水合，煮沸和干燥方法的影响的最新进展。由于担心稻谷水化和煮沸过程中会产生废水，因此需要开发新技术来减少废水的产生及其处理。