Mathematical Modelling and Optimisation of Low-Temperature Drying on Quality Aspects of Rough Rice

Shakeel Ahmed Soomro,Kunjie Chen,Sohail Ahmed Soomro

doi:10.1155/2020/6501257

Shakeel Ahmed Soomro, Kunjie Chen + Show 1 more

Open Access

https://doi.org/10.1155/2020/6501257

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Abstract

Rice when harvested normally has a high moisture content of 20–25% which requires immediate drying, reducing its mass loss and preventing it to spoil. This situation is more crucial with the areas under humid tropical conditions, where moisture and temperature mainly play an important role in deteriorating the quality of rough rice. Keeping the importance of quality attributes of rough rice, the study was carried out to assess the effects of low-temperature drying and suggest an optimum condition. Response surface methodology (RSM) with a central composite design was employed to study the effects of variables, i.e., temperature (X1), time (X2), and air velocity (X3) on responses, i.e., head rice yield (HRY), hardness, lightness, and cooking time. The experimental data were fitted to the quadratic model, studying the relationship between independent and dependent variables. The results revealed that the HRY, hardness, lightness, and cooking time increased with increasing variables, whereas for HRY, it particularly increased and then decreased. It was observed that temperature had more influence on the quality of rough rice followed by time and velocity. Results for analysis of variance revealed that the quality aspects of rough rice were significantly (p<0.05) affected by temperature and time, whereas for velocity, it only significantly affected hardness. The optimal drying conditions predicted by RSM for variables were 25°C, 600 min, and 1 m·s−1, and the optimal predicted HRY, hardness, lightness, and cooking time were 73.93%, 38.28 N, 71.40, and 27.58 min respectively. Acceptable values of R2, Adj R2, and nonsignificance of lack of fit demonstrated that the model applied was adequate and can be used for optimization. The study concluded that the RSM with a central composite design was successfully used to study the dependence of quality aspects of rough rice at low temperature and can be utilized by the rice processing industries.

Highlights

Rice as a staple food is being consumed by a large proportion of the world’s population, making it one of the most demanding cereals [1]
Rice when harvested has a moisture content ranging from 16 to 28% (w.b.) depending on its method, variety, and location [2]. is rough rice with high moisture due to enzyme activity and mold growth is subjected to elevated respiration rates [3], which thereby reduces the quality of rough rice [4]. is situation of high moisture content makes it a crucial problem for further processing and storage purposes, especially for the areas coming under humid tropical climates [5]
Model Description and Accuracy. e variables temperature, time, and velocity as per design were evaluated observing their effects on the responses, i.e., Head Rice Yield (HRY), hardness, lightness, and cooking time. e statistical parameters of responses are presented in Table 3; all models were found to be statistically significant (p < 0.05)

Summary

Introduction

Rice as a staple food is being consumed by a large proportion of the world’s population, making it one of the most demanding cereals [1]. Several researchers have demonstrated their investigations to improve the quality of different rough rice varieties by various drying methods. Schluterman and Siebenmorgen [15] reported that drying at high temperature creates moisture content gradients within kernels, which leads to fissure formation reducing the quality of milling. Combination of temperature, time, and air velocity depending on drying conditions tends to increase/decrease the quality of rough rice. Is study was carried out to determine the effects of temperature, time, and air velocity on rough rice, investigating the optimum conditions being affected by indicators and predicting the variables by mathematical modelling. E responses, i.e., HRY, hardness, lightness, and cooking time being affected by the factors temperature, time, and velocity, were investigated by employing response surface methodology with a central composite design (CCD).

Results and Discussion

1.60 C: velocity

Conclusion