Influence of Drying Temperature and Storage Duration on Fissuring and Milling Quality of <em>Jasmine</em> 85 Rice Variety

Abstract

Moisture and temperature gradients induce the development of fissures during drying of paddy kernels. This affects the milling quality of the paddy and eventually reduces the head rice yield. To this effect, a study was conducted to investigate the influence of drying temperature and storage duration on the cracking behaviour and head rice yield of a local rice variety -Jasmine 85. Freshly harvested paddy samples were thin layer dried in a tunnel dryer with varying drying temperatures (45°C, 50°C, 55°C) as treatments and direct sun drying as control. The drying experiment was performed under three replications using a completely randomised design. Samples after drying were stored for three months in sealed plastic bags at room temperature (28°C). Percentage fissures and head rice yield at each drying treatment was determined using a grain scope and a Satake grading machine respectively after the storage period. The highest head rice yield (76.3%) and the least fissure rate (10%) were attained at the control temperature. This was followed by the 45°C and 50°C treatments which gave head rice yields of 70.8%, and 69.8%, with fissure rates of 13% and 16% respectively. The least head rice yield (64.7%) and the highest fissure rate of 29% were observed at 55°C. There was a significant difference (p ≤ 0.05) between head rice yields obtained at 55°C and the control experiment. However, there was no significant difference (p ≤ 0.05) between head rice yield obtained at 45°C, 50°C and the control temperature. It is evident from this study that, Jasmine 85 can be dried by using a mechanical dryer at higher temperatures of 45°C and 50°C without affecting its milling qualities.

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

“…Litchfield and Okos [42] further reported that HRY due to increasing stress in kernel decreased when dried at 60.8°C. e initial increase and then decrease trend in HRY with respect to temperature are in line with those of Yousaf et al [43]; Akowuah et al [44]; and Siebenmorgen et al [45], all of whom reported that the temperature is the main factor on which HRY is mainly depended on. e regression equation for HRY in coded form is given as follows:…”

Redução do tempo de cocção do arroz integral através da indução de fissuras

“…Já em temperaturas mais elevadas acima de 45ºC, o amido passa para o estado emborrachado, no qual possui maior difusividade, calor e volume específico, e coeficiente de expansão térmica. Tais diferenças nas características de cada estado do amido em diferentes regiões do endosperma do grão possibilitam maior formação de fissuras (Yang, Jia, Siebenmorgen, Pan, & Cnossen, 2003;Akowuah, Addo, & Bart-plange, 2012;Zhao, Yang, Wang, & Wu, 2020).…”

Cracking and breaking response in four rice varieties as influenced by fertilization regime and storage duration

“…Rice cracking was known as sun-cracking by earlier researchers, latter research led to the observation that rice cracking was due to moisture absorption of dried rice (Schluterman and Siebenmorgen, 2007;Akowuah et al, 2012). Some studies in different varieties found that rice cracking begins at moisture content below 14.2 and 18.3% for crack resistant and crack susceptible varieties, respectively (Kumoro et al, 2019).…”

“…Some studies in different varieties found that rice cracking begins at moisture content below 14.2 and 18.3% for crack resistant and crack susceptible varieties, respectively (Kumoro et al, 2019). Another factor that may cause paddy to crack before harvest is nonsynchronous blooming which leads to uneven grain maturity (Schluterman and Siebenmorgen, 2007;Akowuah et al, 2012;Kumoro et al, 2019). In bulk storage of paddy, moisture migration causes lowmoisture grains to absorb moisture from the highmoisture grains and crack when the high-moisture grains had only 4 to 5% more moisture than the low-moisture grains (Akowuah et al, 2012).…”