Effects of Different Solar Drying Methods on Drying Time and Rice Grain Quality

Meas, Pyseth; Paterson, Anthony H.J.; Cleland, Donald J.; Bronlund, John E.; Mawson, Andrew; Hardacre, Allan; Rickman, J.

doi:10.2202/1556-3758.2378

Cited by 10 publications

(7 citation statements)

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“…High temperature is known to affect head rice recovery (Truong et al, 2012, Wongpornchai et al, 2004. In a similar experiment in Cambodia where different methods of sun drying were examined, higher head rice recovery was found when the rice grain was shaded during the peak sun between 11 am and 2 pm (Meas et al, 2011). When grain was harvested at 25 days after flowering, there was no significant difference between nylon net and tarpaulin during sun drying, and this confirms the result of Meas et al (2011).…”

Section: Discussionsupporting

confidence: 55%

“…If temperature of the grain gets too high, head rice recovery is reduced (Truong et al, 2012). Thus, shading around midday and stirring the bed where the rough rice is piled would reduce the damage to the grain (Meas et al, 2011;Paterson et al, 2013). Faster drying through increased air circulation may reduce the time of drying but often increases the damage to the grain (Meas et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…Thus, shading around midday and stirring the bed where the rough rice is piled would reduce the damage to the grain (Meas et al, 2011;Paterson et al, 2013). Faster drying through increased air circulation may reduce the time of drying but often increases the damage to the grain (Meas et al, 2011). A similar point was also made by Imoudu and Olufayo (2000) who found that sun drying on a concrete floor took a longer time than on a matt surface; however, it produced higher head rice recovery.…”

Section: Introductionmentioning

confidence: 99%

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Rice milling quality as affected by drying method and harvesting time during ripening in wet and dry seasons

Xangsayasane¹,

Vongxayya²,

Phongchanmisai³

et al. 2018

Plant Production Science

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Head rice recovery is known to decrease with the delay in harvesting during ripening, but this effect may differ between wet season (WS) and dry season (DS) and among different paddy drying methods. In five experiments, rice was harvested by hand between 25 and 45 days after flowering in DS and WS when temperature around harvest was slightly above and below 30°C, respectively. The highest head rice recovery was generally obtained when rice was harvested at 25 days after 75% flowering. Delaying harvest to 30 days resulted in significant reduction in head rice recovery in 3 out of 7 cases and further delay to 35 days resulted in significant reduction in 8 out of 10 cases. For the crops harvested 25 days after flowering and dried with a flatbed dryer head rice recovery improved compared to sun drying in two experiments. When harvesting was delayed, sun drying tended to reduce head rice recovery compared to artificial drying. Sun drying only in the morning also improved head rice recovery compared to drying for the whole day. For a given drying method, head rice recovery decreased with increase in heat sum from flowering to harvest. It is concluded that rice crops should be harvested in both DS and WS around 25 days after 75% flowering when heat sum with base temperature of 10°C was around 450-500 degreedays. If an artificial dryer is not available, rough rice should be sun dried only in the morning with frequent stirring and mixing to promote more even drying.

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Section: Discussionsupporting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Rice milling quality as affected by drying method and harvesting time during ripening in wet and dry seasons

Xangsayasane¹,

Vongxayya²,

Phongchanmisai³

et al. 2018

Plant Production Science

View full text Add to dashboard Cite

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“…Grain may crack during the process as dried grain adsorbs water, with subsequent breakage during threshing and milling (Calderwood, Bollich, & Scott, 1980;Jindal & Siebenmorgen, 1994). However, HRY of sun-dried rough rice may increase greatly if grain is stirred frequently and kept under shade during the time of intensive solar radiation (Meas, Cleland, Bronlund, Mawson, & Hardacre, 2013;Meas et al, 2011). Artificial drying in protected conditions with constant supply of heat and constant humidity conditions can reduce cracking and subsequent breakage of grains, particularly if high moisture grains are dried under low humidity conditions (Banaszek & Siebenmorgen, 1990).…”

Section: Introductionmentioning

confidence: 99%

Effects of introduction of combine harvester and flatbed dryer on milling quality of three glutinous rice varieties in Lao PDR

Vongxayya

Jothityangkoon

Ketthaisong

et al. 2018

Plant Production Science

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Mechanization is required to increase labour productivity and improve grain quality for rainfed lowland rice in Lao PDR and neighbouring countries. An experiment was conducted in dry season in 2016 with three rice varieties and also in wet season in 2017 with two varieties to investigate the effect of introduction of combine harvester and flatbed dryer on milling quality of glutinous rice. The treatments were different harvest methods (hand and combine harvester), drying methods (sun and forced air drying with flatbed dryer) and storage period up to 6 months. Head rice yield (HRY) improved greatly with forced air drying with mean HRY of 46.1% compared to 28.8% in sun drying. Milling quality of grain harvested by combine was similar to that of handharvested crop. The results also revealed large difference in HRY between varieties; mean HRY across two seasons was 40.1% and 27.1% for Thadokkham (TDK8) and TDK11, respectively. These treatment effects and also their interactions on HRY were strongly related to the proportion of broken rice. HRY declined from 39.4% to 35.4% with 4-month storage, but there was no further reduction with 6-month storage. This study showed that the milling quality of glutinous rice improved greatly with the introduction of flatbed dryer but only little with combine harvester. Milling quality also varied greatly among varieties and slightly with storage period. Further study is required to investigate physiological and morphological characteristics of varieties and postharvest methods that determine the milling quality of rainfed lowland rice.

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“…The model accurately predicted the trends of sun drying experiments across a wide range of conditions Meas et al [50]. In these experiments, the HRY was measured by both milling the rice in a smallscale mill (done in duplicate) and using a mechanical impact method Meas et al (2011) [52]. A total of 80 drying experiments were conducted for a range of drying methods including with and without shading, covering, bed stirring and for four different under bed pad types using two varieties of rice.…”

Section: Introductionmentioning

confidence: 98%

Relating Rice Grain Quality to Conditions during Sun Drying

Meas

Paterson

Cleland

et al. 2013

International Journal of Food Engineering

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Rice grain conditions within the sun-drying bed predicted by a mathematical model during drying were used to relate drying parameters to the head rice yield (HRY) which is the key rice quality metric. A number of parameters were derived to characterise the mechanisms of grain fissures and breakage postulated in the literature, and the model was used to estimate these parameters. These parameters were then regressed against the HRY experimental data to determine the contributing mechanisms. An increase in bed temperature, the maximum temperature at the top of the bed, the size of the moisture content gradients within a rice grain and the difference from the critical point for drying were all found to negatively affect HRY. By stirring the bed regularly and covering and shading the bed during the hottest parts of the day, HRY can be significantly increased leading to better returns to the farmer.

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Effects of Different Solar Drying Methods on Drying Time and Rice Grain Quality

Cited by 10 publications

References 0 publications

Rice milling quality as affected by drying method and harvesting time during ripening in wet and dry seasons

Rice milling quality as affected by drying method and harvesting time during ripening in wet and dry seasons

Effects of introduction of combine harvester and flatbed dryer on milling quality of three glutinous rice varieties in Lao PDR

Relating Rice Grain Quality to Conditions during Sun Drying

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