Correlation among physical properties of parboiled milled rice during hydrothermal pretreatment processing

Jhauharotul Muchlisyiyah, . and Rosnah Shamsudin, . and Roseliza Kadir Basha, . and Radhiah Shukri, . and Syahmeer How, . (2024) Correlation among physical properties of parboiled milled rice during hydrothermal pretreatment processing. Pertanika Journal Tropical Agricultural Science (Malaysia), 47 (2). 421 -438. ISSN 1511-3701

The rice cultivar MR297 has a high harvesting yield but a low milling and head rice yield. Parboiling is one of the methods to increase the head yield of rice varieties. The colour of parboiled rice is intense due to husk colour absorption during soaking. This study researched the influence of hydrothermal pretreatment (soaking time and temperature) on the physical properties such as dimension, thousand kernel weight (TKW), density, volume expansion (Ve), colour, and hardness of parboiled milled rice. MR297 raw rice cultivars were soaked at 1:1 (w/w). Paddy was soaked at 50, 60, and 70°C for 1, 2, 3, 4, and 5 hr and steamed at 100°C for 20 min prior to drying for 24 hr at 38°C. It was discovered that the effects of soaking time and temperature varied with the physical properties of rice. Soaking time and temperatures were found to be significant (p<0.05) in terms of dimensional properties (length [L], width [W], and thickness [T]), TKW, density, Ve, colour (L*, a*, b*) and hardness of parboiled rice. The L, W, T, Ve, TKW, a*, and b* increase proportionally as time and temperature increased, while the density and L* were negatively correlated. The hardness was negatively correlated with the L and colour b* (yellowness) rice measurements. The principal component analysis (PCA) results revealed that the soaking time was associated with L, W, T, density, Ve, and colour properties based on the loading analysis in the PC1. In contrast, the temperature, TKW and hardness were associated with PC2.

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Abstract

The rice cultivar MR297 has a high harvesting yield but a low milling and head rice yield. Parboiling is one of the methods to increase the head yield of rice varieties. The colour of parboiled rice is intense due to husk colour absorption during soaking. This study researched the influence of hydrothermal pretreatment (soaking time and temperature) on the physical properties such as dimension, thousand kernel weight (TKW), density, volume expansion (Ve), colour, and hardness of parboiled milled rice. MR297 raw rice cultivars were soaked at 1:1 (w/w). Paddy was soaked at 50, 60, and 70°C for 1, 2, 3, 4, and 5 hr and steamed at 100°C for 20 min prior to drying for 24 hr at 38°C. It was discovered that the effects of soaking time and temperature varied with the physical properties of rice. Soaking time and temperatures were found to be significant (p<0.05) in terms of dimensional properties (length [L], width [W], and thickness [T]), TKW, density, Ve, colour (L*, a*, b*) and hardness of parboiled rice. The L, W, T, Ve, TKW, a*, and b* increase proportionally as time and temperature increased, while the density and L* were negatively correlated. The hardness was negatively correlated with the L and colour b* (yellowness) rice measurements. The principal component analysis (PCA) results revealed that the soaking time was associated with L, W, T, density, Ve, and colour properties based on the loading analysis in the PC1. In contrast, the temperature, TKW and hardness were associated with PC2.

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Item Type:	Article
AGROVOC Term:	rice
AGROVOC Term:	traditional parboiling methods
AGROVOC Term:	osmotic pretreatment of seed
AGROVOC Term:	soaking
AGROVOC Term:	steaming
AGROVOC Term:	drying
AGROVOC Term:	temperature
AGROVOC Term:	principal component analysis
AGROVOC Term:	chemicophysical properties
Geographical Term:	Malaysia
Uncontrolled Keywords:	Correlation, hydrothermal, paddy MR297, parboiling, physical properties, soaking condition
Depositing User:	Ms. Azariah Hashim
Date Deposited:	19 Mar 2026 02:26
Last Modified:	19 Mar 2026 02:26
URI:	http://webagris.upm.edu.my/id/eprint/2908

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