Correcting Head Rice Yield for Surface Lipid Content (Degree of Milling) Variation

Abstract

Cereal Chem. 84(1):88-91Head rice yield (HRY) is the primary parameter used to quantify rice milling quality. However, HRY is affected by the degree of milling (DOM) and thus HRY may not be comparable between different lots if the DOM is different. The objective of this study was to develop a method by which HRY values can be adjusted for varying DOM values when measured by surface lipid content (SLC). Seventeen rough rice lots including long-grain and medium-grain cultivars and hybrids were harvested from two 2003 and five 2004 locations. Duplicate subsamples of each lot were milled in a McGill No. 2 laboratory mill for 10, 15, 20, or 40 sec after zero, one, two, three, and six months of storage. HRY and SLC were measured. The average HRY versus SLC slope across all milling duration data sets was 9.4. As such, it is suggested that, when milling with a McGill No. 2 laboratory mill, the HRY of a rice lot can be adjusted by a factor of 9.4 percentage points for every percentage point difference between the rice lot SLC and a specified SLC.

Milling quality assessment of Khao Dok Mali 105 milled rice by near-infrared reflectance spectroscopy technique

“…The obtained brown rice, following the method modified from Andrews et al (1992), was subsequently milled with the rice miller friction type milling machine (Sinthavee, Khok Samrong, Lop Buri, TH) under 200 combinations of three conditional factors (e.g., Chen et al 1997;Perdon et al 2001;Cooper and Siebenmorgen 2007) (Fig. 1).…”

“…Surface lipid content (SLC) from 5 g of head rice of each sample was extracted in Soxtec-Avanti 2050 (Foss Co., Denmark) according to the method of Cooper and Siebenmorgen (2007) who adapted from Mastsler and Siebenmorgen (2005). Prior to extraction, the sample in the cellulose extraction thimble was oven-dried for 1 h at 100°C to reduce moisture content.…”

Rice degree of milling effects on hydration, texture, sensory and energy characteristics. Part 1. Cooking using excess water

“…Milling rice to lesser degrees, that is, leaving more bran on milled kernels, can lead to greater milling yields and human nutritional benefits, as well as potential energy savings (Cooper and Siebenmorgen, 2007;Lanning and Siebenmorgen, 2011;Roy et al, 2008). From an energy-use standpoint, milling rice to lesser degrees requires shorter milling durations (Cooper and Siebenmorgen, 2007), thus consuming less energy during milling operations.…”

PaddyCheck—An Instrument for Rice Quality Determination

“…Cracking and fissures can appear before and during harvest, during storage and during the drying process, which results in kernel breakage [6,7]. Furthermore, the degree of milling, handling procedures, harvest moisture and moisture content, immature kernels, diseases, chalkiness and mixture of slender type influences the HRY [8][9][10][11][12][13][14].…”

“…Fang et al [24] showed that multiple rice quality parameters, such as size, HRY and chalkiness, could be determined by using image analysis on the milled rice. However, since the degree of milling affects the HRY [8], it would be preferable to measure the paddy rice directly. Thus, an instrument that combines texture measurements, colour, size and shape as well as translucency of the kernels with limited manual handling and preparations of the samples would have a great potential for measuring the quality of rice kernels.…”