Long‐grain rice variety Kaybonnet was milled to three degree of milling (DOM) levels in two commercial milling systems (a single‐break, friction milling system and a multibreak, abrasion and friction milling system) and separated into five thickness fractions. For both milling systems, the surface lipid content (SLC) and protein content of the milled rice varied significantly across kernel thickness fractions. SLC was influenced by DOM level more than by thickness, while the protein content was influenced by thickness more than by DOM level. Particularly at the low DOM levels, the thinnest kernel fraction (<1.49 mm) had higher SLC than the other kernel fractions. Protein content decreased with increasing kernel thickness to 1.69 mm, after which it remained constant. In both milling systems, thinner kernels were milled at a greater bran removal rate as indicated by SLC differences between the low and high DOM levels. For rice milled to a given DOM level, the multibreak system produced fewer brokens than did the single‐break system.

Cooking history at the center point in chicken patties was quantified in terms of both time-temperature integrated indices (C and F) and endpoint temperature (T max ). Intact cooked patties were scanned for reflectance and transmittance spectroscopy. Reflectance resulted in better calibrations for the indices of thermal history than did transmittance. Three reflectance wavelength ranges, visible (400 to 700 nm), near-infrared (1100 to 2500 nm), and visible/near-infrared (400 to 2500 nm), were evaluated, and visible/near-infrared yielded the highest accuracy. The best calibration resulted in a standard error of prediction (SEP) of 0.11 log 10 (min) for log 10 C, 0.25 log 10 (min) for log 10 F, and 2.54ЊC for T max on an independent validation sample set.

Cereal Chem. 75(3):380-385A digital image analysis method was developed to quickly and accurately measure the degree of milling (DOM) of rice. The digital image analysis method was statistically compared to a chemical analysis method for evaluating DOM, which consisted of measuring the surface lipids concentration (SLC) of milled rice. The surface lipid area percentage (SLAP) obtained by the image analysis method and the SLC obtained by chemical analysis had a high coefficient of determination using a quadratic model (R 2 = 0.9819) and using a logarithmic model (R 2 = 0.9703). The quadratic model and the logarithmic model were validated using the test data set and it received high coefficients of determination (R 2 = 0.9502 and R 2 = 0.9459, respectively).Rice millers grade rice quality for nutritional and economic considerations and, thus, need a fast and accurate grading system as part of their milling assessment operations. The primary physical grading factors are head rice yield, which is the weight percentage of rough rice remaining as head rice (kernels that are 75% or more of their original length after milling), and degree of milling (DOM), which indicates how much bran remains on milled kernels (USDA 1979). Generally, milled rice with a high DOM level has less kernel bran than does milled rice with low DOM levels. The current methods for grading rice quality are subjective and time-consuming. This study developed a digital image analysis method that can quickly and accurately determine DOM.DOM is an important factor in terms of the nutritional value and the economic return of the milled rice. Low DOM level rice contains more protein, vitamins, minerals, and lipids than does high DOM rice (Wadsworth et al 1991). Although low DOM level rice has greater nutritional value, it often has a lower market appeal because most consumers prefer the taste and appearance of well-milled rice. Additionally, the degree to which rice is milled inversely affects head rice yield (Sun and Siebenmorgen 1993). Therefore, adjusting DOM during the rice milling operations is essential for optimizing quality and economic return. DOM can be measured by several methods, including visual inspection, chemical analysis, and optical measurements. Traditionally, DOM has been determined through visual inspection by trained personnel. For official grading, this judgment is made by comparing a sample to one of four official samples representing the four DOM grades (undermilled, lightly milled, reasonably well-milled, and well-milled) defined by the United States Standards for Milled Rice (USDA 1979). The closest similarity between the official representative sample and the inspection sample determines the DOM grade. Visual inspection is not only subjective but also is lacking in terms of quantitatively assessing the milling degree. For accurate measurement, more objective and quantitative methods must be employed to determine DOM.Chemical methods of assessing DOM include the differential dye-staining procedure and the compositional analysis...

Cereal Chem. 76(4): [473][474][475] Within rice varieties, individual kernels vary in size. The effect of kernel size on milling performance and quality has been studied (Matthews and Spadaro 1976, Wadsworth et al 1982, Sun and Siebenmorgen 1993, Chen and Siebenmorgen 1997. These studies focused on long-grain rice milled in single-break, laboratory or commercial-scale friction mills. As rice was milled from a low to high degree of milling (DOM) level, more surface bran was removed from thin kernels than from thick kernels, and thin kernels were broken at a greater rate than thick kernels.There is an increasing trend in use of multibreak milling systems by the rice industry. Chen et al (1998) conducted research on the milling performance of long-grain rice in both single-and triplebreak commercial milling systems. For both milling systems, the surface lipids content (SLC) and protein content of milled rice varied significantly across kernel thickness fractions. SLC was influenced by DOM level more than by kernel thickness, whereas protein content was influenced by thickness more than by DOM level. As milling progressed from a low to high DOM level, thin kernels were milled at a greater bran removal rate than thick kernels, as indicated by SLC. However, protein content decreased much more uniformly across thickness fractions than did SLC during milling.The studies mentioned above were limited to long-grain rice. The objective of the current work was to investigate the bran removal characteristics of medium-grain rice milled in a multibreak commercial milling system. MATERIALS AND METHODSThe three-break commercial milling system used in this study comprised a Satake VTA vertical rice whitener (first break), a Satake VBF vertical rice whitener (second break), and a Satake KB-40 rice-polishing machine (third break) located at Jonesboro, AR. Brown rice was fed into the top of the VTA machine, which applied an abrasive milling action as rice flowed down through the mill. Rice from the VTA machine was fed into the top of the VBF machine, which applied a friction milling action. Water mist was injected into the VBF milling chamber. Rice from the VBF machine flowed horizontally through the KB-40 machine, which applied a friction milling action to polish the rice.To produce milled rice for cereal manufacturers, the system was adjusted to remove only part of the bran from kernels, which corresponded to a low DOM level. For this application, brown rice was passed sequentially through only the first two breaks (VTA and VBF). To produce well-milled rice (medium or high DOM levels), brown rice was passed sequentially through all three breaks. The three-break commercial milling system was slightly different from the commercial milling system used previously to investigate longgrain rice milling performance (Chen et al 1998), in that the second break in the system was a VBF machine, whereas a KB-40 machine was used by Chen et al (1998). Both milling machines are frictiontype mills.Medium-grain rice variety Bengal (≈14% moisture co...