Physical Properties of Indica Rice in Relation to Some Novel Mechanical Properties Indicating Grain Characteristics

Effect of tertiary processing on physical, optical, phytochemical as well as rheological properties of high-protein rice

The first high-protein rice variety of India, CR Dhan 310, developed at ICAR-NRRI, Cuttack is being selected for the study. It contains 10.1% protein in milled rice as compared to 6-7% protein content in the milled rice of any other normal variety. It has intermediate amylose content (25.1%), medium bold grains rich in protein (10.1%) The significant changes in properties of raw and parboiled rice on processing were studied at statistical differences of p ≤ 0.05. These properties included physical, optical, antioxidant and rheological properties which changed with different processing techniques. All the three processes namely, puffing, popping and flaking increased the dimensions as compared to the raw rice. Peak viscosity measurements demonstrated the breakdown of starch molecules, with white rice having the greatest value (4145 cP) and popped rice having the lowest value (2017 cP) as a result of the starch granules being gelatinized during the production of popped rice. Highest anthocyanin content (2.93 mg/100 g) was observed in puffed rice, phenolic content (347.93 mg/100 g) was highest in popped rice and flaked/flattened rice showed highest flavonoid content (127.12 mg/100 g) indicating that tertiary processing of rice obtained higher values of phytochemicals when compared to the plain high-protein rice. This indicates that the processed products of rice can be consumed directly as ready-to-eat or can be used in preparation of other functional foods to combat malnutrition and build nutritional security. The study indicates that processing could improve the nutritional quality of the rice products.

Breakpoint Planning Method for Rice Multibreak Milling

Excessive milling of rice kernels will result in nutrient loss and grain waste. To avoid grain waste, multibreak milling systems have been widely used in large-scale commercial rice mills. However, there is still no reasonable breakpoint planning method to guide the multibreak milling process. To construct a reasonable multibreak milling system, in this research, taking rice milling, a typical heterogeneous cereal-kernel milling process, as an example, the multivariate analysis method was used to comprehensively analyze the characteristic changes of milled rice during the whole milling process. A breakpoint planning method was established, including planning the number of breakpoints, determining the degree of milling or milling time corresponding to each breakpoint, and estimating the actual breakpoint to which the milled rice belongs. The verification results showed the rationality and high accuracy of the planning method. The presented work will help operators to plan the multibreak milling system of rice efficiently and objectively so as to significantly improve the commercial value of milled rice.

Impact of physicochemical properties on duration and head rice yield during abrasive and friction milling of rice

The physicochemical properties of four rice varieties representing high amylose (Jyothi and IR64), intermediate amylose (Taraori Basmati) and waxy (Agonibora) were evaluated to understand their influence on milling. Based on the grain dimensions, Jyothi and Agonibora were classified as long and medium, IR64 as long and slender, and Basmati as extra-long and slender. The head rice yield (HRY) was higher with abrasive milling (61-75%) compared to friction milling (10-60%) although it required longer milling duration. Lower grain thickness, hardness and, amylose and higher bran fat content reduced the friction milling duration while these properties prolonged the duration in abrasive milling. Agonibora variety with low amylose content and high-fat content exhibited the highest HRY in both the types of milling. The study revealed that the selection of milling process should be made with due importance to grain geometry as well as its chemical properties.

Varietal distinctness in physical and engineering properties of paddy and brown rice from southern India

Paddy and brown rice samples were investigated for its physical characteristics which would aid in designing of the equipment and apparatus for processing of grains as sorting, grading and transportation with ease. Significant difference was observed among the different physical properties as geometrical (length, breadth, thickness, equivalent diameter, sphericity, volume, surface area, aspect ratio) gravimetrical (bulk density, true density, porosity etc.) and frictional characteristic such as angle of repose, hygroscopic properties as moisture and water activity and color of paddy and brown rice kernels. Among geometrical properties length was found the maximum in paddy of Mapillai samba (8.21 mm) and Palkudavazhai brown rice (6.34 mm). Among flow properties, Mapillai samba displayed the maximum value for true density of paddy and brown rice varieties respectively. Hardness was reported in the range of (344.1 ± 14.4-594.88 ± 9.5 and 209.31 ± 4.00-395.99 ± 7.05 N) for different varieties of paddy and brown rice cultivars. The color of the brown rice was read as L*, a*, b* where it varied from 36.22 ± 0.71-61.71 ± 0.81, 4.00 ± 0.18-15.29 ± 0.48 and 16.59 ± 0.52-23.81 ± 0.15 respectively. Brown rice varieties can generally be categorized as short bold, long bold and medium slender as per their length and breadth ratio. The significant differences in physical properties of the various cultivars studied, emphasis on varying processing techniques. The physical properties of selected brown rice varieties studied are widely cultivated in southern India, owing to its high nutraceutical potentials.

Mechanical property and quality aspects of rice dried in industrial dryers

The influence of drying methods on selected mechanical properties and qualities of MR219 rice variety has been investigated. The results showed significant effects of drying methods on bending strength and head rice yields while the average bending strength of paddy were 28.6-31.8 MPa. The effect of drying methods on apparent modulus of elasticity of rice was not significant (204.5-222.4 MPa). The fracture energy of rice varied significantly under control drying but not with industrial drying methods. Higher temperature in drying by IBD contributed in making the grains tougher, where the effect of FBD temperature was positive toward the development of fracture energy inside rice kernel. IBD at temperature above 40 °C resulted in lower bending strength in rice kernels which affected head rice yield. Two stage paddy drying practices with FBD using temperature of 115-125 °C as first stage is still acceptable, and inclined bed dryer either as single stage or as second stage after FBD should be operated at temperature of <40 °C to maintain head rice yield. The whiteness and milling recovery of rice achieved from different drying methods were comparable.

Rice: Parboiling and Milling Properties

Parboiling is a hydrothermal processing technique during rice has to pass through many stages which alter the physicochemical properties and nutritional profile of grain. Different parboiling techniques have been developed for preparation and industrialization of rice. During parboiling process, starch granules are gelatinized and retrograded as a result various changes occur in rice kernel, which affects its quality parameters. Parboiling has marked influence on organoleptic properties, improved the strength and nutritional profile of grain. Parboiling treatment principally brings the characteristic change in rice grain such as milling, cooking, storage and eating qualities. Milling is an important unit operation for removing the husk and bran from the rough rice. Milling significantly affects the cooking and nutritional properties of rice. The important parameters focussed during milling are the head rice yield and kernel hardness. Milling technology is therefore geared to obtain maximum outturn of milled rice and to reduce breakage.

Models for predicting the mass of lime fruits by some engineering properties

Grading fruits based on mass is important in packaging and reduces the waste, also increases the marketing value of agricultural produce. The aim of this study was mass modeling of two major cultivars of Iranian limes based on engineering attributes. Models were classified into three: 1-Single and multiple variable regressions of lime mass and dimensional characteristics. 2-Single and multiple variable regressions of lime mass and projected areas. 3-Single regression of lime mass based on its actual volume and calculated volume assumed as ellipsoid and prolate spheroid shapes. All properties considered in the current study were found to be statistically significant (ρ < 0.01). The results indicated that mass modeling of lime based on minor diameter and first projected area are the most appropriate models in the first and the second classifications, respectively. In third classification, the best model was obtained on the basis of the prolate spheroid volume. It was finally concluded that the suitable grading system of lime mass is based on prolate spheroid volume.