Head Rice Yield Research Articles

X-Ray Detection of Fissures in Rough Rice Kernels

Abstract. X-ray imaging is a viable method of fissure detection in rough rice kernels owing to the ability of X-rays to penetrate hulls, thus allowing visualization of internal rice kernel structure. Traditional methods of fissure detection are only applicable for brown and milled rice, and therefore cannot be used to study fissures developed during rough rice drying. In this study, the fissure detection capability of an X-ray system was evaluated and the relationship between head rice yield (HRY), as measured through laboratory milling, and the percentage of fissured rough rice kernels was determined. Long-grain rice lots of various cultivars were dried using heated air at 60°C, 10% relative humidity (RH) for five drying durations to produce different degrees of fissuring, and then milled to determine HRY. A strong linear correlation (R2 = 0.95) between HRY and the percentage of fissured rough rice kernels after drying was determined. This correlation confirms the substantial impact that kernel fissures have on milling yields. Overall, these findings show the effectiveness of X-ray imaging in rough rice fissure detection, which could allow for drying research that may provide a better understanding of kernel fissuring kinetics. Keywords: Fissures, Grainscope, Head rice yield, Rice drying, X-ray imaging.

Influences of harvester and weather conditions on field loss and milling quality of rough rice

A better understanding of factors affecting field losses and milling quality during harvest is needed to improve the economic value of rice. The main objective of this study was to evaluate the impact of harvester header, harvester type, and weather conditions on field loss and milling quality of rough rice. Four popular harvesters equipped with different headers: John Deere 9870 with header D60-S, John Deere 9860 with header D972-S, Hardy, and John Deere 9770 with stripper header were evaluated in this study. The header and total field losses of rice were evaluated for each harvester under regular, rainy and windy weather conditions. Tests were conducted in a rice field cultivated with medium grain rice, variety M206, at Grimes, CA. Total rice yield (TRY), head rice yield (HRY) and whiteness index (WI) were examined to evaluate the effect of weather conditions on milling quality. The obtained results revealed that the rice field loss was affected by harvester header and type, and weather conditions. Among the conventional headers, D60-S significantly reduced the rice loss compared to the D972-S and the Hardy. Harvesting with John Deere 9860 resulted in significant header and field loss compared to other tested harvesters. The average loss increased from 236.2 kg/hm2 and 445.2 kg/hm2 under regular condition to 711.1 kg/hm2 and 907.9 kg/hm2 under windy condition for John Deere 9870 and John Deere 9860, respectively. The corresponding loss percentages increased from 2.6% and 4.9% to 7.9% and 10.1%. HRY was significantly affected by weather condition at harvest time. However, the weather condition had no significant effect on TRY and WI. To minimize the rice field loss and obtain good milling quality, commercial rice harvesting during regular weather conditions is important. A proper combination of harvester type and header could be vital for reducing the rice loss. Keywords: rice, harvesters, field loss, weather conditions, milling quality, harvester header DOI: 10.25165/j.ijabe.20171004.2993 Citation: Khir R, Atungulu G, Ding C, Pan Z L. Influences of harvester and weather conditions on field loss and milling quality of rough rice. Int J Agric & Biol Eng, 2017; 10(4): 216–223.

Aging kinetics of low amylose rice during storage at ambient and chilled temperatures

ABSTRACTThe objectives of this study were to monitor the changes in rice properties during aging and to compare kinetic parameters related to some of those changes. Paddy of three low amylose rice varieties was stored at ambient (30 ± 2ºC) and chilled (8 ± 2ºC) temperatures for 9 and 18 months, respectively. Aging led to a decrease in solid loss, peak viscosity, breakdown, and adhesiveness and an increase in head rice yield, minimum cooking time, water uptake, volume expansion, pasting temperature, final viscosity, through viscosity, setback, and hardness. Low temperature storage efficiently retarded those changes. Data of the time-dependent changes in hardness, adhesiveness, pasting temperature, peak viscosity, and breakdown of all samples stored at 30°C were fitted well with the first-order fractional conversion kinetic model (R2 = 0.77 – 0.98). Higher storage temperature resulted in greater rate constant (k; up to 9 times higher) of those changes.

One-pass drying of rough rice with an industrial 915 MHz microwave dryer: Quality and energy use consideration

Microwave (MW) at 915 MHz has potential to achieve one pass rough rice drying. However, optimising processing parameters to maintain the rice quality is crucial. Effects of MW treatment on rice moisture removal, milled rice characteristics, and energy requirements for continuous one pass drying operation were quantified. Freshly harvested rough rice with initial moisture content of 25% wet basis was dried in a pilot-scale 915 MHz microwave dryer. The dryer was set to transmit MW power ranging between 3 and 24 kW during 8 min of drying. During treatments, rough rice was conveyed at bed thicknesses, 0.01, 0.03, and 0.05 m; supplied specific energy was maintained at 450, 600 and 750 kJ kg −1 of rough rice. Moisture removed varied between 6% and 15% points, depending on rice bed thickness (0.01–0.05 m) and applied specific energy (450–750 kJ kg −1 ). Increasing rice bed thickness and specific energy reduced milling and head rice yields, increased final viscosity of milled rice, but marginally affected rice peak viscosity and surface lipid and protein contents (p −1 and 750 kJ kg −1 of rough rice, 4574 kJ and 5986 kJ were required per kg of water removed, respectively; this translated to 13 and 16 USD per metric ton of dried rice, respectively. The study demonstrated feasibility of one pass MW drying of rough rice; 450–600 kJ kg −1 of rough rice was recommended to preserve rice quality and achieved better energy use efficiency.

Milling Yields and Physicochemical Properties of Long-Grain Rice Thickness Fractions

Thickness grading of rice ( L.) can divert thin, chalky kernels to a secondary processing stream, thus improving milling yields of the primary stream. However, the quantity and functionality of the secondary stream may impact processing operations. Rough rice of multiple long-grain cultivar lots was either left unfractioned (Unf) or thickness graded into fractions comprising A ( 2.05 mm). Mass distribution of rough rice; milled rice yield (MRY), and head rice yield (HRY); kernel dimensions of brown rice; crude protein content (CP) and chalkiness of brown and head rice; and paste viscosities of head rice flour were determined for each cultivar lot/fraction. For all cultivar lots, MRY, HRY, and kernel dimensions increased with increasing thickness fraction, while chalkiness and CP decreased. Milling yields were the greatest for the C/D/E fractions. Including the C fraction (C/D/E) with the primary stream resulted in an average 17.4 percentage point mass increase compared to D/E alone; this with minimal impacts to milling yields of the primary stream. Weighted-average MRYs and HRYs of the combined C/D/E fractions increased by up to 6.9 and 12.8 percentage points, respectively, compared to Unf rice. The A/B fractions were generally of greater chalkiness and CP; however, paste viscosities remained relatively consistent with those of the C/D/E fractions. Thickness grading could be justified on the merits of improved milling yields, kernel uniformity, and reduced chalkiness of the primary processing stream. A small change in the thickness grading procedure decreased the quantity of the secondary stream; moreover when milled, the secondary stream retained functionality similar to the primary stream.

A Comparative Study on the Quality of the Main and Ratoon Rice Crops

AbstractPhysical, milling and cooking attributes of the main and ratoon crops in three rice cultivars, namely Hashemi, Alikazemi and Tarom, were compared in a factorial layout based on randomized complete block design in five replications. The results revealed that for each tested cultivar, the length and slenderness ratio of the main rice grains was significantly (P < 0.01) higher than those of the ratoon crop. The means of head rice yield and whiteness degree in the main crop (76.01 and 46.45%, respectively) were significantly different (P < 0.01) with the corresponding values in the ratoon rice (80.27 and 40.10%, respectively), however, the effect of crop type on the total milled rice yield was not significant. Among the qualities evaluated, the amylase content and alkali spreading value in the main rice crop (21.97% and 4.27, respectively) was significantly lower than those of the ratoon rice (22.93% and 5.50, respectively).Practical ApplicationsRice quality features such as milling and cooking quality is the main factors for its market acceptability. Since ratoon rice as re‐harvested of the main crop can be considered for improving economic status of the farmers because of its low production cost and to encourage the farmers to develop ratoon cultivation in rice fields, it is a need to determine such properties as physical dimensions, head rice yield, milling recovery, whiteness, amylose content, alkali spreading value and other cooking quality as compared to the main rice crop.

History and prospects of hybrid rice development outside of China

Increasing rice production has always been a top priority in Asian countries. The research and development of hybrid rice has contributed significantly to global food security since the 1970s. Inspired by China’s success, many countries, specifically the South and South-East Asian countries, have started hybrid rice programs through introduction, adoption, and localization from the 1980s. Currently, about 20 million hectares of hybrid rice are being produced annually in the world, including 6.4 million hectares outside of China, mostly in the South and South-East Asian countries. The United States of America also became an important hybrid rice growing country since the 2000s. Different countries used various approaches and patterns of technology development and adoption. Planting areas of hybrid rice fluctuated yearly depending on technical adoption, seed supply, weather, and government policies. Adoption rates of hybrid rice in the major rice-producing countries are still low, which leaves great potential for further development. The main constraints for hybrid rice adoption in the tropics are low levels of hybrid heterosis, high price and lower quality of seeds, poor milling gain quality associated with high chalkiness and low head rice yield, low resistance to major pests, and poor education to farmers and unstable government policies. Recent progress of grain quality improvement made hybrid rice more acceptable by farmers and rice consumers. International Rice Research Institute has been playing a significant role in the development of tropical hybrid rice including extensive research, variety breeding and releasing, training and technology extension. Application of semi-dwarf rice varieties, so called the green revolution, has significantly increased rice production in Asia. Unfortunately, the common adaption of semi-dwarf germplasm originated from one source- germplasm homogenesis—might have also contributed to the reduction of germplasm diversity which makes less hybrid vigor and could be one of the main causes for low yield heterosis compared to the hybrid rice in the temperate regions. The concept and practice of heterotic grouping used in hybrid corn have not been applied to hybrid rice development. Recent progress made from the association of public institutes and seed industry has been beneficial to both investors and will support for the sustainable growth of hybrid rice in the future. New challenges such as cultural practices, climate change, market demand, management of intellectual property, and the application of gene transformation technologies require a close collaboration among scientists, farmers, policy-makers, public institutes, and the seed industry.

Mathematical modeling of starch gelatinization and some quality properties of parboiled rice based on parboiling indicators using RSM

AbstractThe effects of parboiling indicators (soaking temperature and steaming time) on the degree of starch gelatinization (DSG) and several rice quality properties [head rice yield (HRY), color value, lightness, and hardness] of parboiled rice were investigated. A mathematical model was used to predict DSG and rice quality from the parboiling conditions, which were varied as follows: 60, 65, and 70 °C for the soaking temperature and 2, 6, and 10 min for the steaming time (at 96 °C). A central composite design was applied and a total of 13 experimental runs were generated for each step. An ANOVA test showed the all models were significant (p < 0.01) and there was no significant lack of fit in any of the response variables. The most appropriate model for prediction the amount of DSG, HRY, color value, lightness, and hardness of samples was linear (R2 = 0.87), quadratic (R2 = 0.92), quadratic (R2 = 0.97), quadratic (R2 = 0.86), and linear (R2 = 0.94) model, respectively. The DSG and hardness increased with increasing soaking temperature and steaming time, while the HRY and lightness showed a maximum at a steaming time of 6 min. The statistical model was used to predict the optimal parboiling conditions for global optimization of the quality properties.Practical applicationsParboiled rice enjoys high popularity because of its high nutritional content. The most important effect of parboiling is rice gelatinization. The degree of starch gelatinization (DSG) and quality properties (head rice yield, color value, lightness, and hardness) of parboiled rice are determined by the parboiling indicators (PI): soaking temperature and steaming time. These properties can be predicted based on PI using mathematical models. Increasing the parboiling indicators increases the cost of parboiling process. For the parboiling industry, it will help to determine the soaking temperature and steaming time of rice to yield the desired product quality. For this reason, optimizing the parboiling process is economically important for the rice industry.

Impact of volunteer rice infestation on yield and grain quality of rice.

Volunteer rice (Oryza sativa L.) grains may differ in physicochemical traits from cultivated rice, which may reduce the quality of harvested rice grain. To evaluate the effect of volunteer rice on cultivated rice, fields were surveyed in Arkansas in 2012. Cropping history that included hybrid cultivars in the previous two years (2010 and 2011) had higher volunteer rice infestation (20%) compared with fields planted previously with inbred rice (5.5%). The total grain yield of rice was reduced by 0.4% for every 1% increase in volunteer rice density. The grain quality did not change in fields planted with the same cultivar for three years. Volunteer rice density of at least 7.6% negatively impacted the head rice and when infestation reached 17.7%, it also reduced the rice grain yield. The protein and amylose contents of rice were not affected until volunteer rice infestation exceeded 30%. Crop rotation systems that include hybrid rice are expected to have higher volunteer rice infestation than systems without hybrid rice. It is predicted that, at 8% infestation, volunteer rice will start to impact head rice yield and will reduce total yield at 18% infestation. It could alter the chemical quality of rice grain at >30% infestation. © 2016 Society of Chemical Industry.

Protein and starch characteristics of milled rice from different cultivars affected by transplantation date.

The effects of transplantation date on milled rice (physicochemical, amino acids composition and protein profiling) of different cultivars and their starch characteristics (granules size distribution, pasting and thermal) were investigated. Head rice yield increased (2.0-4.1%) and chalky grains (5-10%) decreased with delaying the paddy transplantation of different cultivars by 20days. Delayed transplantation of paddy significantly increased asparagine, glutamine, threonine, cysteine, methionine, tryptophan, lysine and proline content in milled rice. Early transplantation of paddy showed higher accumulation of glutelin and prolamines than that in milled rice from delayed transplantation. The change in amino acid composition of milled rice with delay in transplantation was related to variation in accumulation of glutelin and prolamines. Starch from delayed transplanted paddy showed higher peak viscosity and lower breakdown viscosity than those from early transplanted paddy. These differences were due to higher accumulation of amylose in starch from delayed transplanted paddy than that from early transplanted paddy due to exposure of former to lower night air temperature during starch synthesis.

Evolution of mechanical properties of parboiled brown rice kernels during impinging stream drying

ABSTRACTInformation on mechanical properties of parboiled brown rice kernels upon impinging stream drying, which is important for effective control of kernel fissure and head rice yield, is reported. Experiments were performed at the drying temperatures of 130, 150, and 170°C; inlet air velocity of 20 m/s; impinging distance of 5 cm and paddy feed rate of 40 kgdry_paddy/h. Parboiled paddy was dried for up to seven cycles. Between each drying cycle, the paddy was tempered for a period of either 0 (without tempering) or 30 min. The moisture evaporation rate was noted to be very high during the first two drying cycles and rapidly dropped in the later drying cycles. When tempering was included after a particular drying cycle, the drying rate in a subsequent cycle was higher than without tempering. At the kernel moisture contents immediately after drying of 25.3–47.5% (d.b.), the drying temperature and existence of tempering did not affect the mechanical properties although microcracks were formed in the kernels. However, both factors played a more important role on the mechanical properties when the kernels were evaluated at 16% (d.b.). The head rice yield correlated well with the tensile strength of the kernels.

Impact of Soaking and Drying Conditions on Rice Chalkiness as Revealed by Scanning Electron Microscopy

Chalkiness is one of the most influential factors on head rice yield. Parboiling is known to be an effective way to remove chalkiness and improve head rice yield. However, the steps involved in the removal of chalkiness are still not completely resolved. This study investigated the effects of soaking temperature, soaking duration, and drying conditions on the removal of rice chalkiness. Chalky brown rice kernels were selected and soaked at 25, 65, 70, or 75°C for 3 h. After 1, 2, or 3 h, the rice samples were frozen before drying or immediately dried. Soaking at 25°C did not remove chalkiness and caused no morphological change in starch granules. When the soaking temperature increased from 25 to 65, 70, and 75°C, the chalkiness decreased from 100% to 34.1, 29.7, and 15.9%, respectively. Soaking rice at temperatures above the starch glass transition temperature but below the gelatinization temperature reduced chalkiness owing to rearrangement of starch granules and protein denaturation to fill the void spaces in the chalky area. During soaking, the morphology of starch granules also changed from round to angular in shape. Drying at temperatures above the starch glass transition temperature also facilitated rearrangement of starch granules to further reduce rice chalkiness.

Effect of storage temperatures on the head rice yield in relation to glass transition temperatures and un-freezable water

Head rice yield (HRY) in relation to glass transition temperatures and un-freezable water of waxy (San-pah-tawng) and non-waxy (Phitsanulok 2) rough rice were studied. Freezing points and glass transitions were measured by differential scanning calorimetry (DSC) as a function of solid fraction. Both waxy and non-waxy rice samples exhibited similar trends in glass transition when solid fraction was decreased. The transition temperature and enthalpy of ice melting decreased as the solid fraction increased. The on-set (i.e. initial) glass transition was increased from 27 to 35 °C when solid fraction increased from 0.80 to 0.97. Un-freezable water contents were found to be different for both rice samples. The rate of HRY (i.e. rate constant) increased differently (i.e. higher above glass transition) when rice samples were stored above (i.e. 35 and 45 °C) and below glass transition temperatures. It was found that storage of fissured rice (low HRY) at the temperatures especially above glass transition could relax the strains inside a rice kernel and subsequently improved HRY.

Assessment of One-Pass Drying of Rough Rice with an Industrial Microwave System on Milling Quality

Abstract. The volumetric heating phenomenon of microwaves has the potential to dry rough rice rapidly with reduced inter-kernel rice temperature and moisture content (MC) gradients thereby minimizing rice fissuring and maintaining milled rice quality. The objective of this study was to determine the feasibility of using an industrial-type microwave heating system to achieve one-pass rice drying with minimum implications on rice milling quality, especially the head rice yield. Freshly-harvested, medium-grain rough rice samples (cv. Jupiter) at initial moisture content (IMC) of 23% to 24% (wet basis) were heated using an industrial microwave system with a frequency of 915 MHz and set to transmit energy to rice at power levels of 2, 5, 10, and 15 kW for durations of 1, 2, 3, and 4 min. The effects of natural air and forced air cooling and tempering of the rice after microwave treatments on moisture removal and head rice yield reduction were determined. The goodness of fit of linear, quadratic, and cubic models to describe the kinetics of the head rice yield reduction due to the treatments were determined. Results showed that microwave treatments at power levels of 5 and 15 kW for 4 and 1 min, respectively, bore much promise in decreasing the rice MC to 13.0% (wet basis) for a rice bed thickness at 0.03 m. Supplying microwave energy of up to 600 kJ/kg grain followed by 4 h of tempering at 60°C dried the rice to final MCs of 14% to 16%, and the resulting head rice yield was not significantly (p >0.001) different from that of rice dried with natural air at 25°C and relative humidity of 65%. Without a tempering step, microwave heating with energy input exceeding 300 kJ/kg-grain resulted in head rice yield that was 20 percentage points lower than that of the control samples. The cubic model best fitted the correlations of specific energy input and the head rice yield with Root Mean Square Errors (RMSE) of 1.19%, 4.70%, and 5.56% and coefficients of determination (R 2 ) of 0.597, 0.911, and 0.889 for treatment with microwave heating followed by tempering and natural air cooling, microwave heating followed by forced air cooling, and microwave heating followed by natural air cooling, respectively. The marginal reduction in head rice yield, especially resulting from microwave heating followed by tempering treatment, provided a strong justification to optimize the treatments to achieve commercially viable rough rice drying throughput; it was concluded that such endeavors may have immediate applications, especially in rice parboiling operations which typically require rapid drying of rice at high initial moisture contents – often greater than 24% wet basis.

Process of Producing Parboiled Rice with Different Colors by Fluidized Bed Drying Technique Including Tempering

Steamer is utilized to gelatinize rice starch. High pressure or long steaming time is conventionally applied to obtain the dark brown color of the product. A new alternative method to produce dark brown parboiled rice was proposed in this work. High temperature fluidized bed drying technique including tempering was therefore explored to determine the operating condition to meet the requirement of light and dark brown parboiled rice along with high head rice yield. In addition, the couple of heat and mass transfer model was developed to determine the effective moisture diffusion coefficient, the temperature and moisture distributions within a grain kernel during drying. The effective diffusion coefficient was well correlated with grain temperature by Arrhenius equation. The drying temperature and moisture content after drying caused the drop of head rice yield. When the parboiled paddy at the intermediate moisture contents of 22 and 27% d.b. was tempered, the head rice quality was improved while the parboiled rice color was browner. To obtain high drying capacity, high head rice yield, and light brown color, the parboiled paddy should be dried at a maximum allowable temperature of 150 °C and tempered for 30 min. The tempering time should be extended to 60 min for the dark brown parboiled rice.

Physical, milling, cooking, and pasting characteristics of different rice varieties grown in the valley of Kashmir India

AbstractIn the present study, three different rice varieties, namely frome chena (FC), safaid chena (SC), and barkat chena (BC), were evaluated for various quality aspects in terms of physical, milling, cooking, and pasting characteristics. Among the three rice varieties SC had the highest thousand kernel weight and length breadth ratio (L/B). While as, BC had the lowest thousand kernel weight and FC had lowest L/B. Bulk density was found to be highest for FC followed by SC and BC. FC had density of 769.01 kg/m3. Milling characteristic in terms of broken percentage and head rice yield showed non-significant difference between the varieties. Head rice yield was below 70% in all the three varieties. All the three varieties took similar time to cook and cooking time varied non-significantly between 23.66 and 25.83 min. L/B ratio after cooking was found to be highest for FC followed by BC and SC. Elongation ratio of rice after cooking did not varied significantly between varieties. Elongation ratio after cook...

Rice grain discoloration effect on physical properties and head rice yield in three rice cultivars

Rice grain discoloration is a complex disease which develops by a range of micro-organisms. Effects of fungal agents such as Alternaria sp., Curvularia sp., Cladosporium spp., Bipolaris spp. on the physical properties and head rice yield (HRY) were examined during the cropping season 2013-2014. The experiment was conducted in factorial design with two factors; three rice cultivars of Hashemi, Gohar and Khazar, and two grain disease severity levels (high and low) based on a randomised complete design with four replications. In order to attain high disease severity level, water was sprayed at the heading stage of the crop. The grains axial dimensions, geometric and arithmetic mean diameters, sphericity, surface area, volume, slenderness ratio, 1000-grain weight, as well as HRY were measured at a moisture content of 9% (wet basis). The average of length, width, thickness, surface area, volume and 1000-grain weight at the high disease severity were found to be 7.64, 2.04, 1.67 mm, 20.375 mm2, 13.796 mm3 and 2...

Varietal differences in quality characteristics of popped rice

Rice is a versatile cereal and used for consumption in various forms. The three principal rice products of commercial importance which are traditionally being made in India are popped, puffed and flaked rice. Popped rice is a popular product, especially in Asia, because of its crispness and lightness. Hence an investigation was undertaken to study the varietal suitability of rice for popping quality characteristics. Sample of 15 paddy varieties were procured from ARS, Mugad. The physico-chemical parameters, cooking time and gelatinization temperature (GT) of milled rice and popping quality such as popping yield, expansion ratio of popped rice and flake size of popped rice were studied. Physical characteristics of milled rice varieties varied significantly (P<0.01). Among the milled rice varieties, the super fine variety Pusa-basumati had the highest length (7.22 mm) and the lowest in Dodiga (5.33 mm) a common grain variety. The L:B ratio for all the varieties of milled rice ranged from 1.89 to 3.68. In the study the popping yield was positively correlated with thousand kernel weight (r=0.332), bulk density (r=0.605), head rice yield (r=0.571), whereas the popping expansion was positively correlated to L:B ratio (r=0.527) and no significant correlation was found between popping expansion and amylose content and gelatinization temperature. The expansion ratio of popped rice of Intan found to be maximum at 27.6 per cent total amylose and 13.4 per cent hot water insoluble amylase. In the present study, it was observed that rice varieties Intan, Dodiga Udarsali, Navali, Abhilash, Jaya, Champakali posses good processing quality, exhibit optimum cooking time (19.00 to 23.50 min), high amylose content (27.6-30.6% db) and intermediate gelatinization temperature (70.09° to 72.45° C). Hence, it can be concluded that the rice varieties with high amylose content and intermediate gelatinization temperature are most suitable for good cooking, eating and processing qualities.

Impacts of parboiling conditions on quality characteristics of parboiled commingled rice

Commingling of rice cultivars with a wide range of onset gelatinization temperatures (To) could occur during harvesting, drying, storage, and distribution, and consequently impact parboiled rice properties. This study investigated the effects of commingling, soaking temperature and steaming duration on parboiled commingled rice properties. Rough rice of pureline (Taggart and CL151) and hybrid (XL753 and CL XL745) cultivars were mixed at 1:1 weight ratio to obtain 3 commingled rice lots with a difference in To of 1.2, 3.9, and 6 °C. Rough rice was soaked at 65°, 70°, or 75 °C for 3 h, and steamed at 112 °C for 10, 15, or 20 min prior to drying. The effects of soaking temperature and steaming duration were found to vary with commingled rice. Soaking temperature exerted more influence on commingled rice comprising low To cultivars. Commingled rice comprising high To cultivars was less affected by soaking temperature and steaming duration in terms of head rice yield, deformed kernels and pasting viscosities. Both the difference in To among commingled rice cultivars and the To relative to the soaking temperature were important in parboiled commingled rice properties. Commingled rice with a wide range of To tended to result in parboiled rice with less desirable properties.

Comparative Analysis on the Relationship between Head Rice Yield and Its Components in Korean High-quality Rice Varieties

Comparative Analysis on the Relationship between Head Rice Yield and Its Components in Korean High-quality Rice Varieties