Physical Integrity of Long-Grain Hybrid, Pureline, and Medium-Grain Rice Kernels as Affected by Storage Conditions

2020 ◽  
Vol 36 (4) ◽  
pp. 579-588
Author(s):  
Zeinab Mohammadi Shad ◽  
Griffiths Atungulu
Keyword(s):  
Sodium Chloride ◽  
Storage Temperature ◽  
Rice Yield ◽  
Storage Conditions ◽  
List Type ◽  
Milled Rice ◽  
Physical Integrity ◽  
Head Rice ◽  
Head Rice Yield ◽  
The Impact

Highlights Rice kernel physical integrity diminished at higher storage temperature and moisture content. Variation in rice kernel physical integrity was noticeable among rice cultivars. Fungal attack lessened rice kernel physical integrity. Abstract . Rice kernel physical integrity directly correlates with rice milling yield and quality. In this study, the impact of storage conditions on rice kernel physical integrity was examined by assessing changes in head rice yield (HRY) and kernel microstructure. Long-grain hybrid (XL753), long-grain pureline (Roy J), and medium-grain (Titan) rice were stored at different storage moisture contents (16% and 21% MCs, wet basis), storage temperatures (20°C, 30°C, and 40°C), and storage durations (4, 8, 12, and 16 weeks); the samples were also treated with antifungals, sodium chloride, and natamycin. Results show that kernel physical integrity was highly dependent on the rice storage environment. At the same storage conditions, the physical integrity of medium-grain cultivar was significantly higher than that for the two long-grains. Generally, the long-grain hybrid rice exhibited more resilience to breakage than pureline under the same storage conditions. An average of 4% reduction in HRY was seen for the three cultivars when 16% MC rice was stored at 40°C compared to at 20°C; however, the HRY reduction was 12% for rice stored at the highest MC (21%). Decreases in kernel physical integrity were also associated with unique microstructural changes in rice kernels. Sodium chloride treatment of rice kernels significantly and negatively impacted their physical integrity during storage compared to natamycin treatment and untreated control samples. Multiple regression models, developed for each cultivar were applicable for predicting changes in rice kernel physical integrity as a function of studied storage conditions and antifungal treatments. Keywords: Antifungal treatment, Head rice yield, Microstructure, Milled rice quality, Storage, Rice kernel physical integrity.

Prediction of Rice Milling Yield and Quality Attributes during Storage Using Regression Analyses

2019 ◽  
Vol 62 (5) ◽  
pp. 1259-1268
Author(s):  
Soraya Shafiekhani ◽  
Jung Ae Lee ◽  
Griffiths G. Atungulu
Keyword(s):  
Hybrid Rice ◽  
Storage Temperature ◽  
Rice Yield ◽  
Storage Conditions ◽  
Milled Rice ◽  
Yield And Quality ◽  
Head Rice ◽  
Rough Rice ◽  
Milling Yield

Abstract. Regression analyses were performed to determine the storage conditions that exhibited the best outcomes for long-grain, hybrid milled rice yield and quality. This study evaluated mold population on rough rice, milled rice discoloration, and head rice yield (HRY) after storage of rough rice in airtight conditions at moisture contents (MCs) of 12.5%, 16%, 19%, and 21% wet basis and temperatures of 10°C, 15°C, 20°C, 27°C, and 40°C at two-week intervals for 12 weeks. The experiment used a popular long-grain hybrid rice cultivar (XL745). Rice lots were procured from fields with and without conventional treatment of the field with fungicide for plant disease management. Field treatment and no field treatment were considered as a block, and a Mann-Whitney test was conducted to determine effect. The response surface method, an extension of second-order polynomial regression, was used to examine optimal treatment conditions. Mold population and milled rice discoloration from a combination of storage conditions were predicted using regression models. The first-order and second-order terms of temperature indicated a nonlinear relationship between temperature and ln(discoloration). The MC was positively associated with ln(discoloration), but the degree of impact may change with temperature because the interaction term was significant. From the model evaluation (R2 and lack-of-fit test), the discoloration level is expected to be 57% (49% to 66% confidence interval) under conditions of 20% MC, 40°C, and nine weeks of storage for samples procured from fungicide-treated rice fields. This discoloration change is substantial compared to the initial discoloration of 9%. At high temperature (40°C) and MC (21%), discoloration started immediately after two weeks of storage. Anaerobic storage conditions impeded mold growth, especially at high storage temperature (40°C). Low mold populations were observed in rice stored at low MC (16%). According to the regression model, the critical storage temperature that may lead to discoloration is between 27°C and 40°C. Pre-harvest fungicide treatment of rice in the field for disease control significantly improved the HRY but had no significant influence on mold population or discoloration. This study suggests a range of storage conditions to prevent losses in milling yield and quality of rice. In addition, the studied storage conditions mimicked the typical conditions for on-farm, in-bin drying and storage in the U.S. Mid-South, especially for the top layers of rice inside the bin, and therefore provide an important reference for growers and rice processors using in-bin structures to manage the quality of long-grain hybrid rice. Keywords: Discoloration, Head rice yield, Mold population, Regression analysis, Rice quality, Rice storage.

X-Ray Detection of Fissures in Rough Rice Kernels

2017 ◽  
Vol 33 (5) ◽  
pp. 721-728 ◽  
Author(s):  
Zephania R. Odek ◽  
Bhagwati Prakash ◽  
Terry J. Siebenmorgen
Keyword(s):  
Rice Yield ◽  
X Rays ◽  
Milled Rice ◽  
Substantial Impact ◽  
X Ray ◽  
X Ray Imaging ◽  
Head Rice ◽  
Rough Rice ◽  
Head Rice Yield ◽  
Rice Drying

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.

Effect of Storage Moisture Content on Milling Characteristics of Rough Rice

2019 ◽  
Vol 62 (4) ◽  
pp. 1011-1019
Author(s):  
Bhagwati Prakash ◽  
Terry J. Siebenmorgen ◽  
Kristen E. Gibson ◽  
Shweta Kumari
Keyword(s):  
Moisture Content ◽  
Rice Yield ◽  
Surface Lipid ◽  
Milled Rice ◽  
Financial Return ◽  
Head Rice ◽  
Rough Rice ◽  
Head Rice Yield ◽  
Milling Characteristics ◽  
The Mean

Abstract. Rough rice in the Mid-South U.S. is typically stored and milled at a moisture content (MC) between 12% and 13% on a wet basis. Drying harvested rice to lesser MCs requires increasingly greater energy and reduces the overall mass of rice, both of which translate into lesser financial return for the crop. Considering these disadvantages of drying and storing rice at lesser MCs, farmers and grain handlers have been interested in exploring storing rice at slightly greater MCs. The current study was undertaken to evaluate the effect of storing rice at five MCs (11%, 12%, 13%, 14%, and 15%) on milling characteristics, particularly surface lipid content (SLC), milled rice yield (MRY), and head rice yield (HRY); additionally, the effects of storing rice at two storage temperatures (25°C and 35°C) and several storage durations (up to one year) on milling characteristics were investigated. Five long-grain rice lots were harvested in 2016 and 2017 from several locations in Arkansas; rice from each lot was gently dried to the target MCs and then stored in sealed glass jars at selected temperatures. With an increase in storage MC, shorter milling durations were needed to achieve a given SLC, which could potentially reduce the cost of the milling operation. However, rice samples stored at greater MCs were observed to have lesser HRYs, which could reduce the economic value of rice. The mean HRYs of the 15% MC samples were 4.8 to 9.1 percentage points less than the mean HRYs of the 12% MC samples. This study quantifies the milling characteristics of rice when stored for various durations at different MCs and temperatures. Overall, these data will allow the rice industry to make informed decisions related to storage conditions of rice, specifically storage MC. Keywords: Head rice yield, Milling, Moisture content, Rice, Storage.

Understanding Pre- and Post-Milling Crack Formation in Rice Grain

2021 ◽  
Vol 64 (6) ◽  
pp. 1795-1804
Author(s):  
Prakash Oli ◽  
Mark Talbot ◽  
Peter Snell
Keyword(s):  
Crack Formation ◽  
Moisture Absorption ◽  
Rice Yield ◽  
Consumer Acceptability ◽  
Rice Grain ◽  
List Type ◽  
Head Rice ◽  
Before And After ◽  
The Impact

HighlightsCracking and subsequent breakage of rice kernels reduces the marketability and profitability of rice.Pre-milling cracks in rice kernels cause breakage during milling, thereby reducing consumer acceptability.Three types of post-milling cracks reported are: surface, internal, and Hanasaki cracks.Post-milling cracks can be minimized throughout the supply chain.Abstract. Rice is consumed as intact grain, and any broken grains are discounted from the main marketable product. Breakage of rice mainly arises from cracks formed in the endosperm before or after milling. The cracks are formed by stress gradients that arise due to moisture absorption or desorption by grains. As a result of such stress, cracks mostly develop in a direction perpendicular to the length of the grain, making it less physically resistant to the stresses of milling, handling, and soaking processes. Until now, research into rice cracking has mainly focused on minimizing breakage during milling, and no significant knowledge is available on the impact and mechanisms of post-milling cracking and/or breakage and its effect on the downstream quality of rice. This article aims to review the existing information on the causes of rice cracking before and after milling. Keywords: Breakage, Crack, Drying, Glass transition temperature, Hanasaki, Head rice yield, Rice, Tempering.

Effect of Post-Drying Tempering of Rice on Minimizing Kernel Fissuring and Maximizing Moisture Removal

2021 ◽  
Vol 65 (1) ◽  
pp. 1-9
Author(s):  
Zephania Odek ◽  
Terry J. Siebenmorgen ◽  
Andronikos Mauromoustakos ◽  
Griffiths G. Atungulu
Keyword(s):  
Rice Yield ◽  
Yield Reduction ◽  
List Type ◽  
Humidity Ratio ◽  
Percentage Points ◽  
X Ray Imaging ◽  
Head Rice ◽  
Rough Rice ◽  
Head Rice Yield ◽  
Rice Drying

HighlightsMore moisture can be removed in a single drying pass without severely fissuring kernels when samples are tempered than when immediately cooled without tempering.Tempering rice kernels immediately after drying can reduce the percentage of fissured kernels by up to half of that when kernels are immediately cooled without tempering.Abstract. Improper rice drying results in kernel fissuring, leading to head rice yield reduction due to breakage during milling. The objective of this study was to determine the percentage points (pp) of moisture content (MC) reduction that can be achieved in a single drying pass without significantly fissuring kernels. Long-grain rough rice of cultivars CL XL745 and Diamond at initial MCs of 18%, 17%, 16%, 15%, and 14% were dried using air at 45°C/20% relative humidity (RH), 50°C/15% RH, 55°C/12% RH, 60°C/10% RH, and 65°C/8% RH to MCs of 17%, 16%, 15%, 14%, 13%, or 12% with and without post-drying tempering. All temperature/RH combinations resulted in a humidity ratio of 0.012 kg water kg-1 dry air. Tempering was conducted at the drying air temperature for 4 h. The resulting samples achieved between 1 and 7 pp of MC reduction in a single drying pass. The pp of MC reduction that can be attained in a single drying pass without causing significant fissuring varied across the cultivars tested. Generally, ~2 pp of MC reduction was achieved in a single drying pass for CL XL745 and ~4 pp for Diamond without causing adverse fissuring when samples were not tempered after drying. However, with tempering, ~3.5 pp of MC reduction was achieved in a single drying pass for CL XL745 and ~5.5 pp for Diamond without causing significant fissuring. However, these amounts varied depending on the drying air conditions and initial MC. For both cultivars, tempering immediately after drying reduced the fissured kernel percentage by up to half of that when the kernels were not tempered. These findings quantify the importance of rice tempering and provide information on how much moisture can be safely removed in a single drying pass. Such findings may be applied to different dryer types to reduce fissuring due to drying, thereby minimizing head rice yield reductions. Keywords: Drying, Glass transition, Rice quality, Single-pass drying, X-ray imaging.

Effect of Rice Chilling on Drying, Milling, and Quality Characteristics

2020 ◽  
Vol 36 (5) ◽  
pp. 767-776
Author(s):  
Soraya Shafiekhani ◽  
Griffiths G Atungulu
Keyword(s):  
High Temperature ◽  
Cold Storage ◽  
Storage Temperature ◽  
Rice Yield ◽  
Quality Characteristics ◽  
List Type ◽  
Milled Rice ◽  
Heated Air ◽  
Rough Rice

HighlightsThis study experimentally simulated drying of rough rice subjected to various cold storage/chilling conditions.The rice was dried using slightly-heated air and high temperature air with procedures set to mimic those practiced by commercial systems.The moisture removal, drying rate constant, material state transition, milling and quality characteristics of rice upon drying conditions was investigated.The study provides important reference information for growers and rice processors using the relatively new rice cooling technology.Abstract. High temperature (field heat) and moisture content of freshly harvested rough rice promote excessive respiration and microbial growth. Therefore, the rice risks significant deterioration of quality due to delayed drying at peak harvest time when drying capacity becomes limited. The U.S. rice industry has identified that cooling/chilling the rice prior to drying to remove the excess heat, immediately after harvest, significantly preserves the quality of milled rice. This study experimentally simulated drying of rough rice after cold storage/chilling. The rice was dried using slightly-heated air and high temperature air with procedures set to mimic those practiced by commercial systems. Rough rice at moisture contents (MCs) of 16%, 19%, and 21% (wet basis) were stored at storage temperature (Ts) of 10°C, 15°C, and 20°C for up to 4 months. Following retrieval, the samples were dried at drying temperature (Td) of 35°C, 45°C, and 60°C and relative humidity (RH) of 20%. Each drying run comprised of two 20-min drying passes with the rice tempered at the drying Td for a duration of 4 h following every drying pass. Following the drying, the rice was conditioned in an equilibrium MC chamber (T=26°C, RH=56%) to 12.5% MC and then milled to evaluate milled rice yield and quality characteristics. The highest percentage points of MC removal (6.77% points) occurred following drying at air temperature of 60°C for samples with initial MC at 21% and stored at 20°C. Drying with air at 60°C decreased head rice yield (HRY) especially for samples with initial MC at 21% and stored at 10°C (HRY=51.4% versus those at 45°C and 35°C, HRY=55.95% and HRY=58.8%, respectively). Drying air temperatures studied (35°C, 45°C, 60°C) had no significant effect of causing discoloration of samples within the range of the studied initial MCs and storage temperatures. Peak and final viscosities of samples with different initial MCs (16%, 19%, and 21%) stored at 20°C followed by high temperature air drying (60°C) were significantly different from those of samples stored at 10°C and 15°C. The results provided insight into the drying, milling, and quality characteristics of rice after cold storage/chilling. The information provide foundation for development of new recommendations to improve quality of milled rice. Keywords: Conventional drying, Cooling/chilling, Milling quality, Rough rice, Storage.

Milled Rice Quality Assessment

2010 ◽  
Vol 6 (2) ◽  
Author(s):  
Reza Farahmandfar ◽  
Esfandiyar Farahmandfar ◽  
Mahdi Ghasemi Varnamkhasti ◽  
Mahdi Zarei
Keyword(s):  
Rice Yield ◽  
Milling Process ◽  
Milled Rice ◽  
Rice Varieties ◽  
Breeding Lines ◽  
Head Rice ◽  
Rough Rice ◽  
Degree Of Milling ◽  
Head Rice Yield ◽  
Important Processing

Milling, an important processing step of rough rice, is usually done to produce white, polished grains. In this paper the quality of 22 milled rice varieties, common in Mazandaran, Iran, are investigated. These rice varieties included local varieties and breeding lines. Parameters assessed were head rice yield, degree of milling, husk removed percent, and total milling recovery. Results obtained revealed that the Tarom Mahali and Champa varieties have the highest head rice yield as 60.58 and 66.39 % and total milling recovery as 69.96 and 71.38 %, respectively. The greatest degree of milling value was found for the Haraz variety with a mean of 16.06 %. Also, it was found that the husk removed percent values were not statistically different among the varieties studied. Finally, considering all results obtained, the varieties of Tarom Mahali, Champa, and Neda showed to be more economical in the milling process.

scholarly journals EFFECT OF TWO STAGE DRYING EMPLOYING FLUIDIZED BED DRYING, TEMPERING FOLLOWED BY FIXED BED DRYING ON HEAD RICE YIELD OF BRRI DHAN28 RICE VARIETY IN BANGLADESH

2021 ◽  
Vol 2 (2) ◽  
pp. 74-78
Author(s):  
Md. Abdul Wazed ◽  
N. H. M. Rubel Mozumder ◽  
Md. Sazzat Hossain Sarker
Keyword(s):  
Fluidized Bed ◽  
Rice Yield ◽  
Rice Variety ◽  
Fixed Bed ◽  
Control Sample ◽  
Drying Method ◽  
Milled Rice ◽  
Two Stage ◽  
Head Rice ◽  
Head Rice Yield

Drying of high moisture paddy to achieve quality milled rice is an important issue in a paddy producing country like Bangladesh. This study has been conducted to investigate the impact of two stage drying technique namely, fluidized bed drying, tempering and followed by fixed bed drying method on quality of BRRI Dhan28 rice variety in terms of head rice yield (HRY). Moist paddy was dried in fluidized bed dryer (FBD) as first stage drying to reduce moisture from 25-27% to 18-19% using three drying temperatures of 120, 130, and 150°C at three bed thicknesses of 8, 10, and 12 cm. The first stage dried samples were immediately tempered for 30 minutes and dried in second stage drying by fixed bed dryer using 40±10C temperature maintaining bed thickness as 30 cm for the further reduction of moisture content to 13-14% (wb). Sun drying method was followed as complete drying of control sample. Control sample was used to compare the milling quality of rice dried in two stage drying technique. In addition, head rice yield was also compared to existing industrial paddy drying complexes. The results revealed that HRY of rice samples obtained from different drying methods was comparable. All the sets of drying parameters in two stage drying yielded better quality HRY than the control and even existing industrial drying method. The highest HRY (53.43%) of milled rice was obtained in the two-stage drying. On the other hand, the samples dried in the sun drying and industrial drying using Louisiana State University (LSU) dryer yielded 49.77% and 48.25% HRY, respectively. Therefore, the two-stage drying technique can be used for drying of high moisture paddy to obtain quality dried rice.

A Study of Paddy Heating for Insect Elimination and Improving Milled Rice Quality

2012 ◽  
Vol 472-475 ◽  
pp. 1707-1713
Author(s):  
Pradit Ramatchima ◽  
Somposh Sudajan ◽  
Chaiyan Junsiri ◽  
Thavachai Thivavarnvongs
Keyword(s):  
Death Rate ◽  
Feeding Rate ◽  
Rice Yield ◽  
Feeding Rates ◽  
Milled Rice ◽  
Rice Quality ◽  
Head Rice ◽  
Head Rice Yield ◽  
Screen Height ◽  
Temperature Levels

This research was aimed at studying the effects of heating the paddy for insect killing and thereby improving subsequently milled rice quality. The experimental temperatures were in the range of 120-200°C, the paddy feeding rates were 60, 120, and 180 kg/h and the heights of the vibration screen were 5, 6, and 8 mm. The findings indicated that when the feeding rates increased between 120 and 180 kg/h, the insect death rate increased for nearly all temperature levels, whereas the feeding rate of 60 kg/h and the vibration screen height of 6 mm were found to give 100% insect killing efficiency. The resulting head rice yield increased by 0.3-0.7% for a screen height of 8 mm. The quantity of broken rice decreased whereas the total rice quantity did not vary significantly; the milled rice had a whiteness index slightly increased when compared to the reference rice.

scholarly journals Determination of optimal parboiling conditions for nigerian FARO-44 rice variety

2021 ◽  
Vol 39 (4) ◽  
pp. 1247-1254
Author(s):  
A.B. Muochebe ◽  
O.C. Nwajinka ◽  
I.E. Nwatu
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Rice Yield ◽  
Rice Variety ◽  
Milled Rice ◽  
Soaking Time ◽  
Milling Quality ◽  
Head Rice ◽  
Head Rice Yield ◽  
Soaking Temperature

Optimization study was carried out on the parboiling process variables for improving the milling quality of FARO-44 rice variety using Response Surface Methodology (RSM) in Central Composite Design (CCD). The variables studied were initial soaking temperature (IST), soaking time (SKt) and steaming time (STt) including their interactive effects.The range of the input variables studied were 70-90oC, 8-12hrs and 40-50minsfor initial soaking temperature, soaking time and steaming time respectively. For thisstudy, a total of twenty (20) randomized experimental runs comprising one (1) replicate of factorial point, one (1) replicate of axial point (alpha 2.7) and six (6) centre point in the design space. Analyses of variance (ANOVA) were performed on the experimental data sets and models were fitted for all the response variables generated. The result showed that the optimal parboiling variables were, 90 0C, 46mins and 10 hours,for initial soaking temperature, steaming time and soaking time respectively with their corresponding optimum response 58.7%, 6.7% and 58.1% for Head rice yield (based on parboiled paddy weight), breakage ratio and milled rice colour (based on illumination). The  composite desirability is 0.793 which maximized the percentage Head rice yield (HRY) and milled rice colour (MRC) but minimized the percentage Breakage Ratio (BR). Keywords: optimization, Response Surface Methodology, FARO-44, Rice,Head rice, parboiling 

Sign in / Sign up

Export Citation Format

Share Document