Rice Parboiling Research Articles

PARTICIPATORY IMPACT ASSESSMENT OF RICE PARBOILING VIDEOS WITH WOMEN IN BENIN

SUMMARYUsing the sustainable livelihoods framework to evaluate the impact of a farmer-to-farmer video on the improved rice parboiling technology, women in Benin rated financial, social, human, natural and physical capital stocks for the baseline year (2006) and the impact year (2009) on a 0–5 scale. Women who had watched the video and those who had not, but who lived in the same villages, perceived a significant improvement in four out of five livelihood capitals while processors in control villages did not perceive any significant change. Apart from testing the sustainable livelihoods conceptual framework as a participatory impact assessment tool for video-mediated rural learning, this study shows how farmer-to-farmer training videos helped to improve multiple livelihood assets.

Effect of rice parboiling on performance and metabolic responses in rats

This research is aimed at evaluating the effect of rice grains submitted to different processing (white or parboiling) on performance and biological responses in rat. Male Wistar rats were fed with diets containing white or parboiled rice grains of the cultivar IRGA 417. Wet and dry faecal production, fasting serum glucose concentration, serum total protein and organs' weights as liver, kidney and epididymal fat pads were not affected by processing. The animals in the treatment with parboiled rice showed higher body weight gain, feed intake, nitrogen excretion, serum triglycerides, uric acid levels and pancreas weight and lower feed conversion, faecal pH, albumin and serum HDL cholesterol, when compared with the treatment with white rice. The results obtained in this work allow the conclusion that structural change of rice components caused by parboiling results in variations in different essential body metabolic parameters, such as body weight gain, gastrointestinal function and glycaemic control.

Determinants of diffusion and adoption of improved technology for rice parboiling in Benin

The widespread use of traditional rice-parboiling methods in Benin leads to poor quality of final rice. To address this problem, the national agricultural research institute of Benin and Africa Rice Center have developed improved rice parboiling technology. An educational video developed by AfricaRice was used for it diffusion. Women have expressed high interest in the use of the technology and have reported that it helps increase the quality of their final rice despite its' relatively high cost. This paper uses the Average Treatment Effect (ATE) framework and data collected from 200 women rice parboilers in central Benin to estimate the actual and potential adoption rates of this technology and the determinants of its diffusion and adoption. 85% of the sampled women were exposed to the technology in 2008. With this incomplete diffusion, the actual adoption rate is 67%, whereas the potential adoption rate is estimated to be 75%. Being member of a parboilers association'' and Participation in video are positively associated with knowledge and adoption of this technology. This indicates that support and promotion of women parboilers associations is a means to increase technology uptake and access and video-supported training is an extension tool to promote agricultural technology awareness and adoption.

Análises quali e quantitativas de micotoxinas em águas da cadeia produtiva do arroz por CCD e CCDAE

This study validated a simple and applied method for determining mycotoxins aflatoxin B1, aflatoxin B2, ochratoxin A, zearalenone and deoxynivalenol, in water from the rice production chain. Five solvent combinations for extraction were tested, with quantification performed by TLC/HPTLC and confirmation by LC-MS/MS. Mycotoxins in water from field and rice industries were evaluated. Mycotoxin recovery levels were around 90%. Two samples from rice parboiling waste were contaminated (deoxynivalenol/aflatoxin B1, 110/9 ng mL-1; and deoxynivalenol, 100 ng mL-1). Zearalenone, deoxynivalenol and ochratoxin A (36, 30 and 28%) were carried to soaking water during parboiling.

Consumer valuation of improved rice parboiling technologies in Benin

In Benin, traditional parboiling is still widely practiced among rice processors, resulting in inferior grain quality. A new parboiler was introduced to improve the milling yield and intrinsic quality of local rice. We conducted Vickrey second price auctions to elicit rural Beninese consumers’ willingness to pay for rice obtained through the new parboiler and two locally innovated parboilers. The individual auctions were followed by a group discussion during which consensus was reached on socially acceptable prices. Relative to traditionally parboiled rice, consumers were willing to pay price premiums of 9–13% for rice obtained through a local parboiler using a container of which the bottom is a perforated metal, 27% for rice obtained through a local parboiler using wooden sticks at the bottom of the pot, and 25–34% for rice parboiled through the improved parboiler. Bids were influenced by the presentation order of the products according to perceived quality. Bids were also higher when participants had been informed on the benefits of improved parboiling techniques, which is a crucial insight for developing marketing and communication strategies for this improved quality product. Group bids were not significantly different from individual bids which suggests that the latter are within the range of socially acceptable prices defined through group consensus.

Atributos microbianos do solo após a adição de lodo anaeróbio da estação de tratamento de efluentes de parboilização do arroz

O cultivo do arroz é destaque na região Sul, com 60 % da produção total desse cereal no país. A parboilização do arroz é um tratamento hidrotérmico que cozinha parcialmente os grãos ainda em casca, melhorando seu valor nutricional. Desse processo resulta um efluente rico em matéria orgânica e nutrientes, que pode ser utilizado como adubo orgânico na agricultura. O presente trabalho objetivou avaliar a qualidade de um solo com base nas alterações de alguns atributos microbianos decorrentes do acréscimo de lodo anaeróbio da estação de tratamento de efluentes de parboilização do arroz. Foram realizados dois experimentos, sendo o primeiro em casa de vegetação, por meio do cultivo de milho em um Argissolo acrescido de lodo (base seca) nas doses de 2,15; 4,31; 8,62; 12,93; e 17,24 g kg-1, em que foram analisados os teores de C orgânico total (COT) e N total (NT)do solo e da biomassa microbiana. O segundo foi desenvolvido em laboratório, utilizando-se vasos respirométricos, com o mesmo solo e tratamentos do experimento anterior, onde se analisou a atividade da microbiota do solo pela determinação da respiração basal. Como tratamentos controle foram utilizados: solo sem adubação e solo adubado com NPK. Os tratamentos foram dispostos em delineamento completamente casualizado com quatro repetições. A atividade microbiana do solo e o C (CM) e N (NM) da biomassa microbiana aumentaram com as doses de lodo e proporcionaram diminuição no quociente metabólico do solo. A aplicação do lodo não alterou as relações COT/NT, CM/NM, CM/COT e NM/NT, em comparação com o tratamento NPK. A aplicação do lodo ao solo aumentou os teores de COT e causou diminuição nos teores de N mineral (NH4+ e NO3-), quando comparados aos do tratamento NPK. O lodo originado da parboilização do arroz pode ser aplicado ao solo, em doses recomendadas, com benefícios à atividade e à biomassa microbiana.

EFFECT OF ARTISANAL PARBOILING METHODS ON MILLING YIELD AND COOKED RICE TEXTURAL CHARACTERISTICS

ABSTRACT One of the main objectives of artisanal rice parboiling is to reduce the levels of broken grains (brokens) on milling. Rice samples that had been parboiled using different regimes of soaking temperatures and steaming times were analyzed for their physical properties and cooked rice textures. It was established that inappropriate soaking and steaming regimes resulted in greater levels of brokens than raw‐milled paddy. Consequently, in artisanal parboiling, the initial soaking temperature should be about 90C and the steaming time should be more than 8 min, ideally, about 12 min. On cooking, more severely parboiled rice samples had firmer textures than mildly parboiled samples. The commercially parboiled sample and the more severely laboratory‐parboiled samples required a rice‐to‐water ratio of 1:3, while the raw‐milled sample and the mildly parboiled ones required a 1:2½ rice‐to‐water ratio for optimum cooking. PRACTICAL APPLICATIONSArtisanal rice parboiling is carried out mainly to reduce the levels of broken grains and increase the yield of milled rice in many countries. If this is carried out very well, there are economic benefits as more rice of better quality is available to be sold. This study provides information on optimum processing conditions, i.e., initial soaking temperature of about 90C and a steaming time of about 12 min. The study also provides recommendations on optimum cooking conditions, i.e., rice‐to‐water ratio, for the variably parboiled rice samples.

Comparing Farmer-to-Farmer Video with Workshops to Train Rural Women in Improved Rice Parboiling in Central Benin

This article deals with the comparison of the conventional training based on two day community workshops and farmer-to-farmer video used as methodologies for the dissemination of improved rice parboiling process in Benin. From November 2007 to May 2008, we interviewed 160 women and 17 women groups who had been exposed to both, one or other of the methodologies. Data were analysed using ANOVA and logistic binomial regressions. Video reached more women (74%) than conventional training (27%). The conventional training was biased by participant selection, stakes in per diem payment and monopoly by the elite class. Video helped to overcome local power structures and reduced conflict at the community level. More than 95% of those who watched the video adopted drying their rice on tarpaulins and removed their shoes before stirring the rice, compared to about 50% of those who received traditional training and did not watch the video. Group use of the improved equipment was significantly higher for those who watched the video (p< 0.05). By 2009, the various rice videos had been translated into over 30 African languages by Africa Rice Centre (Africa Rice) partners and involved 500 organizations and over 130,000 farmers. This study helps to give a better understanding of the role that farmer-to-farmer video could play in agricultural extension. This comparative analysis is an opportunity for a better understanding of how farmer-to-farmer video improves farmers’ practices and attitudes in agricultural technology dissemination.

The power of video to trigger innovation: rice processing in central Benin

Understanding how to stimulate innovation among farmers and processors is crucial for attaining sustainable agriculture. To explore how farmer-to-farmer learning videos and training workshops changed women's rice processing practices, we interviewed 200 women and 17 women's groups in 20 villages in central Benin, including four villages which had received no intervention at all. Video on improved rice parboiling (a process whereby paddy is pre-cooked by steam without touching the water) had reached three times more women (74%) than hands-on training workshops organized by local NGOs and contributed to more equitable knowledge sharing within communities. In the villages where the NGOs had shown the video, 24% of the women started to use the improved parboiler equipment individually and 56% collectively within their group, compared to none in the control villages. About 92% of the women who attended both video and workshops developed creative solutions based on the idea of pre-cooking paddy with steam, compared to 72% for those who learned only through video. Fewer women innovated after learning through workshops only (19%) and after being informed by their peers (15%). Video watching also made women pay attention to reducing the loss of steam and to use local resources innovatively to conserve energy. More than 90% of the women who watched the video improved the quality of their parboiled rice, for example, by removing dirt, washing rice several times and drying rice on tarpaulins. Workshops stimulated innovations less than video did. Farmer-to-farmer video has great potential to enhance sustainable agriculture by encouraging local innovations.

Power Ultrasound Enhanced One-Step Soaking and Gelatinization for Rough Rice Parboiling

The conventional parboiling of rough rice is a lengthy process that takes 24-28 h to complete. It would be beneficial to the industry if the processing time could be reduced. The objective of this study was to develop an ultrasound based one-step protocol for soaking and gelatinization during rice parboiling. The gelatinization temperature was measured by alkali (KOH) degradation and found to be 72°C. The combined soaking and gelatinization was conducted at 75°C with or without sonication (control). The moisture content during soaking was measured following the AOAC oven method. Starch gelatinization was evaluated by differential scanning calorimetry (DSC). Moisture content after 3 h of ultrasonic soaking (48.6% w.b.) was equivalent to 10 h conventional soaking (44.0% w.b.), indicating that ultrasound reduced some 70% of soaking time. DSC showed that the retrogradation peaks (Tr) values for 80°C soaking and ultrasonic horn (US.horn) soaking, which were accomplished during 4 h, was 53.8°C and 53.5°C, respectively. This showed that US.horn soaked samples at 75°C partially gelatinized at the same time frame (4 h) with the samples soaked at 80°C. This study showed the feasibility of ultrasound to enhance the rice parboiling by reducing processing time.

Caracterização da fração protéica da cianobactéria Aphanothece Microscopica Nägeli cultivada no efluente da parboilização do arroz

O objetivo do presente trabalho foi avaliar a fracao proteica da cianobacteria Aphanothece microscopica Nageli cultivada no efluente da parboilizacao do arroz quando submetida a diferentes condicoes de secagem. A producao da biomassa foi realizada a partir da agua residuaria do processo de parboilizacao do arroz em bioreatores de coluna de bolhas. A biomassa foi separada do efluente por centrifugacao e desidratada em secador descontinuo de bandejas nas condicoes de 40, 50 e 60oC e espessuras de bandejas de 5 e 7 mm. O comportamento eletroforetico das proteinas da biomassa foi analisado por eletroforese em gel de poliacrilamamida na presenca de dodecil sulfato de sodio (SDS-PAGE) e apresentou bandas com peso molecular de 15 kDa a 62,5 kDa. O perfil aminoacidico mostrou teores superiores aos recomendados pelo padrao FAO, com excecao dos aminoacidos lisina e dos sulfurados (MET+CYS). A caracterizacao funcional, expressa em termos de solubilidade e capacidade emulsificante, demonstrou a influencia da condicao de secagem na funcionalidade proteica da biomassa.

Effect of Processing Conditions on Color Change of Brown and Milled Parboiled Rice

ABSTRACTThe effects of the soaking and steaming steps in rice parboiling on color changes and the levels of reducing sugars in rice were studied. Brown rice was soaked to different moisture contents (MC, 15, 20, 25, and 30%). The L*, a*, b* color parameters of the Commission Internationale de L'Eclairage (CIE 1976) indicated that during soaking, red and yellow bran pigments diffused from the bran into the endosperm. The increase in brightness brought about by soaking rice was attributed to migration of rice compounds (e.g., lipids) from the inner to the outer bran layers (rice surface). The levels of reducing sugars in brown and milled soaked rice samples increased with increasing brown rice MC after soaking. The total color difference (ΔE) between parboiled and nonparboiled rice increased with increasing MC after soaking and depended on the intensity of the steaming conditions as reflected in the degree of starch gelatinization. Parboiling affected yellowness more than redness in mildly steamed brown rice and most in intermediately steamed brown rice. Severe steaming of brown rice affected redness more than yellowness. All three parboiling conditions equally affected the yellow color more than the red color in milled rice. Linear regression analyses indicated that parboiling had a larger effect on ΔE of milled parboiled rice than of brown parboiled rice. Furthermore, the linear relationship between the level of gelatinized starch and ΔE of the milled parboiled rice samples showed that both parameters are indicators for the degree of parboiling. Reducing sugars were formed and lost during steaming, suggesting Maillard reactions during steaming.

Starch gelatinization and amylose–lipid interactions during rice parboiling investigated by temperature resolved wide angle X-ray scattering and differential scanning calorimetry

Starch gelatinization and formation of crystalline amylose–lipid complexes during the heat/moisture treatment step in rice parboiling were studied with temperature resolved wide angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) using flour from Puntal (24% apparent amylose) and Jacinto (12% apparent amylose) rice samples [66, 40 or 25% moisture content (mc)]. Temperature resolved WAXS showed that the crystallinity index (CI, i.e. the relative amount of A-type crystals) of non-parboiled rice flours at 66% mc, monotonically decreased between ∼65 °C (Puntal) and ∼70 °C (Jacinto) and ∼90 °C (both Puntal and Jacinto). These temperatures were in agreement with the respective onset and conclusion temperatures of the M 1 endotherm measured by DSC. At 40% mc, the CI decreased monotonically from ∼65 °C (Puntal) and ∼70 °C (Jacinto) until ∼105 °C. In DSC both M 1 and M 2 endotherms were present. The conclusion temperature of the M 2 endotherm was higher than 105 °C. At 25% mc, the CI decreased very gradually and A-type crystals were no longer present at ∼145 °C. Under these conditions, no DSC endotherms were detected. No type II amylose–lipid complexes were formed during heating at 66% mc. In contrast, at 40 and 25% mc, V h-type crystals were formed from ∼100 and ∼130 °C, respectively. Non-parboiled white rice flour had a strong A-type pattern. Mildly parboiled rice had a clear A-type, with a weak V h-type and B-type pattern. Severe parboiling resulted in partially crystalline systems with superimposed A-type, V h-type and B-type crystals. It was concluded that the rice variety, the combination of mc and the moisture distribution in the rice kernel and the temperature during parboiling all impact the level and the types of crystals in the parboiled rice.

13C NMR research on the kerogens of Jurassic source rocks of the northern edge of the Qaidam Basin : Peng, L. et al. Shiyou Xuebao, 2002, 23, (2), 34–37. (In Chinese)

In order to produce briquettes that meet the needs of consumers, different combinations of raw materials and methods were used to produce rice-husk briquettes using a locally fabricated multi-piston press. Particle size, husk–bran ratio, drying method, and water temperature for briquetting were the main influencers of the hardness of rice-husk briquettes at constant pressure. The briquetting process increased the density of rice husk from 120 to 600 kg/m3. The average time for making nine briquettes (loading, compressing, ejection, and transfer to drying tray) was 3.6 min (150 briquettes/h) using the locally fabricated piston press. Briquettes produced using fine particles (< 0.3 mm), hot (97 °C) water, husk–bran ratios of 0:1, 1:2, 1:1, 1:0, 2:1, and dried in the sun for 21 days had mean hardness values of 132, 89, 76, 62, and 31 N. Four types of fuel briquettes were produced: husk–bran–palm press fiber (HBF), husk–bran–palm press sludge (HBS), husk–bran only (HBO), and husk–biochar–clay (HBC). The four types of briquettes recorded shorter start-up time (< 5 min) than charcoal (10 min). The average flame temperatures of HBF, HBS, and HBO during the first 20 min were higher (898 °C) than the average temperature of charcoal (546 °C). The characteristics of HBF and HBO briquettes provide the best option for consumers, especially those in the rice parboiling industry, as these briquettes recorded the following values for hardness (170 and 101 N, respectively), start-up time (2 and 3 min), burning rate (126 and 145 g/min), specific fuel consumption (121 and 136 g/l), and flame temperature (684 °C and 728 °C). It was concluded that briquettes could be produced from rice-milling by-products with acceptable quality using this affordable technology.

MODEL APPLICATION: HYDRATION AND GELATINIZATION DURING RICE PARBOILING

The rate of water absorption of a local rough rice variety at temperatures below and above the corresponding gelatinization temperature was investigated. A mathematical model that describes water diffusion and gelatinization within the grain, was used to simulate rice parboiling. The data were processed using a nonlinear regression procedure to calculate the diffusion coefficients and reaction rate constants in the temperature range 35–95°C. Both coefficients follow an Arrhenius temperature dependency with a break point at 77°C, where rapid gelatinization of rice begins. From the comparison between the activation energies for diffusion and reaction it is concluded that the parboiling process is limited by the reaction of starch with water below 77°C and by diffusion of water above 77°C.

IMPROVEMENT OF RICE PARBOILING PROCESS

IMPROVEMENT OF RICE PARBOILING PROCESS

Quality changes in HTST processing of rice parboiling

AbstractPaddy soaked to saturation level, when treated at a high temperature for a short time in a mechanical sand roaster is parboiled and dried in a single pass of 47 s duration. The extent of drying depends on the sand temperature. The sand temperature is critical as it decides the associated quality changes in the milled rice. Even at a sand temperature of 125°C, paddy could fully be parboiled but with mild effect. The parboiling became severe at high temperatures. Roasting the soaked paddy at 250°C, reduced the cooking time of the resultant milled rice. A sand temperature of 125–150°C was considered suitable for producing normal parboiled rice by this technique.

Quality Aspects of Microwave-Vacuum-Dried Parboiled Rice

One of the consequences of the rice parboiling process is an increase of the moisture content of the rice to approximately 35% (w.b.). It is essential to reduce the moisture of the parboiled rice before it can be stored or milled. The proper drying of parboiled rice thus becomes an important step. This study evaluates the combined use of microwave energy and an evacuated atmosphere to dry parboiled rice on its quality. The effect of two soaking times and two steaming times combined with two vacuum levels and three microwave power levels were tested. Drying times were adjusted to achieve target final moisture levels of 14%, 16%, and 18% (w.b.), respectively. The results showed that it was possible to dry parboiled rice using the microwave-vacuum method and the quality of the finished product was comparable to that produced by conventional methods. It was concluded that the whole kernel yield was reduced with increased microwave power, the effect being more marked at higher vacuum levels. A drop of 5% in whole kernel yield was seen at the lower vacuum level (absolute pressure ==53.3 kPa), this increased to 10% when the vacuum level was higher (absolute pressure = 6.67 kPa). The major factor in the reduction of yields appeared to be the increase of the drying rate as the microwave power and vacuum were increased. Results pertaining to color indicated that the independent variables did not affect it. The percentage of completely gelatinized kernels was found to decrease for increase of microwave power. At the 53.3 kPa level of absolute pressure, the percent gelatinized kernels dropped approximately 8% when the microwave power was increased from 600 W to 1800 W. When the pressure level was decreased to 6.67 kPa (vacuum increased), the corresponding drop in percent gelatinized kernels increased to nearly 14%. The steaming treatment tended to increase the deformity of the parboiled rice kernels.

DRYING IN COMMERCIAL RICE PARBOILING PLANTS

ABSTRACT Two rotary dryers were replaced by one three-stage concurrent flow(CCF) dryer in a commercial rice parboiling plant. Utilization of the CCF dryer has resulted in a 34 percent savings in fuel energy and a significantly higher quality of the final product. Additional advantages include space, power and labor savings.

Parboiled Rice Quality as Affected by the Level and Distribution of Moisture after the Soaking Process

ABSTRACT A study of the soaking process in rice parboiling was conducted to evaluate the effects of level and distribution of moisture after soaking on grain quality. Saturn variety medium grain rice was subjected to dif-ferent soaking times with and without pressure, steaming times, and periods of partial equilibration after soaking. The parboiled rice was processed and analyzed for yields, translucency and color. Photomicrographic examina-tions were also performed. Grain moisture levels as low as 23.5 percent (wet basis) after soaking were found adequate to obtain high head yields. Pressure soaking considerably reduced soaking times, and the partial equilibration of the grains after the soaking stage was observed to improve the percent whole grain, grain translucency and decrease deformity, while increasing the color of the product. Photomicrographs il-lustrated the grain structure.