GRADE QUALITY OF PARBOILED MILLED DOMESTIC AND IMPORTED RICE VARIETIES SOLD IN SOUTH-EAST NIGERIA

The objective of this work was to grade the domestic rice varieties and classify them according to Recommended Model Grading System for Marketing Rice in International Trade. Eighteen (18) domestic rice varieties were collected from Enugu (4), Ebonyi (7) and Anambra State (7). Three (3) imported rice varieties coded Ip1, Ip2, and Ip3 were purchased from Ogige market in Nsukka LGA of Enugu state, Nigeria and served as controls. The rice varieties were cleaned manually by winnowing, graded and classified according to Recommended Model Grading System for Marketing Rice in International Trade. Domestic rice varieties from Enugu state were of grade 1 quality excluding Fortin 16 (old variety). Faro 40 (72.33) and Taraba rice (77.33) from Anambra state were of grade 2 quality while R-Bus (81.33), Igboukwu rice (86.67), Aguleri rice (83.67) and B-G (84.67) were of grade 1 quality. Geshua (68.33) from Ebonyi state was of grade 2 quality while Afikpo-Mas (87.33), Abakiliki-Mas (84.33), R-8 (89.33) and 306 (82.67) were of grade 1 quality. All the imported rice varieties (control samples) were of premium quality.  Omor-Mas (95.33), Akpujie (95.67), kpurukpuru (98.00), and Fortin 16 (old variety) (95.00) were of premium quality and did not differ from the imported rice varieties in grade quality

Physical and Pasting Properties of ‘Ofada’ Rice (Oryza sativa L.) Varieties

ABSTRACTIn this study, grain physical and pasting properties of ofada rice cultivated in South-West Nigeria was evaluated using Standard Evaluation System (SES) for rice with the aim of providing basic information for brand development and utilization of ofada in the development of novel food products. Results showed that size and shape of ofada rice ranged from 5.9 to 9.0mm and 1.8 to 3.0mm respectively. The 1000-grain weight was between 24.0 to 31.0g. Percentage hull was significantly different among the cultivars, ranging from 16 to 21. Peak viscosity ranged between 112.7 and 152.8 BU, minimum, setback and final viscosities varied from 80.3 to 117.2 BU, 104.0 to 143.3BU and 190.8 and 232.3 BU respectively. Gelatinization temperature was not significantly different and varied between 64.1 to 64.7°C. Significant difference (p<5%) was observed among the samples in terms of minimum setback and final viscosities respectively. Significant negative association was observed between kernel length and gelatinization temperature (r=– 0.65), setback and gelatinization temperature (r=– 67) while positive correlation was observed between breakdown viscosity and peak viscosity (r=0.86). The good pasting behaviour makes ofada flour good material for the production of stiff dough products, better palatability and water binding capacity while physical qualities give ofada an advantage during milling. This attributes could be exploited for the development of new varieties and utilization in food development of the ofada rice value-chain

Valuation of rice postharvest losses in Sub-Saharan Africa and its mitigation strategies

Data on rice harvest and postharvest loss in Sub-Sahara Africa (SSA) is scanty making it difficult for stakeholders to appreciate the loss and set priority areas for loss reduction along the value chain. To address this problem, a protocol was developed and validated for postharvest loss (PHL) quantification in SSA. Quantitative losses at each segment were determined by field measurements. Interactive effect of origin of rice (domestic versus imported) and type of processing (white versus parboiled milled) on rice price in 33 markets in Africa was used to estimate qualitative loss for both white and parboiled milled rice. Total PHL for rice in SSA in 2018 is estimated at about US$ 10.24 billion, representing 47.63% of the expected total production. The highest loss recorded was quantitative loss before and during harvesting, followed by qualitative loss along the entire value chain, quantitative loss during milling, parboiling, threshing in that order, with the lowest being quantitative loss during drying. Priority areas to be targeted for PHL reduction in SSA and some loss mitigation tools and technologies piloted or suitable for SSA are proposed

Starch fraction profiles of milled, nonparboiled rice varieties from Nigeria

This study determined the levels of nutritionally important starch fractions in selected milled, nonparboiled rice cultivated in Nigeria. Five improved varieties (FARO 52, FARO 57, FARO 44, FARO 60 and FARO 61) and four local varieties (Kwandala, Yardass, Jeep and Jamila) were evaluated. There were significant differences in starch fractions among varieties. Resistant starch (RS) ranged between 1.43% and 3.13%. Rapidly digestible starch (RDS) was lowest in Jamila (27.70%) and highest in FARO 61 (39.26%). Generally, the local varieties had significant higher RS (2.71%) with a lower RDS (32.82%) compared with improved varieties (RS; 1.88% and RDS; 36.07%). RS was inversely related to RDS and starch digestion index (SDI). The SDI had a highly significant positive correlation with RDS (r = 0.879, P < 0.01). These results highlight the need for further work in the identification of milled, nonparboiled rice varieties with less rapid digestion for its associated health benefits to consumers

Development, nutritional evaluation and optimization of instant weaning porridge from broken rice fractions and bambara groundnut (Vigna subterranea (L.) Verdc) blends

In this study, different instant porridges were formulated from broken fractions of rice blended with bambara groundnut flour through extrusion cooking. Response Surface Methodology (RSM) and Central Composite Rotatable Design (CCRD) were used to optimize the production variables. The objective was to locate the best combination of barrel temperature (X1), feed moisture composition (X2) and feed bambara groundnut composition (X3) that will give optimum porridge having high nutrient density. Regression models and response surface plots were developed and their adequacy tested by examining coefficient of determination (R2, R2adjusted), analysis of variance (ANOVA), lack-of-fit test and analysis of residual. ANOVA analysis indicated significant (p ≤ 0.05) effects of process variables on the nutritional quality of the porridge. Models indicated a non-significant lack-of-fit. Applying the desirability function, the best optimum levels for independent variables (X1, X2 and X3) for the production of instant porridge from rice-bambara groundnut formulations were found to be 120oC barrel temperature, 20 g/100 g feed moisture content and 22.40 g/100 g feed bamabara groundnut composition. At this combinations, optimum moisture, fat, protein, fibre, carbohydrate, and calorie value were 0.89%, 0.73%, 21.66%, 0.89%, 1.34%, 77.81 g/100 g and 394.33 kcal/ 100 g respectively, while optimum Mg, Mn, Fe, Cu, Zn and Ca were 13.82, 5.14, 12.12, 3.67, 5.13 and 25.81 mg/100 g respectively. The optimum product contained high protein and mineral and could be said to appropriate for weaning to reduce protein-energy malnutrition in Africa.Keywords: Rice, bambara groundnut, extrusion, process optimization, response surface methodolog

Comparative studies of the effect of processing conditions on cooking and sensory properties of selected rice varieties

Cooking and sensory properties of rice varieties are important quality indices that influence market value and consumer acceptability. The objective of this study was to evaluate the effect of processing conditions on cooking and sensory properties of five rice varieties grown in Nigeria. The rice varieties; FARO 44, FARO 52, FARO 60, FARO 61 and NERICA 8, were processed using four processing parameters at varying conditions [soaking temperature (65-75°C), soaking time (10-16 h), steaming time (20 – 30 min) and paddy moisture content (12-16%)] using response surface methodology. The effect of processing conditions on cooking properties (cooking time, water uptake ratio and elongation ratio) was analyzed using standard procedures. Quantitative descriptive analysis and principal component analysis were used to describe eleven sensory characteristics (uniform appearance, black specks, whitish appearance, yellow colour, brown colour, creamy flavour, typical rice odour, sweet taste, sticky texture, grainy texture and hard texture) of the rice varieties. The cooking time, elongation ratio and water uptake ratio ranged from 12.75 to 51.58 min, 0.91 to 1.94 and 2.21 to 4.95, respectively. The cooking properties differed with respect to rice varieties and processing conditions. The shortest cooking time, longest elongation ratio and highest water uptake ratio varied from one variety to another. It was observed that NERICA 8 had the shortest cooking time (12.75 min) at 65ºC soaking temperature, 16 h soaking time, 20 min steaming time and 16% paddy moisture content while FARO 52 had the highest water uptake ratio (4.95) at 65ºC soaking temperature, 16 h soaking time, 20 min steaming time and 16% paddy moisture content. The maximum elongation ratio (1.94) was observed at 65ºC soaking temperature, 16 h soaking time, 30 min steaming time and 12% paddy moisture content in FARO 60. The sensory properties of the rice varieties were generally characterised as having uniform appearance, whitish appearance, sweet taste, creamy flavour and rice odour. The information on the cooking and sensory properties of the rice varieties would assist rice processors and consumers in selecting rice variety of choice

Influence of Extrusion Conditions on Nutritional Composition of Rice-Bambara Groundnut Complimentary Foods

In this study, multivariate analysis of the relationship between extruder barrel temperatures (100-140oC), initial feed moisture level (15-25%) and bambara groundnut flour (8-24%) content during twin-screw extrusion of rice-bambara groundnut blends for the production of complimentary food was investigated. Response surface methodology (RSM) and central composite experimental design (CCD) was used for the study. Twenty different blends were formulated based on CCD and extruded in a twin-screw extruder. Extruded samples were analyzed for nutritional quality using standard procedures and data fitted into a regression model. Results indicated significant variation among samples due to the process variability, with protein ranging between 16.99 and 27.36%, calorie value 391.14 and 397.99kcal/100g and Fe 10.1 and 13.02 mg/g sample. The fitted models for the prediction of linear, square and interaction relationships between the process and dependent variables were also significant (p≤0.05), adjusted coefficient of determinations (R2adjusted) > 90% and non-significant (p ≤ 0.05) lack-of-fit. Optimum process conditions of 120oC barrel temperature, 20g water/100g flour, and 22.4g bambara groundnut/100g flour were found to produce extruded complimentary foods having 21.66% protein, 394.33kcal/100g calorie, 1.34% fibre, 12.12mg/100g Fe and 25.81mg/100g Ca with a combined desirability function of 0.9102. The high protein of over 20% and 394.33kcal/100g calorie values are within the recommended values for normal growth and development of weaning and school children and therefore could be recommended for mitigating protein-energy malnutrition in developing countries, while the fitted models could be used in engineering modeling of extruder for food processing and new product development

Statistical Modeling and Optimization of Processing Conditions of Twin-Screw Extruded Rice-Legume Instant Breakfast Gruel

New product development using extrusion cooking, low cost raw materials to meet consumer preference for convenient products are increasingly becoming popular in the field of Food Engineering. The raw materials are usually complex biological materials that may undergo different transformations due to high temperature, pressure and shear in the extruder. This study investigated the effects of extrusion cooking conditions on the physical and functional characteristics of rice-cowpea breakfast gruel and modeled the relationship between the input and output variables for optimum product quality. Fifteen composite blends based on central composite rotatable design (CCRD) in a response surface methodology (RSM) were formulated and extruded at different extrusion conditions of barrel temperature, feed moisture content and rice-legume ratio in the feeds. Data generated from the analysis of the extruded products were fitted to second-order polynomial equation with optimal point located. Results showed significant (p≤0.05) variation in physical and functional characteristics of the extrudates studied. The optimal points for process conditions were obtained at 120oC barrel temperature, 20% feed moisture and 24% feed cowpea composition respectively at desirability value of 0.907, for product quality of 126.14 (expansion index), 0.214g/cm3 (bulk density), 6.83(water absorption index), 8.46 (water solubility index), 99.02% (dispersibility) and viscosity of 12.83Nm2. Fitted models indicated significant coefficients with adjusted R2 of 94.70%, 88.00%, 99.70%, 99.10%, 95.90% and 83.00% respectively for expansion index, bulk density, water absorption and solubility indices, dispersibility and viscosity, while the lack-of-fit test p-values were 0.608, 0.485, 0.513, 0.505, 0.297 and 0.200 respectively. It was concluded that the fitted models could be used to adequately represent the experimental data in their natural state and when extrusion variables are carefully selected, rice-cowpea blends could produce quality gruel of optimum quality for breakfast or complimentary feeding

Processing characteristics, grain quality and end-use quality of hybrids and common improved rice (Oryza sativa L.) varieties from Nigeria

Grain quality characteristics of hybrids and some common improved rice (CIR) varieties were evaluated using standard evaluation techniques as a strategy for recommendation for release and use in various rice-based products. Paddy length varied between 8.22 to 10.53 mm in the hybrid and 9.28 to 9.70 mm in the CIR while paddy shape ranged from 3.56 to 4.94 and 3.95 – 4.49 in hybrids and CIR varieties respectively. Hybrids were lighter and less yellow than the improved inbred samples. Total milling recovery (TMR) was lower in hybrid than CIR and there was significantly (p &lt; 0.05) outstanding performance in terms of milling recovery of FARO 52 and FARO 60 over the hybrids. There was no significant difference (p &lt; 0.05) between the hybrid and CIR in terms of grain elongation ratio, but there was marginal difference in terms of elongation index. Water uptake ratio significantly (p &lt; 0.05) varied between 5.54 and 6.83 in CIR and 5.37 to 6.96 among the hybrids. Hybrids indicated lower cooking time than CIR. Correlation study of the relationship between physical and milling qualities indicated significantly (p &lt; 0.05) high negative correlation (r2 = –0.93) between TMR and percentage hull, while head rice recovery (HRR) compared with broken rice percentage indicated negative significant (p &lt; 0.05) correlation (r2 = –0.96). Lowest paste viscosity (431.17 cP) was observed in NG05 and highest (480.42 cP) in NG03, while 382.04 cP and 511.63 cP was the least and highest values in CIR lines respectively. This result will facilitate the adoption of hybrid rice in Nigeria and improvement of its marketability and application in different food formulations.Keywords: Rice, hybrids, milling quality, cooking quality, pastin