Transformation alimentaire du manioc = Cassava food processing

Diverses techniques autochtones pour la transformation et la préservation des aliments ont été développées et mises en pratique au cours des années par les communautés rurales. La nécessité d'améliorer les procédés de transformation traditionnels oblige à essayer de comprendre les principes scientifiques et technologiques mis en jeu. Ce travail présente une méthode d'analyse des technologies qui identifie les ressources, les opérations unitaires, les produits et les principes scientifiques et technologiques mis en oeuvre pour chaque type de transformation et examine l'ensemble en vue d'une amélioration. Des études de cas dans le domaine de la transformation du manioc sont réalisées en vue de dresser des profils technologiques qui identifient les goulots d'étranglement pour chaque type de transformation et suggèrent des procédés alternatifs pour améliorer les opérations unitaires. L'objectif visé est que ces profils technologiques facilitent l'identification des obstacles aux innovations. (Résumé d'auteur

Combination of malted cereals and cassava starch in the production of sugar syrup

The relative capacity of malted cereals and their optimum conditions of temperature and pH in the hydrolysis of starch were studied. Malted cereals prepared from rice, maize, sorghum and millet were used to degrade cassava starch to produce sugar syrup. Effect of pH and temperature on the level of dextrose equivalent produced indicated that the combination of malted maize, rice and sorghum with cassava starch at pH 5 in 0.015M citrate buffer and pH 5.5 for malted millet produced relatively high amounts of sugar at temperatures of 60oC for malted maize, millet and sorghum and 55oC for malted rice. The combination of malted rice and cassava starch produced the highest amount of sugar syrup among the various cereals studied. JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 2 No. 1 (2000) pp. 87-9

Appropriate Processing And Food Functional Properties Of Maize Flour

The physicochemical properties of whole maize flour (nDF) and dehulled-degermed maize flour (DF) were studied to be able to predict the functional properties of products derived from them. Whole milled grains produced 92% yield of flour; whilst (DF) yielded 65% net from grains.In the production of flour,degerming and dehulling effected reductions in crude protein (8.2- 7.5 %), fat (6.0-1.4 %), crude fibre (1.8-0.5 %), ash (1.5-0.2 %) ; whilst an increase in carbohydrates (74-80 %) was effected. DF showed higher water absorption capacity (197 %) than nDF (154 %) ; thus the swelling capacity of DF was about 1.5 times that of nDF. Brabender hot-paste viscometry showed that 10% total solids slurry (DF) was adequate to produce about 500 BU consistency.The mean peak hot-paste viscosity for DF and nDF were 505 BU and 370 BU respectively.Starch, fat and fibre contents were the major contributing factors in the differences in functional properties exhibited by the two types of flours. DF products would produce more sticky and pasty products than those of nDF. (Af. J. of Science and Technology: 2002 3(1): 126-131

Functional role of ascorbic acid in bread-making

The banning of bromates and the substitution of ascorbic acid as flour improver in 1997, generated a lot of controversy among bakers and flour milling industries in Ghana. This research was carried out to investigate the effects of ascorbic acid on wheat-bread characteristics. Various levels of ascorbic acid and bromate were used in the bread production to compare critical functional properties of bread. The results showed that the specific volume of the loaves increased from 2.80 cm3/g (control) to 3.86 cm3/g at ascorbic acid concentration of 250.0 mg/kg beyond which no significant increases were observed. Loaf tenderness was found to increase with increasing ascorbic acid concentration registering the least value of hardness (2.2 N) at an ascorbic acid level of 500.0 mg/kg. Capillarity, which is an inverse measure of vesicular size of the loaves, decreased with increasing loaf volume registering the least value (3.40 gWater/gLoaf) at the highest loaf volume of 481.70 cm3 at ascorbic acid level of 250.0 mg/kg. Crust thickness of the loaves also followed an inverse relation with loaf volume. The use of ascorbic acid as a flour improver was found to correlate well with the controversial potassium bromate within its accepted levels in terms of the various bread characteristics at correlation coefficient values of 0.85, 0.95, 0.99 and 0.80 for the specific volume, capillarity, tenderness, and crust thickness registered, respectively. JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 2 No. 2 (2000) pp. 10-1

The Combination of Rice Malt and Amyloglucosidase for the Production of Sugar Syrup from Cassava Flour

Hydrolysis of cassava flour by the combination of rice-malt extract (RME) and amyloglucosidase (AMG) on yield and type of sugars were investigated. RME was prepared by malting paddy rice for 10 days at 28°C and diastatic power determined. Effect of rice-malt enzyme concentration on rate of liquefaction and AMG concentration on rate of saccharification were studied. The combined effect of RME and AMG on yield of sugars was investigated. Simultaneous consideration of temperature, pH and time was studied using response surface methodology. Types of sugars present in syrups were identified and quantified by HPLC. Results indicated that the RME had a diastatic power of 91.46-degree Lintner. The highest RME concentration that could liquefy 10% w/v of cassava flour was 8% w/v within an hour. The combination of 8% w/v of RME with 300- units/ml AMG or 10% w/v of RME with 200-units/ml AMG resulted in the highest yield of sugars. Simultaneous consideration of temperature, pH and time indicated that the highest yield of sugars occurred at 60°C, pH 4.5 in 4.5 hours of liquefaction and saccharification. HPLC analysis on sugar syrup produced by RME alone, identified glucose, maltose and other sugars; but the combination of RME and AMG produced glucose and maltose only. In conclusion the combination of rice-malt extract with Amyloglucosidase under the specified conditions of temperature, pH and time could increase yields of sugars to DE 80 from cassava flour. (Af. J. of Science and Technology: 2002 3(1): 11-18