Effect of Drying Method and Variety on Quality of Cassava Starch Extracts

Cassava tubers are main sources of calories and dietary fibre for Nigerians. Cassava tubers are highly perishable and need to be processed immediately after harvest. Cassava can be used for human consumption, livestock feed or industrial purposes. Cassava starch is one of the main industrial products of cassava processing. The long drying times for cassava starch production during sun drying have necessitated the need for alternative drying methods. However, the quality of the starch obtained from these alternative drying methods needs to be investigated. Starch was produced from four different varieties (TME 1, TMS 30572, TMS 01/1235 and TMS 01/1181) of cassava using two drying methods (sun and oven drying at 40oC). The physical (yield and moisture content), functional (water binding capacity, swelling power and solubility) and pasting properties of the starch produced were investigated. The moisture content varied from 9.24 to 10.48%, with oven dried TME 1 having the lowest values and sun dried TMS 01/1181 having the highest value. The yield of starch obtained from drying the four varieties using the two drying methods increased from 458.5 to 687.2g per kg of cassava tuber. The water binding capacity, swelling power and solubility increased from 97.97 to 99.83 g water/g sample, 11.69–14.19 g/ml and 10.20 – 12.96% (g soluble solids/ g DM of whole starch sample) respectively, for the different varieties dried using the two drying methods. Peak viscosity, trough, break down, final viscosity, peak time and pasting temperature values for the four cassava varieties were in the range of 335.76–619.89 RVU, 135.67–192.35 RVU, 199.38–433.99 RVU, 196.01–257.72 RVU, 3.23–3.91 min and 70.05–72.95oC, respectively for the two drying methods. The values obtained from the cassava varieties considered were generally significantly different (except colour) which shows significant effect of cassava variety used on starch properties. Also, cassava starch samples dried at lower temperature have better functional and pasting properties. This indicates that alternative drying methods should be used at temperatures lower than 40oC in order to obtain products of high quality.Key words: Physico-chemical properties, Drying, Cassava, variet

Nutritional and sensory qualities of soymilk kunnu blends

Kunnu, a beverage popular among the Northern Nigerians has a low protein value because it is made from cereals. This may  have a negative effect on the nutritional status of the people who drink it, especially on the growth rate of infants who are given kunnu as a weaning drink. This is because protein is an essential component of the balanced diet required for growth.  Research work carried out on the improvement of the nutritional value of cereals, shows that the fortification of  carbohydrate-rich foods with protein-rich foods improves its nutritious value. As a result of this, a study was carried out to fortify kunnu with soymilk and the effect on its nutritional and sensory properties was evaluated. Kunnu and soymilk were  prepared and it was fortified with soymilk in the ratio 1:1, 2:1, 3:1 and 4:1, and the proximate composition (protein, fat, ash and moisture content), chemical  composition (pH, specific gravity and sedimentation rate) and mineral content (calcium,  magnesium, phosphorus and iron content) were determined. The pH,  protein and mineral content increased as the amount of soymilk added. The pH value ranged from 4.8 to 4.3, while the protein content increased from 2.35 to 2.45%. The calcium and magnesium content also increased from 0.08 to 0.15% and 0.18 to 0.29% respectively. The fat and ash content,  however, decreased respectively from 2.8 to 2.0, and 0.91 to 0.891 with an increase in addition of soymilk. The proximate, chemical and mineral content were significantly different at P < 0.05 while the sensory properties were not significantly different at the same level. The sensory properties (colour, taste, texture, flavor and general acceptability) were, however, observed to decrease with the increase in fortification level of soymilk. The results obtained show that the fortification of  kunnu with  soymilk will result in a more nutritious beverage, but it may have a low level of acceptance with the local populace.Keywords: fortification, kunnu, soymilk, blendsLe Kunnu, une boisson populaire chez les Nigérians du Nord, a une basse valeur en protéines parce qu’il est fabriqué à partir de céréales. Ceci peut avoir un effet  négatif sur l’état nutritionnel des personnes qui le boivent. Il peut avoir un effet négatif surtout sur le taux de croissance des enfants en bas âge à qui l’on donne du kunnu comme boisson de sevrage, étant donné qu’une protéine est une composante essentielle d’un régime alimentaire équilibré requis pour la croissance. Des travaux de recherche menés sur l’amélioration de la valeur nutritive des céréales montrent que la fortification d’aliments riches en  hydrates de carbone par des aliments riches en protéines améliore sa valeur nutritive. Comme résultat de ceci, une étude a été menée en vue de fortifier le kunnu avec du lait de soja et l’effet sur ses propriétés nutritives et sensorielles a été évalué. Le kunnu et le lait de soja ont été préparés et le kunnu a été fortifié avec du lait de soja dans la proportion 1:1, 2:1, 3:1 et  4:1. La composition rapprochée (la teneur en protéines, graisses, cendre et humidité), la composition chimique (pH, gravité spécifique et taux de sédimentation) et la teneur en minéraux (calcium, magnésium, phosphore et fer) ont été déterminées. La teneur en pH, en protéines et en minéraux augmentait au fur et à mesure que la quantité de lait de soja augmentait. La valeur du pH se situait entre 4,8 et 4,3, tandis que la teneur en protéines augmentait de 2,35 à 2,45%. La teneur en calcium et en magnésium a également augmenté de 0,08 à 0,15% et de 0,18 à 0,29%  respectivement. Par contre, les matières grasses et la teneur en cendre ont baissé de 2,8 à 2,0, et de 0,91 à 0,891 avec une augmentation en plus du lait de soja. Les teneurs  rapprochées, en matières chimiques et minérales, étaient très différentes à P < 0,05 tandis que les propriétés sensorielles  n’étaient pas très différentes au  même niveau. Cependant, il a été observé que les propriétés sensorielles (couleur, goût,  texture, saveur et acceptabilité générale) baissent avec l’augmentation du niveau de fortification par du lait de soja. Les  résultats obtenus montrent que la fortification du kunnu par du lait de soja aura comme résultat une boisson plus nutritive,  mais qui peut avoir un niveau insuffisant d’acceptation auprès de la population locale. Mots-clés: fortification, kunnu, lait de soja, mélanges 

Pretreatment effect on sun and solar drying of carrot slices

Carrot slices pretreated (water and steam blanching, addition of ascorbic acid) and untreated carrot were dried in the sun and in a solar dryer. The drying time for pretreated carrot slices was shorter than untreated. Four mathematical models were fitted to the experimental data. Results obtained from regression analysis of experimental data shows that the Page model represents drying characteristics better than other models. The effective moisture diffusivity values ranged from 2.91 x 10-10 m2s-1 to 3.74 x 10-10 m2s-1 and 3.32 x 10-10 m2s-1to 5.01 x 10-10 m2s-1 for samples dried in sun and solar respectively.Keywords: Sun-drying; Solar-drying; ModellingJournal of Applied Science, Engineering and Technology, 7 Volume 1

Effect of Drying Method on Quality of Tapioca from Different Varieties of Cassava (Manihot esculenta)

Some physical, functional and pasting properties of tapioca produced from different varieties of cassava using sun and oven drying methods were studied. The effect of drying method, rather than variety, was found to be more significant on the functional properties considered. The water binding capacity, swelling power and solubility of ovendried cassava increased from 82.93 to 84.39 g water/g sample, 12.15 to 12.78 g/ml and 11.36 to 11.67 respectively. The values for the sun-dried cassava varieties varied from 82.79 to 84.30 g water/g sample, 12.10 to 12.64 g/ml and 11.09 to 11.45 respectively and were generally lower than that of oven-dried samples. For both drying methods, TMS 01/1235 had the highest pasting values while TME 1 had the lowest values. The peak viscosity, trough and breakdown viscosity increased from 230.09 to 434.14 RVU, 163.23 to 222.03 RVU, 41.06 to 221.78 RVU respectively with the lowest being oven-dried TME 1 and highest sun-dried TMS 01/1235. The final viscosity, peak time andpasting temperature also increased from 243.05 to 297.63 RVU, 3.98 to 5.6 min and 72.59 to 76.8oC respectively with sun-dried TME 1 as the lowest and oven-dried TMS 01/1235 highest. The pasting values of the cassava varieties were however more significantly different (except colour) than those of the drying methods at p < 0.05 as well as on starch properties. Generally, oven-dried tapioca samples had better functional and pasting properties than sun-dried samples. This indicates that oven drying can be used to replace sun drying to obtain products of high quality during the production of tapioca. In addition, the results suggest that oven drying of tapioca will improve functionality in complementary food formulations, including puddings for weaning foods

Effect Of Blanching Methods On Drying Kinetics Of Bell Pepper

Various blanching methods and drying temperatures were applied to bell pepper ( Capiscum annum ) to investigate the effect on its drying characteristics. Pepper (Capiscum annum) is an abundant and cheap source of vitamins, minerals and fibre. However, its high moisture content makes it susceptible to deterioration. The most common method of preservation is drying but the dried products obtained are of reduced nutritional qualities. Pretreatment of pepper before drying improves the quality of the dried pepper and increases its drying rate. Steam and water blanching as a form of pretreatment has been reported to increase drying rate and improve the quality of dried products but there is not much information on other types of oil/water blanching methods. The effect of blanching (steam, water, palm oil/water and groundnut oil/water) as a pretreatment on the drying kinetics of bell pepper dried at temperatures of 50, 60, 70, 80 and 90°C, was studied. Drying of raw untreated bell pepper was taken as a control. The results indicate that water removal at the initial stage of the drying process was highest and there was a rapid decrease as drying continued until equilibrium was reached at the end of process. The blanched samples generally had higher drying rates (at p0.05) than the untreated samples. The values for the drying rate for steam and water blanched samples were higher (but not at p<0.05) than the drying rates for samples blanched in oil/water mixtures. The drying rate as well as effective moisture diffusivity, Deff, increased with increasing drying temperature. Values of Deff varied from 3.55 x 10-9 m2/s to 2.34 x 10-9 m2/s with the highest being SB (steam blanched) at 80°C and the lowest UB (unblanched) at 50°C. The drying process took place mainly in the falling rate period. The activation energies varied from 39.59 to 83.87 kJ/mol, with PB (palm oil/water blanched) samples having the lowest and UB having the highest Ea value. The lower values for pretreated samples imply that water movement from the internal regions is faster in pretreated samples. This suggests that blanching as a method of pretreatment generally increases water diffusion

Design and fabrication of a cassava peeling machine

The varying shapes and sizes of cassava tubers have made cassava peeling to be one of the major problems in the mechanization of cassava processing. A cassava peeling machine was designed and constructed. The design parameters include a power requirement of 0.36hp, belt tensions of 349.7 and 1807.5N and shaft diameter of 35mm. Its main component is a peeling chamber, which consists of two perforated drums rotating in the opposite direction. The machine had an average capacity of 44.50kg/hr, an average peeling efficiency of 83% and an average percent flesh loss of 5.38%.Keywords: cassava, peeling, peeling efficiency Nigerian Food Journal Vol. 23 2005: 231-23

Performance evaluation of a roaster for groundnut and palm kernel nut

No Abstract. Journal of Applied Science, Engineering and Technology Vol. 1(1) 2001: 67-7