Effect of varieties on physicochemical and pasting characteristics of water yam flours and starches

Water yam (Dioscorea alata) flour and starch of ten varieties were processed using standard wet-milling procedure prior to the determination of their physico-chemical and pasting properties. The swelling power of the samples was characterized in the category of high restricted-swelling starch (9.21 to 11.03% for flours; 9.49 to 13.80% for starches). This characteristic is desirable for the manufacture of value-added products such as noodles and composite blends with cereals. The pasting temperature (78.05 to 86.13°C, for flours; 80.38 to 86.15°C for starches) and time (4.44 to 5.17 min for flours; 4.53 to 5.17 min for starches) of test varieties indicate higher gelatinization temperature and longer cooking time. Results of analyses of physico-chemical and pasting properties indicated significant differences (P < 0.05) among the varieties. All the varieties studied gave the potentials for the manufacture of these value-added products and non-food applications of starch such as in paper and textile industries. Moreover, the results obtained in this study also show that potential exists for selecting nutritionally superior varieties of D. alata (TDa 297 and TDa 00/00194 for flour, TDa 297 and TDa 98/01183 for starch) and these varieties could be good sources of diets to its consumers and serve as food security in developing countries.Key words: Water yam, physico-chemical, pasting, flour, starch

INFLUENCE OF CATALYST QUANTITY AND REACTION TIME ON IN-SITU PRODUCTION OF BIODIESEL FROM RAW CASTOR BEAN SEED USING RESPONSE SURFACE METHODOLOGY

Trans-esterification is the most commonly used methods of biodiesel production. In-situ trans-esterification process uses oil (triglycerides) in seeds directly without the need for initial extraction. The in-situ production of biodiesel from raw castor bean seed with a batch processor was studied at initial catalyst quantity of 0.1, 0.5 and 1.5%, reaction time of 30, 60 and 90 min with a reaction temperature of 600C and alcohol seed ratio of 1:1 using the response surface methodology.  Initial catalyst concentration and reaction time were subjected to central composite experimental design of the response surface methodology.  Initial catalyst quantity and reaction time were found to have significant (P<0.05) effects on the yield of castor biodiesel produced, with increased catalyst quantity giving a negative effect on the yield after an initial amount of between 1.0 and 1.2%.  The reaction time had a positive effect on the yield until after 90 minutes after which biodiesel yield reduced with increased time. The CA-Time interactions influence was small and negative, due to the superior effect of initial catalyst quantity by the formation of by-products (soaps) leading to difficult ester separation from glycerol. A second-order model was obtained to predict the yield as a function of all factors. The model predicted well the observed data with a R2 value of 0.983. The biodiesel produced had properties comparable to the standards of ASTM while the specific gravity was higher than the specified standards

EFFECT OF TEMPERATURE AND PERCENTAGE OF INITIAL CATALYST ON THE IN-SITU PRODUCTION OF BIO-DIESEL FROM CASTOR OIL BEAN SEED USING RESPONSE SURFACE METHODOLOGY

The use of vegetable oil and animal fats for biodiesel production has recently become a great concern because of the competition with food materials.  As the demand for vegetable oil increase tremendously in recent years it has become impossible to justify the use of these oils for fuel production. In-situ trans-esterification process uses the oil (triglycerides) in the oil seed directly without the need for initial extraction as compared with the conventional trans-esterification. Castor oil bean seed contains between 35 and 55% oil and does not compete with food grade oil because of the seed’s toxicity. This study evaluated the effect of temperature and percentage of initial catalyst on yield of castor ethyl ester.  Raw castor oil bean seed kernel at moisture content of 4.68 % (db) was subjected to in-situ trans-esterification in a batch processor with ethanol as the solvent and sodium hydroxide as the catalyst.  Central composite design (CCD) of the Response surface methodology was applied to evaluate the main and interactive effects of initial catalyst amount (0.5 – 1.5%) and reaction temperature (40 – 70OC), on yield of castor ethyl-ester, at reaction time of 120 minutes and alcohol-seed weight ratio of 1:1.  A quadratic non-linear polynomial model was obtained to describe the effect of the factors on yield.  The model was significant (P< 0.05) with a non- significant Lack-of-Fit value (P< 0.05) and R2 value of 0.944. Second order response surfaces and contour plots obtained from the model revealed that initial catalyst amount was the more effective factors on yield while reaction temperature had less effect. The Temperature–percentage of initial catalyst interaction was small and negative, due to the combined effects of formation of by-products (soaps) and saponification. The biodiesel produced from ground castor oil bean seed during this study met the requirements of ASTM standard D6751-02 but specific gravity was higher than the ASTM standard confirming that biodiesel produced from castor bean seed using the in-situ technique can be used as replacement fuel for fossil diesel

REVIEW ON CASSAVA MASH SIF TING METHODS AND MECHANISMS

Cassava is presently the most important food crop in Nigeria from the point of view of both the area cultivated and the tonnage produced.Cassava has transformed greatly into high yielding cash crop, a foreign exchange earner as well as a crop for world food security and industrialization. As a result of this, there has been an unprecedented rise in the demand for cassava and its numerous products worldwide for both domestic and industrial applications. However, cassava processors are currently finding it extremely difficult to respond positively to this increase in demand due to the prevalence of the traditional processing methods employed the sifting operation inclusive. This has made the appraisal of the current sifting technologies pertinent in order to address the areas that need technical improvement and further research efforts towards the evolution of cost effective sifting technologies with improved efficiencies which would enhance the capacity to exploit the cassava market potential.  Therefore, this paper reviews the efforts made, and currently being made towards an efficient and cost effective mechanization of cassava mash sifting operation so as to overcome the challenges being faced using traditional method of sieving cassava mash

Effect of Storage Temperature on Some Ogi Properties

Abstract: The study aimed at investigating the effect of storage temperatures on some quality properties of Ogi putting into consideration the peculiar situation of power supply in Nigeria. Ogi was processed using traditional method and stored at different temperatures (27±3, 5 ±2, -10±3 and -20±3ºC) for a period of 12 weeks. Proximate, pH, total titrable acidity, pasting characteristics and sensory evaluation were carried out. The total titratable acidity (Lactic acid based) began to decrease as from week 2 and throughout the period of storage in ogi samples stored at ambient temperature of 27±3ºC. A similar observation was noticed in the ogi stored at 5 ±2ºC, while ogi stored at -10±3 and -20±3ºC maintained the total titrable acidity when compared with the fresh ogi. The mean values of pH were significantly different (p<0.05) in all the storage conditions, while high pH values of 3.61±0.25 and 3.65±0.05 were recorded at week 12 of ogi stored at ambient temperature and 5±2ºC respectively. There was significant difference (p<0.05) in moisture content throughout the period of storage. There was significant difference in proximate composition (p<0.05) in all the storage conditions and throughout the storage period. The peak viscosity and final viscosity of ogi stored under the ambient temperature witnessed a noticeable reduction throughout the period of storage compared with the fresh sample of ogi. Storage at 5±2,-10±3 and -20±3ºC conditions maintained the hold strength (hot paste viscosity). The range of pasting temperature for ogi samples throughout the period of storage was between 76 and 80ºC. There was no significant difference (p<0.05) in multiple comparison results of sensory evaluation and the values for consistency were 2.7 and 2.75 at weeks 8 and 10 respectively for ogi stored at ambient temperature. The acceptability results for consistency and colour showed a significant difference (p<0.05). Ogi stored at low temperatures (-10±3 and -20±3ºC) were preferred

Influence of catalyst amount and alcohol-seed ratio on the production of bio-diesel from raw castor oil bean seed using in-situ technique

Trans-esterification is the most commonly used methods of biodiesel production. In-situ trans-esterification process uses oil (triglycerides) in seeds directly without the need for initial extraction. The in-situproduction of biodiesel from raw castor bean seed with a batch processor was studied at initial catalyst quantity of 0.1, 0.5 and 1.5%, reaction time of 30, 60 and 90 min with a reaction temperature of 600C and alcohol seed ratio of 1:1 using the response surface methodology. Initial catalyst concen-tration and reaction time were subjected to central composite experimental design of the response surface methodology. Initial catalyst quantity and reaction time were found to have significant (P<0.05) effects on the yield of castor biodiesel produced, with increased catalyst quantity giving a negative effect on the yield after an initial amount of between 1.0 and 1.2%. The reaction time had a positive effect on the yield until after 90 minutes after which biodiesel yield reduced with increased time. The CA-Time interactions influence was small and negative, due to the superior effect of initial catalyst quantity by the formation of by-products (soaps) leading to difficult ester separation from glyc-erol. A second-order model was obtained to predict the yield as a function of all factors. The model predicted well the observed data with a R2 value of 0.983. The biodiesel produced had properties com-parable to the standards of ASTM while the specific gravity was higher than the specified standard

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A b s t r a c t. This study was conducted to investigate effects of extrusion conditions on physicochemical properties of blend of yam and bambara nut flours. A blend of white yam grit (750 µm) and Bambara nut flour (500 µm) in a ratio of 4:1, respectively was extrusion cooked at varying screw speeds 50-70 r.p.m., feed moisture 12.5-17.5% (dry basis) and barrel temperatures 130-150°C. The extrusion variables employed included barrel temperature, screw speed, and feed moisture content, while the physicochemical properties of the extrudates investigated were the expansion ratio, bulk density, and trypsin inhibition activity. The results revealed that all the extrusion variables had significant effects (p&lt;0.05) on the product properties considered in this study. The expansion ratio values ranged 1.55-2.06, bulk density values ranged 0.76-0.94 g cm -3 , while trypsin inhibition activities were 1.01-8.08 mg 100 g -1 sample. K e y w o r d s: yam-bambara blend, extrusion cooking, physicochemical propertie

EFFECT OF TEMPERATURE AND PERCENTAGE OF INITIAL CATALYST ON THE IN-SITU PRODUCTION OF BIO-DIESEL FROM CASTOR OIL BEAN SEED USING RESPONSE SURFACE METHODOLOGY

The use of vegetable oil and animal fats for biodiesel production has recently become a great concern because of the competition with food materials. As the demand for vegetable oil increase tremendously in recent years it has become impossible to justify the use of these oils for fuel production. Insitu trans-esterification process uses the oil (triglycerides) in the oil seed directly without the need for initial extraction as compared with the conventional trans-esterification. Castor oil bean seed contains between 35 and 55% oil and does not compete with food grade oil because of the seed’s toxicity. This study evaluated the effect of temperature and percentage of initial catalyst on yield of castor ethyl ester. Raw castor oil bean seed kernel at moisture content of 4.68 % (db) was subjected to in-situ trans-esterification in a batch processor with ethanol as the solvent and sodium hydroxide as the catalyst. Central composite design (CCD) of the Response surface methodology was applied to evaluate the main and interactive effects of initial catalyst amount (0.5 – 1.5%) and reaction temperature (40 – 70OC), on yield of castor ethyl-ester, at reaction time of 120 minutes and alcohol-seed weight ratio of 1:1. A quadratic non-linear polynomial model was obtained to describe the effect of the factors on yield. The model was significant (P< 0.05) with a non- significant Lack-of-Fit value (P< 0.05) and R2 value of 0.944. Second order response surfaces and contour plots obtained from the model revealed that initial catalyst amount was the more effective factors on yield while reaction temperature had less effect. The Temperature–percentage of initial catalyst interaction was small and negative, due to the combined effects of formation of by-products (soaps) and saponification. The biodiesel produced from ground castor oil bean seed during this study met the requirements of ASTM standard D6751-02 but specific gravity was higher than the ASTM standard confirming that biodiesel produced from castor bean seed using the in-situ technique can be used as replacement fuel for fossil diesel

Effect of extrusion variables on extrudates properties of water yam flour a response surface analysis

Water yam (Dioscorea alata) flour was processed using standard wet milling procedure prior to the extrusion process, which led to the determination of extrudate properties of the flours.A single-screw extruder (DCE 330, NJ) was used in evaluating the extrudate properties, which included torque, mass flow rate, residence time, specific mechanical energy and expansion ratio of the flours from the water yam samples. The effect of extrusion and process variables: feed moisture content, screw speed and barrel temperature on the extruder torque, residence time, mass flow rate, specific mechanical energy and expansion ratio for the variety were determined and predictive models were also developed using response surface methodology. It was observed that changing the feed moisture content, barrel temperature and screw speed significantly (P < 0.05) affected expansion ratio, torque, mass flow rate, residence time and specific mechanical energy of all the extrudates. Increasing the feed moisture content (18–28% db) and screw speed (80–180 rpm) resulted in a substantial decrease in expansion ratio (46.6%), residence time (27.5%) and specific mechanical energy (83.6%); whereas, increasing the screw speed significantly increased the mass flow rate (64.5%) of extrudates. Regression analysis indicated that screw speed and feed moisture content were the major process variables showing significant (P < 0.05) linear, quadratic and interaction influences on mass flow rate, expansion ratio and specific mechanical energy

Bread from composite cassava wheat flour. II: effect of cassava genotype and nitrogen fertilizer on bread quality

There is an increasing interest in the use of cassava roots for food and industrial purposes especially in the baking industry in Nigeria. Development of some cassava mosaic disease (CMD) resistant clones and application of inorganic fertilizers are principal strategies targeted in the country to boost and sustain cassava root production and utilization. A study was conducted to determine the effect of cassava genotype and field application of nitrogen fertilizer on some physical properties of bread from composite cassava– wheat (CCW) flour. Five CMD cassava clones were planted in a randomized complete block design with two level of fertilizer treatments (0 and 160 kg nitrogen/ha) with two replications while harvesting was done 12 months after planting. Composite flour was produced at a ratio of 10/90 (cassava/wheat flour, w/w). The oven spring, specific volume, crumb texture (softness) and crumb moisture of loaves ranged from 0.57 to 0.63 cm, 4.37 to 6.85 cm3/g, 18.4 to 29.4 mm and 31.40% to 34.70%, respectively. The crust’s tristimulus color parameters L*, a*, b* and brownness index also ranged from 54 to 67, 9 to 15, 22 to 29, and 57 to 83, respectively. These values differed significantly from each other at p < 0.01. Out of all these loaf properties, crumb texture was the most affected by the main and interactive effects of cassava genotype and fertilizer application (p < 0.001) while loaf weight was only affected by their interactive effects (p < 0.05). Digital image analysis of the bread crumb showed that the total number of cells, number of small cells and total cell area of the bread crumb ranged from about 22 to 27 cm 3, 20 to 25 cm 3 and 12% to 29%, respectively. The distribution of large cells and total cell area occupied in the crumb were principally determined by the genotypic difference (p < 0.05) in the cassava roots. The main effect of fertilizer application significantly affected the distribution of small cells, total number of cell and the cell area (p < 0.05). However, the interactive effects of genotype and fertilizer application was more significant (p < 0.01) on the crumb cell characteristics. The study indicated that optimal quality of CCW bread loaf could be attained by appropriate selection of cassava genotype and fertilizer application