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

Effect of Blanching methods on drying kinetics of bell paper

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 90oC, 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 p<0.05) 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 80oC and the lowest UB (unblanched) at 50oC. 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

Theoretical investigation of the performance of some environment-friendly refrigerants in a sub-cooling heat exchanger refrigeration system

As a result of global concerns over the depletion of the earth’s protective stratospheric ozone layer by the atmospheric release of chloroflurocarbons (CFCs) and hydrochlorofluoro-carbons (HCFCs) refrigerants, their production has been restricted and they are no longer choices fornew equipment. This paper presents theoretical investigation of the performance of some environment-friendly refrigerants in a sub-cooling heat exchanger refrigeration system. Five promising environment-friendly refrigerants (R23, R32, R134a, R143a and R152a) were selected frommethane and ethane derivatives and they were investigated theoretically. Sub-cooling heat exchanger was used to evaluate the impact of selected refrigerants on the exchanger effectiveness, system capacity and coefficient of performance (COP). The results obtained showed excellentperformance of R152a and R134a, and fair performance of R143a when compared with R12 in vapour compression refrigeration system. The results also showed that using R23 and R32 in the refrigeration system will be detrimental to the system performance

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

Development Of A Manual Fruit Juice Extractor

A manual fruit juice extractor was developed. The machine had an average performance efficiency of 78.09% and 75.72% for orange and pineapple respectively. The expression rates for orange and pineapple juice were 4.40kghr-1 and 4.06kg-1hr respectively. The juice extractor is simple in design and can be operated easily by low-skilled operators without any limitations on age or gender. Key words: Fruit juice, extraction, performance efficiency. Nigerian Food Journal Vol.22 2004: 178-18

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

Mortality and Co-Morbidities Among Hospitalised Hypertensives in Nigeria

Background: There is paucity of data on the burden of morbidities, clinical characteristics and mortality related to systemic hypertension in Nigeria. The present study therefore aimed to systematically assess the co-morbidities and in-hospital outcomes among hypertensives admitted to 3 Teaching Hospitals in Nigeria. Methods Medical records of all subjects admitted to the medical wards of the study centres with an established diagnosis of hypertension in 2013 were reviewed. Admission, discharge and mortality registers of the medical wards were used to identify the cases, those discharged and those who died. The records of the patients were then reviewed and included if the inclusion criteria were satisfied. Results 288 hypertensive patients were consecutively admitted in the medical wards of the 3 centres in 2013, of whom 146 (59.8%) were males. 88.4% of males and 87.8% of females had 1 or more co-morbidities at admission, and the commonest among all patients was heart failure (HF) followed by stroke/transient ischemic attack (TIA), in 76 (31.2%) and 69 (28.3%) patients respectively. The most frequent co-morbidity among males was HF in 34.3% of them, while stroke/TIA was more common among female patients, in 34.7% of them. Non-cardiovascular co-morbidities were uncommon, and the most frequent was community acquired pneumonia in 7.4% of all patients. 7.8% of all patients (13 males and 6 females; p=0.427) died in-hospital. The deceased had higher systolic blood pressure than the survivors, and majority of them (52.6%) were not on any antihypertensive medications at admission, which was the only predictor of mortality in the present study, increasing its odds by 7.5 fold (odds ratio=7.5; 95%confidence interval=2.8-20.0; p<0.001). Conclusions Co-morbidities were found in more than four-fifths of male and female patients, and the most frequent among males was HF while stroke and TIA were most common among female patients. Non-cardiovascular co-morbidities were uncommon. The prevalence of in-hospital mortality was relatively low, and not being on antihypertensive treatment at admission increased its odds by 7.5 fold