OPTIMISATION OF LYE-PEELING OF CASSAVA (Manihot esculenta Crantz) USING RESPONSE SURFACE METHODOLOGY

Cassava (Manihot esculenta Crantz) is an important root crop in many tropical developing countries. Conventional peeling, done manually using knives is wasteful and unsuitable for industrial scale operation. Optimum condition for the peeling of cassava by immersion in hot lye (NaOH) solution was determined using Response Surface Methodology (RSM) for pre-determined three levels of Peeling Efficiency Index (PEI). Some cassava was peeled manually and some with hot lye solution. The effects of lye–concentration (4-12%), immersion temperature (75-100°C) and immersion time (2.5-10min.) on PEI (removal of 11-15% of root) obtained from 23 experimental points and three replication were analyzed with design expert and statistical analysis system software. Complete lye–peeling (removal of 11% of the root) was achieved at 9.7%, 86°C and 5min respectively which were within the critical optimization range (R2=43%, CV=44% and root mean square error 0.3935) generated by the RSM

OPTIMIZATION OF LYE PEELING OF BREADFRUIT (Artocarpus comminis Frost) USING RESPONSE SURFACE METHODOLOGY

Breadfruit (Artocarpus communis  Frost) is an important food crop in many tropical developing coun-        tries. Conventional peeling, done manually using knives is wasteful and unsuitable for industrial scale        operation. Optimum condition for the peeling of breadfruit by immersion in hot lye (NaOH) solution was        determined using Response Surface methodology (RSM) for pre-determined three levels of Peeling        Efficiency Index   (PEI). Some   breadfruit   was   peeled   manually   and   some   with   hot lye   solution.   The        effects of lye–concentration (0.5-2.0%), immersion temperature (70-90°C) and immersion time (2.5-        10min.) on PEI (removal of 6-11% of peel) with subsequent soft and abrasive washing of the peeled        crop obtained from 14 experimental points and three replication were analyzed with design expert and        statistical analysis system software. Complete lye–peeling (removal of 6% of the fruit ) was achieved                                                                                                   2        at   1.6%,   80°C   and   5min   respectively   which   were   within   the   critical   optimization   range   (R =52%,        CV=75.9%) generated by the RSM.&nbsp

CHEMICAL AND MICROBIOLOGICAL PROFILE OF ‘LEGO’-A LOCALLY PRODUCED FLAVOURED DRINKS

The study assessed the chemical and microbial safety of street vended local drink ‘Lego’ collected from three different vendors in Abeokuta metropolis. A control sample was prepared in the laboratory and nine samples of three different flavours (orange, pineapple and blackcurrant) were collected.  Total Vibrio count, total faecal Coliform and total staphylococcus count were estimated in all the samples. Total Vibrio cholera is completely absent while Five samples were found to harbour total staphylococci counts of bacteria within the range of 0.7-1.5x104cfu/ml. All the samples exhibited the presence of Coliform counts within the range of 1.0-9.5x104cfu/ml and Staphylococcus aurous, Micrococcus acidophilus and Klebsiella aerogenes species were bacteria isolated from the samples collected. Heavy metals were also estimated in all the collected samples. Chromium and lead were absent but cadmium was present and is within 0.01-0.025mg/g. The lowest is from orange flavour at camp with 0.01 mg/g while the highest is from Lafenwa in pineapple flavour with 0.025mg/g. Total titratable acidity ranges from 0.175 – 0.219 and the pH ranges from 4.21±0.14 and 5.40±0.00. Hence, these implies that Lego flavoured drink is bacteriologically and chemically unsafe for consumption.      &nbsp

VARIETAL CHARACTERIZATION OF THE PHYSICAL PROPERTIES, PROXIMATE AND MINERAL COMPOSITION OF IMPROVED SESAME (Sesamun indicum) SEEDS

The study was conducted to characterize the physical properties, proximate and mineral composition of improved sesame varieties. Fourteen improved varieties of sesame seeds were analyzed for their physical properties, proximate and mineral composition following standard analytical procedures. The arithmetic mean diameter (AMD), sphericity, geometric mean diameter (GMD), aspect ratio and surface area were in the range 1.51-1.91 mm, 0.57-0.64 mm, 1.32-1.70 mm, 61.50- 75.00%, and 84 - 8.94 mm2, respectively. Ca, Fe, Mg and K contents were also in the range 5.4-20.2 mg/kg, 0.5-3.0 mg/kg, 1.5-7.4 mg/kg, and 2.9-12.9 mg/kg, respectively. There was significant varietal differences (P<0.05) in the physical properties, proximate and mineral composition of the improved sesame seeds. The improved sesame varieties were characterized into three groups with distinct physical properties, proximate and mineral composition using hierarchical clustering procedure. Cluster 1 consists of varieties with relatively low proximate and mineral composition while cluster 2 comprises varieties with higher amounts of these nutrients. The variety in cluster 3 was characterized with exceptionally low content of minerals. The diversity obtained in the physical properties and proximate composition of the improved sesame seeds from this study underscores the huge potentials of the improved sesame seeds in food and non food use

PRODUCTION AND SOME QUALITY ATTRIBUTES OF RICE-BAMBARA NUT FLOUR EXTRUDED FLAKES

The proximate, functional and sensory properties of Rice-Bambara flakes were investigated. The flour was mixed at different proportions (100% Rice flour, 90:10, 80:20, 70:30, 60:40, 50:50 Rice-Bambara flour). The proximate composition, functional properties and sensory acceptability of the flakes were determined using standard laboratory procedures. The water absorption capacity ranged from 1.90 to 2.50. The swelling power and solubility index ranged from 3.51-4.37 and 13.35-20.50, respectively. The fat, protein, ash, crude fiber, moisture and carbohydrate contents ranged from 1.33-3.13%, 5.30-18.37%, 0.37-1.34%, 0.26-1.38%, 4.99-6.79%, and 69.35-85.18% respectively. Sensory panelists«¤?? scores for color, taste, aroma, texture and overall acceptability ranged from 4.46-7.23, 4.11-6.70, 5.00-7.09, 4.32-6.14, and 4.73-6.91 respectively. There were significant differences (P<0.05) between the sensory, functional and proximate properties of the flakes. The study showed that 90:10 Rice-Bambara flour extruded flakes had better functional properties and sensory acceptability

CHEMICAL AND MICROBIAL SAFETY OF STREET VENDED EGG ROLL IN ABEOKUTA METROPOLIS

A total of 12 samples of egg rolls retailed in three locations in Abeokuta and a laboratory prepared sample serving as control were analyzed for their microbial load and presence of heavy metals (Lead, Cadmium, Chromium). The samples were analyzed for bacteria using standard procedures. Analysis of the food samples showed that total viable bacterial count ranged from 1.2 x 105 to 4.2 x 105 cfu/g, total staphylococcus count ranged between 1.2 x 104 and 6.4 x 104 cfu/g, coliform count ranged from 1.0 x 104 to 3.0 x 104cfu/g, total campylobacter count ranged between 1.0x104 and1.3x104 cfu/g and there were no growths for the total listeria count. Five bacteria genera were isolated including Staphylococcus aureus, Escherichia coli, Klebsiella aerogenes, Salmonella typhi, Campylobacter coli. Cadmium and Chromium contamination ranged from 3.50±0.71 - 12.50±0.71 and 0.75±0.35 - 3.50±0.00 respectively. Statistical analysis of the heavy metals shows a significant difference (p<0.05) between the control and samples. The level of microbial contamination could be associated with inadequate handling and processing by processors and vendors, contamination caused by either poor hygiene or poor quality of water used. Moreover, contamination of cadmium and chromium in all the samples could be incident upon the water used in producing it, however lead was absent in all the samples. It is therefore recommended that health education should be done for food handlers and consumers about food safety.     &nbsp

Effect of frying treatments on texture and colour parameters of deep fat fried yellow fleshed cassava chips

Effects of frying treatments on texture (hardness) and colour parameters (L, a, b, Delta) during deep fat frying of yellowfleshed cassava root slices (TMS 01/1371) were investigated. Slices (dimension of 40mm × 25mm × 3 mm) were divided into three portions and subjected to vacuum frying (fresh slices) and atmospheric frying (fresh and predried slices) and equivalent thermal driving forces (ETDF) of 60∘C, 70∘C, and 80∘C were maintained during frying. The quality attributes investigated were best preserved in vacuum fried chips. The overall colour change in chips fried under vacuum conditions at 118∘C and 8 min was the least (21.20) compared to fresh and atmospherically predried ones (16.69 and 14.81, resp.). A sharp reduction in the breaking force was obtained for all frying treatments after 8 min and this effect was the least in vacuum fried chips. First-order kinetics modeled the changes in quality attributes for all the temperatures investigated. Rate constants k (min−1) obtained for vacuum frying were almost equal to that of atmospheric frying while activation energies for hardness and colour change were 53.30 and 467.11 KJ/mol, respectively. Quality attributes studied were best preserved during vacuum frying

Adsorption isotherms and thermodynamics properties of water yam flour

Adsorption isotherms of water yam flour were determined by static gravimetric method of saturated salt solutions in the range of water activities between 0.11 and 0.96 and at temperatures of 25, 35 and 45 °C. The experimental sorption data was fitted to five models: Guggenheim-Anderson-De Boer (GAB), Peleg, Iglesias-Chirife, Exponential and Oswin and the differential enthalpy and entropies were determined. Equilibrium moisture contents decreased with increase in temperature at all the water activities studied. Peleg model gave the best fit for the sorption isotherm of water yam flour. Monolayer moisture content values estimated from the GAB-model were found to decrease with increases in temperature. The differential enthalpy and entropy decreased with increases in moisture content. The isokinetic temperature was 371.32 K and the compensation theory was satisfied

EFFECTS OF COOKING CONDITIONS ON THE TEXTURE PROFILE, SENSORY AND PROXIMATE QUALITIES OF PRESSURE COOKED BAMBARA NUTS

This study evaluated the effects of pressure cooking on the textural attributes of Bambara nuts using Response Surface Methodology (RSM).The  study optimized cooking condition {Weight of Bambara (250 – 1000g), cooking time (20 -90 min) and post cooking resident time (2-12 min)} for the pressure boiling on the textural and qualities of Bambara. Five out of the eleven optimised solutions (Desirability Index range of 0.919 to 0.936) were compared with samples from conventionally boiled Bambara for proximate and sensory (colour, texture, aroma and Overall acceptance) qualities.  Data were analysed using RSM, analysis of variance and PPMC. Models for hardness, springiness, cohesiveness, fracturability and sensory texture with adjusted R2 values of 83.41%, 80.99%, 67.37% ,  93,75%  and  88.96%  respectively adequately explained the textural and sensory qualities of boiled bambara. The range of values for moisture, fat, ash, crude protein and carbohydrate were 47.88, 2.24, 1.98, 24.30, 20.91 % to 50.58, 2.58, 2.19, 25.49, 21.87% respectively.  Boiled Bambara produced at verified optimisation solutions (527.62g, 82.55, 10.43 min and 591.69g, 82.96, 9.52 minutes) were not significantly different (p >0.05) from that produced by conventional  method (weight and Cooking time: 500g and 125 min.) in spite of the relatively longer cooking time  of the later.   &nbsp

Mineral and antinutrient content of high quality cassava-tigernut composite flour extruded snack

This study investigated the mineral and antinutrient composition of extruded snack produced from different blends of high quality cassava and tigernut flour. The extruded snacks were produced using a single-screw laboratory extruder at constant feed moisture (27%), screw speed (60 rpm) and barrel temperature (80C). It was observed that the extrudates had higher values for mineral composition (phosphorus, calcium, magnesium, potassium and iron) than the composite flour which showed that extrusion cooking improves the absorption of the minerals. The antinutrient (tannin, phytate, saponin, oxalate, alkaloids and total phenolic) contents of all the flour blends significantly (P < 0.05) increased with tigernut flour inclusion. Extrusion cooking resulted in significant (P < 0.05) reduction in the antinutrients of the extrudates. The study showed that extrusion cooking reduced the antinutritional factors thereby increasing the bioavailabilty of minerals. Also, the minerals were not affected by the extrusion cooking process probably because minerals are heat stable