Theses and Dissertations
Permanent URI for this collection
Theses and Dissertations (Food Science & Technology)
Browse
Browsing Theses and Dissertations by Issue Date
Now showing 1 - 8 of 8
Results Per Page
Sort Options
- ItemOpen AccessEffect of Maize Fermentation on Some Physico-Chemical Properties of 'Ógi'.(Obafemi Awolowo University, 1985) Beckley, Olufela; Adeyemi, I. A.The effect of fermentation or souring period on some physico-chemical properties of ogi, manufactured by the wet- and dry-milling processes from downy mildew resistant white maize variety (DMR white) were evaluated. Determinations were carried out for titratable acidity, starch, diastatic activity, damaged starch, reducing and non-reducing sugars, liquefaction number, Brabender amylograph pasting characteristics and Adam's consistometer value. The results showed that titratable acidity increased from 0.18% to 0.37% lactic acid, while starch content was reduced from 89.2 to 70.5% with period of fermentation, although souring did not produce any appreciable change in starch content. Similarly, there was no appreciable change in diastatic activity, damaged starch and reducing and non-reducing sugars, except for samples fermented or soured for six days. Amylograph peak viscosity was higher for wet-milled ogi than dry-milled ogi being in the range of 1030 to 1250 B.U. and 210 to 960 B.U. respectively. Peak viscosity was observed to increase with souring period of maize flour. Set-back value, index of gelatinization and Adam's consistometer value were observed to decrease with either fermentation or souring period. The use of souring water in preparing ogi porridge, appreciably increased its titratable acidity, but produced ogi of poorer pasting viscosity.
- ItemOpen AccessExtrusion Characteristics of Cereal and Legume Flours.(Obafemi Awolowo University, 1985) Akinjayeju, Oluwole; Onayemi, O.Some physical factors that determine the extrusion characteristics of cereal-legume blends were examined. These were particle size, substitution level and type of legumes. Corn (Zea mays L.), Cowpea (Vigna unguiculata) and Winged beans ( Psophocar tetragonolobus L.) of three particle sizes namely flour (<:425 microns), grits (>425 microns, <600 microns) and coarser grits (>600 microns,< 850 microns) were used. Blends containing 10% and 20% of each legume with the respective corn fraction were prepared and analysed for proximate composition, water absorption capacity, pasting (cooking) characteristics and viscosity. Addition of legumes increased the nutritional composition of corn-meal with more increases in corn-winged bean than corn-cowpea blends. Winged bean produced greater adverse effects on viscosity and pasting characteristics of corn-legume blends than did cowpea. Statistical analysis showed that the type of legume had the greatest effect on most of the characteristics examined while substitution level produced the least effect. The CWBF (80:20), CWBG 600 (80:20) and CBG 600 (80:20) blends would most probably give the best extruded products since these blends would be able to withstand extrusion conditions of high shear and pressure. The CWBF (80:20), CWBG 600 (80:20) and CBG 600 (80:20) blends would most probably give the best extruded products since these blends would be able to withstand extrusion conditions of high shear and pressure.
- ItemOpen AccessThe Development, Construction and Evaluation of a Micro-spray Dryer(Obafemi Awolowo University, 1985) Anjorin, Mojisola Oluyemisi; J., WypychA co-current laboratory spray dryer was designed to meet multipurpose requirements for drying food materials and constructed from relatively cheap locally available materials. Tests, on the basis of 100% moisture were carried out to characterise the equipment and milk was dried to determine the particle size distribution. The dryer efficiency at optimum conditions, varied between 44.7%-59.7% and the average particle size was 10ym - 20um. The highest temperature of the air possible for drying was 413K while the lowest was 355K and the maximum air flow rate in the chamber was 31 litres/minute. The drying rate was 0.65g/min and, the maximum relative humidity of the outgoing air at the minimum temperature was 96%.
- ItemOpen AccessInvestigations into the Textural Characteristics of Agidi (A Fermented Corn Meal).(Obafemi Awolowo University, 1986) Osungbaro, Taiwo Olujide; Adeyemi, I. A.The effect of particle size, maize variety, fermentation periods and methods of milling on textural properties of 'agidi' was investigated. Textural properties were evaluated, using the Brabender Amylograph, Gel tester, and sensory evaluation. The data obtained showed that 'agidi' manufactured from wet-milled ogi of 4 425 pm particle sizes exhibited the highest gel strength while that from the dry-milled ogi of .0 600 pm particle size fractions recorded the highest gel strength. Of the five maize varieties investigated, FARZ-27 had the best gelling characteristics for 'agidi' manufacture, while FARZ-34, recorded the lowest gel strength and kewesoke recorded the lowest stability and setback values. 'Agidi' from wet-milled ogi fermented for 4 days recorded the highest gel strength, peak viscosity and index of gelatinisation values. While the dry-milled ogi soured for 2 days recorded the highest values for the above parameters. Gel tester results were highly correlated with sensory evaluation for 'agidi' samples of the same particle size manufactured either from different maize varieties or subjected to different days of fermentation.
- ItemOpen AccessAn Investigation into the Keeping Quality of “Agidi”.(Obafemi Awolowo University, 1986) Oluwamukomi, Mathew Olusola; Adeyemi, I. A.The effect of storage time and temperature, souring period, surfactant and packaging materials on the keeping quality of Agidi was investigated. Changes in quality were evaluated by determining the moisture content, syneresis, iodine blue value, acidity and pH. The gel strength, microbial load and the sensory qualities were also determined. The results showed that moisture content of Agidi decreased while syneresis increased with storage time. With increase in storage period, the gel strength of Agidi also increased up to a maximum value and later decreased for samples stored at 28oC and 50°C. There was an increase in acidity value and a corresponding decrease in pH for agidi samples stored at 28°C. Agidi prepared from 4 day soured ogi had a higher syneresis value and a faster staling rate than that prepared from a 2 day soured ogi. The use of surfactant resulted in an increase in initial gel strength of Agidi wrapped in Leaves but with relatively no effect on canned Agidi. The total microbial load also increased with increase in storage temperature, the counts obtained being 750,000/g at 28°C and 2,484,000/g at 50°C after 9 days storage for Agidi wrapped in Leaves. Corresponding counts for canned samples were 2000/g and 6000/g respectively after 8 weeks of storage. Sensory observation showed that Agidi wrapped in Leaves, PVC and Aluminium foil had shelf life of 6, 9 and 16 days respectively while canned Agidi maintained its quality throughout the 8 weeks of storage period.
- ItemOpen AccessNutritional Evaluation of a Fortified Maize Weaning Food.(Obafemi Awolowo University, 1987) Komolafe, Abiola; Adeyemi, I. A.Nutritional evaluation was carried out on pregrelatinized maize flour blended with undefatted soy bean flour at 20, 32, 40 and 50% levels. The samples were evaluated for proximate composition, pepsin digestibility and mineral analysis for phosphorus, calcium and iron contents. The data were compared with values for Ogi, Soy-Ogi and Cerelac. Rat feeding experiments were also carried out on pregelatinidec maize flour fortified with soybean flour (at 30% Level), and cerelac. Protein content and pepsin digestibility Values: for fortified gelatinized maize flour samples found to range from 12 to 19% and 82 to 86% respectively. The corresponding values for Ogi, Soy-Ogi and cerelac were 7.06, 11.70 and 16.09% and 70.52, 78.73 and 91.55% respectively. Phosphorus contents of the pregrelatinized maize flour, 30% fortified maize flour, Ogi, Soy-ogi and cerelac were 280, 265, 200, 285 and 285mg/100g respectively. The corresponding values for calcium were 0.5, 56.5, 4.2, 205.3 and 352.5mg/100g respectively, while the values were 1.8, 3.1, 1.5, 5.6 and 6.8mg/100g respectively for iron. From rat feeding experiments, Protein Efficiency Ratio (PER), Net Protein Utilization (NPU) and Biological Value (BV) were1.14, 55.05% and 0.62 respectively for fortified maize flour while cerelac had corresponding values of 1.99, 71.09% and 0.83 respectively. It was apparent from the results obtained that pregelatinized maize flour fortified at 30% level with undefatted soybean flour could be nutritionally adequate as a weaning food.
- ItemOpen AccessInfluence of Yeast Strains on the Quality of Sorghum Beer.(Obafemi Awolowo University, 1987) Ogunyemi, Toyin Oluyemisi; Abiose, S.Studies were carried out on the influence of two commercial yeasts and palm wine yeast isolate (Saccharomyces cerevisiae) on the quality of sorghum beer. One of the two commercial yeasts was obtained from Africana Brewery, Ibadan and the other was a Bavarian bottom fermenting yeast purchased from host Germany. The sorghum wart samples were fermented at selected temperatures of 9°C, 15°C and 15°C /9°C (alternating both 15°C and 9°C) for 6, 4, 5 days respectively. The sorghum beer samples were evaluated for pH, acidity, alcohol content, sugar and protein content. The specific gravity of the samples and the yeast count of each culture were also monitored daily. Organoleptic tests were also carried out on the finished products. The results indicated that the different temperatures employed, produced differences in the levels of alcohol content, unfermented carbohydrate, protein, acidity and overall flavour of the products. The two commercial yeasts were observed to utilize more sugars and to produce more alcohol than palm wine yeast. The Africana brewery yeast particularly utilized the highest amount of sugar at all the throe temperatures and produced the highest percent alcohol at 9°C and 15°C while at 15°C /9°C, the Bavarian yeast produced the highest amount of 6.8% alcohol. The result obtained from the protein analysis of the final beer; samples showed that beer of better stability can obtained at 15o C and 15°C /9°C. The pH values of the beer samples ranged between 3.95 and 4.20. At 15°C and 15/9o C the palm wine yeast produced the lowest pH values of 3.95 and 4.05 respectively. It also produced' the highest amount of titratable acidity at the three temperatures. The quality evaluation of flavour, taste and acceptability of the finished products indicated that the palm wine yeast cave products of highest quality. This shows that the use of palm wine isolate may produce beer of acceptable quality.
- ItemOpen AccessStudies on Some Aspects of Oil and Protein Content of Conophor Nut (Tetracarpidium Conophorum)(2015-09-30) Gbadamosi, Saka OlasunkanmiThe functional properties, solubility profile, in vitro digestibility and antioxidant properties of Tetracarpidium conophorum (conophor nut) were studied. The storage stability and thermal oxidative changes of its oil were also evaluated with a view to increasing the underutilized nut as food ingredient. A portion of fresh conophor nuts was processed to obtain defatted flour, concentrate and isolate by a combination of solvent extraction, isoelectric precipitation, and lyophilization. The flour, protein concentrate and isolate were then subjected to chemical analyses using standard methods. Crude and purified oils were also obtained from another portion of the nuts subjected to cooking, shelling, drying, milling and solvent extraction. Samples of crude and purified oils were stored at ambient and refrigeration temperatures and the acid value, peroxide value, p-anisidine value and fatty acids composition were monitored as indices of oxidation. Thermal oxidative changes of conophor oil used for frying plantain slices were evaluated by determining changes in viscosity, colour, conjugated dienes and trienes, peroxide and p-anisidine values. Samples of plantain chips obtained by frying in conophor oils were compared with those obtained when fried in soy oil by sensory evaluation. Data obtained were subjected to appropriate statistical analysis. The results showed that conophor flour, concentrate and isolate exhibited high oil (2.35 - 2.95g oil/g sample) and water (4.03 - 4.88 g water/g sample) absorption capacities but low emulsion (3.00 - 7.50 mL oil/g sample) capacities. The foam capacities for isolate, flour and concentrate were 5, 20 and 27%, respectively. The least gelling concentrations (flour, 8%; concentrate 10%, isolate, 12%) were also low. The most effective conophor protein solubilizer was O.1M NaOH while water and 0.1M potassium phosphate buffer were the least effective protein solubilizers. The protein fractionation revealed that glutelins and globulins accounted for the major proteins of conophor nut. Moist heat and dry heat increased digestibility of conophor nut but moist heat was found to be more effective than dry heat. The total phenolic content was significantly (p < 0.05, LSD) higher in 100% methanolic extract (1.49 g/100 g crude extract) than in 100% acetone extract (0.85 g/100 g crude extract). The methanolic extracts exhibited a high radical scavenging effect (59.85%) compared to value of 44.67% in acetone extracts. Both primary and secondary oxidation products were low at low temperature but were found to be high at elevated storage temperatures. Apart from refractive index which remained almost constant, other physical and chemical characteristics of the oils such as acid value, peroxide value, conjugated dienes and trienes, and p-anisidine value increased with increasing frying sessions. Taste panel analysis showed plantain chips obtained by frying in purified conophor oil were preferred (5.70) to those fried in crude conophor oil (3.10) on 7-point hedonic scale. The study has shown that conophor nut flour, concentrate and isolate are useful as ingredient in food formulation.