Rahman Akinoso

Effect of delayed harvesting and pre-treatment methods on the antinutritional contents of trifoliate yam flour

Effects of delayed harvesting and pre-treatment methods on the anti-nutritional contents of trifoliate yam flour were examined. Trifoliate yam tubers were washed, peeled, sliced and subjected to pre-treatment methods, such as soaking, pre-cooking and blanching/soaking. The phenols, phytate, oxalate, tannin and alkaloid profiles of the flours were evaluated and the values of phenols, tannin, oxalate and phytate contents were 0.02-0.32, 0.04-0.53, 0.11-4.32 and 0.20-1.05mg/100g, respectively. The predominant alkaloids in trifoliate yam flour were dioscorine and dihydrodioscorine. The white trifoliate yam flour had higher levels of anti-nutrients than the yellow trifoliate yam flour. Alkaloid contents of trifoliate yam flour increased slightly with delayed harvesting periods. Blanching/soaking method drastically reduced the anti-nutrient contents of trifoliate yam flour than other methods.

Effect of harvesting periods on the chemical and pasting properties of trifoliate yam flour

The effects of delayed harvesting on the chemical and pasting properties of trifoliate yam flour were studied. The tubers were harvested at 7, 8, 9, 10 and 11months after maturity and were processed into flours. Chemical and pasting properties of the flours were determined. White trifoliate yam flour at 11months was significantly different (p<0.05) from other flours in dry matter and fibre contents but the lignin content (1.83%) was not significant different (p>0.05) from yellow trifoliate yam flour at 11months. Amylose and starch contents decreased while the sugar contents increased with harvesting periods. Yellow trifoliate yam flour had higher amylose at 10months while the white trifoliate yam flour had higher starch at 9months and sugar contents at 11months. Potassium and sodium were the major minerals found in the yam with higher values in yellow trifoliate yam flours. Peak viscosity and breakdown decreased while the holding strength and final viscosities increased with harvesting periods. Harvesting trifoliate yam tubers at 7-9months produced flour with high quality and prevents post harvest losses.

Some Physical Properties of Kola Nuts – A Response Surface Approach

Abstract This work studied the effect of drying temperature and duration on some physical and mechanical properties of two varieties of kola nuts using a response surface methodology approach. Physical properties determined were length, breadth, thickness, sphericity, aspect ratio, colour and moisture loss, while mechanical properties were force at break, yield, and peak, deformation at break and peak, energy to peak, energy to break, and yield, and Young modulus. At 5% level of significance, only mass, moisture loss, and sphericity were the physical properties affected. However, all measured mechanical properties were affected by drying temperature and duration (p<0.05).

Nutritional quality and essential oil compositions of Thaumatococcus danielli (Benn.) tissue and seed

Nutritional quality and essential oil compositions of Thaumatococcus danielli (Benn.) tissue and seed were determined. Oil was extracted from the seed using standard methods while the fatty acids of the oil, chemical and anti-nutritional properties of defatted seed flour were determined. Total fat yield of the seed flour was 12.20%. Defatted seed flour had higher crude fibre (36.92%), carbohydrate (40.07%) and ash (8.17%) contents. Major mineral contents were potassium, calcium, sodium and magnesium. The tissue contain appreciable amount of vitamin C (8.10 mg/100 g). Oleic acid (42.59%) was the major fatty acid in the seed oil and the total unsaturated fatty acid was 62.38%. The seed oil had higher acid and saponification values and low iodine value. Oxalate (11.09 mg/100 g) content was the major anti-nutrient in the defatted seed flour. Defatted T. danielli seed flour serves as good source of dietary fibre and energy.

Physical and Functional Properties of Trifoliate Yam Flours as Affected by Harvesting Periods and Pre-treatment Methods

The physical and functional properties of trifoliate yam flours processed using different pre-treated methods at varying harvesting periods were examined. The flours were subjected to physical (bulk density) and functional (water absorption, solubility and swelling power) analyses. The bulk density values for the trifoliate flours ranged from 0.54-1.03 g/cm3. The parboiled flours had higher bulk densities in both cultivars of trifoliate yam flour. The parboiled white trifoliate yam flour harvested at 10 months had higher water absorption capacity (4.52 ml H2O/g) and was significantly different (p>0.05) from other flours harvested at other periods. Soaked (60°C) flours harvested at 11 months had the least solubility (3.49%) while the parboiled trifoliate yam flour had higher solubility. At 60-80°C, parboiled flours had higher swelling power values than the other flours while at 90°C, the raw flours harvested at 7 and 9 months had higher values which was significantly different (p<0.05) from other flour samples. The physical and functional properties of trifoliate yam flours were more dependent on the pre-treatment methods rather than the harvesting periods.

Optimization of oil extraction from giant bushel gourd seeds using response surface methodology

Abstract Gourd seeds have been identified as a source of edible oil, but there is sparse literature on the effect of processing factors on the characteristics of oil extracted from any Lagenaria spp. Optimization of oil extraction with the aid of expeller was achieved by applying response surface methodology. The variables were roasting temperature (87.70–172.0°C) and roasting duration (7.93–22.07 min), while the responses were oil yield and oil quality (free fatty acid, color, specific gravity, saponification value, moisture, and refractive index). Data obtained were analyzed at P < 0.05. Roasting conditions significantly influenced all the responses at P < 0.05. The optimum roasting condition was 100°C for 20 min, which gave 27.62% oil yield with good quality attributes (free fatty acid: 0.61%, color: 3.47 abs, specific gravity: 0.90 g/mL, saponification value: 289.66 mL, and refractive index: 1.47).

Effect of freeze–thaw cycles on the nutritional quality of some selected Nigerian soups

Abstract Freezing and thawing are heat transfer processes, involving chemical changes which may greatly affect product quality. Due to sparse literature on freeze–thawed cycles and its effects on soups quality, the effect of freeze–thaw cycles on the nutritional quality of selected Nigerian soups has to be investigated. Soups (Ila, Ewedu, Ogbono, and Kuka) were prepared using standard recipes. The soups were packaged in plastic and aluminum containers, frozen at −20°C, and thawed with microwave oven, hot water (100°C), and at ambient condition for four cycles of 5‐day interval. After each cycle, chemical compositions of the samples were determined using AOAC methods. Data were analyzed using ANOVA at P = 0.05. Moisture, protein, fat, crude fiber, ash, and carbohydrate contents of the freeze–thawed soups were 63.6–88.6%, 3.6–8.8%, 1.0–6.1%, 0.8–1.2%, 1.8–4.6%, and 0.9–15.6%, respectively. Mineral contents were iron (5.0–6.8 mg/100 g), calcium (68.1–190.8 mg/100 g), sodium (144.4–231.7 mg/100 g), potassium (200.4–302.1 mg/100 g), and phosphorus (228.0–337.2 mg/100 g). Vitamins were vitamin A (29.5–59.9 mg/100 g), vitamin B (10.1–36.4 mg/100 g), and vitamin E (28.4–90.2 mg/100 g). Microwave‐thawed plastic soups had limited nutritional losses when compared with other thawing methods, and should not be extended beyond the third cycle because of increasing reduction in fat and protein, indicating deterioration.

Determination of Energy and Time Requirement for Cooking Pigeon Pea (Cajanus cajan)

Purpose: High energy requirement and long cooking time are limiting consumption of pigeon pea (Cajanus cajan), a nutritious food. This study was performed to estimate energy and time demand by different methods of cooking pigeon pea. Methods: Pigeon pea (150 g) was soaked in 2.0 L of water at ambient temperature (29 ± 2°C) to determine hydration behavior. Cooking experiments were conducted using aluminum and pressure-cooking pots. Efficiency of cooking was evaluated using four types of cooking appliances (kerosene, liquefied petroleum gas (LPG), electric, and charcoal stoves). Normal (continuous heating until the food was satisfactorily cooked) and control (controlling the energy input to closely match the actual energy required) cooking were conducted. Energy requirement and duration of cooking were determined using standard procedures. Results: Soaking increased moisture content from 11.99 to 30.01% in 90 min, while water absorption rate decreased with soaking duration. In cooking 150 g of pigeon pea using kerosene stove, presoaked normal pressure-pot cooking method consumed the least energy (10 800 kJ) and time (205 min), while unsoaked normal cooking consumed the highest energy (18 450 kJ) and time (336 min). Using LPG stove, unsoaked normal cooking method required the highest energy (52 470 kJ), while presoaked control pressure-pot required the least energy (14 405 kJ). For electric stove, the lowest energy (15 560 kJ) and shortest duration (105 min) were recorded during control cooking of presoaked sample in the pressure-pot. Conclusions: Control cooking was not practicable using charcoal stove. Generally, kerosene stove consumed the least energy, while electric stove was found to have the shortest duration of cooking.

Evaluation of colour in white and yellow trifoliate yam flours in relation to harvesting periods and pre-processing methods

Colour is one of the important sensory properties that determine the acceptability of food products. Therefore, this work determines the colour in white and yellow trifoliate yam flours in relation to harvesting periods and pre-processing methods. Freshly harvested trifoliate yam tubers were prepared into flour using four pretreatment (untreated, soaking at ambient temperature, soaking at 60 o C and parboiling at 98 o C±2) methods. The flour colour was analyzed and the whiteness index was determined. L (brightness) value ranged from 68.90 in parboiled yellow trifoliate yam harvested at 8 months to 96.57 in the raw white trifoliate flour harvested at 9 months. Parboiled trifoliate yams from the two cultivars harvested at 11 months were darker in colour than other flour. Parboiled yellow trifoliate yam flours were significantly ( p >0.05) different from other samples in colour. The intensity of colour of the parboiled yellow trifoliate yam flour was more pronounced than others. However, the colour of the flour became deeper with prolonged harvesting periods and prominent in parboiled samples at 11 months. Keywords: Colour, Harvesting periods, Pre-treatment, White trifoliate yam, Yellow trifoliate yam

Design, Fabrication and Evaluation of a Plantain Roaster

Roasted plantain (boli) is a delicacy in Nigeria. The conventional method of processing this food is crude, stressful and unhygienic. In this work, an electric roaster capable of roasting twenty-one plantain fingers per batch was designed, fabricated and tested. The roaster had two electric heating elements (one at the top and the other at the base of the roaster) supplying power at the rate of 2.4 kW. In addition, moisture release pipe and a temperature regulator were incorporated. The roaster was used to produce plantain, product was compared with roasted plantain prepared using the conventional method to test acceptability. At a p < 0.05 significance level, it was observed that the samples had no significant difference in appearance, aroma, texture and overall acceptability. However, sample at the upper layer of the roaster was significantly different from the other samples in taste. Generally, sample roasted in the lower part of the roaster was most preferred.