Sesame (Sesamum indicum L) is one of the oldest cultivated plants. Its seed contains about 42-54 % quality oil, 22-25 % protein, 20-25 % carbohydrates and 4-6% ash. This composition varies with genetic and environmental factors. Conditioning of oil seeds which include roasting, flaking, size reduction, cooking, pre-pressing and drying, is an important operation in the production line of sesame oil. This work investigated effects of initial moisture content, roasting duration and temperature on initial Peroxide Value (PV) and Oxidative Stability (OS) of unrefined sesame oil using response surface methodology. Goza-25, a variety of sesame seed that is commercially cultivated in Nigeria was used for the study. Initial moisture content levels were 4, 7, 10, 13 and 16 % wet basis (wb). Roasting duration and temperature levels were 5, 10, 15, 20 and 25 minutes, and 50, 70, 90, 110 and 130 o C respectively. The recorded minimum and maximum PV were 3.9 and 15.4 meq/kg respectively. Mean value was 9.85 ± 3.9 meq/kg. Peroxide value increased with increasing moisture content and reduced with increasing roasting duration. Analysis of variance and regression analysis of obtained data showed that application of quadratic model to predict effect of initial moisture content, roasting duration and temperature on peroxide value is significant at p ≤ 0.05. Within the studied range, 13 h was the minimum OS recorded while maximum were 63.3 h. Mean of the data was 38.37 ± 16.02. Using the conversion factor of one hour of an active oxygen hour as being equivalent to 15 days; the expressed sesame oil in its present form will retain its quality for a maximum period of 949 days. Rise in roasting temperature and duration increased the oxidative stability, a reverse was observed with initial moisture content. High moisture content reduced the quality and storage life while heat treatment increased both the initial quality and storage life of the mechanically expressed oil. Peroxide value and oxidative stability of crude sesame oil significantly (p ≤ 0.05) depend on moisture content of the seed, roasting duration and temperature.

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The importance of utilizing oilseeds as complementary nutrient sources for human consumption has received considerable attention in recent years. There exists wide varieties of oil crops including sesame seed (Sesamum indicum L.), which are reported in literature to be rich in oil and nutrients; however, the presence of anti nutritional factors limits its uses. Processing grain using fermentation results in enhanced nutrition, stabilization of original raw materials, and detoxification of anti nutritional factors. There was lack of adequate traditional fermentation containers hence the need for use of some modern containers. This work, therefore, studied the effects of using banana leaf and plastic (high density polyethylene) bowl as containers for fermentation on the nutrients and anti nutritional factors of sesame seed. Samples were fermented separately using banana leaf and plastic bowl for seven days at temperature of 35 ± 2°C. Samples were drawn at intervals during fermentation to determine proximate composition, elemental concentrations and anti-nutritional factors concentrations using standard procedures. The pH decreased in the first 5 days and then increased as fermentation progressed coupled with a consistent rise in titratable acidity. Proximate analysis showed an increase in ash and crude fat contents with corresponding decrease in the carbohydrate and protein contents during fermentation. Protein ranged between 15.25% and 15.37% in banana leaf and plastic bowl respectively, compared to raw seed (26.20%). Fat increased from 51.02% in raw sesame to 60.20% and 59.33% in banana leaf and plastic bowl, respectively. However, fermented samples obtained from the plastic bowl had higher vitamin (thiamine and riboflavin) and minerals (calcium, phosphorus, potassium, magnesium, iron, selenium, zinc and manganese) in comparison to samples fermented in banana leaf. Fermentation in banana leaf and plastic bowl significantly reduced oxalate content of raw sesame by 35.40% and 29.12% respectively. In addition, phytate content was significantly reduced by 36.37% and 34.43% respectively. The present study showed that fermentation container had significant effect on nutritional composition during the fermentation of sesame seed.

Nutritionally, oils obtained from oilseeds provide the calories, vitamins and essential fatty acids in the human diet in an easily digested form. The rate of vegetable oil consumption is increasing compared with animal fat due to its low sterol. In addition to being nutritious, edible vegetable oils also have industrial uses. Separation of oil from oil seeds is an important processing operation because it affects the quality and quantity of oil obtained from the oil seeds. Literature on oil extraction from some cultivars of citrus seeds showed good potential, therefore, focus on optimization of oil extraction could enhance economic status of the seed. In this study, response surface modeling approach was employed to optimize oil extraction from orange (Citrus sinensis) seed. Each sample was roasted for 10, 20, 30, 40 and 50 minutes at temperatures of 110, 120, 130, 150, and 170 oC. The parameters analysed included oil yield, free fatty acid, color, refractive index, specific gravity and pH. The treatments resulted in oil yield ranging from 32.0 ± 2.7 to 56.0 ± 6.5 %, free fatty acid (0.3 ± 0.0 to 3.01± 1.7%), colour (3.45 ± 1.9 to 20.5 ± 1.8 abs), refractive index (1.4 ± 0.1 to 1.46 ± 0.1), specific gravity (0.87 ± 0.1 to 0.94 ± 0.0) and pH (4.05 ± 1.0 to 5.66 ± 1.1). Maximum oil yield of 56.0 ± 6.5 % was obtained after roasting citrus seed at 170 oC for 30 min. Roasting temperature and duration showed significant (p < 0.05) effect on oil yield, free fatty acid, colour and specific gravity of the oil. However, nonsignificant (p > 0.05) effect was recorded on refractive index and pH of the extracted oil. The computer software package (Design-Expert) used for optimization gave four possible optimum conditions with desirability ranging from 0.50 to 0.68. The best desirability (0.68) was achieved at roasting temperature and duration of 150o C and 20 min., respectively. At these conditions oil yield was 52.6 ± 0.1%; free fatty acid, 1.4 ± 0.0%; colour, 4.7 ± 0.0 abs; specific gravity, 0.92 ± 0.0, and pH, 5.4 ± 0.1. The quantity, free fatty acid, colour and specific gravity of extracted oil from orange seed significantly depend on temperature at which the seed is roasted and duration of roasting.