Process optimization and roasting conditions’ influence on the quality of oil from desert date (Balanites aegyptiaca) seed

Abstract

Desert date is widely consumed without the industrial application of its oil-rich seed. Despite the wide distribution of desert date (Balanites aegyptiaca) in tropical Africa, Desert Date Seed (DDS) is yet to be fully explored industrially due to dearth of information on its optimum roasting condition for oil extraction. The response of DDS oil to roasting could influence its application. Hence, process optimization and the influence of DDS roasting conditions on its oil quality using response surface methodology was studied. Desert date seeds were subjected to three roasting temperatures (110°C, 130°C, and 150°C) and roasting time (20, 40 and 60 min). Oil extraction from the roasted DDS was done by standard procedure. The responses obtained were oil yield, Free Fatty Acid (FFA), saponification values, peroxide value, specific gravity, iodine value, colour and oxidative stability. The data obtained were subjected to ANOVA and regression analysis at p < 0.05. The result of roasted DDS oil yield ranged from 16.21 g to 22.59 %, with the oil colour ranging from 0.06 PCI to 0.27 PCI while the specific gravity ranged from 0.91 to 0.94 G/cm. Chemical properties of oil samples were saponification value (178.63–188.09 mgKOH/g), peroxide value (1.70–2.63 Meq/kg), iodine value (67.54–73.64 Wijs), FFA (1.52–2.32 %) and acid value (3.05–4.60 mgKOH/g). Models fitted were significant with a strong positive correlation between roasting conditions and responses. An optimum roasting condition (117.08 °C for 34.422 min) would yield oil with desirable properties, and oxidative stability thereby establishing its use as edible oil with numerous industrial applications.