Morphological characteristics and physicochemical properties of bakery shortening produced from interesterified blend of Allanblackia, African walnut and fluted pumpkin seed oils

Abstract

The objective of this work was to evaluate the morphological characteristics and physicochemical properties of bakery shortening produced from inter-esterified oil blends from Allanblackia (Allanblackia floribunda), African walnut (Tetracarpidium conophorum) and fluted pumpkin (Telfairia occidentalis) seeds. Oils were extracted using hot water floatation methods, blended in the ratio of 60:20:20 (Allanblackia: African walnut: fluted pumpkin seed oil) and interesterified at optimum temperature, time and catalyst concentration of 74.6°C, 46 min and 0.28%, respectively. Bakery shortenings produced with the interesterified oils, non-interesterified oils, commercial bakery shortenings (local and imported) gave melting point of 32.53, 33.47, 42.70 and 40.10°C, respectively. Specific gravity and viscosity ranged from 0.9117 to 0.9377 and 21.75 to 38.19 cSt, respectively. Refractive index and smoke point of the interesterified shortening were significantly (p<0.05) higher than the non-interesterified and the commercial bakery shortenings. Percentage Free fatty acid was significantly (p<0.05) low (0.08%) for interesterified shortening and higher iodine value of 75.91g/100g. Presence of heavy metals such as mercury, arsenic, cadmium and lead (Hg, As, Cd, Pb) which has health and environmental implications were negligible. Great variation in microstructural morphology were apparent between all the bakery shortenings. Use of African walnut and fluted pumpkin seed oils for bakery shortening production is highly recommended based on their high content of polyunsaturated fatty acids (omega-6 and omega-3).