Chemical composition and consumer acceptability of oyster mushroom and sorghum-pearl millet based composite flours

Abstract

Due to over-reliance on starchy staple foods in Kenya Micronutrient deficiency (MD) and Protein Energy Malnutrition (PEM) are the major nutritional concerns. Despite these foods being characterized by low nutrient densities, they are still used as main food ingredient especially in making porridges. Therefore, this study intended to develop composite flour of sorghum-pearl millet blends fortified with oyster mushroom and further evaluate its chemical composition and consumer acceptability. The sorghum and pearl millet were soaked in tap water then solar dried followed by milling into flour. Oyster mushrooms were also solar dried and milled. Subsequently, oyster mushroom was substituted to sorghum-pearl millet blends at 10–50 % to achieve the composite flours. Proximate composition of the samples was determined using standard methods, Inductively Coupled Plasma Optical Emission Spectroscopy and Ultra Performance Liquid Chromatography Ultraviolet Spectroscopy/Mass Spectrometry were used for mineral and vitamin analyses, respectively. In addition, consumer acceptability test was done on thin porridges was also carried out using untrained panelists. Protein content of the composite flours increased from 11.15–19.74 %, and there were significant increases in fiber (2.68–10.66 %) and ash (1.38 % to 5–79 %). Mineral content increased with Ca, P, Na, K, Mg, Zn and Fe as high as 286.25 mg/100 g, 2088.05 mg/100 g, 167.55 mg/100 g, 1833.05 mg/100 g, 136.75 mg/100 g, 4.22 mg/100 g and 9.46 mg/100 g respectively. An improvement of B1, B2, B3, B6 and B9 vitamin contents was also observed. Sensory analysis showed relatively moderate overall acceptance of thin porridges from the composite flours, although the acceptability decreased with the increase in oyster mushroom. Specifically, composite flour with 50% oyster mushroom was rich in most nutrients but it had the lowest scores for the sensory attributes. In conclusion, addition of oyster mushroom increased the overall nutritional composition of local cereal based staple foods an indication of potential solution to PEM and MD.