Extraction and Optimization of Anchote (Coccinia Abyssinica) Tuber Starch and Its Application as Stabilizer for Yogurt Production

Abstract

Anchote is an indigenous tuber crop found in the Western and South Western part of Ethiopia. It belongs to the family Cucurbitaceae and the Afan Oromo name for Coccinia abyssinica. Particularly, Anchote is known in Kellem Wollega, Western Wollega, Eastern Wollega, Illu Abba Boora, and Jimma. Starch can be extracted from anchote tuber by chemical method. This study investigates the production of starch from anchote tuber which is underutilized crop and used as indigenous food. The Production of anchote starch from Anchote tuber was done by different chemical solutions such as sodium chloride, sodium metabisulphite, ammonia with different concentrations (0.5, 1 and 1.5%) and control with water. The starch was isolated by cleaning, peeling, cutting into small pieces, wet grinding, filtration, sedimentation, decantation of the supernatant, drying, and the starch yield was recovered. The maximum yield of the starch produced was 20.86% fresh weight basis with a 1.5% sodium chloride solution. The optimum yield of starch was characterized by physicochemical and functional properties. Bulk density, true density, tapped density, Carr’s index, and Hausner ratio of anchote starch were 0.46,1.5,0.65, 23.97, and 1.32 respectively. The X-ray Diffraction result of the starch had the strongest sharp peak diffraction pattern at 17.12° of 2θ angle which indicatesthe B-type starch. The moisture, ash, fat, fiber, protein, total carbohydrate, amylose content, and starch purity were 12.14%, 0.30%, 0.0%4, 1.64%, 1.66%, 83.82%, 17.42%, and 95.6% respectively. The pH of the starch was 7.32 which was almost neutral. The functional properties of anchote starch such as water absorption capacity and oil absorption capacity were 0.17ml/g for both. swelling power and solubility index of anchote starch with increasing temperatures (30, 50, 70 and 90℃) were respectively (1.90, 2.53, 8.10, and 11.65) and (0.31, 0.9, 4.8, and 15.43%). The extracted starch was used as a stabilizer in yogurt manufacturing with different proportions (0.5, 1 and 1.5%). The yogurt produced with 1.5% anchote starch shows good results of pH and syneresis. The titratable acidity and sensory result showed the best result for yogurt prepared with 1% and 1.5% anchote starch