Development of biscuits using sweet potato flour (Ipomoea batatas L.) and evaluation of its physicochemical, microbiological and sensory properties

Abstract

Biscuits are one of the most important food products consumed by people in the world regardless of gender, age, religion, caste, creed etc. Exploring the possibility of using various flour types in biscuit manufacture has been an important research area among scientists in the recent past. Therefore, the objectives of the present study were to explore the possibility of using sweet potato flour in biscuit manufacture and to evaluate its physicohemical, microbiological and sensory properties. Well-mature, peeled off orange color sweet potato pieces (1cm3) were dried at 60°C for 6 - 8 h and flour was prepared using a laboratory grinder (Waring Commercials, Torrington, USA) and a sieve (mesh size = 0.5mm). The recipe for the biscuit dough consisted of flour, butter, milk powder, baking powder, sugar, salt and shortening agents. Biscuit cutter (d = 2 inch) was dipped into the dough to cut round-shaped biscuits. Biscuits were baked in a preheated oven (180°C) (Tesmacks, Hvidovre, Denmark) for 10 - 12 min until a golden colour was observed. Biscuits containing 70%, 80%, 90% and 100% (w/w) sweet potato flour were prepared and were compared with a commercial biscuit sample in terms physicochemical and sensory properties. Moisture content, proximate composition, microbiological and sensory properties of Sweet potato biscuits were determined during storage at 30°C. Sensory properties were determined on a fivepoint hedonic scale with 30 untrained sensory panelists. Sensory results were analyzed using Kruskal Wallis non-parametric ANOVA test with STATISTIX Computer software (Ver 2.0) for windows. Biscuits containing sweet potato flour (90%) and wheat flour (10%) showed significantly higher (P<0.05) overall acceptability. Moisture content of the sweet potato biscuit increased from 8.8% to 11.8% during storage. The proximate composition of the sweet potato biscuit included proteins (11.34%), fat (14.2%), ash (2.8%), fiber (0.48%) and carbohydrates (62.38%). Yeast and mold populations in all the biscuits were less than 102 CFU/g and E. coli was not detected throughout the storage period. Shelf-life of the biscuit was approximately 90 days considering the changes in moisture content and microbiological and sensory properties. Therefore, it can be concluded that sweet potato flour can successfully be introduced to the biscuit industry-in order to develop a novel value-added biscuit with improved sensory and nutritional properties.