Studies on Development of Value Added Products from Sweet Potato and its Quality Evaluation during Storage

Abstract

The present investigation was carried out to develop sweet potato (Ipomoea batatas (L.)) and flax seed flours and development of cookies and dhokla based on these flours. The analysis of flours was done to evaluate the physico-chemical properties of flours, functional properties of flours as well as composite flour and color characteristics of composite flour used for baking of cookies. Experiments were also carried out to evaluate the physical properties, chemical properties, color characteristics, microbial quality and sensorial quality of cookies and dhokla. Cookies were prepared by blending the wheat flour with sweet potato and flaxseed flours in the ratios of T0 (90:0:10), T1 (80:10:10), T2 (60:30:10), T3 (40:50:10), T4 (20:70:10) and T5 (0:90:10) respectively while dhokla were also prepared from the semolina, sweet potato and flaxseed flours blending together in the ratios of T0 (95:0:5), T1 (75:20:5), T2 (55:40:5) and T3 (35:60:5) respectively. After preparation, cookies were stored in aluminium laminated pouches and dhokla were stored in PET jar for storage studies. The physical properties and color index (L*, a*, b* values) of cookies and dhokla were determined just after preparation. However, the physico-chemical and sensory quality attributes of value added products were determined just after preparation and during storage period of 90 days for cookies and 7 days for dhokla under ambient conditions. During storage of flours, moisture content, titrable acdity and optical density increased while pH, protein, fat, fiber, carbohydrate and ash content decreased during storage. During storage of cookies, highest moisture content, pH, fiber, optical density and carbohydrate was found in T5 cookies incorporated with 90% sweet potato and 10% flaxseed flours and lowest was in control samples (90% wheat and 10% flaxseed flours). The protein and fat content was observed maximum in control samples and minimum in case of T5 sample having 90% sweet potato and 10% flaxseed flours incorporated cookies and ash content was observed maximum in T4 sample having wheat flour 20%, sweet potato flour 70%, flaxseed flour 10% and minimum in case of T5 sample having 90% sweet potato and 10% flaxseed flours incorporated cookies. During storage of dhokla, moisture content, ash, carbohydrate and fiber was found maximum in case of dhokla incorporated with semolina 35%, 60% sweet potato flour and 5% flaxseed flour and minimum in control samples (95% semolina and 5% flaxseed flours). The protein and fat content was observed maximum in control samples and minimum in case of semolina 35%, 60% sweet potato and 5% flaxseed flours incorporated dhokla. Our findings showed that on the basis of sensorial analysis, the overall acceptability of cookies and dhokla was decreased with storage period. As per composition of flours, the T3 composition (incorporated with 40% wheat flour, 50% sweet potato flour and 10% flaxseed flour) in cookies and the T1 composition (incorporated with 75% semolina, 20% sweet potato flour and 5% flaxseed flour) of dhokla had highest overall acceptability score and were more acceptable by the panel