Enhancing separation efficiency and functional properties of starch and protein from air-classified starch-rich pulse flours using wet extraction
Date
2024-09-27
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Masters
Abstract
Starch-rich pulse flours are recognized as an underutilized and low-value by-product from air classification of pulses, mainly due to the presence of impurities (e.g., proteins, dietary fibers, flavor and aroma compounds) that limits their industrial use. Therefore, this study aimed to develop an effective wet isolation method that can further separate starch and protein from starch-rich pulse flours. Alkaline extraction was performed on air-classified starch-rich faba bean and pea flours over a range of pH (8.5, 9.5, 10.5, and 11) and temperature (25, 30, 40, and 50 °C) to identify the optimum pH and temperature combinations to extract starch and protein with maximum yields and purity. The techno-functional attributes of the isolated starches and protein isolates were compared with those of commercial pea starch and protein isolate, respectively, to evaluate the effect of alkaline extraction conditions on proximate composition and functional properties of the obtained starch and protein samples. The pulse starches isolated from the optimum conditions demonstrated high purity with starch content of 95.1-97.2% and low contents of protein (≤ 0.31%) and ash (≤ 0.07%). The granular morphologies of the isolated pulse starches were generally comparable to that of commercial pea starch, but the isolated starches showed more damaged starch granules, particularly for those extracted at pH 11.0 and and 50 °C. Thermal, pasting, and gelling properties of the isolated starches were affected by the extraction conditions, with significant differences observed in gelatinization temperatures and enthalpy changes, pasting temperatures and viscosities, and gel strength. Under the optimum extraction conditions, protein isolates obtained from air-classified starch-rich pulse flours had protein purity of 77.6%-94.0% with less than 5% ash. The surface properties of protein isolates varied with extraction conditions, thereby affecting their functional properties including solubility, emulsion stability, foam capacity and stability, and water-holding capacity and oil-absorption capacity. The findings of this study highlighted the influence of extraction conditions on the purity and techno-functional attributes of the isolated starch and protein components. The comprehensive analysis provided meaningful information for the potential applications of these isolated components in various food and industrial products.
Description
Keywords
Pulses, Wet fractionation, Alkaline extraction, Starch-rich flours
Citation
Degree
Master of Science (M.Sc.)
Department
Food and Bioproduct Sciences
Program
Food Science