竹芋(Marantha arundinacea)於糯米複合粉之應用

Abstract

Arrowroot (Marantha arundinacea) is an underutilized tropical and perennial tuberous plant much valued in the food industry for its easily digestible starch. Due to its high (＞85%) starch content, arrowroot has been used in the food industry as thickeners and stabilizers in puddings, sauces, jellies, cakes, and for therapeutic use in broths, as well as a supplement for infants and invalids. Experiments were conducted to evaluate the food processing potential of arrowroot by measuring the physicochemical properties of mixtures of waxy rice flour (WRF) and arrowroot flour (AF) or mucilage (AM) (1, 3, 5, and 7% w/w, dry basis). Proximate analysis indicated that AF contained more than 75% starch and relatively high mucilage (6.2%). Results showed that swelling power (SP) and water solubility index (WSI) tended to increase with increased temperatures and increments of AF and AM. However, WSI was significantly reduced with the addition of AM at temperatures above 85°C. Differential Scanning Calorimetry (DSC) analysis revealed a linear increase on the endothermic profiles (onset, peak, and conclusion temperature) of WRF with increments of AF and AM. A lower addition of 1% AM exhibited significantly higher gelatinization temperatures, while 5% and 7% AF were needed to produce similar results, compared to WRF. RVA analysis indicated that increased concentrations of AM tended to reduce all viscosity parameters but increased pasting temperatures. Addition of AF increased the trough, final and setback viscosities; however, it decreased peak and breakdown viscosities. Freeze-thaw stability tests results showed that the percentages of syneresis, after several freeze-thaw cycles, were significantly decreased with increasing AF addition probably due to the mucilage content in AF. When arrowroot flour (AF) was added to mochi, a popular Taiwanese starch-based snack produced from waxy rice, it exhibited a softer texture, but its original color was slightly altered. Nevertheless, according to the sensory evaluation, mochi made from waxy rice with 7% AF was the most acceptable product. The results indicated that composite flours of WRF-AF or WRF-AM resulted in improved gel thermo-stability with reduced syneresis and stable gels at different temperatures as well as improved texture and overall acceptability of mochi products. Therefore, AF and AM could be considered as an additive in starch-based formulations in order to improve the texture, heat stability, freeze-thaw stability, shelf life, and overall quality of Taiwanese traditional snacks, especially mochi.