ABSTRACT
Like most roots and tubers, taro (Colocasia esculenta) corms
have a short shelf-life due to the high
moisture content, which aggravates their post-harvest losses. They also
contain high amounts of calcium oxalates, limiting their use in food
applications. To help add value and diversify the use of taro corms as well as curb food losses, various strategies have
been proposed, such processing of the corms into flour. This study aimed
at evaluating the total oxalate content and
techno-functional properties of taro flour as affected by the pre-gelatinization conditions (i.e., method and time). Pre-gelatinized
taro flour was prepared by subjecting peeled and cleaned taro corms to roasting
(190°C), boiling
(100°C), and
steaming (100°C) for 10
min, 20 min and 30 min, respectively, for each method, followed by drying at 55°C and milling. Generally, all the properties
of flour were significantly affected by the pre-gelatinization conditions (P < 0.05). The total oxalate
content of the pre-gelatinized taro flour ranged from 33.26 to 76.90 mg/100g.
Pre-gelatinization by boiling significantly reduced the oxalate content
(56.7%), while roasting resulted in the least reduction (36.2%). The flour
colour i.e. L*, hue, and
chroma ranged from 38.47° - 70.30°, 42.64° - 69.43°, and 7.78° - 10.58°, respectively. Roasting resulted in flour with the largest L* (70.30°) and hue angle (69.43°). Boiling also resulted in flour with the highest
bulk density (BD) (0.86 g/cm3)
and the lowest water solubility index (WSI) (9.39%). Steamed flour had the
highest water absorption index (WAI) (3.81
g/g), water holding capacity (WHC) (4.59 g/g), and swelling capacity (SC) (4.86 g/g). This
study shows that pre-gelatinization (i.e. by boiling, steaming or roasting) significantly affects the total oxalate
content and techno-functional properties of taro flour, which in turn
influences its use in other food applications thus increasing the utilization
and production of taro simultaneously.