Physicochemical Characterization of Alocasia macrorrhiza Corm Flours as Affected by Thermal Processing

Alocasia macrorrhiza, an underutilized corm, can play an important role in food security. High moisture content and acrid flavor are two major problems of corms that can be overcome by converting into flour after applying thermal processing which alter the flour properties. Therefore, this study aimed to evaluate physicochemical properties of flours as affected by thermal processing. After milling raw, boiled and roasted corm into flour, they were subjected to proximate and mineral elements analysis. Then granular morphology, particle size, and color of flours were analyzed. Carbohydrate (76.96±0.16%-79.57±0.08%), protein (2.75±0.07%-2.82±0.21%), and moisture contents (9.10±0.03%-11.89±0.52%) showed a significant difference between the samples while fat (0.90±0.03%-0.91±0.01%), ash (3.39±0.11%-3.73±0.02%), and fiber contents (3.76±0.19%-3.91±0.35%) were not significantly affected by thermal processing of corm. Thermal processing increased sodium (1.45 to 2.44-2.99 mg.100 g^-1), potassium (145.27 to 159.85-193.13 mg.100 g^-1), calcium (234.04 to 244.44-269.28 mg.100 g^-1), iron (16.99 to 17.69-18.32 mg.100 g^-1), and zinc (7.26 to 8.91-10.45 mg.100 g^-1) contents of flours. The water activity of flours was ranged from 0.25±0.01 to 0.58±0.01 which was safe from microbial growth. Flours were slightly acidic according to the pH values (5.67±0.02-6.05±0.03). Both raw and processed corms produced gluten free flours. Color analysis results revealed that boiled corm flour was the brightest flour and the highest whiteness index was recorded for raw corm flour followed by the wheat flour. The particle size of flours (1.050-1.527 μm) were not significantly changed by thermal processing of corms. The scanning electron micrographs revealed corm flours have irregular shaped granules and the poor protein network when compared to the wheat flour. In conclusion, processed corm flour can play an important role in human nutrition and boiled corm flour has shown the better physicochemical properties.