Abstract:

Isoelectric point (pI), denaturation temperature, amino acid composition, and molecular weight of taro protein
isolates were studied in this research. The results showed taro protein isolates had two main pI bands near 6.73 and
5.21, accounting for 16.36% and 27.30% of the total proteins, respesctively. Sodium dodecyl sulfate-polyacrylamide gel
electrophoresis (SDS-PAGE) analysis indicated that taro protein isolates were mainly composed of four subunits with
relative molecular weights distributed around 57 000, 46 300, 34 200 and 8 500 D. A new band having a molecular weight
of about 23 100 D appeared with added mercaptoethanol suggesting that taro protein isolates had disulfide bonds between
subunits. Differential scanning calorimetry (DSC) analysis confirmed that denaturation temperature of taro protein isolates
was (71.3 ± 0.2) ℃ with an enthalpy change (ΔH) of 1.550 J/g. Amino acid analysis demonstrated that the contents of
non-polar and polar amino acids were 37.26% and 62.74%, respectively. The content of essential amino acids except for
tryptophan was 39.02% and the content of semi-essential amino acids for very young children was 9.9%.

Key words: taro protein isolates, isoelectric point, denaturation temperature, amino acid composition, molecular weight