Degree of Gelatinization of Chinese Noodles Measured by the FT-IR and BAP Methods and Relationship to Physical Properties

Abstract

The gelatinization properties of four kinds of noodles, Japanese (flour and salt water), kansui (flour and kansui), egg (flour and egg white) and egg and kansui (flour, egg white and kansui), were measured by the β-amylase-pullulanase (BAP) method and Fourier-transform infrared spectroscopy (FT-IR/ATR). The peak height at around 1,025 cm⁻¹ of the FT-IR spectra markedly increased with increasing ratio of pre-gelatinized flour. The absorbance at this wavelength reflects an increase in the OH groups which were hydrated due to the gelatinization of starch. There was a high correlation in the degree of gelatinization between the FT-IR method and BAP method, although the value with FT-IR method was slightly higher. This result might have been due to the difference of the remaining protein between the two methods of measurement. There was a high correlation between the values for breaking stress and breaking energy after one day of storage by the FT-IR and BAP methods. This suggests the influence of moisture penetrating inside the noodles which equalized the hardness.