NEAR-INFRARED DIFFUSE-REFLECTANCE SPECTRO PHOTOMETRIC ANALYSIS OF MYCELIAL WEIGHT IN RICE KOJI AND SEARCH FOR CHARACTERISTIC WAVELENGTH FORMYCELIA

Mycelial weight in rice koji was estimated accurately, simply and rapi dly by near infrared diffuse reflectance spectrophotometric analysis ( NIR) with granular cells. The most accurate calibration was obtained b y multiple linear repression analysis using the second derivative (d(2 ) log (1/R)) of absorbance at four specific wavelengths with 2348 nm a s the main one. In this case, multiple correlation of coefficient and standard error of calibration were 0.988 and 0.496, respectively. Pred iction values using this calibration curve were not influenced by prod uction year, variety, polishing ratio or shape of the rice used as the raw material. Certain characteristic wavelengths in the NIR spectrum of cultured mycelia, including 2348 nm, were observed in the spectra o f whole dry koji. Acetone extraction and enzyme lysis of the cell wall of cultured mycelia revealed that absorption at 2348 nm was responsib le for fat in the mycelia of rice koji.