Abstract:
The aim of this research was to study the effect of physical factors to 2- acetyl-1-pyrroline(ACPY) production, the major compound contributing to the aromatic rice flavor. Seven strains ofA. oryzae were investigated for their ability to produce ACPY in a synthetic liquid medium, Syn 18.ACPY was analyzed and quantified by gas chromatographic method. Aspergillus oryzae TISTR3256 revealed higher ACPY production than the other fungus strains previously reported,Acreminuim nigricans and Aspergillus awamori TIRST 3379. Consequently, the effect of thefollowing physical factors on ACPY production by A. oryzae TISTR 3256 were studied with fullfactorial experimental design; 4 levels of temperature (25, 28, 30, 35'~), 3 levels agitation (150,200, 250 rpm) initial pH (4.5, 5.5, 6.5), and spore concentration (1.5X109, 2.5x109, 3.5~10'sporesll). The level of ACPY concentration was shown as dilution unit obtained by using sensorymethod. Statistical analyses showed that all physical factors studied significantly affected ACPYproduction at 95% level of confidence (p<0.05). The average dilution unit of ACPY in each groupof physical factors studied was 306.07,272.89, 398.22, and 318.74 at 28'~, 200 rpm, initial pH 5.5and spore concentration 2.5X 10' sporesll, respectively. The highest dilution unit of ACPY,896, wasobtained at optimal conditions of 28'~, 200 rpm, initial pH 5.5 and spore concentration 2.5X 10'sporesll. The equation fitted model for ACPY production yielded from response-surfaceoptomazation was Y=-1.3757.1+477.83x3+4.88x2+2148.27x3+626.99x4-7.33xกำลัง2+0.02x2กำลัง2-190.94x3กำลัง3-108.27x4กำลัง2+0.003x1x2-4.68x1x3+0.19x2x3+0.10x2x4-11.66x3x4