Fermentation and quality of yellow pigments from golden brown rice solid culture by a selected Monascus mutant

摘要

A single peak (λmax 370) yellow pigment-producing mutant derived from Monascus sp. TISTR 3179 was used for the pigment production in solid rice culture. Various factors affecting yellow tones were investigated. Hom-mali rice variety was the best amongst five Thai local varieties used for fungus culture. It was also better than corn, mungbean, soybean, potato, sweet potato, or cassava tubers. The moisture content and temperature were the key environmental factors affecting the color tones of creamy, tangerine, and golden brown rice solid cultures. The golden brown rice culture gave the highest yellow pigment concentration. Under an optimum room temperature of 28-32 C, an initial moisture content of 42 %, and 7-day-old inoculum size of 2 % (v/w) the maximum yield at 2,224.63 A_(370)U/gdw of yellow pigment was produced. A mellow yellow powder at 550 A_(370)U/gdw could be obtained using spray-drying techniques. The powder had a moisture content of 5.15 %, a water activity value of 0.398, a hue angle of 73.70 (yellowish orange), high lightness (L*) of 74.63, color saturation (C*) of 28.97, a neutral pH of 7.42, 0.12 % acidity and solubility of 0.211 g/10 ml. It was noteworthy that the Chinese fresh noodle with spray-dried yellow powder showed no discoloration during 8-day storage.