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Pigments produced by Monascus purpureus with regard to quality and quantity

PIGMENTS

PRODUCED BY Monascus purpureus WITH REGARD TO QUALITY AND QUANTITY C. U. BRODERand P. E. KOEHLER

ABSTRACT A simple methanolic extraction was used to evaluate intracellular pigments produced by Monascus purpureus NRRL 2897 utilizing different carbon and nitrogen substrates. The colors of the pigment extracts were specified by C.I.E. dominant wavelength and purity as an indicator of the differences in hue and saturation. Media containing maltose as the sole carbon source yielded pigment extracts with the longest dominant wavelength (most red). Glucose and fructose containing media also yielded red pigments. Yeast extract was a superior nitrogen source for production of red pigments. The color specification of water solubilized pigment complexes depended greatly on the ammo acid or protein to which the pigment was associated. Water solubilized pigment complexes were considerably stable to pH changes but did not withstand high temperatures such as would be required for thermal processing.

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INTRODUCTION PIGMENTS are formed in nature in a variety of plants, animals, and microorganisms. Microorganisms are of particular interest because of their present commercial use in producing antibiotics and other organic molecules. Monascus purpureus, a fungus long used in the production of a Chinese food known as ang-kak or red rice, produces red and yellow pigments which promise application to food systems. Until now, most studies involving Monascus purpureus have dealt with cultural conditions affecting mold growth

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W.wdength(nm) Fig, l-Absorbance Monascus purpureus -.-‘ .;ethanolspectra of four organic solvent extracts of 2897:. methanol -..-..-..; chloroform - - - - - -;acetone

and pigment production (Palo et al., 1960; Lilly and Barnett, 1962; McHan and Johnson, 1970; Manandhar and Apinis, 197 1; Lin, 1973; Yoshimura et al., 1975; Carels and Shepherd, 1977). Little emphasis has been placed on characterizing the color of the pigments produced by Monascus purpureus under different cultural conditions. This study

explores variations in cultural conditions as they affect color quality and quantity. A brief look at the stability of the pigments under different pH conditions and heat reveals the type of food systems in which Monascus pigments might be applicable. EXPERIMENTAL OF FIVE Monascus species screened, Monascus purpureus NRRL 2897 was the most potent pigment producer and was used throughout the study. Erlenmeyer flasks (250 ml) containing 50 ml of liquid media were used to study growth variations with different carbon and nitrogen sources. The carbon sources, glucose, sucrose, fructose, maltose, galactose or ethyl alcohol were individually added to 50 ml of distilled water containing 2% yeast extract to make final concentrations of 2, 5,8, 10, and 15% of each carbon source. The nitrogen sources, polypeptone, tryptone, yeast extract, NaNO,, NH, NO,,

and urea were

added to make final concentrations of 0.2, 0.4, 0.8, 1.6, and 3.2% in media containing 5% glucose, 0.1% KH,PO,, 0.5% MgSO, .7H, 0 and 0.1% CaCl, *2H, 0. All media were inoculated by the addition of 5 mm discs taken from 14-day old cultures grown on media containing 2% yeast extract, 10% sucrose, and 2% agar. Cultures were incubated 14 days at 28’ C in total darkness to allow for full color development. Selection of solvent for pigment extraction Four grams of oven-dried myceha produced by Monascus purpureus 2897 were ground in a micromill grinder for 1 min and divided into l-g lots. Twenty-five ml of four different solvents (chlo roform, ethanol, methanol, and acetone) were added to the individual ground mycelia samples. The solvent and powdered mycelia were shaken vigorously for 1 mm, allowed to stand for 15 min, and filtered through Whatman#l filter paper before determining the absorbance on a double beam spectrophotometer. Extraction of pigments for color specification

Author Koehler is with the Food Science Dept., Univ. of Georgia, Athens, GA 30602. Author Broder, formerly of the University of Georgia, is now with the Dr. Pepper Co., Box 5086, Dallas, TX

75222. 0022-1147/80/0003-0567$02.25/O 01980 Institute of Food Technologists

Mycelial mats were filtered and dried at 80°C for 24 hr. The dried mycelium was then blended with 20 ml of methanol in a 50 ml Sorvall Omni Mixer cup at l/2 maximum speed for 2 mm. The blended mixture was filtered and absorbance readings were taken on a Bausch and Lomb Spectronic 20 calorimeter. For concentrated solutions, the absorbance of an appropriate dilution was determined and the absorbance of the full-strength extract was calculated. Color determinations and specifications on mycelial extracts were made with a Color Eye, Signature Model, using standard 1 cm depth, glass cuvettes. A HunterLab Colorimeter D25A-2 was employed for reflectance specifications. Reflectance readings were taken by filling 1 cm depth glass cuvettes with mycelial extracts and tightly sealing the cuvettes in order to place them on their side against a white plate. The HunterLab instrument was equipped with a digital display capable of giving both L, a, b and C.I.E. X, Y, 2, specifications. Preparation of water soluble monascus pigment

Water soluble Monascus pigments were prepared following procedures developed by Yamaguchi et al. (1973). The ammo acids

Volume 45 (1980)-JOURNAL

OF FOOD SCIENCE-567

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

Pigments produced by Monascus purpureus with regard to quality and quantity

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