Utilization of Food Industrial Waste for Microbial Color Production

Abstract

newline ABSTRACT newlineColor has always fascinated man and is the most important characteristic in determining the acceptability of commodities especially food. Many artificial food colors in foodstuff, dyestuff, cosmetics and pharmaceuticals pose various hazardous effects and cause damage to vital organs. Natural colors are generally extracted from fruits, vegetables, roots and micro-organisms and are often called as Biocolors . Micro-organisms serve as a potential source of natural colors. Hence, in the present investigations different color producing microorganisms were isolated from different sources viz. soil, spoiled fruits, water etc. The different isolated microorganisms produced different color shades viz. Neisseria sp. (yellow color), Staphylococcus sp. (orange color), Streptococcus sp. (yellow color), Micrococcus sp. (yellow color), and Serratia sp. (pink color). On the basis of morphological, biochemical characteristics and non-pathogencity, the Micrococcus sp. was selected further for molecular identification. However, on the basis of molecular identification the isolated strain (SU4) was identified as Micrococcus luteus and selected as one of the potential micoorganism for microbial colour production. The waste generated from brewery called Brewer s spent grain is used as a substrate for pigment production by Micrococcus luteus. The highest biomass yield (5.30 g/l) and carotenoid production (24.43 mg/100g) was recorded when the Micrococcus luteus was grown on media with pH 6, containing 40 g/l brewer s spent grain (BSG) along with peptone (3 g/l), yeast extract (2.5 g/l), agar (30 g/l) and NaCl (5 g/l), at a temperature of 37°C for a period of 96 hrs. The addition of sucrose as carbon source at a concentration of 0.3 per cent and sodium nitrate (0.5%) as nitrogen source also enhanced the pigment production by Micrococcus luteus. Further, pigment extracted from the selected microorganism showed maximum solubility in methanol as solvent with absorption at 436 nm. The three functional groups and two carotenoid pigments indentified were belonged to canthaxanthin and xanthophylls groups. The extracted pigment showed maximum (28 mm) zone of inhibition against E. coli followed by Pseudomonas aeruginosa (26 mm). The pigment extracted has also shown higher antioxidant activity (88.07 %). Among the different chemicals tried, for chemical modification of microbial pigment to water soluble pigment, p-amino benzoic acid was found best with a conversion of 70 per cent. The storage stability of Micrococcus luteus pigment in RTS drink based model solution showed maximum stability at both temperatures (68.5°C and 121°C) and pH (4 and 6) with minor losses at higher temperature. Further, the pigment was also more stable under dark conditions of storage then day light. newlineKeywords: Biocolors, microorganisms, brewers spent grain, pigments, storage stability.