Use of yellow pigment extracted from turmeric (Curcuma longa) rhizomes powder as natural food preservative and colorant

Abstract

This investigation was carried out to extract yellow pigment from powder of turmeric (Curcuma longa) rhizomes by using acetone and hexane solvents (2:3 v/v). Then, concentrated the oleoresin-containing solvent (yellow pigment extract) for development of both liquid                to obtain water-soluble and oil-soluble yellow pigment color. Moreover, evaluate the preservative/antioxidant activity of oil-soluble yellow pigment at concentrations 0.5, 0.1 and 0.2% (w/w) in soybean oil after accelerated oxidation at 65°C for 7 days compared with soy bean oil free from antioxidant (control), with 0.02% butylated hydroxytoluene (BHT)           (synthetic antioxidant). In addition, use of sensory evaluation to select the best ratio of water-soluble yellow pigment at ratios 0, 1, 3 and 5% (w/w) to blend with chicken breast fillet samples for improving the color, flavor and appearance. Then, the results of sensory evaluation showed that the ratio of 3% (w/w) of water-soluble yellow pigment was the best ratio to blend with chicken breast fillet samples. Thus, based on the results of sensory evaluation the effects of combined treatment of water-soluble yellow pigment at ratio 3% (w/w) as natural colorant, antimicrobial and antioxidant and gamma irradiation at dose levels of 1, 3 and 5 kGy on the microbiological, chemical and sensory characteristics of chicken breast fillet samples during cold storage (4±1°C) to extend the shelf-life of chicken breast fillets were investigated. The results revealed that the addition of 0.2% oil-soluble yellow pigment caused detectable increments in the oxidative stability of soy bean oil compared with control and other treatments under investigation. On the other hand, the sensory evaluation of chicken breast fillets samples blended with different ratios from water-soluble yellow pigment (0, 1, 3 and 5% w/w) extracted from turmeric powder as natural food colorant was carried out firstly to select the best ratio improved the color, flavor and appearance. The results presented that ratio of 3% water-soluble yellow pigment were selected for improving color, flavor and appearance compared with the other ratios (1 and 5%). The results showed that the ratio of 3% of water-soluble yellow pigment reduced the total bacterial count, Psychrophilic bacteria, lactic acid bacteria, enterobacteriaceae, total molds and yeasts, Staphylococcus aureus, Bacillus cereus, Enterococccus faecalis and Salmonella spp, was not detected in all treated samples. Also, shelf-life periods were increased 39 days for chicken breast fillet samples treated by 3% water-soluble yellow pigment and gamma radiation at dose level of 5 kGy. Thus, these results illustrate that yellow pigment extracted from turmeric rhizomes exhibit strong antioxidant and antimicrobial activities. Therefore the use of these yellow pigment extracts in food is recommended to suppress lipid oxidation and may be useful as natural food colorant and preservative and an alternative to synthetic dyes that are harmful to health effects.

Key words: Yellow pigment/ Turmeric/ Colorant/ Food/ Preservative.