Extraction and Stability of Yellow Pigments from Ginkgo biloba Leaves

To make full utilization of Ginkgo biloba leaf resource,enhance its added value and provide experimental reference for exploration of natural food colorants,critical parameters affecting extraction of yellow pigments from Ginkgo biloba leaves including extraction solvent kind,liquid/material ratio and extraction time and temperature were investigated by orthogonal array design and the light,temperature and pH stability of the product obtained were evaluated.Results indicated that the pigments dissolved in petroleum ether exhibited a maximum absorption at 445 nm wavelength.Four-time extraction for 30 min each time using a mixture of ethyl acetate and petroleum ether(70:30,V/V) as extraction solvent at 40 ℃ and a liquid/material ratio of 25:1(mL/g) gave an optimal yield of yellow pigments of up to 3.0% and the color value of the products obtained was 20.49.The pigments had poor light stability and consequently should be stored in the dark.After 1 h exposure to a temperature below 60 ℃,a low degradation ratio was observed in the pigments,whereas 1 h exposure to 70 ℃ led to a high degradation ratio.The pigments were stable in acidic and alkine media.