Characterization of major betalain pigments -gomphrenin, betanin and isobetanin from Basella rubra L. fruit and evaluation of efficacy as a natural colourant in product (ice cream) development.

Abstract

Basella rubra L. (Basellaceae) commonly known as Malabar spinach is a leafy vegetable which accumulates pigments in its fruits. To find out the feasibility of utilizing pigment rich extracts of its fruit as natural food colourant, fruits at different stages were analysed for pigment profiling, carbohydrate content, physical dimensions and weight. Total betalains content increased rapidly from early (green) through intermediate (half-done red-violet) to matured stage (red-violet). Maximum pigment content was observed in ripened fruits (143.76mg/100g fresh weight). The major betalain pigment characterized was gomphrenin I in ripened fruits (26.06mg), followed by intermediate fruits (2.15mg) and least in early fruits (0.23mg) in 100g of fresh deseeded fruits. Total carbohydrates content and the chroma values (redness) were also increased during ontogeny of B. rubra fruits. The textural characters of developing fruits showed the smoothness of green fruits with lower rupture force (0.16 N/s) than ripe ones (0.38 N/s). The pigment-rich fruit extract was used as natural colourant in ice-cream, to evaluate its effect on physicochemical properties and acceptability of the product. After six months of storage at-20°C, 86.63% colour was retained in ice-cream. The ice-cream had good overall sensorial quality and was liked by consumers indicating that addition of B. rubra fruit extract did not alter the sensory quality of the product. The colour values also indicate that there was no significant decrease of this pigment-rich extracts of fruits for its incorporation in food products.