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 (143.76 mg/100 g fresh weight). The major
betalain pigment characterized was gomphrenin I in ripened
fruits (26.06 mg), followed by intermediate fruits (2.15 mg)
and least in early fruits (0.23 mg) in 100 g 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.