Isolation and characterization of a microbial pigment obtained from Serratia marcescens as a natural food colourant

Abstract

The use of naturally sourced pigments in the food industry is limited due to their
instability when exposed to processes and parameters such as light, pH, and high
temperatures. Research has moved towards exploiting pigmented microorganism
as sources of potential natural colorants, with the color red representing the largest
market segment in the color industry, utilized in various food applications. This
study was aimed isolation and characterization of Prodigiosin obtained from
Serratia marcescens for potential application as a food colorant. Optimization
results were achieved by cultivation in lysogeny broth (Lb) at 25ºC for a duration
of 120h at pH 6.5, prodigiosin showed a gradual reduction in pH stability as well
as a rapid change in color upon the addition of respective buffers due to
protonation and deprotonation of respective groups. Instability to light due to
chemical reaction such as oxidation and metal ion loss and instability at high
temperatures was due to destruction of pyrrole group which is responsible for the
reddish characteristic color. Results concluded that prodigiosin would be more
applicable for utilization as a colorant in food applications within a temperature
range of 0 to 20ºC and pH of range 2 to 7.