Production of natural colorings from monascus purpureus and penicillium purpurogenum: determination of conditions for optimum Yield and stability of the colorings

Abstract

Synthetic food colorings are cheap and they are more stable to environmental changes than natural colorings. Some of these synthetic colorings, however, have been proved to be harmful to human health, and their presence may also pollute the environment. The purposes of this research were to develop natural coloring products that are safe to be consumed, and to preliminarily study the preferred conditions for the production of the colorings. In particula,; the synthesis of two types of natural coloring from two fungi species, Penicillium purpurogenum and Monascus pwpureus fungi has been studied. The result showed that potato extract is the best carbon source for the growth of the fungi, as well as for the production of the coloring from four alternative carbon sources utilized (corn extract, potato extract, glucose, and sucrose). lhe coloring produced by Monascus purpureus has higher red color intensity compared to the coloring from Penicillium pwpurogenum. The colorings produced were further subjected to stability tests to determine their response to several environmental parameters: the presence of light (ultraviolet and sunlight), the presence of heat and pressure (the colorings were autoclaved at I 21 oC, I 5 psi and I 05oC, 17.5 psi), the addition of food preservatives (citric acid, ascorbic acid, and sodium bisulfite) , and the medium acidity (pH). The test showed that the colorings produced are very stable in the presence of food preservatives, but they are sensitive to other environmental parameters (the presence of heat and pressure, light, and pH of the medium).