Microbial production, pigments

Dufosse, L., Microbial production of food grade pigments. Food Technol. BiotechnoL, 44, 313, 2006. 

Several pigments, vitamins and coenzymes like carotenoids, riboflavin (B2), cobal-amine (B12), ascorbic acid (Q, ergosterol (D2), biotin (H), gibberellin, etc. are produced during the normal metabolism of microorganisms. Microbial production of some of... 

Phenoxazines — The microbial phenoxazines like actinomycins are well-known antibiotics. Actinomycin D produced by Streptomyces anibioticus is an effective antineoplastic agent that inhibits nucleic acid synthesis. The main function of ommochromes is to act as screening pigments in the eyes of insects and other arthropods, as pattern pigments in the integument, and as excretion products of excess tryptophan. ... 

Typical attributes for evaluating food quality are safety, shelf life, color, taste, flavor, texture, health, and convenience. The level of a quality attribute is determined by levels of physical, microbial, physiological, chemical, and biochemical food processes, product composition, and applied technological conditions. For example, a combination of enzyme-degrading colorants, compositions and concentrations of pigments, and food structure properties contribute to a certain color level perceived by consumers. Depending on the match of expectation and experience, certain attributes will or will not be perceived as quality. ... 

Recently, a new polyketide biosynthetic pathway in bacteria that parallels the well studied plant PKSs has been discovered that can assemble small aromatic metabolites.8,9 These type III PKSs10 are members of the chalcone synthase (CHS) and stilbene synthase (STS) family of PKSs previously thought to be restricted to plants.11 The best studied type III PKS is CHS. Physiologically, CHS catalyzes the biosynthesis of 4,2, 4, 6 -tetrahydroxychalcone (chalcone). Moreover, in some organisms CHS works in concert with chalcone reductase (CHR) to produce 4,2 ,4 -trihydroxychalcone (deoxychalcone) (Fig. 12.1). Both natural products constitute plant secondary metabolites that are used as precursors for the biosynthesis of anthocyanin pigments, anti-microbial phytoalexins, and chemical inducers of Rhizobium nodulation genes.12... 

Moisture, impurities, and unsaponifiables (MIU) A summation of the non-acylglycerol materials in the product. Moisture is undesirable because it will support microbial growth and facihtate hpid hydrolysis. Unsaponifiables are any materials that will not saponify (form soap) when incubated with sodium hydroxide. These include sterols, pigments, and hydrocarbons. These are natural components of both animal and plant lipids, but excessive amounts can indicate a sample that will not perform comparably with a sample richer in acylglycerols, and they can indicate adulteration or contamination by petroleum products. 

The incorporation of acetaldehyde derived bridges between anthocyanins and flavan-3-ols via acetaldehyde condensation reactions has been well described in fermented beverages such as red wine. The presence of acetaldehyde in alcoholic solutions is attributed to either oxidatative products of ethanol or microbial byproducts. In the case of cranbeny fruit and spray dried juice neither product was subjected to yeast fermentation. It becomes a concern then that die observed anthocyanin-pigments may be an arti ct of harvest, storage, juice processing or analytic techniques. 

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