Quality analysis of commercial <Emphasis Type="Italic">Chlorella</Emphasis> products used as dietary supplement in human nutrition

Chlorella vulgaris is one of the best-studied phototrophic eukaryotes. From the 1950s on, C. vulgaris and some other algal species were cultivated in huge quantities to meet the growing demand for alternative protein sources. After drying, algal biomass can be merchandised as tablets, capsules, extract or powder with specific biochemical qualities. However, the products quality, e.g. the containing species, microbial contamination or content and quality of pigments varies enormously. In this study, commercial Chlorella products, unprocessed Chlorella powders and several production strains were investigated. Molecular analysis of the 18S rDNA confirmed either the existence of more than one species per product or only other green algae species in about half of the samples tested. Many of the examined samples contained critical amounts of bacterial contaminations. Furthermore, cyanobacteria were detected in some of the samples. The content of chlorophyll a varied greatly between the samples and pheophytin, a degradation product of chlorophyll, was detected in some samples in large concentrations. These data indicate that quality control of microalgal products is an important issue that should be addressed by the manufactures.