Berries anthocyanins

Prior, R.L. Wu, X. Gu, L. Hager, T.J. Hager, A. Howard, L.R. 2008. Whole berries versus berry anthocyanins interaction with dietary fat levels in the C57BL/6J mouse model of obesity. J. Agric. Food Chem. 56 647-653. 

Nurmi, T. Mursu, J. Fleinonen, M. Nurmi, A. Fliltunen, R. Voutilainen, S. 2009. Metaholism of berry anthocyanins to phenolic acids in humans. J. Agric. Food Chem. 57 2274-2281. 

Anthocyanins belong to the flavonoid derived phytochemicals. In common berries, anthocyanins act mainly as red to purple pigments. Anthocyanins were shown to be potent anti-oxidants, hence the interest in anthocyanins as functional food ingredients is continuously increasing. Anthocyanin extracts prepared from red/blue berry varieties gained much consumer attraction as health-promoting dietary supplements. 

Consequently, detailed knowledge of the chemical properties of anthocyanins occurring in berries and of analytical methods used are important to judge the quality of anthocyanin extracts from berries. The following overview introduces the chemistry of berry anthocyanins and their occurrence in individual berries, addresses all relevant topics of anthocyanin analysis, substantiate the need to replace simple by sophisticated methodology and proposes a sequence analytical methods for quantitative and qualitative analysis under routine conditions. 

Find on the following Table 1 the commonly used berry anthocyanin sources and their botanical classification. 

Anthocyanins and anthocyanidins are stable as chloride salts in solid state preferably stored at frozen conditions. Berry anthocyanins are excellent soluble in water and polar organic solvents. In case of anthocyanidins, water solubility is limited therefore polar organic solvents (ethanol, methanol or acetone) are preferred solvents for anthocyanidins and anthocyanins. 

Alternatively berries can be freeze dried prior to extraction. Dried, berry anthocyanin extracts are dissolved in methanol or ethanol containing 0.1-2.0 % cone. HCl, kept for 5 minutes in an ultrasonic bath and finally cleared by filtration. Deny juice is best acidified with HCl (0.1-2.0 %) for stabilization and diluted with an appropriate solvent. If anthocyanins are extracted from dietary supplements or from processed food products (i.e., beny jam or ice cream), repeated extraction with mixtures of polar organic solvents and aqueous acids is usually appropriate. The aqueous part is most often necessary for dissolution of the other ingredients (e.g., sugars, proteins). 

Purification of anthocyanins extracted fi om berries is not deemed necessary if measurement of UV/VlS-absorption (>500 nm) for quantification is used. Except in cases of adulteration with red or blue food colorants the measurement wave lengths are selective enough to quantify anthocyanins in crude extracts. If berry anthocyanins are extracted from complex matrices (dietary supplements or food products) removal of other ingredients extracted is advantageous [125, 126]. For structural elucidation, for the analysis of the specific glycosidation/acylation pattern or the requirement to enrich anthocyanins from low content sources, crude extracts need to be purified and eventually fractionated [63, 67, 114, 118, 127-131]. 

HPLC is the method of choice to confirm the distribution/occiurence of individual anthocyanins hence HPLC is most often conclusive for the evaluation of source material and product quality. HPLC is mandatory for berry anthocyanin analysis especially for extracts claimed to stem from a specific berry source. 

Table 13. Typical mass fragments for typical berry anthocyanins obtained...

On basis of the published literature presented in this chapter and with our own practical experience gathered, we developed following approach for accurate and reliable anthocyanin analysis in berries, berry extracts and products containing berry anthocyanins. 

The metabolism of berry anthocyanins resulting in phenolic acids in humans was recently studied [63]. The main anthocyanin metabolites detected were homovanillic and vanillic acids. 

Increasing evidence supports an effect of berry anthocyanins in vascular protection through reduced lipid peroxidation, anti-inflammatory... 

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