Direct analysis of anthocyanins-rich Mao fruit juice using sample dilution method based on chromophores/fluorophores of both cyanidin-3-glucoside and pelargonidin-3-glucoside
2017
Sripakdee, T. | Mahachai, R. | Chanthai, S
Anthocyanins are mostly classified as natural colorants in fruit, vegetables and other plant materials. The anthocyanin-rich foods or food products are of interest because of their health benefits. In Thailand, “Mao” (Antidesma thwaitesianum Muell. Arg.) the wild berry fruit with reddish violet pigment at ripening stage are well known as high antioxidants according to anthocyanins and polyphenolics content. Total anthocyanins in some Mao juice samples determined by pH-differential method (AOAC method 2005.02) were ranged between 35.1-578 mg/L Cya-3-glu equiv. and 22.6-357 mg/L PGD-3-glu equiv. depending on their chromogenic absorption. In this study, direct analysis of the anthocyanins in an appropriate diluted juice was developed attributing for the photoextinction of chromophores/fluorophores of the two standards by UV-Visible and fluorescence spectrophotometry. Concerning on their spectral characteristics of Cya-3-glu and PGD-3-glu, both of their calibration curves were constructed resulting in similar trends of the pigments determined, but gave too high contents according to its dilution factor, compared with those of the standard method. In fact, since their dilution factor and recovery study are certainly validated, the developed methods are undoubtedly sensitive, even if, due to negligibly biased spectral interferences. Advantage of the specific extinction of any major anthocyanins in the juice samples with at least 103-fold dilution factor is, therefore, unexpectedly reported.
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