Quantificação das antocianinas majoritárias do açaí por cromatografia líquida de alta eficiência

Abstract

Açaí (Euterpe oleraceae Mart) is a fruit with a high energetic and nutritional value that presents high content of phenolic compounds, mainly anthocyanin pigments directly related to its color. Over the past few years the interest on these pigments has been intensified as many scientific studies demonstrate that the anthocyanins and their aglycones are bioactive compounds and they can be related to disease prevention, mainly those caused by cellular oxidation. The food industry has a great interest in technological innovations that attend for of the requirements of the consumer market. The use of membrane processes, particularly microfiltration, represents an option that justifies the investments and researches on this subject. In general, these processes are conducted at room temperature without heat or phase change, preserving the sensory and nutritional quality of the products in addition to the reduction in the energetic costs involved in the process. The objective of this work was to evaluate the content of the main anthocyanins, cyanidin-3-O-glicoside and cyanidin-3-Orutenoside, using high performance liquid chromatography (HPLC) by using standards previously isolated from freeze-dried açai samples, in the clarification of açai juice by microfiltration. In order to decrease the juice viscosity and the pulp content, consequently increasing the efficiency of the process it was introduced two steps before the microfiltration, an enzymatic hydrolysis followed by the juice centrifugation. The use of HPLC allowed the isolation of analytic standards from natural sources with a high purity level more than 97% allowing the quantification of each anthocyanin and its yield in each step of the process. The main anthocyanins isolated were conclusively identified by HPLC and mass spectrometry confirming data reported by other researches about the presence of anthocyanins cyanidin-3- O-glucoside and cyanidin-3-O-rutenoside as major anthocyanins of açaí. This technique can also contribute to the characterization of new matrix , allowing the confirmation of previously published data. The obtained results showed that it is possible to use new matrix to isolate standards and to characterize other samples with confidence and economy. Regarding the microfiltration evaluation, it was possible to quantify the levels of cyanidin-3-O-glicoside and cyanidin-3-O-rutenoside in the feed and permeate fractions, respectively, 37 and 97 μg / 100g for the feed and 15 and 54 μg / 100g for the permeate.