Development and validation of analytical methods for the identification and quantification of phenolic compounds from Euterpe oleracea fruits
(2014)
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- Abstract
- Euterpe oleracea is a widespread palm of the Amazonian floodplains. Its fruits, called açai, have gained much attention because of their phenolic constituents, such as anthocyanins (ATC) and non-anthocyanin polyphenols (NAP) that have shown potential health benefits, associated with antioxidant and anti-inflammatory activities. Quality of açai-based products is one of the greatest uncertainties that consumers, producers, clinicians, regulators and researchers face. In order to promote their quality control and to give them an added value, their chemical characterization is a critical step. The general aims of this thesis were to identify and quantify phenolic compounds in açai fruit extracts and juices. Specifically, the objectives were to develop and validate analytical methods based on UHPLC−PDA−LTQ-Orbitrap MS for the identification and quantification of major ATC and NAP, and apply the methods to samples from different origins. Fruits were harvested in the Brazilian Amazonian region. They passed through different processes of pre-treatment, extraction, and solvent evaporation to produce extracts that were used for the experiments. The sample preparations were improved compared to other published procedures. Complete chromatographic separation of major compounds and several minor ones was reached. Sensitivity of the methods was improved by optimizing the dissolution media of the extracts. A total of 41 phenolic compounds were identified (or tentatively), 7 ATC in fruit extracts and 34 NAP in juices. Among them, 10 compounds were tentatively identified for the first time in these raw materials (2 ATC and 8 NAP). The methods were validated for a total of 14 compounds (2 ATC and 12 NAP) with accuracy profile method, using total error as a decision criterion (β-expectation tolerance interval and acceptance limits being 95% and ±20% for ATC, whereas for NAP they were 90% and ±30%, respectively). Several diagnostic criteria were also evaluated in order to assess the performance of the methods, such as trueness, repeatability, intermediate precision, response function, matrix effect, linearity and selectivity. The application of the ATC method showed similar contents for all samples analysed, which were inferior to the literature data. Contents in NAP showed a significant variability among the different batches of juices and were generally superior to the literature data. Considering the concentration variability of these compounds and the economic importance of these raw materials, the validation of analytical methods is of primordial importance for consumers, producers, and regulatory bodies by providing guarantees on the results. Concretely, this work contributes to give an added value to the products and can be useful for their quality control. Additionally, these methods can be used in the selection of raw materials from different origins, maturity stages, and processings. Finally, these methods could also be a support for pharmacological studies on extracts derived of fruits, because the chemical characterization is a crucial step to better understand their biological effects.
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De Sousa Dias, A. L. (2014). Development and validation of analytical methods for the identification and quantification of phenolic compounds from Euterpe oleracea fruits. https://hdl.handle.net/2078.5/202324