Proposed Benchmark Methods for Analyzing Acai (Euterpe oleraceae Mart.)

Robert      E. Smith; Janete      Eaker; Kevin      Tran; Cynthia      Smith; Douglas      M. Monroe; Ellen      M. da Silva Menezes; Armando      U. O. Sabaa-Srur; Rensheng      Luo; Wei      Wycoff; William      H. Fales

Abstract

Methods are proposed for analyzing acai. They start with gravimetric methods for total lipids and insoluble solids, 1H-NMR to determine the relative distribution of the types of lipids, CPMAS 13C-NMR to analyze insoluble solids, and ICP-AES to measure the amounts of total Ca, Mg, K and P. The ratio of K to Ca can be used to distinguish between acai products and grape juice. These methods were used to analyze samples. The total lipids were 46.7±2.5%, as triglycerides. The triglycerides contained 24.8±2.8% saturated fatty acyls, 66.1±2.8% mono-, 7.58±0.52% di- and 1.46±0.05% omega-3 unsaturated fatty acyls. A CPMAS 13C-NMR spectrum of the insoluble solids contained peaks due to C=O and/or phenolic carbons, aromatic carbons, glycosidic carbons and aliphatic carbons, with chemical shifts and peak sizes that were different from those of other types of insoluble fibers. HPLC and LC–MS/MS found cyanidin-3-Oglucoside and cyanidin-3-O-rutinoside. Anion chromatography found lactate, acetate, formate, galacturonate, chloride, sulfate, malate, oxalate, phosphate, inositol hexaphosphate (phytic acid), citrate and isocitrate. No Salmonella, coliform bacteria, pesticides, herbicides, fungicides or industrial chemicals were found in genuine Brazilian acai.

Keywords: Acai, triglycerides, NMR, ion chromatography, phytic acid, potassium, calcium, pulp, aroma, magnsium