Use of stable isotopes of carbon to detect coconut water adulteration

Abstract

Industrialized coconut water may have been adulterated by adding sugar above the limit permitted by law. According to Brazilian law, industrialized coconut water can receive the maximum addition of 1 g of sugar per 100 mL of the drink. This work aimed to detect adulteration in industrialized coconut water produced in Brazil and measure the relative isotopic enrichment in fresh coconut water, using the techniques of stable isotopes of carbon. Fresh coconut water samples from 13 locations, industrialized coconut water samples of 17 different brands and cane sugar were analyzed by Isotope Ratio Mass Spectrometer coupled to an elemental analyzer. The relative isotopic enrichment found for fresh coconut water samples ranged from -26.40 to -23.76. From 17 brands of coconut water analyzed, 11 were adulterated by excess sugar and two were already adulterated by presenting soluble solids content higher above the threshold permitted by law. In 65 % of Brazilian industrialized coconut water, the amount of exogenous sugar is higher than the limit permitted by law. Most Brazilian companies do not respect the legal limit of adding cane sugar established by law.

Comparison between isotope ratio mass spectrometry (IRMS) and cavity ring‐down spectroscopy (CRDS) for analysing the carbon isotope ratio and detection of adulteration in coconut water

“…Carbon-13 isotope values of almost all natural coconut water collected from different regions of Thailand varied between −26.0‰ and −23.5‰ (Figure 2) which fell within a natural range of C3 plant-derived products (−37‰ to −21‰) (O 'Leary, 1988). These values agreed well with a study of Brazilian coconut water (−26.5‰ and −23.7‰) reported by Imaizumi et al (2019). In addition, the δ 13 C values from different regions were significantly different within some provinces; however, there was no significant difference between regions of Thailand.…”

“…In addition, the δ 13 C values from different regions were significantly different within some provinces; however, there was no significant difference between regions of Thailand. Similarly, the Imaizumi et al (2019) study reported no relationship between δ 13 C value and latitude of harvesting area.…”

Selected Instrumental Techniques Applied in Food and Feed: Quality, Safety and Adulteration Analysis

“…In this scenario, bees will be more likely to collect nectar and pollen, for their honey production, from C3 flowers and hence will exhibit a different 13 C/ 12 C ratio (or δ 13 C) than those derived from the C4 pathway [ 210 ]. An analogous principle is used during coconut water adulteration with sugar [ 211 ].…”

“…In this scenario, bees will be more likely to collect nectar and pollen, for their honey production, from C3 flowers and hence will exhibit a different 13 C/ 12 C ratio (or δ 13 C) than those derived from the C4 pathway [210]. An analogous principle is used during coconut water adulteration with sugar [211]. Coffee IRMS-based analysis includes Arana and coworkers [212], who assessed the carbon ratio of coffee from Colombia and compared it to "fingerprints" from other nearby countries.…”

Classification of organic and ordinary kiwifruit by chemometrics analysis of elemental fingerprint and stable isotopic ratios

“…In recent years, element fingerprints and stable isotope ratio methods have been widely used in food traceability (Choi et al., 2020; Gonzalvez et al., 2009) and proved to be powerful tools to classify geographical origins (Cantarelli et al., 2011), cultivars, species, and frauds (He et al., 2020; Zhang et al., 2020; Imaizumi et al., 2019). As an effective data analysis method, chemometrics is also widely popularized in the identification of food origin and quality (Zaukuu, et al., 2019; Monteiro, et al., 2019; Baqueta et al., 2019; de Carvalho et al., 2020).…”