Detection of adulteration using statistical methods over carbon isotope ratios in carob, grape, fig and mulberry pekmez

Abstract

Pekmez, produced from different fruits, such as grape, mulberry, fig, apple and date, is a traditional Turkish food and widely consumed in Turkey. However, pekmez is among the most adulterated food products. This study used carbon isotope values to detect adulteration of carob, fig, grape and mulberry pekmez samples with glucose and fructose syrups at the ratio of 0%, 10%, 20%, 30%, 40%, 50%, 60% and 70% (by weight). The EA-IRMS chromotograms were recorded and results were used to propose the statistical models. All of the pure pekmez samples were found to be more negative than −23.5‰ and the results decreased by the addition of adulterants. Parametric statistical analysis was used to test the distribution of pekmez and adulterants. Linear fit models were constructed and higher regression coefficient values were obtained for adulterated carob, fig and grape pekmez samples while adulterated mulberry pekmez samples showed lower values. It was determined that the proposed linear fit models can be used as a tool to elucidate the possible detection of varying adulteration levels of pekmez samples, even at low levels. These models may be an introductory step in the detection of adulteration of other Turkish traditional food products.