Development a new method for determination of adulteration in cocoa powder with carob powder

In this study, it is aimed to determine a new method for detection of adulteration with carob powder in cacao powder. On this purpose, a sugar alcohol called D-pinitol which is an ingredient of carob but is not found in cocoa was used as marker. Carrez solutions, activated charcoal, PVPP and perlite which are generally used in sample preparation in food analyses were applied to the samples with different concentrations during sample preparation stage. With these applications, it was aimed to obtain appropriate chromatogram in terms of smoothness. It was also aimed to have a better understanding on the effects of different concentrations of each substance in the combination. In the end of optimization study, the most suitable preparation method was found as the combination of 0,05 mL Carrez I solution, 0,05 mL Carrez II solution, 0,50 g /L activated charcoal and 0,50 g/L of PVPP. On the other hand, increasing active charcoal concentration gave positive results by the means of sugar adsorption even though determination of sugar composition was not the main objective of this study. Besides, perlite was determined as non-effective agent on sample preparation. The samples, intentionally added with carob powder at different concentrations and treated with determined conditions, were analyzed at HPLC. A linear equation was provided by the peak areas of D-pinitol from obtained chromatograms of samples at different adulteration ratios. The obtained calibration equation was used to determine the presence and level of carob powder adulteration to commercial cacao powders. As a result of the analyses, No carob powder adulteration was determined in commercial samples but one of the commercial cacao samples had 50% less nitrogenous organic compounds compared to the other samples. However, the characteristics of adulteration could not be described. Consequently, a new sample preparation and chromatographic analysis method for determination of cocoa adulteration with carob powder was defined. This method is thought to be used successfully in qualification of commercial samples.