Determination of adulteration of added sugar syrups to nar ekşisi (pomegranate molasses) by FTIR-ATR spectroscopy

Due to the increasing demand for pomegranate sour, unethical companies in the market resort to many tricks to gain more profit and to gain market advantage over their honest competitors. These tricks include adding cheap commercial sweeteners, diluting them with water, and adding cheaper juice. As well as, the addition of cheap commercial sweeteners or intense red colored fruit juice to pomegranate sour are frequently applied food fraud. For this reason, it is thought that chemometric methods together with infrared (IR) spectroscopy can be a solution for the detection of sugar added to pomegranate sour in order to protect the consumer and prevent unfair competition. Unlike traditional analysis methods, Fourier transform infrared (FTIR) spectroscopy is a fast, low-cost and non-destructive method. Due to the addition of commercial corn syrup and sucrose, 2 types of commercial corn syrup (High Fructose syrup and Glucose-Fructose syrup) with different properties. 58 pomegranate sour samples were obtained from small firms and producers. Most of the pomegranate sour samples, Brix, pH, total acidity, sugar analyzes were made and the results were found to be in accordance with the TSE 12720 Standard. The samples that are not suitable are discussed in accordance with the standard. Two different corn syrup and sucrose syrup (5-10-20-30-40-50%) added to the pomegranate sour samples at different rates were determined qualitatively and quantitatively using Fourier Transform Infrared (FTIR) Spectroscopy. Spectra of pure and adulterated pomegranate sour samples were taken in the wavenumber range of 4000-400 cm-1 in FTIR-ATR spectroscopy. The specific absorbance values of carbohydrates, known as the fingerprint region, were obtained in the wavenumber range of 1200-900 cm-1 and were used in chemometric methods. The samples were evaluated qualitatively and quantitatively by applying Principal Component Analysis (PCA), Least Squares-Discriminant Analysis (PLS-DA) and Least Squares Regression Analysis (PLS-R) analyzes to FTIR data. Pure and adulterated pomegranate sour samples were differentiated with the PCA model, and PC1 and PC2 were shown to explain 83.1% of the total variance. According to the PLS-DA results, in the classification of pomegranate sour to which high fructose corn syrup was added, a total of 93.62% correct classification rate in the calibration set and XIII a total of 91.6% in the validation set, the calibration set was 100% in the samples to which glucose fructose syrup was added, and the total % in the validation set. In the samples with 91.6% correct classification and sucrose added, the calibration set had 100% correct classification rate, and the validation set had a total correct classification rate of 95.8%. In the PLS-R analysis, adulteration rate was determined in pomegranate sour samples with high fructose syrup, glucose-fructose syrup and sucrose added. RMSEC and RMSEP values of PLS-R models are 2.06% and 1.88%, respectively; 1.26% and 2.93%; While it was calculated as 1.84% and 1.61%, the correlation coefficient (R2> 0.958) was also obtained quite high. A high correlation (R2> 0.9) was obtained as a result of the application of PLS-R analysis to the FTIR data with the glucose, fructose and sucrose contents of the pomegranate juice samples determined by HPLC. RMSEC and RMSEP values of glucose content were found to be 1.81%, 2.44%, fructose content 1.63%, 0.81%, and sucrose content 3.89% and 3.23%, respectively. As a result of using chemometric methods together with FTIR-ATR spectroscopy of commercial corn syrup and sucrose syrup added to pomegranate sour samples, both qualitatively correct classification and quantitatively high correlation coefficient and adulteration rate were determined.