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Small amounts of low cost carob flour do not change the colour, aroma or taste characteristics of cocoa powder. Therefore, Spanish researchers have developed a NIR (near infra-red) method combined with chemometrics to determine that adulteration with carob flour has  taken place, and the amount of carob flour that has been used. Data sets using cocoa powders with different alkalisation levels, carob flours with three different roasting degrees, and adulterated samples prepared by blending cocoa powders with carob flour at several proportions, were obtained. For qualitative results, a principal component analysis (PCA) and a partial least squares discriminant analysis (PLS-DA) were used, giving a 100% classification accuracy to distinguish pure cocoa powders from adulterated samples. For quantitative analysis, a partial least squares (PLS) regression analysis was performed giving a root mean square error of prediction of 3.2%, thus making the method fit for purpose for determining the amount of carob flour in cocoa powder within this error.

              Read the abstract at: cocoa powder adulteration with carob flour

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Chinese researchers have developed an integrated approach combining HPLC/DAD, GC/MS, near infrared (NIR) spectroscopy, and chemometrics  to geographically discriminate saffron samples from Iran and China. Using a dataset based on 98 samples of saffron, the saffron compounds picrocrocin and two types of crocins were found to be the discriminating markers, and the Chinese samples had higher contents of safranal and picrocrocin but lower cis-crocin 3Gg, kaempferol-3-O-sophoroside and isophorone. 

 Furthermore, an NIR method was successfully established to rapidly distinguish the Chinese and Iranian samples. The relationship between an ISO standard and the contents of the chemical indices was also studied. The results indicated that the ISO standard should be revised, especially for analysing safranal.

Read the abstract here

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This article looks at the application of certain spectroscopic techniques to determine the presence of adulterants in food ingredients and products. Applications cited include the detection of melamine in baby formula, saffron and ginger authenticity, and the detection of substitutes in beef mince.

Read the article at: spectroscopic techniques fight food fraud

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