Fourier transform infrared (FTIR) spectroscopy and attenuated total reflection (ATR) sampling have been used to detect adulteration of raspberry purees. A database of 871 spectra of pure and adulterated fruit purees was collected between 1993 and 1994. Partial least-squares (PLS) regression of the spectra onto a dummy variable representing sample type was performed. A 95% confidence interval for the prediction values for pure raspberries was defined: within this region, spectra were accepted as pure raspberry; outside this region, spectra were rejected. Using this criterion, 95% of pure raspberries were accepted as such. Adulteration with apple and plum could be detected at minimum levels of ∼20% w/w, with sucrose at ∼4% w/w. Spectra of 150 additional samples harvested during 1995 served as further validation samples: comparable classification success rates were obtained. The speed of FTIR spectroscopy makes this technique a rapid method for screening raspberry purees for adulterants.
|Number of pages||7|
|Journal||Journal of Agricultural and Food Chemistry|
|Publication status||Published - 18 Dec 1996|