Detection of adulteration of raspberry purees using infrared spectroscopy and chemometrics

E. K. Kemsley, J. K. Holland, M. Defernez, R. H. Wilson

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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.

Original languageEnglish
Pages (from-to)3864-3870
Number of pages7
JournalJournal of Agricultural and Food Chemistry
Issue number12
Publication statusPublished - 18 Dec 1996
Externally publishedYes


  • Adulteration
  • Fruit
  • Infrared
  • Purees
  • Spectroscopy

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