Preliminary Discrimination of Butter Adulteration by ATR-FTIR Spectroscopy

Abstract

The Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR)  was applied for the discrimination of butter samples adulterated with solid fraction of palm oil. For FTIR fingerprinting of butter samples, with or without controlled additions of palm oil as adulterant was firstly obtained, using a Shimatsu Prestige 21 Spectrophotometer, including a horizontal diamond ATR accessory with reflection in the MIR region (3873-690) cm -1 .The spiked butter samples including 0 level and seven increasing concentrations of palm fats, up to 50% were fingerprinted and the calibration curve was obtained (n=19). In parallel, the validation was realized using different set of spiked butter samples ranging 1-44.4 % of palm fat (n=7). Finally, an independent set of commercial samples was analized (n=14).Partial least squares (PLS) model was used for statistical data processing in accordance with standard method. The value of the correlation coefficient (R 2 = 0.977) between actual and predicted values was statistically significant (p<0.001), considering the superposition of  actual vs predicted” curves. This combined FTIR-PLS evaluation revealed that 3 out of samples of butter were suspected of adulteration with palm oil, presented values 14 ranging 4-12%.In conclusion, ATR-FTIR methodology may offer an rapid evaluation of  butter samples authenticity. The low value for detection limit (3%palm oil in butter) and the low limit of quantification (9.8% palm oil in butter) confirms that ATR-FTIR spectroscopy  is a sensitive method to identify the adulteration of butter with  palm oil.  Â