Fingerprinting Maple Syrup by Vibrational Spectroscopy and Pattern Recognition
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Food Science and Technology Undergraduate Research Theses; 2019
Maple syrup is prone to be adulterated with cheap cane, beets or corn syrup due to its expensive ingredient – sap of sugar maple, and the simplicity in its chemical composition. Bourbon barrel (BBL) aged maple syrup is the premium maple syrup product produced by aging syrup in oak bourbon barrel for several weeks to months to develop richer bourbon flavor. The high price of BBLs may prompt the potential counterfeit of aging process. Traditional authentication methods include chromatography and stable isotope ratio analysis, which are time-consuming and cost-prohibitive for most companies due to the requirements of expensive instrumentation and trained personnel. Advances in miniaturization of spectroscopy instruments combined with powerful chemometrics have allowed new portable devices to be field deployable for non-destructive and real-time analysis, however, their accuracy and precision have not yet been determined in maple syrups. Our objective was to develop a predictive algorithm to fingerprint the unique compositional make-up of maple syrup, allowing for fast product authentication and detection of potential ingredient tampering. Samples were kindly provided by Bissell Farms (Jefferson, OH) that included pure maple syrups and Bourbon barrel (BBL) aged maple syrup. Also, we purchased commercial maple syrup samples (n=21) and syrup blends (n=5) from local grocery stores. Spectra were collected by modular Raman 1064 spectrometer and Fourier-transform infrared (FTIR) spectroscopy and analyzed by pattern recognition (SIMCA) and partial least square (PLS) regression. Both Raman and FTIR spectra showed interesting signature patterns that the strong fluorescence in corn syrup samples were highlighted while the syrup blends were resembling patterns of maple syrups. All corn/blended syrups were easily discriminated from maple syrup by chemometrics. Furthermore, BBL maple syrups clustered away from “pure” maple syrups (single ingredient with no foreign substances). Interestingly, three BBL maple syrups grouped with the “pure” samples, indicating limited aging process. Our data showed clustering of “pure” maple syrups by geographical origins (US or Canada) and by lignin contents, which is due to variation in oxidation precondition during sap evaporation. Our data supports the application of a classification algorithm based on the unique Raman and FTIR spectra profile of maple syrup.
Academic Major: Food Science and Technology