Development of a Rapid Analytical Tool for Determination of Capsaicin Content in Commercial Hot Sauces

Diana Karajeh
Undergraduate (Food Science)
Dr. Luis Rodriguez-Saona
Food Science and Technology

The compounds contributing to the hot sensation of chili peppers are members of a family known as capsaicinoids. Among these, capsaicin (8-methyl-N-vanillyl-6-nonenamide) is the dominant flavor compound causing pungency and burning sensation. The quantitative determination of capsaicin in peppers is done by using the Scoville scale by sensory panels or liquid chromatography (HPLC). Our research aimed to provide a rapid prediction of capsaicin content in hot sauce samples by using a field-deployable portable FT-IR spectrometer. Forty commercial hot sauces were purchased from local groceries (Columbus, OH) and online sites, and their capsaicin content were quantified by HPLC-PDA. The spectra of hot sauces were collected by directly applying the samples (5µL) onto the diamond crystal of an attenuated total reflectance (ATR) infrared spectrometer and evaporating the excess water under vacuum (~2min). An alternate approach was to mix the hot sauce with hexane to isolate the non-polar components and eliminate the effects of interfering ingredients such as xantham or guar gum that were present in some samples. The calibration model was developed by using partial least square regression (PLSR) using full cross-validation. A wide viability in the levels of capsaicinoids were quantified in the hot sauces ranging from 0.8 to 1200ppm. A high correlation (RCV = 0.95) between the reference capsaicin values and FT-IR predicted values was observed from the model. The standard error of cross validation (SECV) was 33ppm and 19ppm for direct analysis and hexane extracts, respectively, indicating good predictive accuracy of capsaicin content in hot sauces. FT-IR technology can be an ideal method for routine in-plant assessment of capsaicin content in hot sauce that would provide processors with accurate results in shorter time and lower cost than traditional wet chemistry methods.