1H-NMR fingerprinting of brown rice syrup as a common adulterant in honey

Abstract

Honey is often adulterated because of its high economic value and increasing consumption. Among the most common adulterants, brown rice syrup (B.R.S.) is relatively difficult to detect. We present here a simple and fast quantitative ¹H-NMR method to identify adulteration of honey by brown rice syrup using the concentration conversion factor. The principal component analysis of the ¹H-NMR spectra of honey and B.R.S. showed a characteristic pattern at δ_H 5.39 for B.R.S. identification. Good linearity (r² = 0.9713) was obtained between the % B.R.S. in honey and the integrated area of the peak at δ_H 5.39. With the newly developed method, we successfully quantified B.R.S. in two commercial honey samples at 22.3% and 37.3% with a precision of 0.1–1%. As a result, a simple, efficient and precise ¹H-NMR method was developed to quantitatively identify the presence of B.R.S. in honey without any complicated sample preparation.