CHARACTERISATION OF PEPPER AND PEPPER OLEORESINS BY FOURIER- TRANSFORM RAMAN SPECTROSCOPY

Abstract: NIR-FT-Raman spectroscopy in combination with efficient chemometric algorithms was applied for rapid and non-destructive determination of piperine in ground pepper, green whole pepper berries as well as pepper oleoresins. Most of the well resolved Raman signals detected in the spectra of pepper and the relating oleoresins can be assigned to piperine which is known to be the main pungent principal in these products. According to these specific signals also selective Raman mappings were performed to determine in situ the distribution of piperine in the whole green berry and the dried peppercorn. It was found that the pepper alkaloid is predominantly located in the outer perisperm of the green fruit. The main pungent principle in the green berries of pepper (Piper nigrum L.) is piperine. At least five other alkaloids, structurally related to piperine, also occur in smaller amounts. “Black pepper” is obtained from the unripe but mature green berries on sun drying while fully ripe dried fruits devoid of pericarp form the commercial “white pepper”. Generally the piperine content of black or white peppercorns lies within the range of 3 to 8 g/100g, whereas the content of the minor alkaloids piperyline and piperettine have been estimated as 0.2-0.3 and 0.2-1.6 g/100g, respectively [1]. The International Organization for Standardization (ISO) [2], the American Spice Trade Associatio