Infrared-based protocol for the identification and categorization of ginseng and its products Kevin Yi-Lwern Yap a , Sui Yung Chan b , Chu Sing Lim a,c, * a Biosensors Group, Biomedical Engineering Research Centre, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, XFrontier Block, Level 6, Singapore 637553, Singapore b Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore 117543, Singapore c School of Chemical and Biomedical Engineering, Nanyang Technological University, 50 Nanyang Avenue, S4 Level B3b, Singapore 639798, Singapore Received 18 September 2006; accepted 25 November 2006 Abstract Quality assurance of ginseng is important since many ginseng products sold today are in various formulations, and it is difficult to identify them by morphological means such as physical appearance, smell, or even taste. Different chemical constituents in herbs like ginseng tend to exhibit characteristic infrared fingerprints. We have established a simple and rapid protocol based on infrared wave- lengths and principal component analysis for the identification and categorization of ginseng, and called it the 2-6PC rule. The advantage of this protocol is that it is able to provide rapid identification of natural products since it avoids tedious extraction or purification pro- cedures. Our results show that this protocol was not only able to discriminate raw ginseng roots, but also different types of ginsengs in three commercial ginseng products. The potential of the novel 2-6PC rule as a rapid quality surveillance tool in the authentication of ginseng and its products is definitely appealing. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Ginseng; Infrared spectroscopy; Panax ginseng; Panax quinquefolius; Principal component analysis 1. Introduction Ginseng, a well known Chinese herb, exists as two major varieties – Panax quinquefolius L. (American) and Panax ginseng C.A. Meyer (Asian) (Li & Fitzloff, 2002c). It is con- sidered adaptogenic to improve physical and mental per- formance (Fuzzati, 2004). Different species and parts of ginseng are believed to have different medicinal properties (Lum et al., 2002), and the ginseng root is said to relieve medical conditions involving the immune, endocrine, car- diovascular and central nervous systems (Attele, Wu, & Yuan, 1999; Fuzzati, 2004). Although herbal medicine is generally known to be effec- tive and safe, there have been reports (Blackwell, 1996; Ernst, 1998) of adverse reactions with the use of certain herbs such as ginseng. Many factors could contribute to these adverse reactions, of which poor quality control is one of them (Blackwell, 1996). Several cases of renal and liver damage were described in a review by Blackwell (1996) which occurred in patients taking Chinese herbal medicine for slimming treatment and skin disease, some of which were due to adulteration of the products, incorrect weight of active ingredients in the products, and 0963-9969/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2006.11.009 Abbreviations: DLATGS, deuterated L-alanine triglycine sulfide; FTIR, Fourier transformed infrared; HPLC-MS, high performance liquid chro- matography-mass spectrometry; IR, infrared; KBr, potassium bromide; MIR, mid-infrared; PCA, principal component analysis; PCs, principal components; TCM, traditional Chinese medicine. * Corresponding author. Address: Biosensors Group, Biomedical Engi- neering Research Centre, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, XFrontier Block, Level 6, Singapore 637553, Singapore. Tel.: +65 6316 2936; fax: +65 6791 2274. E-mail address: MCHSLIM@ntu.edu.sg (C.S. Lim). www.elsevier.com/locate/foodres Food Research International 40 (2007) 643–652