Research Article Received: 18 March 2013 Revised: 26 August 2013 Accepted article published: 1 October 2013 Published online in Wiley Online Library: (wileyonlinelibrary.com) DOI 10.1002/jsfa.6427 Prediction of essential oil content of oregano by hand-held and Fourier transform NIR spectroscopy C´ edric Camps, a* Marianne G ´ erard, a,b M´ elanie Quennoz, b C´ ecile Brabant, c Carine Oberson c and Xavier Simonnet b Abstract BACKGROUND: In the framework of a breeding programme, the analysis of hundreds of oregano samples to determine their essential oil content (EOC) is time-consuming and expensive in terms of labour. Therefore developing a new method that is rapid, accurate and less expensive to use would be an asset to breeders. The aim of the present study was to develop a method based on near-inrared (NIR) spectroscopy to determine the EOC of oregano dried powder. Two spectroscopic approaches were compared, the first using a hand-held NIR device and the second a Fourier transform (FT) NIR spectrometer. RESULTS: Hand-held NIR (1000–1800 nm) measurements and partial least squares regression allowed the determination of EOC with R 2 and SEP values of 0.58 and 0.81 mL per 100 g dry matter (DM) respectively. Measurements with FT-NIR (1000 – 2500 nm) allowed the determination of EOC with R 2 and SEP values of 0.91 and 0.68 mL per 100 g DM respectively. RPD, RER and RPIQ values for the model implemented with FT-NIR data were satisfactory for screening application, while those obtained with hand-held NIR data were below the level required to consider the model as enough accurate for screening application. CONCLUSION: The FT-NIR approach allowed the development of an accurate model for EOC prediction. Although the hand-held NIR approach is promising, it needs additional development before it can be used in practice. c  2013 Society of Chemical Industry Keywords: hand-held NIR; FT-NIR; PLS; essential oil content (EOC); oregano INTRODUCTION Owing to its high demand, especially in the food industry, as dry grass or in the form of essential oil, 1 oregano has been the subject of numerous studies, including breeding programmes. 2,3 Although the chemical composition differs depending on the species and variety, 4 – 6 the trade name ‘oregano’ includes species that are rich in monoterpenoid phenols, mainly carvacrol and occasionally thymol. 5,6 It has been shown that the essential oil, which is rich in these molecules, has antimicrobial 7 and antioxidant 4,7 properties that can be used not only for the benefit of human health but also in the farming and food industries. 7 Currently, qualitative and quantitative analyses of the components of oregano or its essential oil by conventional methods (i.e. hydrodistillation, gas chromatography, high- performance liquid chromatography) are time-consuming and expensive. In terms of speed of analysis, such methods are difficult to use when a series of hundreds of samples has to be analyzed, as in the case of a breeding programme. 8 In the last 20 years a predictive, rapid and low-cost method based on near-infrared spectroscopy (NIRS) has been developed for determining the quality of various agricultural and food products. Several studies have already been carried out successfully in the field of aromatic and medicinal plants. 9,10 Studies have been reported on cumin, 11,12 fennel, 11,13 coriander, 11 green tea leaves, 14 sage, 15 thyme 9 and rosemary. 16 The aim of the present study was to develop a method to quantify the contents of oregano essential oil by NIRS. The method developed must be fully usable in the context of a breeding programme. Two technologies have been tested, a hand-held NIR device and a Fourier transform (FT) NIR spectrometer, both adapted to the needs of a breeding programme. MATERIALS AND METHODS Plant material The oregano samples used in this study comprised species and varieties grown in the experimental fields of Agroscope Research Station (Conthey, Switzerland). Samples were gathered from two harvest years (2009 and 2010) and stored at room temperature in ∗ Correspondence To: Cedric Camps, Agroscope Research Station, Research Department of Production and Plant Protection of Crops in Alpine Areas/Greenhouse Crops, Route des Vergers 18, CH-1964 Conthey, Switzerland. E-mail: cedric.camps@acw.admin.ch a Agroscope Research Station, Research Department of Production and Plant Protection of Crops in Alpine Areas/Greenhouse Crops, Route des Vergers 18, CH-1964, Conthey, Switzerland b Mediplant, Route des Vergers 18, CH-1964, Conthey, Switzerland c Agroscope Research Station, Research Department of Arable Crop Plant Breeding and Genetic Resources, Route de Duillier 50, CP 1012, CH-1260, Nyon, Switzerland J Sci Food Agric (2013) www.soci.org c  2013 Society of Chemical Industry