To date several techniques have been used for the authentication and classification of apple juices and similar beverages, these include chemical profiling (Souza et al., 2011) stable isotopes analysis (Magdas & Puscas, 2011), infra-red spectroscopy e.g. NIR, MIR, FT-IR (Kelly and Downey, 2005, León et al., 2005 and Sivakesava et al., 2001),
chromatographic techniques e.g. GC–MS (Fisk et al., 2012, Guo et al., 2012, Lignou et al., 2013 and Montero-Prado et al., 2013) and HPLC (Yamamoto et al., 2008) and direct injection spectrometric techniques such as PTR-MS (Biasioli et al., 2003 and Biasioli et al., 2011). Direct injection APCI-MS has been successfully applied in a number of areas, Roxadustat most of these relate to the real time tracking of volatile compound release (Taylor, Linforth, Harvey, & Blake, 2000) to understand the dynamic partitioning from complex systems such
as food (Linforth, Baek, & Taylor, 1999) and beverages (Shojaei, Linforth, & Taylor, 2007) or as tool to evaluate different processing methodologies (Fisk et al., 2011, Fisk et al., 2012, Yang et al., 2012 and Yu et al., 2012) Notwithstanding its use as tool for real time aroma analysis, APCI-MS can also provide a rapid and informative mass spectral fingerprint of a foods volatile compliment; it can therefore be hypothesised that APCI-MS could be used for the monitoring of food authenticity. The aim of the present work was to evaluate APCI-MS as a novel tool for the classification (based on geographical PF-02341066 order and botanical origin) of a foods volatile compliment, using a real food (clarified apple juice) with broad commercial diversity as an exemplar. Five
cultivars (Braeburn, Golden Delicious, Granny Smith, Jazz (Scifresh), and Pink Lady) harvested in three different countries of Protein kinase N1 the South hemisphere (New Zealand, South Africa, Chile) were purchased from four local supermarkets. For each cultivar, 12 apples were randomly selected and used for the preparation of apple juice samples. Apples were peeled, cored, sliced and placed in an antioxidant solution to retard enzymatic browning, as previously illustrated by Ting et al. (2012). Apple flesh was squeezed using a household juicer (Philips, UK) and the freshly extracted apple juice was immediately heat treated at 60 °C for 30 s using a water bath to retard any further enzyme activity. Excessive pulp and foam were removed from the juice by filtering through a 100-mesh cloth filter. Clarification of the apple juice was conducted by pectinase (Sigma–Aldrich, UK) treatment at 37 °C for 60 min and subsequent centrifugation of the juices at 5000 rpm (Beckman Ltd., J2-21M, UK) for 10 min. A total of 210 apple juices were prepared. For GC–MS headspace analyses six individual apple juices samples per cultivar referring to different market suppliers and geographical origin were selected.