A screening method based on UV–Visible spectroscopy and multivariate analysis to assess addition of filler juices and water to pomegranate juices Raffaella Boggia ⇑ , Maria Chiara Casolino, Vilma Hysenaj, Paolo Oliveri, Paola Zunin Department of Pharmacy, University of Genoa, Via Brigata Salerno, 13, I-16147 Genoa, Italy article info Article history: Available online 16 November 2012 Keywords: Pomegranate juice Filler juices Dilution Antiradical scavenging activity UV–VIS spectroscopy Design of experiments Multivariate analysis abstract Consumer demand for pomegranate juice has considerably grown, during the last years, for its potential health benefits. Since it is an expensive functional food, cheaper fruit juices addition (i.e., grape and apple juices) or its simple dilution, or polyphenols subtraction are deceptively used. At present, time-consuming analyses are used to control the quality of this product. Furthermore these analyses are expensive and require well-trained analysts. Thus, the purpose of this study was to propose a high-speed and easy-to-use shortcut. Based on UV–VIS spectroscopy and chemometrics, a screening method is proposed to quickly screening some common fillers of pomegranate juice that could decrease the antiradical scavenging capacity of pure products. The analytical method was applied to laboratory prepared juices, to commercial juices and to representative experimental mixtures at different levels of water and filler juices. The outcomes were evaluated by means of multivariate exploratory analysis. The results indicate that the proposed strategy can be a useful screening tool to assess addition of filler juices and water to pomegranate juices. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction In these last years, interest in functional foods is increasing in almost all industrialised countries (Bech-Larsen & Scholderer, 2007; Siró, Kápolna, Kápolna, & Lugasi, 2008). In particular, fruit juices – and, among them, pomegranate (PG) juices – are considered a good source of phenolic compounds with strong antioxidant activity (Faria & Calhau, 2010), whose con- sumption could improve cardiovascular health and inhibit the pro- liferation of many cancers (Braga et al., 2005; Malik et al., 2005; Noda, Kaneyuki, Mori, & Packer, 2002; Vidal & Fallarero, 2003). Nowadays, there is universal agreement that the presence of a highly constant group of six anthocyanins together with punicala- gins characterises polyphenols in PG (Zhang et al., 2009). PG con- tains a significantly high level of powerful antioxidants ellagitannins such as ellagic acid, punicalagin and punicalin (Lansky & Newman, 2007; Visioli & Hagen, 2007), as well as anthocyanins (i.e., delphinidin, cyanidin and pelargonidin 3-glucosides and 3,5- diglucosides) (Hernandes, Melgerajo, Tomas-Berberan, & Artes, 1999; Zhang et al., 2009) responsible for its red–purple colour. Ellagitannins found in the outer part of the fruit are largely responsible for the antioxidant activity of PG. Among these ellagit- annins, punicalagin (punicalagin anomers A and B) is responsible for over 50% of the antioxidant activity of PG (Gil, Tomas-Barberan, Hess-Pierce, Holcroft, & Kader, 2000) and its content can vary from 1500 to 1900 mg/L depending on the cultivar of pomegranate, juice processing and storage methods (Gil et al., 2000). Punicalagin is the most characteristic compound of PG and it is found most exclu- sively in PG (Tzulker et al., 2007). Several studies have even shown that authentic PG contain much more antioxidant compounds than other common fruit juices and beverages (Gil et al., 2000). Due to these characteristics the demand for PG has increased significantly in the last years (Fischer, Carle, & Kammerer, 2011). Consequently adulterations have become of concern. The most common way for adulteration is either a simple dilu- tion or an addition of another foreign juice, such as grape, apple, sour cherry and strawberry to PG (Zhang et al., 2009). Another po- tential fraud in this field could be the extraction of polyphenols in order to subtract these great value compounds to be used for other purposes. The effects of this potential practise may be considered equivalent to a dilution of polyphenols. Another important concern related with such types of adulter- ations may involve health risk, i.e., undeclared juices could contain potential allergens (Besler, Steinhart, & Paschke, 2001; Marzban et al., 2009). For these reasons, analytical methods able to verify authenticity of fruit juices are of great importance. Vardin, Tay, Ozen, and Mauer (2008) published (Vardin et al., 2008) an analytical method 0308-8146/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodchem.2012.11.020 ⇑ Corresponding author. Tel.: +39 010 3532643; fax: +39 010 3532684. E-mail addresses: boggia@difar.unige.it, boggia@dictfa.unige.it (R. Boggia). Food Chemistry 140 (2013) 735–741 Contents lists available at SciVerse ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem