Chemical composition and sensory profile of pomelo (Citrus grandis (L.) Osbeck) juice Mun Wai Cheong a , Shao Quan Liu a , Weibiao Zhou a , Philip Curran b , Bin Yu b,⇑ a Food Science and Technology Programme, c/o Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore b Firmenich Asia Pte. Ltd., 10 Tuas West Road, Singapore 638377, Singapore article info Article history: Received 20 February 2012 Received in revised form 7 June 2012 Accepted 2 July 2012 Available online 11 July 2012 Keywords: Pomelo (Citrus grandis (L.) Osbeck) Juice PCA PLS regression Sensory evaluation abstract Two cultivars (Citrus grandis (L.) Osbeck PO 51 and PO 52) of Malaysian pomelo juices were studied by examining their physicochemical properties (i.e. pH, °Brix and titratable acidity), volatile and non-volatile components (sugars and organic acids). Using solvent extraction and headspace solid-phase microextrac- tion, 49 and 65 volatile compounds were identified by gas chromatography–mass spectrometer/flame ionisation detector, respectively. Compared to pink pomelo juice (cultivar PO 52), white pomelo juice (cultivar PO 51) contained lower amount of total volatiles but higher terpenoids. Descriptive sensory evaluation indicated that white pomelo juice was milder in taste especially acidity. Furthermore, princi- pal component analysis and partial least square regression revealed a strong correlation in pomelo juices between their chemical components and some flavour attributes (i.e. acidic, fresh, peely and sweet). Hence, this research enabled a deeper insight into the flavour of this unique citrus fruit. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Citrus juices are well known as complex mixtures of aromatic volatiles (e.g. esters, aldehydes, ketones and alcohols) and non-vol- atile components (e.g. organic acids and sugars) (Barboni et al., 2009; Rouseff, Perez-Cacho, & Jabalpurwala, 2009). Although aro- matic volatiles are generally present in trace levels, they are essen- tial to characterise the aroma of citrus juices (Allegrone, Belliardo, & Cabella, 2006; Buettner & Schieberle, 2000). Also, the flavour profiles of citrus juices depend on the balance between sugars and organic acids, which are among major non-volatiles. Their nat- ure and concentrations significantly contribute to the perception of citrus juices (Kelebek & Selli, 2011). Furthermore, the interaction of volatile and non-volatile components has played an important role in the organoleptic quality of food (Frøst, Heymann, Bredie, Dijksterhuis, & Martens, 2005; Hewson, Hollowood, Chandra, & Hort, 2008; Stampanoni, 1993). Multivariate analyses (e.g. principal component analysis (PCA) and partial least square (PLS) regression) have been widely applied to extract meaningful information from complex data sets (Boudaoud & Eveleigh, 2003; Bro et al., 2002). In order to under- stand the relationship between chemical composition and sensory profile of foods, PCA has been used to describe the data set composed of sample mean scores as observations and chemical components as variables, and then captures the maximum variance (Jouquand & Chandler, 2008; Pérez-Martínez, Sopelana, de Peña, & Cid, 2008). Furthermore, PLS regression offers several advantages over the classic regression techniques, in which the chemical interaction among variables can be modelled into the cal- ibration (Aznar, López, Cacho, & Ferreira, 2003). So, PLS regression could be used for exploring the best combination of X-variables (chemical components) to produce a good prediction of the Y-data (intensity of flavour attributes) (Jumtee, Komura, Bamba, & Fukusaki, 2011; Kvaal & McEwan, 1996). This technique has been already successfully applied to develop the electronic nose and electronic tongue in the wine analysis (Kirsanov, Mednova, Vietoris, Kilmartin, & Legin, 2012), understand the effects of ther- mal processing on fruit smoothiess (Keenan, Brunton, Mitchell, Gormley, & Butler, 2012), and correlate the sensory profile of com- mercial orange juice with its aroma components during acceler- ated storage (Petersen, Tonder, & Poll, 1998). However, there is still limited information on correlating chemical components (volatiles and non-volatiles) with the sensory perception of citrus juices. Pomelo (Citrus grandis (L.) Osbeck), also known as pummelo, shaddock or Chinese grapefruit, is commonly classified as common (or white) or pigmented (or pink) (Morton, 1987; Sawamura, Shichiri, Ootani, & Zheng, 1991). It tastes sweet, and is slightly acidic with a hint of bitterness. Although some comparisons have been made on the volatile fractions of Nakon (Shaw, Goodner, Moshonas, & Hearn, 2001) and Chandler pummelo (González- Mas, Rambla, Alamar, Gutiérrez, & Granell, 2011), the flavour profile of pomelo juice is still inexplicit. Our initial studies on the 0308-8146/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodchem.2012.07.012 ⇑ Corresponding author. E-mail address: bin.yu@firmenich.com (B. Yu). Food Chemistry 135 (2012) 2505–2513 Contents lists available at SciVerse ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem