Characterisation of fresh bread flavour: Relationships between sensory characteristics and volatile composition Samuel P. Heenan a, * , Jean-Pierre Dufour a , Nazimah Hamid a , Winna Harvey c , Conor M. Delahunty a,b a Sensory Science Research Centre, Department of Food Science, University of Otago, P.O. Box 56, Dunedin, Otago 9001, New Zealand b Food Science Australia, North Ryde, NSW 1570, Australia c New Zealand Institute for Crop and Food Research Limited, Christchurch, New Zealand article info Article history: Received 16 July 2008 Received in revised form 5 February 2009 Accepted 17 February 2009 Keywords: Bread Descriptive analysis Proton transfer reaction mass spectrometry (PTR-MS) Flavour Odour Consumer Freshness abstract The sensory properties and volatile composition of bread flavour were measured to allow improved understanding of perceived bread freshness. Twenty bread varieties consisting of specialty breads (n = 10) and commercial breads (n = 10) were evaluated by descriptive sensory analysis, and volatile com- position of all breads was measured by proton transfer reaction mass spectrometry (PTR-MS). The spe- cialty breads (n = 10) studied had been evaluated by consumers, and perceived freshness was known. All sensory attributes and 33 mass ions representative of the PTR-MS spectra significantly (p < 0.05) dis- tinguished between the different breads. Partial least squares regression (PLSR) was used to model and predict sensory profiles as a function of volatile composition for all breads. In addition, a separate model that related volatile composition to known consumer freshness of the 10 specialty breads was created. For each model, accuracy was validated by comparing the differences between predicted and actual, sen- sory and freshness intensities. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Fresh bread flavour is central to consumer acceptability and product recognition. The flavour perception perceived while eating involves complex interactions between sensory sensations of olfac- tion, taste and trigeminal stimuli (Lawless & Heymann, 1999). From this aspect, sensory descriptive analysis has been commonly applied to measure the odour and flavour impressions of food (Meilgaard, Civille, & Carr, 1999; Stone & Sidel, 2004). Among the various intrinsic properties of bread, volatile flavour compounds play a key role in the perception of fresh bread flavour. However, the perceived fresh bread flavour often relies on the type of bread, ingredients, method of production and shelf life. Considerable research has focused on describing bread flavour using descriptive sensory analysis (Caul & Vaden, 1972; Chang & Chambers, 1992; Lotong, Chambers, & Chambers, 1999; Shogren, Mohamed, & Carriere, 2003). Additionally, several studies have ap- plied descriptive sensory analysis to describe consumer percep- tions of different bread varieties (Hersleth, Berggren, Westad, & Martens, 2005), effects of bread produced from different wheat grains (Annett, Spaner, & Wismer, 2007), influences of processing (Heinio, Liukkonen, Katina, Myllymaki, & Poutanen, 2003), as well as influences of farming system, harvest, milling and baking techniques (Kihberg, Johansson, Kohler, & Risvik, 2004; Kihlberg, Ostrom, Jahansson, & Risvik, 2006). Heenan, Dufour, Hamid, Harvey, and Delahunty (2008) showed that sensory characteristics from dif- ferent bread varieties influenced consumer perceptions of freshness and demonstrated that by relating subjective consumer freshness judgements to descriptive sensory attributes from a trained panel, an objective understanding of bread freshness could be obtained. Research has been carried out on the flavour of fresh bread by identifying key odour active volatile compounds (Chang, Seitz, & Chambers, 1995; Kirchhoff & Schieberle, 2001; Schieberle & Gros- ch, 1992; Seitz, Chung, & Rengarajan, 1998; Zehentbauer & Grosch, 1998a, 1998b). According to Schieberle and Grosch (1992), the loss of fresh bread flavour results from specific compound volatility, where important odourants rapidly decreased during storage, whilst less desirable odourants characterised from lipid oxidation remained relatively unchanged. Sensory and instrumental volatile analysis has shown that dif- ferent fermentation conditions and the amount of yeast, changed the flavour profile for crust aroma of baguettes (Zehentbauer & Grosch, 1998a, 1998b). Other studies have reported distinct differ- ences between the headspace volatile composition of commer- cially made breads that included white sandwich, Irish oatmeal, soft rye, hearty rye, sourdough, home-like white and onion-basil (Seitz et al., 1998), and between breads produced from different 0308-8146/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2009.02.042 * Corresponding author. Tel.: +64 3 479 5463; fax: +64 3 479 7567. E-mail address: heesa187@student.otago.ac.nz (S.P. Heenan). Food Chemistry 116 (2009) 249–257 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem