Comparison of food boluses prepared in vivo and by the AM2 mastication simulator Anne Mishellany-Dutour a,⇑ , Marie-Agnès Peyron b , Jocelyn Croze a , Olivier François a , Christoph Hartmann c , Monique Alric d , Alain Woda a,e a Dental Faculty, EA 3847, DIDO, 11 boulevard Charles-de-Gaulle, 63000 Clermont-Ferrand, France b Institut National de la Recherche Agronomique, Human Nutrition Unit, 63122 St-Genès-Champanelle, France c Nestlé Research Center, P.O. Box 44, CH-1000 Lausanne 26, Switzerland d Faculty of Pharmacy, ERT-CIDAM, 28 place Henri-Dunant, 63000 Clermont-Ferrand, France e CHU, Clermont-Ferrand, Service d’Odontologie, Hôtel-Dieu, F-63001 Clermont-Ferrand, France article info Article history: Received 3 September 2009 Received in revised form 6 December 2010 Accepted 14 December 2010 Available online 17 December 2010 Keywords: Chewing Food bolus Median particle size Mastication simulator Validation Young dentate subjects abstract To study food disruption and bolus formation, a simulator of mastication (AM2) was developed to mimic masticatory behaviour and allow collection of a bolus at any stage in the masticatory sequence. Here we set out to validate the AM2 by comparing boluses obtained in vitro and in vivo. Boluses were obtained from the AM2 and 30 young dentate subjects chewing peanuts and carrots. Median particle sizes (d 50 ) of the boluses were extracted from image analysis results. The number of cycles was set at the mean in vivo value. The force range was chosen to match in vitro and in vivo values. The AM2 proved reliable; no significant difference between repetitions was observed. The in vitro and in vivo boluses displayed the same d 50 values for each food. In vitro and in vivo boluses obtained at dif- ferent times during the chewing process were also similar. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction The main purpose of mastication is to turn food into a bolus fit for swallowing (Lillford, 1991; Prinz & Lucas, 1995; Woda, Foster, Mishellany, & Peyron, 2006). This entails mechanical disruption and comminution of food with simultaneous lubrication by saliva. Observation of food bolus characteristics yields important infor- mation for the study of the different roles of mastication, such as preparing for swallowing. However, intra-oral food breakdown and bolus formation mechanisms remain largely unknown for three main reasons: (i) knowledge of food bolus rheology and of the chemical changes occurring during bolus formation is scant (Lillford, 1991; Prinz & Lucas, 1997; Seo, Hwang, Han, & Kim, 2007), (ii) at the time the bolus is collected, just before the final swallow, about half of the bolus mass has already been lost to intermediate swallowing (Mishellany-Dutour, Renaud, Peyron, Rimek, & Woda, 2008) and the characteristics of this lost portion are not known, and (iii) the bolus is frequently analysed in terms of its particle size distribution, but these values cannot be com- pared between studies because granulometric patterns vary widely according to the methods used (Hoebler, Devaux, Karinthi, Belleville, & Barry, 2000; Hoebler et al., 1998; Mahmood, Watson, Ogden, & Hawkins, 1992; Shi, Guan, & Tian-Wen, 1990). The study of the food bolus is hampered by the mere fact that it is formed in- side the mouth, hindering or preventing the close examination of many factors. For example, it is not yet possible to determine how the proportion of saliva, food fluids and solid nutrients modify bolus characteristics during the masticatory process. To help overcome these problems, machines designed to mimic mastication have been proposed. They can provide information that is unobtainable by human experimentation (e.g., from non- cooperating subjects or on bolus textures that impede swallowing). The populations concerned are large and the impact of poor masti- cation on general health is significant and underestimated (Hutton, Feine, & Morais, 2002). In France, for instance, it is estimated that 2 million people are totally edentulous and that many more de- pend on others for feeding. Such machines can thus help improve our knowledge of the structural modifications of food in the mouth. This information may make it easier to adapt texture and food to nutritional needs and to the physiological capacities of tar- get populations, while preserving the hedonistic quality of the food. Most of these machines do not, however, allow collection of a complete food bolus after an action simulating the mechanical pro- cess occurring inside the human mouth (DeLong & Douglas, 1983; 0950-3293/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodqual.2010.12.003 ⇑ Corresponding author. Address: EA 3847, DIDO, Université d’Auvergne, U.F.R. d’Odontologie, 11 boulevard Charles-de-Gaulle, 63000 Clermont-Ferrand, France. Tel.: +33 4 73 17 73 84; fax: +33 4 73 17 73 88. E-mail address: anne.mishellany@u-clermont1.fr (A. Mishellany-Dutour). Food Quality and Preference 22 (2011) 326–331 Contents lists available at ScienceDirect Food Quality and Preference journal homepage: www.elsevier.com/locate/foodqual