The effectiveness of palate cleansing strategies for evaluating the bitterness of caffeine in cream cheese Elizabeth A. Johnson, Zata Vickers* Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108, USA Received 24 December 2002; received in revised form 9 April 2003; accepted 29 April 2003 Abstract The objective of this study was to compare the effectiveness of seven methods used to cleanse the palate including: water, sparkling water, carrots, crackers, plain cream cheese, and rinsing six times or not at all before evaluations. Twenty subjects rated the bitterness intensity of cream cheese samples varying in caffeine content. Each participant completed seven sessions, using a different palate cleanser in each session. We found no differences in the effectiveness of these palate-cleansing strategies for their ability to control adaptation and build-up, or for their ability to increase panelists’ discrimination among samples. Rinsing with sparkling water depressed the perceived bitterness at all levels of caffeine. # 2003 Elsevier Ltd. All rights reserved. Keywords: Palate cleansers; Rinsing; Rinse agents; Bitterness; Cream cheese 1. Introduction Palate cleansers are commonly employed in sensory evaluation studies to cleanse the mouth before and in between samples. Their purpose is to minimize residual substances in the oral environment that would other- wise interfere with the evaluation of a product. Theore- tically, palate cleansers reestablish a baseline oral environment. Reestablishing the same oral environment before every sample minimizes the effects of residuals in the mouth that may otherwise influence perceptions. The use of palate cleansers is common practice in both informal and formal sensory evaluation settings. For example, fine restaurants may serve a lemon sorbet between courses in a meal, and slices of rare roast beef may be offered to counteract the effects of high-tannin red wines at wine tasting-events (Lawless & Heymann, 1999). More formal sensory evaluation studies use water or commercially available food products as palate cleansers and typically do not regulate the methodology or number of rinses to be made by panelists. Common palate cleansers include water, sparkling water, crack- ers, carrots and apples. They are generally used in an ad-lib procedure by which the panelists determine the amountofrinsingrequiredtocleansetheirpalate.Inspite of the widespread use, we found little published literature regarding the effectiveness of these materials or methods. People have reported a few different strategies for evalu- ating the effectiveness of palate cleansers. O’Mahony (1972) physically measured salt residues in the mouth. More effective rinsing methods (e.g. rinsing five times with water) left fewer residuals. O’Mahony and Godman (1974) measured detection and recognition thresholds for a compound to indicate the effectiveness of a rinse procedure. More effective rinse strategies (i.e. rinsing with water) produced lower thresholds than less effec- tive strategies (i.e. an interstimulus rest period). Bett and Johnsen (1996) used analysis of variance (ANOVA) of duplicate consecutive samples as an indicator of the effectiveness of rinse agents for evaluating 2-methyliso- borneolinfish.Moreeffectiverinseagents(e.g.untainted fish) did not produce statistically significant differences between duplicate samples. O’Mahony’s (1972, 1973) work strongly suggests that currently used methods of palate cleansing may incom- pletely remove residual food. He had subjects place 15 ml of a mixture of NaCl and LiCl in their mouths then use several rinsing/expectoration procedures. He mon- itored the NaCl and LiCl concentrations in the expec- torated saliva and water rinses. With a single water rinse half the people needed more than 10 min for their saliva to reach a normal resting level of NaCl. When asked to 0950-3293/03/$ - see front matter # 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0950-3293(03)00071-5 Food Quality and Preference 15 (2004) 311–316 www.elsevier.com/locate/foodqual * Corresponding author. Tel.: +1-612-624-2257; fax: +1-612-625- 5272. E-mail address: zvickers@umn.edu (Z. Vickers).