Journal of Texture Studies 36 (2005) 139–156. All Rights Reserved. © Copyright 2005, Blackwell Publishing 139 ACOUSTIC ENVELOPE DETECTOR FOR CRISPNESS ASSESSMENT OF BISCUITS JIANSHE CHEN 1 , CATHRINE KARLSSON and MALCOLM POVEY Procter Department of Food Science University of Leeds Leeds LS2 9JT U.K. Received for Publication October 10, 2004 Accepted for Publication February 17, 2005 ABSTRACT The crispness of food materials based on the force/displacement behav- ior and their acoustic nature was assessed using an Acoustic Envelope Detec- tor (AED) attached to the Texture Analyzer, wherein six kinds of biscuits were used: Carr’s Table Water, Crackerbread, Digestive, Dutch Crispbakes, Rich Tea fingers and Shortbread. The force/displacement and acoustic signals were simultaneously recorded during the breakup of biscuits. For each detected acoustic signal, there was a sudden drop in the compression force. The analysis of the force/displacement curve demonstrated the links between the second derivative of force curve and the acoustic event, indicating the energy released through the air of these crack events. The acoustic behavior of the biscuits was assessed in terms of maximum sound pressure level and the number of acoustic events, which were further interpreted as the acoustic events per unit area of newly created surface area and the acoustic event per unit time. The acoustic ranking of biscuits from instrumental assessment was in very good agreement with that from sensory panel tests. The normal inte- gration time (1.25 ms) for the AED was generally effective in detecting acous- tic signals for crisp biscuits, but a shorter integration time (0.25 ms) was found advantageous in detecting acoustic signals that occur within a very short time period and gave better differentiation of crisp biscuits. KEYWORDS Acoustic Envelope Detector, bending-snapping, biscuits, crispness, sensory, sound Blackwell Science, LtdOxford, UKJTSJournal of Texture Studies0022-4901Copyright 2005 by Food & Nutrition Press, Inc., Trumbull, Connecticut.2005362139156Original Article CRISPNESS ASSESSMENT OF BISCUITSJ. CHEN, C. KARLSSON and M. POVEY 1 Corresponding author. TEL: (00) 44-113-3432748; FAX: (00) 44-113-3432982; EMAIL: j.chen@food.leeds.ac.uk