Sensory, Acoustic and Textural Properties of Cocoa Butter Alternatives
S.B. Gregersen1,M. Povey2, U. Kidmose1, M.D. Andersen3, M. Hammershøj1,L. Wiking 1
1Dept. of Food Science, Aarhus University, DK-8830 Tjele, Denmark
2School. of Food Science and Nutrition, University of Leeds, Leeds, United Kingdom
3AarhusKarlsHamn Denmark A/S, DK-8000 Aarhus C, Denmark

This study demonstrates how simultaneous texture and acoustic measurements provide an improved evaluation of vegetable oils used in the chocolate and confectionery industry. For such products, the snap, defined as the sound upon breakage, is one of the most important sensory attributes. Although, it is generally accepted that fat plays a central role in the development of a suitable snap, evaluation of the acoustic properties of fats has been neglected in the scientific literature, and the relationship between texture and sound is not established. The aim of this study was to evaluate the snap of four different cocoa butter alternatives by simultaneous texture and acoustic measurements as well as a sensory evaluation 
The studied fats were based on either symmetric or asymmetric monounsaturated TAGs and had different content of palmitic acid (a POP-rich fat and a PPO-rich fat) and steric acid (a SOS-rich fat and a PSO-rich fat). Simultaneous sound and force measurements were obtained by texture analysis combined with an envelope detector system. A more sensitive evaluation of the sound event was obtained by applying a high-speed broadband (2-200 kHz) microphone and detector system. The textural characteristics of the fats were further evaluated by needle penetration test, cone penetration test and compression analysis. A sensory evaluation of the aural and textural properties was obtained by a sensory descriptive analysis of the studied fats. 
The result shows clear differences in the acoustic properties of the evaluated fats. The highest sound pressure level upon breakage was found for the POP-rich fat and the PSP-rich fat. The sound pressure level was found to be slightly lower for the PPO-rich fat compared with the POP-rich fat and the PSO-rich fat. No detectable sound evaluation occurred upon breakage for the SOS-rich fat, even though it is a hard fat. The sensory evaluation demonstrated a high correlation between instrumental determined sound pressure level and the sensory experience of the acoustic event upon breakage of fat. Correlation coefficients of 0.97 and 0.96 were found between measured sound pressure level and the sound intensity experienced upon breakage of fat samples by the fingers and during biting, receptively. No direct relation between the aural behavior of the studied fats and determined force at fracture, hardness, brittleness or stress and strain values from compression analysis was found. This demonstrates the importance of characterizing the aural properties of fats applied in the chocolate and confectionery industry.