Quantitative and qualitative measurements of odor are indispensable for the development of odor display systems that can reproduce odor at any place in any time. This chapter covers odor evaluation techniques based on human senses, instrumental analyses, odor sensors, and data analysis methods dedicated to odor measuring techniques. The chapter consists of the four following sections: sensory evaluation, gas analysis instruments, odor sensing system, and pattern analysis for odor sensing system. The first section describes odor evaluation methods with human senses. The second section gives an overview of instrumental laboratory techniques for olfaction research. The third section surveys sensor devices for odor detection. Finally, the last section gives the basic statistical methods and advanced pattern analysis for odor sensing systems.
TopSensory Evaluation
This section covers sensory evaluation to examine sensory characteristics using human senses. First, methods generally used in sensory evaluation are briefly summarized. Second, important points to acquire reliable data in the sensory evaluation are given. Finally, a case study of sensory evaluation for the study on yuzu aroma is presented. Yuzu is widely used in Japanese cuisines for its pleasant flavor. To clarify the odor-active volatile compounds, which differentiate yuzu from other citrus fruits, sensory evaluation methods were applied to yuzu peel oils. In order to extract information from the results of the evaluation, statistical analyses were performed using the comparison by cobweb chart, the analysis of variance, Tukey’s multiple-comparison test and multivariate analysis.
According to the Institute of Food Technologists (IFT), sensory evaluation has been defined as “a scientific discipline used to evoke, measure, analyze, and interpret reactions to those characteristics of foods and materials as they are perceived by the senses of sight, smell, taste, touch, and hearing” (IFT, 1975).
Sensory evaluation using the human senses is a method to measure the strength, texture, and preference of objects. The evaluation is subjective, sometimes ambiguous about reproducibility. Since such sensory evaluation is based on the human senses, it can be said that the evaluation includes subjective factors such as mistakes, overlooking, and sensory fatigue that do not arise with objective equipment. To solve these problems, proper designs of experiments that minimize the subjective influences caused by the assessor’s mental and physical conditions is introduced.