Classification of instant coffee odors by electronic nose toward quality control of production

Electronic nose (e-nose) is a device that plays an important role for odor assessment due to its low cost and wide-range applications. Currently, e-nose is widely used in the food industry such as coffee, wines, beers etc. Coffee is one of the most popular beverages in the human history. There are various types of products, for examples, roast/round, instant/soluble and ready-to-drink coffees etc. At present, coffee shop businesses are growing in Thailand and each of which has promoted its identity of coffee aroma. Nevertheless, the taste and aroma of the coffee are often not well controlled due to the lack of method to identify the odor standard. Hence, this problem should be solved to maintain consumers' satisfaction. In this paper, we have studied about the factors that affect on coffee taste and coffee aroma by using electronic nose. This instrument was designed to be portable and capable of measuring the coffee samples in both liquid and solid forms. Metal oxide semiconductors (MOS) were used as the sensing materials to detect changing of coffee odor at different conditions. The e-nose is composed of a flow system, a sensor array and data acquisition/analysis. It was found that the e-nose is capable to distinguish different brands of instant coffee products and is able to classify coffee odors at different mixtures. The results reveal that the concentrations and temperatures can affect the smell of quality of coffee. Based on this study, we are very optimistic that this e-nose will be very useful for coffee industry in Thailand.