Hedonic and Descriptive Sensory Evaluation and Analysis--An Application to Taiwan Alpine Tea
研究紀要 Research Summary
Taiwan alpine (high mountain) tea products are very popular with consumers due to their unique flavors and aroma, and have become high-priced agricultural products in recent years due to the planting altitude. In practice, there is a lack of attribute research to identify and evaluate product quality, and to use as a reference for pricing the tea efficiently. Application of quantitative analysis of the tea's chemical composition for determining the source of tea products is also quite limited. These limitations make it quite difficult to distinguish the various products in the different producing areas, and often lead to confusion and disputes.
The present study identified and applied five primary sensory evaluation constructs of tea, namely appearance, tea color, taste, aroma, and leaf shape, to evaluate whether a hedonic attribute index of alpine tea can adequately describe products from different areas. A total of seventeen indices were chosen from the five constructs of the most popular tea competition evaluation standards. Twenty-two sensory experts conducted the evaluation of fifteen tea samples from the five tea areas of Renai (Cingjing, Hehuanshan, Fushoushan, Qilaishan, and Dayuling) in Nantou to identify the specific attributes of that area's tea. We tested the significance of the practical attribute items corresponding to the five sensory characteristics with a partial least squares path model and examined the differences in sensory evaluation indicators between the five Nantou tea areas with multi-group analysis.
The major conclusions are as follows: (1) The main chemical components of tea, such as total catechins, showed significantly different results in tea products of the same tea species at different altitudes. Thus, quantitative analysis of the main chemical components can provide clues to the altitude of the tea plantation location. However, if the tea areas are very close to each other, this method may not effectively discriminate between the differences. (2) Practical hedonic indexes for high mountain tea sensory application were established. The results show that the sensory attributes effectively provide a sound basis to identify alpine tea products for different tea regions. In this study, based on the existing five major constructs of the evaluation framework, and by expert opinions and practical operations, we established seventeen descriptive operational variables for the evaluation of mountain tea in five areas. (3) A workable attribute tool for segmenting tea products was established. A two-dimensional map framed by taste and aroma, two popular sensory constructs, was developed and is provided with the multi-group analysis. The descriptive evidence can assist the local industry chain in promoting its local agricultural products by linking the qualities of tea products to their specific areas of origin.
The present research shows that the hedonic attribute index for Taiwanese alpine tea established in this study is able to accurately measure the products of different mountain tea areas. Quantitative analysis provides the altitude information of the tea product at the first stage. The sensory indexes in this study are then able to further identify the source of the product by its attributes, and should effectively reduce market disputes and improve efficiency.