In order to obtain the best out of each infusion in sensory experience, it is necessary to optimize the factors that influence their preparation, such as the water quality, the quality of the raw material, concentration, temperature of the water and the infusion time. Moreover, it becomes necessary to study whether there is any correlation between consumer preference and color variation that can result from different forms of preparation of infusions. Thus, the main objective this work is to optimize the preparation conditions (water temperature and infusion time) for lemon verbena, lemongrass, white peppermint and lemon thymus. To this end, we have used a total of ten binomials “infusion time / temperature of the water” presented to acceptance evaluation in a random order, by applying the statistical method Response Surface. Resorted to the colorimetry method using the CIELAB system, to complement the color measurement. Different herbs require different conditions of preparation, it is possible to identify that the optimal points of infusion are between 4 and 8.5 minutes and between 92 and 99 °C. Through the analysis of open-ended comments it was possible to study the positive and negative attributes associated with each of the time / temperature infusion preparation. In addition, time / temperature binomials with greater acceptance, are associated with a greater number of positive characteristics. By colorimetry, it was found that there is relationship between color and consumer preference, and it was found that for any of herbs, the time / temperature binomials highlighted with higher ratio values and / or more of positive attributes had lower brightness values. With regard to chromaticity values, there is a greater preference when they are higher, although this fact is only noticeable in the infusions of verbena and lemongrass. With regard to the hue, althought the combinations of different time and temperature gave a differents colour intensity samples, for all the herbal plants, excluding lemongrass, the colours is in an expectable and characteristic range. Thus, the maximum sensory acceptance occurs in the following infusion time / temperature of the water combinations: 6 min / 96 °C, 8,5min / 99 °C, 4min / 95 ºC and 7 min / 92 °C for infusions of lemon verbena, lemongrass, white peppermint and lemon thymus, respectively.
Date of Award | 14 Jul 2016 |
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Original language | Portuguese |
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Awarding Institution | - Universidade Católica Portuguesa
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Supervisor | Rui Costa Lima (Supervisor) |
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- Herbal tea
- Herbs
- Infusion time
- Water temperature
- Sensory acceptance
- Colorimetry
- Mestrado em Engenharia Alimentar
Análise sensorial de infusões de ervas aromáticas: determinação das condições ótimas de preparação de infusões
Ferreira , C. F. D. S. (Student). 14 Jul 2016
Student thesis: Master's Thesis