Influence of drying on browning and sensory characteristics of dried whole longan
- Publikations-Art
- Kongressbeitrag
- Autoren
- Mahayothee B, Wongtom R, Keowmaneechai E, Phupaichitkun S, Haewsungcharern M, Janjai S, Müller J
- Erscheinungsjahr
- 2006
- Veröffentlicht in
- Proceedings of the15th International Drying Symposium
- Herausgeber
- Farkas I
- Verlag
- Szent Istvan University Publisher , Gödöllö (Hungary)
- Band/Volume
- A-B-C/
- ISBN / ISSN / eISSN
- 963 9483 59
- Seite (von - bis)
- 1562-1566
- Tagungsname
- 15th IDS 2006
- Tagungsort
- Budapest (Hungary)
- Tagungsdatum
- 21.08.2006
The impact of drying on color, browning reactions and sensory evaluation of dried whole longan was investigated. Longan (Dimocarpus longan Lour.) cultivar Edor was chosen. This cultivar is commercially used for production of dried longan in Thailand. The fruits with size AA, diameter 27 mm, and free from visual damages and diseases were selected. The whole fruits were dried in a single layer at temperatures of 60, 70 and 80°C with air velocity of 0.2 m/s using a laboratory hot air dryer with a throughflow mode system. Fruits were dried until the water activity, aw, was below 0.6. The drying time needed for reaching this value was about 47, 35 and 28 hours for fruits drying at 60, 70 and 80°C, respectively. The drying rate was increased with increasing drying temperature. The total soluble solids of fresh longans used in the study was 16-18 °Brix,
while titratable acidity was 0.9 mg/100g edible. The major sugars found in fresh and dried longan were sucrose, glucose and fructose. Glucose and fructose are the main substrates for maillard reactions. These two sugars can also obtained from the degradation of sucrose by heat treatment. Therefore, the extent of browning in longan flesh dried at 80°C was found to be the highest. This resulted in the lowest score of the acceptance especially in color and taste of the product. Sensory properties of dried products were evaluated by twenty-two of trained Thai panelists using a 9- point hedonic scale (1=extremely dislike to 9=extremely like). Browning reactions plays an important role on the sensory characteristics. The optimum temperature was 70°C for drying the whole longan in this investigation.