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Effects of steam‐microwave blanching and different drying processes on drying characteristics and quality attributes of Thunbergia laurifolia Linn. leaves
Author(s) -
Phahom Traiphop,
Phoungchandang Singhanat,
Kerr William L
Publication year - 2017
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.8167
Subject(s) - blanching , spray drying , chemistry , freeze drying , food science , moisture , water content , chromatography , organic chemistry , geotechnical engineering , engineering
Abstract BACKGROUND Dried Thunbergia laurifolia leaves are usually prepared using tray drying, resulting in products that have lost substantial amounts of bioactive compounds and antioxidant activity. The maturity of the raw material, blanching techniques and drying methods were investigated in order to select the best condition to produce high qualities of dried T. laurifolia leaves. RESULTS The 1st stage of maturity was selected and steam‐microwave blanching ( SMB ) for 4 min was adequate for blanching leading to the maximum recovery of bioactive compounds. The modified Halsey model was the best desorption isotherm model. A new drying model proposed in this study was the best to fit the drying curves as compared to five common drying models. Moisture diffusivities were increased with the increase of drying temperature when combining SMB and heat pump‐dehumidified drying. Microwave heat pump‐dehumidified drying ( MHPD ) provided the shortest drying time, high specific moisture extraction rate ( SMER ) and could reduce drying time by 67.5% and increase caffeic acid and quercetin by 51.24% and 60.89%, respectively. CONCLUSION MHPD was found to be the best drying method and provided the highest antioxidant activity and bioactive compounds content, high SMER and short drying time. © 2016 Society of Chemical Industry