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Determination of critical storage conditions of coffee oil microcapsules by coupling water sorption isotherms and glass transition temperature
Author(s) -
Frascareli Elen Cristina,
Silva Vanessa Martins,
To Renata Valeriano,
Hubinger Míriam Dupas
Publication year - 2012
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/j.1365-2621.2012.02939.x
Subject(s) - maltodextrin , whey protein isolate , differential scanning calorimetry , gum arabic , sorption , gravimetric analysis , water activity , glass transition , arabic , materials science , adsorption , chemistry , chemical engineering , chromatography , spray drying , whey protein , thermodynamics , water content , organic chemistry , composite material , polymer , physics , engineering , geotechnical engineering , linguistics , philosophy
Summary Coffee oil microcapsules were produced by spray‐drying using as encapsulating agents gum Arabic, whey protein isolate (WPI) and mixtures of maltodextrin (MD) and WPI, at three different proportions (3:1, 1:1 and 1:3). Sorption isotherms were determined by the gravimetric method, and the glass transition temperature ( T g ) was measured by differential scanning calorimetry. Microcapsules produced with gum Arabic showed the highest water adsorption and underwent a stronger water plasticising effect. At the highest water activity (0.843), this sample had a T g value of −18.3 °C, while those produced with WPI at higher proportions showed values around 25 and 30 °C. The good fit of experimental data by Guggenheim‐Anderson‐de Boer and Gordon–Taylor models allowed the determination of the critical storage conditions, at which powders are not susceptible to deteriorative physical changes. The samples produced with 1:1 and 1:3 of MD/WPI were the most stable ones, showing critical water activity values of 0.890 and 0.938, respectively.