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Microstructures formed by spray freezing of food fats
Author(s) -
Gwie C. G.,
Griffiths R. J.,
Cooney D. T.,
Johns M. L.,
Wilson D. I.
Publication year - 2006
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-006-5162-3
Subject(s) - microstructure , supercooling , tripalmitin , nucleation , materials science , spray drying , chemistry , analytical chemistry (journal) , chromatography , chemical engineering , crystallography , thermodynamics , organic chemistry , physics , engineering
The spray‐freezing of two food fats, tripalmitin (PPP) and cocoa butter (CB) and mixtures thereof, has been modeled experimentally using a novel single droplet freezing apparatus configured so that temperature profiles or samples for microstructure analysis can be obtained. For 2 mm diameter droplets suspended in a cold air flow at temperatures around 2–15°C, initial cooling rates were on the order of 10 K s −1 and the temperature profiles could be correlated directly to DSC data collected at 20 K min −1 , indicating that minimal supercooling of the materials occurred in the droplet form. Microstructure analysis confirmed that PPP crystallized preferentially in mixtures, and that the surface structure was very sensitive to storage conditions. The bulk structure was much less sensitive, and the internal microstructure of the PPP droplets revealed distinct nucleation sites, which were absent from the CB: These persisted in the mixtures up to 50 wt%. X‐ray analysis indicated that the fats crystallized in their more stable forms, namely, β for PPP and Form V/V1 in CB.