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COMMONW£ALTHSCŒNŒC ANDINDU…MSEARCH
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DIVISION OF FOOD PRÈSÊRVÀTION, RYDË, N. S. W., AUSTRALIA
INTRODUCTION
In developing economm processesfor freezedrymgfood the theory andpracüœ of heat
former is the prîcîÿâï‘
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subhmaüon rateof1œ W1thm Ï
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‘The transfer of vap'oû'r” in fddpdt rymttmg 1»
of current interest in thfdmt1ptfgw mpm… 1:41n t4çhe
present VVork VapOur ttàs‘fet àäîfâë'èèÏfonthecourse of freeze
beenstud1ed
in 801116 detail, because it is ï°Ç°gÏZÇd that theoutwardpassageof watervapour ÎhI°“Ëh
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drying has only bœ
hocway2,3mterms ôf
according to Stefan’s di"usion equation. THè ‘r,stÏ'ëùâo aÿpes‘only When there is no
ow resistance, as in a high Vacuum au@_thesecondtothogasout81dethe.swfgœ of …fçhç
product
owequaüonsforpomusmaterialshave also
tdyng pu…fphm
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It is pr0poSèd ”to èÏidW
productthe Submation
process involves VàpOur transferfrom an 10€ mterfaceboundary movmg
from and dry part—°» of the dtdthtthbpt aldmtt how the
1stransferredFurther1tlsproposedwsh0Wthatthe
theory
dèp‘ënds On
pi'0per
and permeability coeîcients
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for;watèr V&pour1freeze—dedpr0du0tsmîh€type0fVäP0ur
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