200
FREEZE—DRYŒG
'
'
B. MICROBIOLOGÏCAL ASPECTS
_
‘
Introduction
_
,
'
.
_
‘
The microbiology of
foods is a complex subjectWith a number of variables,
'
each of which may affect the nal dehydrated and rehydrated product in terms of types
and numbers of orgæaiSms surviving and
signicance thereof from a public health
as well as a practical point of view.
For convenience, the factors
which are of importance and which Will be analyzed herein
.
may be grouped under the following :
_
1. Types and numbers of organisms in the raw material to be processed and freeze-dried.
2—; .E‘ect‘s of preliminary processing-stages on these organisms.
'
_
'3. Effects Of freezing”'on
‘
_
‘
4. Ebcts of the
these organiSms.
_
5… Effects of storage;;c0ditions
organisms.‘
.
_
’
Effects of
and"sub3equent Storage conditions on these organisms.
For a detailed review of the
thiseld, the reader is referred to Silverman and
Goldblith
.
'
.,
;
:
,,
«
Techniques of Measurement of Microbiological Survival
'
Classical methods of food miCrobiblO’g‘y used
of«the typesand quantities
of organisms present
a food stuff are based on
the
an organism to
‘
grow ina selected Or,
growthmed1um
temperature.
' .
various factors
aboÿe
can impose
certain
the
béÇii studied to some extent
ÿamage to cells by
1943, _H_aÏnæn and
1963),
(Pristgate
and HUPËŒ» l953; Str?ïÿk@-?älë f
ëëhÿdtüÿi°9W@bbà
‘
°tal1962WassermanandHopkms 1957)
measuredl
Ofmlcf°bloï°glcmœîesûsthateach0fthesethree“fesses18mvoïved'înf©P???°SSiâ
'
_of_“almQSt every
'Sins1{ey et
(l964)stud1edthe importance
the
.
Thus
-degœeofrecweryof orgamsmsfmm fœezedŒdf00dstus 0bkuY Väflousmed1a
‘
‘
mTab1€slZad3 IV1°W°ffhesedata°nemustrecogmZhü mordef’°
_
taüvelymeamngfulPreïmarY Studœsona Pamcu1&r lyoph1ædfoodsm° sh0u1dbe
……
madet°asœamthatthemedwand°°d1üonsusedare°Ptmaïfortheæcovery°f…a
Particular8pwes
'
'
'
‘
1 TheaboverefercnœsarenŒâ“mduSWebutar6m°relyexamplesofsome 1mporæntreferenœsontbe subject
FREEZE—DRYŒG
'
'
B. MICROBIOLOGÏCAL ASPECTS
_
‘
Introduction
_
,
'
.
_
‘
The microbiology of
foods is a complex subjectWith a number of variables,
'
each of which may affect the nal dehydrated and rehydrated product in terms of types
and numbers of orgæaiSms surviving and
signicance thereof from a public health
as well as a practical point of view.
For convenience, the factors
which are of importance and which Will be analyzed herein
.
may be grouped under the following :
_
1. Types and numbers of organisms in the raw material to be processed and freeze-dried.
2—; .E‘ect‘s of preliminary processing-stages on these organisms.
'
_
'3. Effects Of freezing”'on
‘
_
‘
4. Ebcts of the
these organiSms.
_
5… Effects of storage;;c0ditions
organisms.‘
.
_
’
Effects of
and"sub3equent Storage conditions on these organisms.
For a detailed review of the
thiseld, the reader is referred to Silverman and
Goldblith
.
'
.,
;
:
,,
«
Techniques of Measurement of Microbiological Survival
'
Classical methods of food miCrobiblO’g‘y used
of«the typesand quantities
of organisms present
a food stuff are based on
the
an organism to
‘
grow ina selected Or,
growthmed1um
temperature.
' .
various factors
aboÿe
can impose
certain
the
béÇii studied to some extent
ÿamage to cells by
1943, _H_aÏnæn and
1963),
(Pristgate
and HUPËŒ» l953; Str?ïÿk@-?älë f
ëëhÿdtüÿi°9W@bbà
‘
°tal1962WassermanandHopkms 1957)
measuredl
Ofmlcf°bloï°glcmœîesûsthateach0fthesethree“fesses18mvoïved'înf©P???°SSiâ
'
_of_“almQSt every
'Sins1{ey et
(l964)stud1edthe importance
the
.
Thus
-degœeofrecweryof orgamsmsfmm fœezedŒdf00dstus 0bkuY Väflousmed1a
‘
‘
mTab1€slZad3 IV1°W°ffhesedata°nemustrecogmZhü mordef’°
_
taüvelymeamngfulPreïmarY Studœsona Pamcu1&r lyoph1ædfoodsm° sh0u1dbe
……
madet°asœamthatthemedwand°°d1üonsusedare°Ptmaïfortheæcovery°f…a
Particular8pwes
'
'
'
‘
1 TheaboverefercnœsarenŒâ“mduSWebutar6m°relyexamplesofsome 1mporæntreferenœsontbe subject