MEAT AND MEAT—PRODUCTS
187
These authors were unable to
avoid the inuence of oxygen in deterioration because gas
chromatography showed srgn1cany higher amounts of oxygen in the head space gas
after storage
than in the original nitrogen gas pack, indicating that oxygen was adsorbed
onto the drred meat at the completion of the drying cycle (when the vacuum was released
With dry air) and desorbed during subsequent storage in hermetically ’sealed containers.
-
If this be the case, there should be an advantage in commercial systems of drying and
packaging that avoid any possible contact of the dried meat with air.
El-Gharbaive and Dugan
8
sealedsamples of freeze-dried raw beef with head space
oxygen limited to a range of 0 to 2.0 percent asmeasured initially.
They found a continuous decrease in total soluble protein and non—protein nitrogen
as storage progressed, the fall-o increasing With higher oxygen levels. The phospholipid
component of the tissue fat was more susceptible to oxygen than the neutral lipids and
oxidized rst.
Once again there is a possibility that the oxygen level was higher than recorded because,
at the completion of the drying operation, the vacuum was broken with air with the chance
that oxygen was absorbed by the dried tissue and subsequently released in the storage
cans.
Oxygen absorption of freeze-dried meat was studied by Tappel 22, who concluded that
only a small proportion of the total was taken up by ether—extractable lipids, much less
than was absorbed by either non—extractable fat or protein.
Chipault and Hawkins 5 describe
oxidative change as a two step process
involving rst, oxidation of the boundlipids followed after a variable period by rancidity
of the glycerides. The oiÏ—avour that develops rapidly in freeze—dried raw or cooked beef
when exposed to oxygen appears to be due. to the oxidation of the bound lipids and to the
formation of stale odours by water soluble non—lipid components of the crude bound lipid
fraction. These water solubles do not themselves absorb oxygen. Chipault and Hawkins
also give results to indicate that cooking increases the susceptibility of freeze—dried beef
to oxidation although general experience is that raw beef is less stable than cooked.
Taken as a whole, these results imply that initial storage changes taking place with
freeze-dried raw meat are connected With oxygen absorption by protein and bound lipids.
There may be suîcient oxygen available in the average commercial package to permit
appreciable loss of acceptability,
Meat protein denaturation can be examined from the point of view of loss of extractability
of actomyosin and loss of
actomyosin A. T. P.—ase as studied by Connell 7,
Cole “, and Partmann
14…
-
-
In _spite of its greater commercial potential, the storage properties of cooked beef have
not been studied to thesame extent as the raw meat. A mild avoured product soon develops
& stale taste when exposed to air. On the other hand, a slightly browned freeze—dried beef
with a roast avour has good
Freeze—dried white chicken meat slowly aequires a “cardboard” taste in air but rancidity
may take years to develop. The dark meat rancidies
much more quickly presumably
due to the catalytic inuence of the higher concentraüon
of haem pigment.
Because of this superior shelf life,
only is used by many dned soup packers.
Sometimes it is coatedWith'hydir0genated’or'stabilized fat, although-whether this is of any
value is debatable.
.
,
a
_
»
.
.
.
.
The tendenoy
ham to develop rancrdrty lrnnts
the value of what are, When freshly prepared, very good products. Var1aüons m cunng
187
These authors were unable to
avoid the inuence of oxygen in deterioration because gas
chromatography showed srgn1cany higher amounts of oxygen in the head space gas
after storage
than in the original nitrogen gas pack, indicating that oxygen was adsorbed
onto the drred meat at the completion of the drying cycle (when the vacuum was released
With dry air) and desorbed during subsequent storage in hermetically ’sealed containers.
-
If this be the case, there should be an advantage in commercial systems of drying and
packaging that avoid any possible contact of the dried meat with air.
El-Gharbaive and Dugan
8
sealedsamples of freeze-dried raw beef with head space
oxygen limited to a range of 0 to 2.0 percent asmeasured initially.
They found a continuous decrease in total soluble protein and non—protein nitrogen
as storage progressed, the fall-o increasing With higher oxygen levels. The phospholipid
component of the tissue fat was more susceptible to oxygen than the neutral lipids and
oxidized rst.
Once again there is a possibility that the oxygen level was higher than recorded because,
at the completion of the drying operation, the vacuum was broken with air with the chance
that oxygen was absorbed by the dried tissue and subsequently released in the storage
cans.
Oxygen absorption of freeze-dried meat was studied by Tappel 22, who concluded that
only a small proportion of the total was taken up by ether—extractable lipids, much less
than was absorbed by either non—extractable fat or protein.
Chipault and Hawkins 5 describe
oxidative change as a two step process
involving rst, oxidation of the boundlipids followed after a variable period by rancidity
of the glycerides. The oiÏ—avour that develops rapidly in freeze—dried raw or cooked beef
when exposed to oxygen appears to be due. to the oxidation of the bound lipids and to the
formation of stale odours by water soluble non—lipid components of the crude bound lipid
fraction. These water solubles do not themselves absorb oxygen. Chipault and Hawkins
also give results to indicate that cooking increases the susceptibility of freeze—dried beef
to oxidation although general experience is that raw beef is less stable than cooked.
Taken as a whole, these results imply that initial storage changes taking place with
freeze-dried raw meat are connected With oxygen absorption by protein and bound lipids.
There may be suîcient oxygen available in the average commercial package to permit
appreciable loss of acceptability,
Meat protein denaturation can be examined from the point of view of loss of extractability
of actomyosin and loss of
actomyosin A. T. P.—ase as studied by Connell 7,
Cole “, and Partmann
14…
-
-
In _spite of its greater commercial potential, the storage properties of cooked beef have
not been studied to thesame extent as the raw meat. A mild avoured product soon develops
& stale taste when exposed to air. On the other hand, a slightly browned freeze—dried beef
with a roast avour has good
Freeze—dried white chicken meat slowly aequires a “cardboard” taste in air but rancidity
may take years to develop. The dark meat rancidies
much more quickly presumably
due to the catalytic inuence of the higher concentraüon
of haem pigment.
Because of this superior shelf life,
only is used by many dned soup packers.
Sometimes it is coatedWith'hydir0genated’or'stabilized fat, although-whether this is of any
value is debatable.
.
,
a
_
»
.
.
.
.
The tendenoy
ham to develop rancrdrty lrnnts
the value of what are, When freshly prepared, very good products. Var1aüons m cunng