Principles of Cheese Technology 263Photo - oxidation is distinguished from
spontaneous auto - oxidation in several ways.
Light energy can catalyze oxidative initiation
reactions by stimulating the production of
free radicals or by causing the formation of
singlet oxygen. After initiation, light can
catalytically degrade hydroperoxides by pho-
tolysis. Ultraviolet light and some wave-
lengths of the visible spectrum cause
light - induced off fl avors in dairy products.
Green, red, blue, and brown materials have
been used to prevent light induced off fl avors.Dehydration
Many cheeses may be categorized as
intermediate - moisture food with high water
activity. Without packaging, the cheese
develops a rind due to water evaporation
from the surface as was practiced in the
industry in the past. The rind retards, but does
not stop, further loss of moisture from the
cheese. A water barrier of not less than
1 g/100 in^2 /24 hours for cheese packaging
materials in necessary. Most modern cheese
packaging fi lms and foils provide a good
moisture barrier. Except in cases of extensive
seal leaking or pinholing, fi lm - packaged
cheese generally does not lose more than
0.1% moisture.References
Andren , A. 2003. “ Rennets and Coagulants. ” Encyclo-
pedia of Dairy Sciences. Roginski , H. , Fuquay , J.W. ,
Fox , P.F. Academic Press , London. 281 – 293.
Aneja , R.P. , Mathur , B.N. , Chandan , R.C. , Banerjee ,
A.K. 2002. Technology of Indian milk products. Dairy
India Yearbook, New Delhi, India. 183 – 196.
Bachmann , H.P. , Butikofer , U. , Isolini , D. 2003. “ Swiss -
Type Cheeses. ” Encyclopedia of Dairy Sciences.
Roginski , H. , Fuquay , J.W. , Fox , P.F. (eds). Academic
Press , London. 363 – 371.
Banks , J.M. 2003. “ Cheddar - Type Cheeses. ”
Encyclopedia of Dairy Sciences. Roginski , H. ,
Fuquay , J.W. , Fox , P.F. (eds). Academic Press ,
London. Pages 356 – 363.
Barbano , D.M. 2001. “ Moisture nonuniformity and sam-
pling errors in large cheddar cheese blocks. ” Journal
of AOAC International. 84 : 613 – 619.
Barbano , D.M. , Lynch , J.M. 2006. “ Major advances in
testing of dairy products: Milk component and dairybeen cited as the major cause of decreased
shelf life in tight - wrapped cheese compared
to cheese packaged by gas - fl ush or vacuum
techniques. Wax treatment after tight wrap-
ping, or the use of sorbates, may improve
package and product stability.
Heat sealing is commonly used for shrink
bag, vacuum, and gas - fl ush systems.
Extensive leaking of the heat seal can cause
package failure in gas - fl ush and evacuation
methods. A seal integrity test should be con-
ducted at regular intervals on the cheese
packaging line to ensure proper settings on
the packaging equipment.
Oxidation
Oxidation typically begins on the exposed
food portion. It depends on the presence of
oxygen, and is catalyzed by light, metals,
enzymes, heat, and ioninizing radiation or
ultraviolet light. Oxidation problems can
occur in consumer - sized packages because of
their relatively large surface area and expo-
sure to fl uorescent light while sitting in
display cases at the grocery store. The sensi-
tivity of the annatto (Bixin) pigment to oxi-
dative deterioration is ascribed to its highly
double - bonded structure. Storage tempera-
ture infl uences oxidative degradation of
cheddar cheese. Temperature may infl uence
both oxidation kinetics and microbial activ-
ity. Young and active cultures may reduce or
eliminate necessary oxygen despite the posi-
tive effects on oxidative kinetics. Mold
growth and fat oxidation seldom occur
together. It is postulated that mold develop-
ment utilizes oxygen within the package. A
higher incidence of discoloration of cheddar
cheese has been observed at lower tempera-
tures. Storage at 2 ° C (36 ° F) is reported to
increases peroxide values (indicator of oxida-
tion) of vacuum - packed cheddar as compared
to storage at 13 ° C (55 ° F). This has been
attributed to greater reducing power at the
elevated temperature as a result of increased
bacterial activity.