"On Ice Cream" featured in Dairy Foods magazine
and sourced from "On Ice Cream" technical short courses.
Defects - Pink Discolouration in Vanilla Ice Cream:
What causes pink discoloration in vanilla ice cream?
Discoloration in vanilla ice cream made using exempt, or so-called natural
colors, can occur with changes in mix oxidation/reduction potential.
Non-exempt artificial colors do not typically change color with minor
changes in pH or acidity and that's one of the benefits of artificial
Annatto (an exempt color), which typically produces a desirable light
to golden yellow color in vanilla ice cream, can range in hue from reddish/orange
to yellow. If the oxidation/reduction potential of the mix changes due
to composition and/or microbiological and chemical contamination, pink
discoloration can result. A frequent compositional cause of such discoloration
is from use of certain whey ingredients.
Whey can be sourced from different cheeses and processed differently,
which impacts coloration with annatto. Interestingly, titratable acidity
and pH do not seem to play major roles in ice cream discoloration due
to whey. However, whey that is heat processed to improve water immobilization
effects in the finished ice cream can cause pink discoloration. It is
postulated that whey albumins, which coagulate with heat, indirectly
change mix chemistry and are the cause. When low-temperature processed
whey is used, pink discoloration does not occur.
Typically, modern whey processing does not apply this excess type of
However, as more concentrated whey protein products are used and higher
process temperatures applied, issues related to ice cream color could
It is also important to be aware that whey from cheeses to which color
has been added can also discolor ice cream in a different way. Oxidizing
agent(s), which are used to bleach out color in the resulting whey,
can be carried into the finished whey ingredient. Over use or misuse
of the oxidant can also directly or indirectly discolor the finished
ice cream due to oxidation of a variety of mix components. This can
result in faded, washed out, or in other ways, atypical coloration.
It can also cause the development of oxidized flavor in ice cream.
Remember, whey ingredients are limited to 25% of total milk solids nonfat.
If that restriction were to be removed, the quality, including the process
history, of each individual whey ingredient becomes even more important
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