American Ed. Dec 2019
American Ed. Dec 2020
On Ice Cream
"On Ice Cream" featured in Dairy Foods magazine
and sourced from "On Ice Cream" technical short courses.
Life of Ice Cream:
Question: We would like to change our "sell by" date from 9 to
12 months. What implications does this have on product quality?
Answer: Quality degradation of packaged ice cream primarily involves
body and texture, with the most common problem being the development
of a coarse, icy texture. Control over the stability of body and texture
begins with the freezing point of the mix composition. It includes water
immobilization properties that involve stabilizer type and level, protein
functionality and the amount and type of sweeteners. Processing control
elements include dairy ingredient variables, pasteurization and homogenization
conditions and mix aging, as well as a myriad of freezing factors like
mix temperature, barrel residence time, exit temperature and condition
of the scraper blades. There are also post-freezing variables that need
to be monitored. These include the nature of the package, including
any shrink-wrap application, the rate of hardening and the final hardened
temperature, as well as the amount of post-hardening heat shock to which
the product is exposed.
A sample of ice cream representing the most favorable combination of
conditions could maintain excellent quality for a year or more. However,
a sample from another batch representing undesirable processing elements,
as well as possibly having suffered heat shock abuse during distribution
might reach an unacceptable level of quality much sooner. Since there
is no way to identify the conditions under which ice cream will be handled
once it leaves the control of the manufacturer, it is not practical
to predict the shelflife of any ice cream product.
Accelerated shelflife testing, which involves extremes of heat shock
exposure under controlled conditions, is useful in evaluating shelflife,
but only in a relative way and only if it is correlated with consumer
acceptance data. Accelerated testing is useful in comparing behavior
of one product to another or to a given control; however, it will not
provide information about the specific shelflife of the product, given
the uncertain nature of the conditions to which it will be exposed.
A more practical approach can be based on the profile of consumer or
customer complaints received, combined with the evaluation of products
purchased at or near the sell by date. A low level of complaints involving
body/texture deterioration, or other quality attributes in most aged
products would support a decision to extend the sell by date. Ongoing
monitoring to evaluate the effect of that extension is necessary.
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