Food Protection Trends - January/February 2022 - 86

Figure 1. Acid/Acidified Flowchart.
Acidified foods
Certain foods are characteristically acidified foods, per
the acidified foods rule. The products mentioned in the
preambles to the rule and in the rule itself almost always have
a low-acid particulate food to which acid is added. These
products are often referred to as pickles or pickled. These
products also tend to require a significant time to reach the
finished pH equilibrium (e.g., several hours).
Conceivably, there could be products that present
some other challenge to reliably achieving the proper pH
equilibrium. There could be a product that has variable
buffering capacity, which requires variable amounts of the
acidulant to achieve an equilibrium pH within the product's
specified range. These products could be determined by the
Process Authority to be acidified.
Acid or acidified?
The regulation excludes (and, thus, implicitly designates
as acid food) products that may have " small amounts of
low-acid food(s) and have a resultant finished equilibrium
pH that does not significantly differ from that of the
predominant acid or acid food. " Given the history of the
rule and the food safety concerns it is designed to address,
this language could be informed by examining the pH
equilibrium time.
If a food has low-acid particulates in low enough
quantity or that are small enough dimensionally, such that
a relatively short-finished pH equilibrium time is achieved,
then these products could be considered acid foods. The
percentage, by itself, of the low-acid food has no food
safety implications. Rather, it is the impact of the low86
Food
Protection Trends January/February
acid food on the pH equilibrium time that could impact
the food safety of the product. Therefore, the proposal is
that the evaluation of the criterion of " small amounts of
low-acid food(s) " as stated in the rule should not be made
based on the percentage of the low-acid ingredient(s)
in the formulation, but, rather, should be interpreted by
examining the effect on the pH equilibrium time.
Similarly, guidance on the words " significantly differ " is
not provided in the rule. Given that the food safety focus of
the regulation is on the growth of C. botulinum, if the finished
equilibrium pH is 4.6 or less, then one could conclude that
there is not a significant difference.
Precise changes in pH (i.e., pH shifts) and comparisons of
the acid ingredients to the finished product equilibrium pH,
although important to know, have no bearing on whether a
product should be considered acid or acidified. The pH shift
in isolation has no food safety implications. The relevant
measure is the equilibrium pH. For an acid or acidified food,
the equilibrium pH must be at 4.6 or below. The proposal
is that if the finished equilibrium pH is 4.6 or less, then the
resultant finished equilibrium pH would not be considered
significantly different from that of the predominant acid or
acid food.
Note that the equilibrium pH is also sometimes used in
determining the appropriate process to apply to the product
to make it safe and shelf stable.
Figure 1 is a flowchart that can be used for the acid
versus acidified food determination. This chart deals with
the products that are the main concern of the regulation:
those that consist of low-acid particulates and are pickled
by the addition of acid ingredients. As stated in the rule,
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