PET Food Processing - September 2018 - 54

FORMULATION

"Consumer perception continues to be a hurdle for
traditional additives as many customers don't fully
understand the benefits of these chemicals."
Robert Mason, Balchem
specific product and correct dosage. "The major issue
with using additives is determining the best location to
add the additive in order to have good distribution," she
says. "Poor or uneven distribution is a key reason for
poor performance. Kemin's products have been optimized for microbial growth control and palatability."
Some traditional mold inhibitors such as potassium sorbate and traditional bacterial control ingredients such as propionic acid are synthetic. Alternatively,
natural sources of acids offer effective microbial growth
control that is consistent with natural product labelling,
Deffenbaugh says.
Antimicrobial agents (AMAs) are generally bacteriostatic rather than bactericidal and work by inhibiting the
growth of microorganisms, says Hanna Bemer, research
and development specialist for KDR/Plato Pet Treats,
Fresno, California. AMAs include acids like acetic acid
(commonly found in vinegar), benzoic acid and citric
acid, as well as non-acids like nitrites and sulfites.
Several factors must be considered when selecting the
appropriate AMAs for a food system. "Most importantly,
the pKa (an index to express the acidity of weak acids) of
the AMA must be higher than the pH of the food for it
to be effective," Bemer says. "This is because AMAs work
best in their un-ionized form. The effectiveness of an
antimicrobial agent is related to the high-lipid solubility
of its un-ionized form, which allows it to accumulate on
cell membranes or on structures and surfaces of the bacterial cell, effectively inhibiting its cellular activity." For
example, if the pKa is equivalent to the pH, then only
50% of the AMA is in its effective (un-ionized) form.
Other factors to account for when choosing the best
AMAs for pet food products, Bemer says, include presence
of other inhibitors (salt, smoke, sugar), moisture content,
solubility, length of storage and temperature conditions.

Encapsulated acids
Acids affect metabolism of microbial cells in such a way
that eventually leads to cell death. "Weak" acids such as
vinegar or citric acid are used because they effectively
control microbial growth but are not too harsh to handle
and use. "Strong" acids such as phosphoric acid or hydrochloric acid effectively reduce pH but are dangerous
for operations staff to handle and may also negatively affect palatability of products, Deffenbaugh says.

PET FOOD PROCESSING | September 2018 | www.petfoodprocessing.net

Monteleone of FoodSafe Technologies says the primary difference between acids and encapsulated acids is
that acids are meant to come into direct contact with the
food source prior to ingestion by the targeted animal,
and encapsulated acids are controlled-release substances
meant to target organisms beyond the stomach of the
target animal, in the lower gastrointestinal tract.
"Much science needs to be used when applying encapsulated antimicrobials, because there are many beneficial microbes and flora within the gut of each targeted
species," he says. "So, the delivery of encapsulated antimicrobials must be done with competency towards these
good-guy flora."
Robert Mason, senior food scientist for New
Hampton, New York-based Balchem Corp.'s Animal
Health and Nutrition Division says encapsulated acids
are encapsulated to prevent any pre-reactions with the
matrix's composition, whether that is protein denaturation, purging of moisture, discoloration/off-flavors or
dough-forming interference. "Encapsulated acids do
not 'shock' meat materials like raw acids can," he says.
"Encapsulation allows for a specified control release."
In the realm of acidulants, acetic acid and lactic acid
seem to have additional bacteriostatic properties beyond
the general pH reduction found in other organic acids,
Mason adds. "The goal of either product is to enable the
producer to deliver a finished good that is consistent in
quality and safe for our pets," he says.

Controlling oxidation
When it comes to improving product stability and shelflife, delaying the onset and the rate of lipid oxidation is
key. "The addition of antioxidants is acclaimed as being
the most effective, convenient and economical strategy
for stabilizing foods," Bemer says. "Oxidation is known
to occur during harvesting, processing and storage of
foods. Lipid oxidation can cause nutritional deterioration and produce undesirable flavor, color and toxic
compounds that often make food less acceptable to pets."
Antioxidants work by scavenging free radicals such
as lipid peroxy radicals, controlling transition metals,
quenching singlet oxygen and inactivating sensitizers.
"Hydrogen atoms are donated by antioxidants to free
radicals and as a result, convert them to more stable,
nonradical products," Bemer says. "Antioxidant activity

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PET Food Processing - September 2018

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