Petfood Industry - January 2018 - 48
48 | www.PetfoodIndustry.com
Greg Aldrich, PhD
Agar-agar: gelling agent option
for canned dog and cat foods
Product consistency, texture and
uniformity are important to consumers.
They foster confidence regarding safety
and promote repeat purchase. Given
the variable nature of ingredients and
the complexity of the manufacturing
process, creating that consistency for the
manufacturer can be a challenge. The
industrial size, scale and scope complicate matters, as well.
In canned pet foods, this need for
consistency is part of the reason we have
to use food additives like gums and gels
to help improve viscosity and structure
of the product. Customers expect it
and pet food companies deliver with
judicious use of hydrocolloids. These
additives create a gel at a low concentration, perform consistently and require
minimum amounts of additional inputs
(e.g., minerals or other pH modifiers).
The stability of the loaf can be created
with starches (e.g., corn) but these often
take extensive cook time to create the
desired viscosity and final product
texture. So most pet food companies
use a gel like carrageenan, xanthan or
others. Carrageenan has been criticized
unnecessarily for health issues and
xanthan falls in a gray area for use. Thus,
alternatives are being explored and agaragar could be one of them.
Agar-agar origins and
Most might recognize agar-agar
as the solid-media gel used in plating
microbiological samples. This use was
part of the discovery by Robert Koch
in 1882 because it tolerated elevated
temperatures and humidity conditions
for incubation of bacteria. The use of
agar-agar was suggested to him by his
wife from her experience with it in jams
and jellies. Using this gel ultimately
allowed Koch to discover the cause of
tuberculosis, for which he was awarded
the Nobel Prize in 1905. Agar-agar
continues to be used in microbiological
analysis to this day.
Agar-agar has only recently come
on the scene in pet food; however, as a
hydrocolloid or gelling agent, it has been
used in food for more than 350 years.
It is a natural extract that originates
from Japan and is derived from red
seaweed in the family Rhodophyceae. It
is produced commercially from Gelidium
seaweeds and Gracilaria seaweeds.
The former are slow growing and
resist commercialization, whereas the
latter have been effectively cultivated.
The seaweeds are processed by first
washing, then treating with alkali (2-5
percent sodium hydroxide) at 85-90
C for one hour to convert the sulfate
groups. The agar-agar is then extracted
under pressure with hot water (95-100
C) and filtered hot to remove insolubles.
The resulting gel is cooled in pans and
frozen; it is the freezing step that creates
its functionality. Upon thawing, the gel
is concentrated then pressed to dewater
(syneresis). It can then be sliced into
strips or flakes; but for most commercial
purposes, it is dried to a powder - the
most concentrated form.
By the numbers:
agar-agar in pet
According to Dog and Cat Food Ingredient Center (www.pet-ingredients.com)
data, agar-agar is found in wet pet food,
but not in dry pet food. As a gelling agent,
this is to be expected. Via the database,
agar-agar is on the ingredient list for:
* 3.6 percent of canned/wet cat food
* 4.4 percent of canned/wet
Source: WATT Global Media Dog and Cat Food Ingredient
Center, December 2017 data
Dr. Aldrich is president of Pet Food & Ingredient Technology Inc. He is also the author of Petfood Industry magazine's monthly
column, "Ingredient Issues."