Page 183 - Small Animal Clinical Nutrition 5th Edition

Commercial Pet Foods 185

will require more time to attain proper core temperatures; con-
VetBooks.ir versely, higher temperatures require less time to achieve sterili-
zation. Because of high process temperatures and vacuum con-
ditions in cans, canning destroys aerobic and anaerobic bacte-
ria, making it the best method to preserve high-moisture foods
for extended periods.
One newer method is the increasing use of foil pouches that
most often contain a single serving of food. Products pack-
aged in pouches usually contain increased moisture levels
compared to that of loaf style cans. The high moisture con-
tent allows foods to be poured from the package into the feed-
ing bowl. Pouches meet the needs of consumers who desire
easy to store foods and single serving freshness. However,
pouches increase the cost of feeding compared to dry or con-
ventionally canned foods.
Figure 8-20. Process flow diagram for moist commercial pet food
production.
Product Form
Several types of moist pet food products and various sizes and rating during processing, so the pieces remain suspended.
shapes of packaging materials exist. Early canned dog foods The food pieces may be natural tissues or extruded vegetable
were composed primarily of ground offal and horsemeat as by- and meat proteins. In some pet food markets, intact vegetable
products of the human food industry.These products were high matter such as peas and carrots have consumer appeal. These
in protein, fat and moisture and were similar in appearance to elements can be natural or made from textured vegetable pro-
pâté. More contemporary forms include chunk and gravy, tein. Diced pieces can originate from large, flat cakes made
flaked, ground meat and shredded, all of which mimic foods from dough premix.
consumed by people.
“Loaf” products contain some carbohydrate sources (corn, Canning Process
rice, etc.) that balance the amount of protein and fat. These The canning process is usually continuous flow, highly auto-
products are usually lower in moisture,and because of the struc- mated and carefully controlled. Fresh and/or frozen meats are:
tural properties that starch imparts, are found in finely formed 1) ground, 2) may or may not be mixed with grains, 3) subject-
loaves. Vegetable gums and other hydrocolloid thickeners are ed to steam and water, 4) filled into cans, 5) sealed and steril-
used to create a firmer texture in canned products that contain ized with a pressure cooking device, 6) cooled, 7) labeled and 8)
little carbohydrate. A popular form for moist dog and cat foods put in cases (Figure 8-20).
is pieces of meat or fish in jelly. These products may range in
form from a finely ground pâté in jelly to large chunks of meat MEATS/ANIMAL PROTEIN GRINDING
suspended in aspic (e.g., jelly mold). A hygroscopic medium is One of the major ingredients of any moist pet food is the ani-
used to create a two-phase food texture: a “piece” suspended in mal protein component. Fresh meats and meat by-products
a medium. The viscosity of the suspension medium can vary require frequent shipments, a large refrigerated area for storage
from a semi-liquid gravy, to a jellied, savory coating to a solid, and a system of “just-in-time” manufacturing that uses the
suspending jelly. ingredients quickly to reduce waste and spoilage and assure
In manufacturing, the viscosity of the suspension medium is freshness. Frozen meats require a very large freezer storage
selectively regulated by using different combinations and ratios capacity and specialized grinding equipment, but offer the
of hygroscopic sucroglycerides, starches, gums, pectins and algi- manufacturer flexibility in ingredient use.
nates. (See Additives.) Many gums and starches are functional Generally, meats, whether fresh or frozen, require grinding
food “thickeners” for binding free water into semi-liquid gravies before canning and sterilization. In a continuous canning
or soft jellies at room temperature. Carrageenan, car- process using frozen ingredients, a predetermined sequence and
boxymethylcellulose, agar, carob, guar, acacia and xanthan gums amount of meat is fed into a machine that chips the frozen
are examples of thickeners. Pectin and alginates (seaweed deriv- blocks of meat into smaller portions.The chipped meat is then
atives) create more “solid” jellies, suspend pieces and conform to conveyed to the final grinding step where it is forced through a
the container to form a loaf. Jellies are often golden and translu- plate that contains many one-fourth- to three-fourth-inch
cent to reveal the internally embedded pieces. Gravies are fre- openings. The mechanical shear grinds the frozen meats and
quently opaque due to the inclusion of animal tissue meals, begins the thawing process. If multiple meat sources are used,
caramel coloring or both. meats may require mixing to create a homogeneous blend.The
In addition to the water-binding capacity of the jellying meat mixture then proceeds to a cooking step that increases the
agents, the viscosity and specific gravity of the suspension temperature of the product to a level appropriate for processing.
medium should approximate the density of the pieces at pro- In a batch process, the ingredients are measured by weight,
cessing temperatures. Parity in density will help prevent sepa- ground and placed into a cooker/mixer in one large batch. The