Pet Food Ingredients
On October 24, 2008

Broth: connecting food with feelings

It's the finishing touch that can meet both owner and pet needs.

Mention chicken broth or beef stock, and the mind conjures up comforting thoughts of crisp autumn days, warm woolen jackets, family gatherings and savory aromas wafting from mother's kitchen as meaty bones or giblets stew in the stock pot. This visceral connection is our mental GPS to memories, when the senses are flooded to the brim and overflowing with feelings of vitality and belonging.

These feelings are so linked to our primitive nature that they are a part of our literary lexicon as we "take stock" of our blessings, read about "chicken soup for the soul" and sip broth soups to fend away the common cold (Ohry and Tsafrir, 1999). With such a strong emotional connection, it's no wonder that prepared foods commonly feature broth as a prominent ingredient. And it's no surprise that some petfood manufacturers, understanding this connection, are using broth in producing foods for dogs and cats.

No measurable impact

While it has all these wonderful attributes, let's be clear that broth's place in petfood is virtually the same as that for human foods. It's more of an emotional connection for the purchaser than a nutritional or taste driver for the pet.

In petfood, the most common application has been in canned foods in lieu of the "water sufficient for processing" or in specialty gravies and sauces. Despite conventional wisdom, in these formats broth doesn't impart a measurable impact to the overall palatability.

Further, it has only minimal, if any, impact on the aroma of most petfoods. This is probably because these foods have pretty strong and distinctive aromas already and any beneficial aroma from the broth simply gets overwhelmed. On the other hand, in more subtle offerings such as fortified water for dogs, there may be some measurable palatability benefit to broth/stock additions.

Since the solids in broth are so small, any beneficial nutrient contributions are overwhelmed by the rest of the ingredients. However, broth does contribute an interesting array of water soluble proteins, nucleic acids, sugars, salts and fats from muscle, bone and marrow of the simmered meats and trimmings. During production, most of the fat is removed (or rendered), but volatile short chain fatty acids and alcohols contribute to the aromas. The soluble and gelatinous proteins from cartilage contribute to the viscosity of the broth and to the taste and mouth-feel due to the high content of glutamic acid in collagen.

Another contributing factor are 5' nucleotides from the rupture of the muscle cell nucleus (e.g., cytidine-5'-monophosphate, uridine-5', guanosine-5, inosine-5' and adenosine-5'-monophosphate). These compounds are associated with the mouth-feel/taste sensation of umamia savory sensory note most commonly associated with the flavor of soy sauce.

By any other name

Broth, stock, au jus, essence, bouillon, consommé and extract are all synonyms of this watery meat derivative. The actual definition for petfood allows for only the name "broth or stock." These names are derived from the US Department of Agriculture definition for beef stock, which sets a minimum amount of solids, rather than chicken broth, which does not.

The AAFCO definition for stock/broth reads:

" is obtained by cooking mammalian or poultry bones, parts and/or muscle tissue. The crude protein content of stock/broth must be no less than 90% on a dry matter basis. In order for the stock/broth to be labeled as such, the moisture to crude protein ratio must not exceed 135:1 (135 parts water to 1 part crude protein). The product must bear a name descriptive of its kind, composition or origin, such as, but not limited to, meat, beef, pork, poultry, chicken, turkey: and may be called either stock or broth."

While compliance with this definition may seem convoluted, most of the broth/stock suppliers are able to unravel how this directly impacts a petfood formula and can provide directions and amounts to meet a specific need.

Home vs. commercial

At home, broth in its simplest incarnation is meat parts simmered or roasted with water, onion, celery and other seasonings; then the liquid is strained from the larger particles for incorporation into recipes. Generally, commercial broth is much simpler with no vegetables or seasonings added; the idea is that the cook will add his or her own.

An example of a middle-of-the-road commercial chicken stock process starts with layers or heavy hens cooked in large kettles for two to three hours at 190-200 degrees Fahrenheit until the meat is tender. A much more subtly flavored commercial chicken broth is produced from ground meats (no bones) cooked for a short time. At the other extreme, some beef stocks are derived from bones cooked for six to 12 hours under high pressure and temperature. In general the more intense processes give higher yields and stronger flavors.

On grocery shelves

In the grocery store, broth is sold canned or in dried cubes as bouillon. These preparations may be high in sodium and other additives. Commercial broth used in prepared foods is most commonly available as frozen blocks or a spray-dried powder. The frozen products are sold as 16% and 32% solids.

Spray-dried products often need carriers, such as maltodextrins, to help achieve the right drying conditions and final product consistency. Frozen broth must be maintained in this state until use or it will spoil. Dry broth is more shelf-stable but must be held in a dry environment as it can be hygroscopic.

Monitoring turnover

The flavor and aroma of broth is often best right at the time of productionfresh. The volatile flavor (aroma) notes are affected by freezing, packaging, drying and storage time. For the few petfood applications that rely upon such subtleties, production dates and turnover will need to be monitored closely.

Broth is produced commercially for the human prepared foods and home use market. No pet or "inedible" specific stock is commonly found.

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