Tomato Pomace in Dog Food - Dog Nutrition DB

Tomato pomace in dog food is a source of dietary fiber, but can also provide other nutrients as well as some bioactive compounds such as lycopene, a natural antioxidant.

Contents

What is Tomato Pomace?

Tomatoes (Solanum lycopersicum) are a common vegetable (although botanically, they are classified as berries).

Tomatoes are related to other plants in the nightshade family (Solanaceae) such as potatoes or eggplants.

Unripe tomatoes and green foliage contain tomatin, a solanine-like alkaloid that can be toxic to dogs and cause digestive upset. However, as the tomato ripens, the tomatin disappears and is not a problem in tomato pomace^[4].

While most tomatoes are sold fresh, they are also the world’s leading vegetable for processing. A significant portion of the tomato harvest is turned into canned products, tomato juice, tomato paste or puree, sauces and ketchup.

Per the official definition, tomato pomace in dog food is a dehydrated blend of tomato skins, pulp, and crushed seeds^[1].

In other words, tomato pomace is the main by-product that remains after whole tomatoes have been processed.

It is an unavoidable by-product when producing tomato sauces, paste or ketchup and often ends up in landfills.

But it can be recycled into an animal food ingredient reducing its environmental impact and converting it into a usable resource.

Fresh tomato pulp is high in moisture. To make it more stable and convenient to use, it gets dehydrated an sometimes ground or pulverized into a powder before it is used in dog food.

It is added to dog food products as a source of dietary fiber and some other nutrients. But its quality can vary.

Many other factors affect the quality of tomato pomace such as the proportions of seed, peels and pulp, tomato cultivar, processing methods, storage, and molds.

For example, it may be contaminated with pesticides when high proportions of tomato skins are added.

Tomato Pomace Nutrition

Tomatoes are a natural source of at least some vitamin C, E, A, K and B vitamins as well as lots of dietary fiber.

But overall, they are not a significant source of micronutrients.

Tomato by-products, on the other hand, are a concentrated source of multiple nutrients such as vitamins and phytochemicals.

They also contain an abundance of bioactive compounds such as the carotenes lycopene and beta-carotene, and polyphenols making them a functional ingredient in pet food.

Tomato pomace is simultaneously rich in fat, protein and fiber.

Dry Matter Nutrients^[4]	Tomato Pomace
Crude Protein	17-35%
Crude Fat	9-22%
Ash	3-8%
Crude Fiber	28-57%
– Lignin	21-41%

Typically, dried tomato pomace in dog food contains about 20% protein, 12% fat, and 4% minerals^[3].

But is mainly a dietary fiber ingredient and provides about 30-60% of crude fiber on a dry matter basis^[4].

Much of the fiber in tomato pomace is made from insoluble lignin, depending on how many peels are included^[8].

While lignin can be considered a nutrient-free “filler”, tomato pomace for dogs also contains soluble pectins and has been shown to be moderately fermentable for the gut microflora^[7].

But since this dog food ingredient is a mixture of different proportions of seeds, skins and residual pulp, its chemical composition is highly variable.

Tomato seeds are richer in protein and fat while peels are high in carotenoids such as lycopene. But both are high in fiber.

The major fatty acids in tomato seeds are linoleic acid, oleic acid and palmitic acid. While tomato pomace can be high in omega-6 fatty acids it is poor in omega-3 fatty acids^[4,8].

Why is Tomato Pomace in Dog Food?

Tomato pomace is the main waste material of the tomato processing industry. Many pulps and pomaces like this are used in dog food because they are plenty available, economically priced, and do a good job as dietary fiber ingredients.

Using tomato pomace in pet food as a fiber ingredient is a sustainable way to recycle leftovers into a usable ingredient.

Dried tomato pomace in dog food is a widely used specialty ingredient found in a moderate amount of products.

About 4.900 tons of tomato pomace are included in dog foods each year (very little compared to 37.500 tons of beet pulp)^[2].

We all know by-products don’t have the best reputation. Understandably, feeding cheap food industry leftovers to pets doesn’t sound very convincing at first, right?

Overall, however, tomato by-products can provide lots of nutritional value. They contain micro- and macronutrients, bioactive phytonutrients, and high levels of dietary fiber.

While fiber is not an essential nutrient for dogs it is thought of as beneficial and necessary in processed dog foods.

Dietary fibers help promote gut health, regulate digestion, and firm your dog’s “output”.

But too much fiber in the diet can reduce overall nutrient digestibility^[5,6]. For this reason, inclusion levels for tomato pomace in dog typically stay below 7%^[3].

Additionally, tomato pomace is also a source of color and flavor.

You know that many tomatoes have a sweet taste, right?

Tomato pomace can have a sugar content up to 28% of dry matter with high levels of fructose^[8].

Tomatoes are also a significant source of umami flavor since they contain lots of glutamic acid and aspartic acid.

And lycopene is not just an antioxidant, it is also a natural pigment and is often used in pet food as a color additive.

In summary, tomato pomace is mainly a source of dietary fiber. It is an inexpensive by-product of tomato manufacturing with some nutritional value but it is not a premium ingredient.

What is Tomato Pomace?

Tomato Pomace Nutrition

Why is Tomato Pomace in Dog Food?

Further Reading