If you’re like most people you put some thought into choosing your pets’ foods. Maybe you spoke to an authority you trust and they recommended it. The product’s advertising or labeling might seem to align with your criteria and values. Or you might use a product that your family has used for years.
One thing is for sure, you’re picking one that delivers on your values. There might be some garbage products out there, but yours isn’t one of them. You would never choose a product that contains “trash,” or one that’s hazardous to health.
Unfortunately, even expensive “designer,” or “natural” foods may contain ingredients that are literally garbage. Not just low quality or cheap… we mean actual discarded trash. Mass produced foods intended to fill shelves at low cost in locations nationwide are the worst offenders. The following ingredients leave plenty of room for deception and may be damaging your pets’ health:
- Any kind of “Meal”
- Any kind of “Fat,” or “Animal Fat” (including pork fat, beef fat, turkey fat, chicken fat, etc)*
- Any kind of “Oil,” “Vegetable Oil,” or “Vegetable Fat,” “Hydrolyzed Fat,” or “Hydrolyzed Oil.” (including safflower oil, canola oil, sunflower oil, corn, olive, rapeseed, etc)*
- Fish Oil (16)
Flip over your pets’ packages of food and see if those are listed. You might think, “Sure, I see it… but it doesn’t sound that bad.”
The label might be misleading and your pets’ health may be suffering as a result of it. The particular ingredient we’re about to investigate may be one of the primary culprits for increasing rates of heart diseases, cancers, diabetes and obesity in American pets AND PEOPLE.
(WARNING: gross and upsetting facts and imagery about pet food below. Please read through our references to show that the manufacturers of these products are very clear that this trash is used primarily in high-heat processed kibble and canned pet food!)
I first want to acknowledge that humans have fed garbage to dogs and cats since they were first domesticated. It wasn’t such a bad idea before factory farming came along. On a family farm pet food was offal (nutritious organs and connective tissues), excess vegetables, broken eggs and recently soured milk. Food went straight from the dinner table to the bowl. You could see every ingredient. In modern times, food industries grew and so has the processing. Human junk-food manufacturers, expired or recalled grocery meats, restaurant trash, factory farms, and breweries all contribute waste products to the pet food industry. Many arrive at the factory weeks or months after being discarded.
Waste needs to be rendered. Rendering plants do a service by grinding up our trash, cooking it at high-heat, and stabilizing it with chemicals. They care very little about the history of the waste before it gets to them. Their job is to “recycle” it into something that can be used elsewhere, no matter what comes to them. They turn a biohazard into a shelf stable product that can be reused in high-demand industries.
In many cases it is actually illegal to discard these wastes into landfills because they are too toxic or contaminated with pathogens. You can see this on Safety Data Sheets that make statements like, “Not to be landfilled. Do not flush to sewer … Recommended Use: Feed/Pet Food Ingredient, raw material for the manufacture of Chemicals/Biofuels.” (1) Additionally, millions of pounds of food and agricultural wastes in landfills results in an increased rodent and pest population – thus spreading disease.
Now you’re probably thinking, “BIOFUELS?! That’s great that our waste is being used as Biofuel!” Sadly, the Energy Information Administration (EIA) states, “Due to competition from these other industrial sectors (pet and livestock feed, soap manufacture, makeup, clothes, rubber and detergents)… less than a third of yellow grease could be spared for biodiesel production annually.” (2)
Yellow Grease, aka “Used Cooking Oil,” is important to learn about because it is likely to be in your pets’ high-heat processed kibble or canned (even many “natural” and “high quality”) brands.
“Yellow grease” starts in a restaurant fryer. It is often delivered by the same company that picks it up for recycling/rendering. (3)(4) It’s delivered in the form of a nice golden oil, like Canola or soybean, to be used in restaurant fryers at temperatures as high as 600*F. (5)(6) These oils are often Hexane extracted, steam distilled, refined, high-heat bleached, (7) treated with TBHQ, (8) ethoxyquin (9) and/or silicone anti-foaming agents. (10)(3)
Oils/Fats are used for frying French fries, chicken strips, potato chips, and other fried foods… meat and veggies alike are cooked in the grease. The fryers are open to the air which makes it so the grease is slowly oxidizing (going rancid.) This is why there are food safety regulations dictating that it must be discarded after a certain amount of use.
When it becomes too oxidized and contaminated with particles it is discarded into an outdoor open air grease bin out back. The grease dumpsters are kept back there out of sight, often under lock and key. The last thing they want customers to see and associate with their food products is the rancid bin of congealed grease by-product of their preparation.
It gets a little technical (and more graphic) from here on…. (Thank you to everyone who contributed questions and criticism on Facebook which helped flesh out the details on this topic.)
These oils are high in calories, increasing the calories of 100 grams of potato from 93 to 319 when fried. (11) This makes them a valuable commodity to the pet and agricultural food industry. Oils/Fats are an inexpensive source of calories that can be added to animal feeds to make them more affordable to consumers.
At this point you’re probably thinking what most people are:
- There’s no way that MY pet’s food contains used cooking oil
- There’s no way this stuff is even legal in pet food
- If it IS used in pet food, they must do something to it to make it safe – I mean, they can make clean water out of poop, right?
I’m going to address each of these concerns and it will be gross and unpleasant – but it’s imperative to know about it if you want your pet to avoid the most common modern diseases like heart disease, obesity, diabetes and cancers.
“THERE’S NO WAY MY PETS FOOD CONTAINS USED COOKING OIL”
The Chicago Tribune posted an article regarding oils used for frying at McDonald’s, stating, “the company’s 13,700 U.S. restaurants alone use more than 75 million pounds of oil each year to prepare the chain’s french fries, chicken McNuggets, chicken strips, and fish fillets.” (12)
So, let’s try to make a conservative educated guess how much of this stuff is going into pet food.
There are over 660,700 restaurants in the United States. (13) If on average each US restaurant uses as much oil/fat for frying as the average McDonald’s location uses that leaves over 3.6 TRILLION pounds of used cooking oil/yellow grease available for “recycling” annually. (Some more, some less – but we’re leaving out manufacturers of fried foods that come in boxes, too). As stated above, the EIA says that 2/3rds+ of that (or 2.4 trillion+ pounds) is used in the manufacture of 6 other industrial products, with pet and livestock feed topping the charts for use. If each sector uses an equal amount of recycled oil, pet food alone can use 397,866,788 pounds a year.
Mars Petcare (Pedigree, Iams, Greenies, Eukanuba, Royal Canin, Cesar, Nutro, Sheba, FreshPet, California Naturals, Crave, Innova, Karma, Kumpi),
Nestle Purina PetCare (Purina, ONE, Alpo, Felix, ProPlan, CatChow, Fancy Feast, Chef Michael’s, Bakers, Friskies, Dog Chow, Beneful, Gourmet, Merrick, Whole Earth Farms, Zuke’s),
J.M. Smucker (9Lives, Canine Carry Outs, DAD’s, Gravy Train, Kibbles’n Bits, Meow Mix, Milk-Bone, Milo’s Kitchen, Natural Balance, Nature’s Recipe, Pup-peroni, Rachael Ray Nutrish & other products (Ainsworth), Big Heart Pets brands, Snausages, Ol’Roy)
Hills Pet Nutrition (Science Diet),
Diamond Pet Foods (Ainsworth, American Nutrition, Mulligan Stew, Wellness, CJ Foods, Castor & Pollux, Dr. Foster’s & Smith, Nature’s Variety, Rotations, 4Health, Apex, Chicken Soup for the Pet Lover’s Soul, Taste of the Wild, Diamond/Diamond Naturals, Kirkland, Nature’s Domain, Country Value, Solid Gold, Premium Edge, Professional, Elmira Pet Products, Happy Paws, Happy Tails, K9 Premium, Nutram, Sigma 7, Petcurean, By Nature, Dogswell, Pet Time, Pure Vita, Natural Planet Organics, Life’s Abundance, and
Blue Buffalo (General Mills) (14)
account for 6 of the top 10 pet food manufacturers in the world. (15)
I’m not claiming to know exactly which companies utilize Used Cooking Oil/ Yellow Grease in their products, or that these companies are the only ones – but these companies alone could each use 60 million pounds a year and there’d still be over 37.8 million pounds leftover for everyone else. The agency that manages statistical data of the pet food industry states that approximately 385.31 million units of dog food were produced in the U.S. in 2019. (52) ** This allows for 0.97lbs of Used Cooking Oil/ Yellow Grease, on average, for each unit sold to American pets.
**the manufacturers listed above comprise this statistical number, while small manufacturers are listed separately.
“THERE’S NO WAY THIS STUFF IS EVEN LEGAL IN PET FOOD”
… actually, it is legal ….
Per FDA instruction, AAFCO (American Association of Feed Control Officials) is responsible for publishing legal ingredient definitions for manufacturers to use as guidelines when producing pet and agricultural feed products. (16)
“33.21 Yellow Grease, Feed Grade, is the rendered product from the tissues of mammals and/or poultry blended with used cooking or frying oil from human food preparation, consisting of animal and/or vegetable fats or oils. It must contain, and be guaranteed for, not less than 90% total fatty acids, not more than 2.5% unsaponifiable matter, and not more than 0.5% insoluble impurities, and not more than 1% moisture. Maximum free fatty acids must also be guaranteed. This product may not include recovered trap grease or material recovered from sanitary sewer sources. If an antioxidant(s) is used, the common name or names must be indicated, followed by the words “used as preservative.” If the product contains tallow (from cattle) containing greater than 0.15% insoluble impurities, then it must be labeled with the BSE* caution statement “do not feed to cattle or other ruminants.”
*BSE – Bovine Spongiform Encephalopathy, aka Mad Cow
“33.24 Used Cooking Oil, Feed Grade, is the product of used cooking or frying oil from human food preparation, consisting of animal and/or vegetable fats or oils, collected from commercial human food facilities and then heated to reduce moisture. It must contain, and be guaranteed for, not less than 90% total fatty acids, not more than 1% unsaponifiable matter, and not more than 1% moisture. Maximum free fatty acids must also be guaranteed. This product may not include recovered trap grease or material recovered from sanitary sewer sources. If an antioxidant(s) is used, the common name or names must be indicated, followed by the words “used as preservative.”
We know what you’re thinking: “Right, but ‘yellow grease’ and ‘used cooking oil’ aren’t on the label to my pet’s food so they can’t use it in there.” Actually, this is where you may have been misled –
All of the ingredients listed at the beginning of this article have AAFCO definitions that are
1) either vague enough that virtually anything could be used and approved as those ingredients, OR
2) their definitions almost exactly match the definition of Yellow Grease or Used Cooking Oil.
Here’s one of the many examples:
“33.1 Animal Fat is obtained from the tissues of mammals and/or poultry in commercial processes of rendering or extracting. It consists predominantly of glyceride esters of fatty acids and contains no additions of free fatty acids or other materials obtained from fats. It must contain, and be guaranteed for, not less than 90% total fatty acids, not more than 2.5% unsaponifiable matter, and not more than 1% insoluble impurities. Maximum free fatty acids and moisture must also be guaranteed. If the product bears a name descriptive of its kind or origin, e.g. “beef,” “pork,” “poultry,” it must correspond thereto. Rendered animal fat derived from only pork raw materials can be labeled as white grease. Rendered animal fat derived from only cattle raw materials can be labeled as beef tallow. Tallow containing greater than 0.15% insoluble impurities must be labeled with the BSE caution statement “do not feed to cattle or other ruminants.” If an antioxidant(s) is used, the common name or names must be indicated, followed by the words “used as preservative.”
Therefore, by definition yellow grease and used cooking oil meet the requirements necessary to be labeled as “animal fat,” as well as all of the ingredients listed at the top of this article.
For the remaining ingredient definition examples from the AAFCO 2020 OP see this link
Right behind nearly every restaurant in America there are bins for fried sludge. The bin closest to me for inspection belongs to Darling Ingredients. (17) I decided to look into them to see if they sell to pet food manufacturers because I have proof that they collect used cooking oil, leave their oils outside in the smoking section for months, and have minimal protective cover to prevent rodents, insects or wild animals from falling in… and it stinks like garbage. (18)
Their website states that they are an, “animal food manufacturing company.” The Chairman and Chief Executive Officer of Darling Ingredients since 2003, Randall C. Stuewe, was the Keynote Speaker at AAFCO’s 2020 Mid-year meeting. (19) Their website will show you green, clean looking imagery with cute puppies and beautiful children.
The sector of Darling Ingredients that handles pet feed and biodiesel ingredients is called Dar Pro Ingredients. Their slogan is, “Transforming your grease and meat by-products into valued feed and fuel ingredients.” (20) They also claim, “DarPro Solutions, part of the Darling Ingredient Family, repurposes used cooking oil and meat by-products across the United States into renewable biofuels, animal feed ingredients and other household and industrial resources.”
From DarPro Ingredients you can click on “Pet Food Ingredients.” (21) Click “Feed Grade Proteins & Fats” to see that they offer Yellow Grease, Used Cooking Oil, and other ingredients for animal feed use. These ingredients would be illegal to use in human foods. (22)
Below are Google Maps satellite view images of the DarPro rendering plant in Denver. It’s at 5701 York street near the Purina Factory. This must at least partially explain why it smells so bad over there.
Obviously every manufacturer works to ensure that their product does not pose any immediate threat to life or health. They could no longer sell their products if they did.
In the case of Yellow Grease it is “made safe” through a process of:
– Water removal
– Sifting of large particles (bone, hair, metal, undecomposed parts of insects, rats, feral animals, etc.)
– Heating at high temperatures to sterilize (causes further oxidation and production of more trans-fats)
– Adding carcinogenic ethoxyquin (9)
– Adding phosphoric acid
– Adding carcinogenic t-butylhydroquinone (TBHQ). T-butylhydroquinone is more toxic than arsenic. T-butylhydroquinone toxicity = 700mg/kg. Arsenic toxicity = 763mg/kg. (8)(23)(24)(25)
– Silicones to reduce foaming (10)(26)
Employees of some rendering facilities state that their production areas are contaminated with “buckets of dead rats… live rats, a lot of rat droppings… (and) maggots.” (27)
There are two ways to make something gross into something use-able:
Filter out toxins and particles thus eliminating dangers
Add numerous chemicals (anti-biotics, preservatives, stabilizers, etc.) and high-heat to sterilize
Obviously there is a dramatic difference. All I can say is that I personally think that method number one sounds much safer and more pleasant. But in the case of oils filtration alone cannot return it to its pre-oxidized state.
What are the health ramifications of this ingredient?
Trans-fats are produced in high levels when fats are hydrogenated (heated to very high temperature). Science links trans-fats to heart disease, (28) diabetes, (29) and obesity. (30) Hydrogenated vegetable oils contain more than 5% trans-fat. (31) In order to decrease the risk of cardiovascular disease, the FDA recommends 0% trans-fats from hydrogenated oil sources in the diet. (32)
Some say trans-fats don’t harm health in dogs and cats and only improve palatability and acceptance of feeds. (33) Yet, research shows that trans-fats, even in mild or moderate levels, do cause health damage in dogs and cats. In dogs, pancreatitis, Cushing’s disease and kidney diseases are shown to be caused by elevated VLDL-associated triglycerides from trans-fat consumption. In cats, disorders associated with these fats include Diabetes Mellitus and Nephrotic (Kidney) syndrome. Scientists state, “While cats and dogs are spared the risk of atherogenesis and coronary artery disease…many of the dyslipoproteinemias seen in dogs and cats appear to be similar to those observed in humans… (including) hypothyroidism, diabetes mellitus, and pancreatitis.” (34)
Also, high-temperature cooking results in higher concentrations of acrylamides (11) which are linked to: (35)
– Kidney cancer
– Reproductive tract cancers
– Excessive perspiration
– Muscle weakness
– Organ damage (liver, lungs, kidneys, central nervous system)
– Thyroid neoplasms
How do I find out if the brand of pet food that I’m using uses rendered ingredients or “yellow grease”?
Reconsider buying pet food from a manufacturer who sources their fats or oils from any of the following companies which sell and/or pick-up and recycle yellow grease:
(You might have to read through a bit, but each link to these renderers is to a page that specifically states they gather and render used cooking oil/yellow grease and sell it for use in animal and/or pet feed)
- Darling Ingredients/ DarPro (18)
- Farmers Union Industries/Midwest Grease/Performance Pet/ Redwood Farms Meat Processors/Central Bi-Products/ Northland Choice/ Artex (39)
- A. Wintzer & Son (40)
- Kaluzny Bros / Mahony Environmental (42)
- Mendota Agri products (43)
- SRC Companies (45)
- Valley Proteins (46)
- West Coast Reduction (47)
- Aspen Oil (48)
There may be renderers that are not on this list. Ask the manufacturer of the brand that you purchase who they source their oils, fats, gravy’s, aspics, etc from and research the company online to determine if they provide the service of rendering used cooking oil/yellow grease for use in pet food/feed. If they provide you with a document that proves that they are purchasing from a supplier that is not a renderer make sure it’s a RECENT purchase date.
Also, try not to buy products from feedlot or factory farmed animals who have been fed this same grease. Not only do the animals suffer from the toxicity of it but it can impact the quality of their tissues, fats, milk and eggs. Animals can actually store these oils in their fats when they don’t have the large quantities of vitamins D and E necessary to convert them to normal fats. You and your family could still be consuming these ingredients by eating feedlot meats. (49) Also, check soaps and detergents for grease ingredients. These are made with chemical stabilizers which can permeate through the skin and cause irritation and illness according the MSDS sheets.
Which of these seems like a smarter modern solution for recycling food waste?
an engine…. or…
a cat …
I like to feed my cat food.
Well that’s all very depressing. What do I do now?
Of course, there are other widely accepted foods and chemicals as toxic as Yellow Grease. A bucket of fried chicken might have a comparable impact on your body. However, a human is able to make an informed choice to take that risk and possibly suffer the consequences. They’re also able to verbalize their suffering and seek help if it does make them ill.
Hopefully nobody is knowingly choosing those foods or chemicals as an exclusive food source for their pet. In the case of most pets, there is rarely rotation away from any single contaminant or ingredient. Especially since so many high-heat processed brands of food use the same sources for ingredients. That means it can keep building up throughout the pet’s life.
Don’t demonize rendering plants. Rendering is a necessity, a way for us to live in modern civilization with consumable goods without being overloaded with trash. But if we as consumers demand that manufacturers use oil for biodiesel rather than animal feed we’d have a much cleaner environment and better health. If we stuck with this demand we could have almost 398 million more pounds a year available for biofuels!
Biodiesel is nontoxic, renewable, and biodegradable. It can be used in cars, railways, aircrafts, as heating oil, for cleaning oil spills, and in biodiesel generators. Biofuels could dramatically reduce smog, ozone and sulfur emissions. Biodiesel use also reduces poisonous carbon monoxide, unburned hydrocarbons and particulate matter. Biodiesel indisputably improves environmental health. (50)
Increased popularity of Biofuels could create a competitive market for these ingredients – thus decreasing their use in pet foods. This change can help consumers recognize the value of fresh feeding – because the price of buying “trash” in the form of kibble pellets would compete with the price of buying fresh, whole foods. Plus, it will give the sustainable fuel industry the demand and money to purchase these fats for use as fuel. And it will remove toxic ingredients from your pets’ foods, your own meat and dairy products, and your soap and detergent products.
Yellow Grease is far from the worst waste ingredient used in high-heat processed pet food. However, we should use it as sustainable fuels rather than disease-inducing ingredients in pet food. It is the responsibility of pet food consumers to reject products made with this profitable waste.
We also must spread the word. Because every company is trying to market their products as “good,” “beneficial,” and “safe.” Manufacturers of high-heat processed, shelf-stable junk foods use attractive marketing to do so. Unregulated marketing such as the word “supreme” or “natural” is ubiquitous. Beautiful stock photos offset the public perception of feed grade products. The public’s love and support of “green” things is leveraged with misleading advertising.
It is an incredibly important lesson in the conditions we live in as consumers. The world we live in now requires, perhaps more than anything, that we become wise to the intents and purposes behind marketing and branding.
For nearly 20 years I’ve been digging for hidden truths in the pet food industry. The grease dumpsters that you can find behind every restaurant in America provide a little insight into the gap I’m trying to close between perception and reality every single day.
Tell your friends. For the sake of their own health and their pets’ health please pass this information along. There is something we can do about it if we all change our buying habits.
*“Chemically, oils and fats are the same, differing only in melting point…” (51)
- Darling Ingredients SDS, Yellow Grease – https://d1p6n69pfnpnhu.cloudfront.net/DAR_PRO_Ingredients/DAR_PRO_I_Files/Spec%20and%20SDS%20Sheets%20Combined/Yellow%20Grease%208-3-16.pdf
- Wikipedia – Yellow Grease – https://en.wikipedia.org/wiki/Yellow_grease#cite_note-2
- Mahony Environmental – Fresh Oil Services – https://www.mahoneyes.com/services/fresh-oil/
- Mahony Environmental – Used Cooking Oil Recycling – https://www.mahoneyes.com/services/used-cooking-oil-recycling/
- Mahoney Environmental – https://www.mahoneyes.com/
- USDA FSIS Deep Fat Frying and Food Safety – https://www.fsis.usda.gov/wps/wcm/connect/65f762d0-e4d0-4278-b5cb-2836854a3eda/Deep_Fat_Frying.pdf?MOD=AJPERES
- Canola Oil refining, bleaching, deodorizing – https://www.compassionatehealthcareonline.com/made-canola-oil-several-processing-chemical-steps-making-refined-canola-oil/ https://www.hsph.harvard.edu/nutritionsource/2015/04/13/ask-the-expert-concerns-about-canola-oil/
- t-butylhydroquinone MSDS – https://fscimage.fishersci.com/msds/01325.htm
- Ethoxyquin MSDS – https://www.spectrumchemical.com/MSDS/E3251.PDF
- Antifoam – Dimethylpolysiloxane – https://www.spectrumchemical.com/MSDS/A1303_AGHS.pdf
- Healthline – Why Are Fried Foods Bad For You? https://www.healthline.com/nutrition/why-fried-foods-are-bad#section1
- Chicago Tribune, Oil Makes Grade On Fries – https://www.chicagotribune.com/news/ct-xpm-2007-01-28-0701280346-story.html
- Statista – Number of Restaurants in the US- https://www.statista.com/statistics/244616/number-of-qsr-fsr-chain-independent-restaurants-in-the-us/
- Dog Food Brands Share Manufacturing Facilities – https://www.dogingtonpost.com/dog-food-brands-share-manufacturing-facilities/
- Most productive pet food manufacturers – https://www.petfoodindustry.com/directories/211-top-pet-food-companies-current-data
- AAFCO OP 2020 pages 386 (Yellow Grease), 387 (Used Cooking Oil), 336 (Aspic), 341 (Gel), 337 (Carriers), 340 (Fat), 341 (Gravy), 341 (Grease), 342 (Meal), 343 (Oil), 383 (Animal Fats, all varieties), 373 (Vegetable Fats and Oils, all varieties), 383 (Hydrolyzed Vegetable Fats and Oils, all varieties), 399 (Fish Oil)
- DarPro Solutions – https://www.darpro-solutions.com/about-dar-pro-solutions
- Darling Ingredients main page – https://www.darlingii.com/solutions/pet-food
- AAFCO 2020 Mid-Year Meeting, Albuquerque – Darling Ingredients Keynote Presentation – https://zoom.us/webinar/rgister/WN_jJtpJvTwQLiNtlHgCMOK4Q
- Dar-Pro Grease Use Statement – https://www.darpro-solutions.com/
- DarPro Pet Food Ingredients – https://www.darpro-ingredients.com/where-worlds-meet/petfood-ingredients-2
- DarPro Feed Grade Proteins & Fats – https://www.darpro-ingredients.com/solutions/feed-grade-ingredients
- Arsenic MSDS – https://www.spectrumchemical.com/MSDS/A5860.pdf
- Mahony Environmental – The turnkey solution for cooking oil management – https://www.mahoneyes.com/services/fresh-oil/
- NIH PubMed – Antioxidant for Yellow Grease – https://pubchem.ncbi.nlm.nih.gov/patent/EP0466674
- Silicone for use in feed – https://www.ppgsilica.com/Applications/Carrier-and-Free-Flow/Feed.aspx
- Truth About Pet Food, Pet Food and Rendering Plants – https://truthaboutpetfood.com/pet-food-and-rendering-plants/
- New England Journal of Medicine – Effect of Dietary trans Fatty Acids on High-Density and Low-Density Lipoprotein Cholesterol Levels in Healthy Subjects – https://www.nejm.org/doi/full/10.1056/NEJM199008163230703
- NCBI PubMed – Health Effects of trans fatty acids – https://www.ncbi.nlm.nih.gov/pubmed/9322581
- Oxford Academic, American Society for Nutrition, Journal of Nutrition – Consumption of Trans Fatty Acids is Related to Plasma Biomarkers of Inflammation and Endothelial Dysfunction – https://academic.oup.com/jn/article/135/3/562/4663700
- NCBI PMC Toxicological Research, Analysis of Trans Fat in Edible Oils with Cooking Process – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609978/
- AccessData FDA.gov, Trans Fat can increase the risk of developing cardiovascular disease – https://www.accessdata.fda.gov/scripts/InteractiveNutritionFactsLabel/trans-fat.html
- Timely Topics in Nutrition, American College of Veterinary Nutrition, Facilitative and functional fats in diets of cats and dogs – https://www.avma.org/sites/default/files/resources/javma_229_5_680.pdf
- Timely Topics in Nutrition, Lipoprotein-mediated transport of dietary and synthesized lipids and lipid abnormalities of dogs and cats – https://avmajournals.avma.org/doi/abs/10.2460/javma.2004.224.668
- Wiley Online Library, Acrylamide (MAK Value Documentation) – https://onlinelibrary.wiley.com/doi/full/10.1002/3527600418.mb7906e0003
- Baker – https://www.bloomberg.com/profile/company/0072783D:US
- BHT – http://bhtonline.com/
- Cargill – https://www.cargill.com/doc/1432081484258/feed-safety-safe-feed-for-animals.pdf
- Farmers Union Industries/Midwest Grease/Performance Pet/ Redwood Farms Meat Processors/Central Bi-Products/ Northland Choice/ Artex – http://midwestgrease.com/used-cooking-oil/
- A. Wintzer & Son – https://www.gawintzer.com/product
- JBS – https://jbssa.com/our-business/rendering/
- Kaluzny Bros/ Mahony Environmental – https://www.leagle.com/decision/1988555165illapp3d3901507
- Mendota Agri products – http://www.mendotaagriproducts.com/markets-served/animal-feed/
- Sanimax – https://www.sanimax.com/
- SRC Companies – http://www.srccompanies.com/rendering_services.html#by-product
- Valley Proteins – https://www.valleyproteins.com/fats-and-proteins/fats-and-oils/
- West Coast Reduction – http://www.wcrl.com/used-cooking-oil
- Aspen Oil – https://www.aspenoilrecycling.com/our-services/
- Meat Contamination – https://www.peta.org/living/food/meat-contamination/
- Iowa State University – The effect of biodiesel oxidation on engine performance and emissions – https://lib.dr.iastate.edu/rtd/11950/
- Wikipedia – Frying – https://en.wikipedia.org/wiki/Frying
- Statista – Sales Volume of Cat and Dog food in the United States in 2019 – https://www.statista.com/statistics/954641/pet-food-sales-volume-us-by-category/