Dear Mark: Bacon Fat Stability, Noise Machines, and Pig Feed

Is there any food more lauded and feared, beloved and bewitching, hated and praised – all at the same time – than bacon? Have full-fledged Internet subcultures sprung up around any other animal product? Does any food but bacon inspire obvious longing masquerading as righteous rancor and vitriol? And yet no matter how much has been written about bacon, questions inevitably and indefinitely remain. Case in point: today’s round of questions. That’s right, we have two bacon-related questions and one unrelated question about noise therapy and sleep. I’ve got to say – this really warms my heart. Not only are you trying to find pastured bacon and wondering about what the pork you eat is being fed, you’re also trying to figure out how to sleep better. How much more Primal can you get?

Hello Mark,

My wife and I have been keeping our bacon grease to cook eggs and other things for a couple days.  How long can we keep the grease in the fridge before it’s too oxidized or rancid for safe use?

For now we’re using uncured bacon from Trader Joe’s. Any suggestions for finding some pastured bacon sources? We live in Phoenix and have been unable to find it as easily as grass fed beef.



To my knowledge, there aren’t any studies looking at the issue of the oxidative stability of bacon grease, but one study (PDF) looked at the oxidative stability of purified olive oil (antioxidants and other polyphenols removed, just like bacon fat which has zero endogenous antioxidants), which is high in monounsaturated fat (like bacon fat) and low in polyunsaturated fat (like bacon fat, depending on the amount of PUFA in the pig’s diet), when exposed to moderately warm conditions and allowed to sit out in the open. At 40 degrees ºC or 104 degrees ºF – a toasty number, but a believable one if the bacon grease is kept on or around a stove that sees a lot of use – the olive oil was pretty stable for about five days, after which the oxidation products began to slowly rise. At ten days, the rise in oxidation products took off and sharply increased. At 50 (122 ºF) and 60 (140 ºF) degrees ºC, the oxidative products rose sharply almost immediately and maintained their upward trajectory. I think this gives us a decent idea as to the stability of bacon fat, although you should keep a couple things in mind:

If the bacon comes from a pig who ate lots of corn, soy, and corn/soybean oil, it will be higher in PUFAs than the olive oil tested in the study. This will make it go rancid faster.

The bacon grease already got exposed to heat when you cooked the bacon. The degree of oxidation depends on how long and at what temperature you cooked it. Best to go low temperature to keep the oxidation down.

Lesson? When in Death Valley, the Sahara, or camping on the outskirts of Las Vegas in summer, you probably want to toss your bacon grease.

Keeping it in the fridge, where it’s away from heat and light and far cooler than 40 degrees ºC (let alone 50 or 60), however, eliminates two major oxidative stressors. Put it in a sealed jar and you’ve minimized another major oxidative stressor: air (PDF). And you’re only keeping it for “a couple days”? You’re probably safe.

As for pastured bacon in Phoenix, I found a couple promising leads.

Hopkins Hog Farm, located near Aguila, raises their heritage pigs outside in large paddocks and finishes them on pasture. The bulk of their diet comes from freshly-ground grains. No mention as to the types of grains used, but I’d imagine it involves corn and soy. They sell at the Mesa Community, Ahwatukee, and Old Town Scottsdale farmers markets, although I’m not sure if they actually make bacon. Their web page lists a variety of different cuts and sausages, but no mention of bacon. Of course, I’ve never heard of a pork farmer that didn’t do bacon.

M Triangle Ranch is a bit farther out, but this Arizonan who was desperate for pastured pork had great things to say about their truly pastured bacon. She was able to email the owner and arrange for a meet-up point where a clandestine bacon exchange occurred. If you’re ever in Tucson, you might think about looking them up or visiting a farmers market that sells their products.

Date Creek Ranch also has pastured pork. They do receive grains (no mention of which; probably corn), but once weaned, the pigs are turned out and allowed to “root and behave like pigs!”

There’s also The Meat Shop, which has great prices and selection but doesn’t appear to feature pastured pork.

For everyone else, to find quality meat suppliers in your area take a look at Eat Wild and Local Harvest,

Good morning, Mark. I am following a beta test exercise program that also provides weekly challenges. This week’s challenge is to buy a sound therapy machine and use it while sleeping, but with no explanation why/how it is beneficial. I already black out my room, have no ambient light such as an alarm clock, get as many hours before midnight as possible – what is your take on the sound machine?


Ottawa, Ontario

Morning, Linnea.

White noise, which most sound machines tend to focus on, does seem to help people sleep. I started using white noise in college as a means of partially drowning out the all-night-every-night disruptive sounds in the dorm. As an overtrained endurance athlete/scholar, I found I slept much better with the sound of a window fan kept on a low setting. I use that same technique today to actually introduce ambient sound over an otherwise completely quiet (and blacked-out) bedroom. It’s as if too much noise is bad, but not enough is also disruptive. In fact, the first thing I check in a hotel room when I’m on the road is the quality of sound coming from the AC or the fan!

There aren’t many studies, but there are a couple.

In a group of newborns, researchers exposed them to either white noise or no noise. 80% of the white noise babies fell asleep within five minutes of exposure, while just 25% of the control babies managed to fall asleep in five minutes without any noise at all. “White noise may help mothers settle difficult babies.” Of course, they probably have to be out of the womb if white noise is to have any beneficial effect on their ability to sleep. Sorry, fetuses.

To study how the frequently disruptive soundscape in an intensive care unit could be mollified, researchers exposed subjects to several different environments – baseline (no sound), recorded ICU sounds, and recorded ICU sounds accompanied by white noise – through the night and recorded the number of “arousals.” The baseline group had the fewest number of arousals, at 13.7 per subject. The ICU sound group had the most, at 48.4 arousals. The ICU sound/white noise group had just 15.7 arousals, very similar to the baseline group. Since the change in sound from baseline to peak seemed to determine whether or not a subject would be aroused, researchers determined that the white noise “filled in the gaps” of silence with noise, thereby creating a higher “baseline.”

It makes sense, doesn’t it? We know intuitively that sound certainly affects sleep, both positively and negatively. An alarm blaring in the night, the steady drip drop drip of a leaky faucet, and a baby’s wailing seem evolutionarily designed to keep or make us awake, don’t they? Sharp noises in the dead of night can mean scary things, things that threaten a hominid’s immediate survival. Think snapping twigs, the snarl of a tiger, the whoop of a war cry. Our problem nowadays is that aural disturbances are the norm. Cars honk, motorcycles rev, radios blare. White noise appears to be a neutral sound akin to the soothing hum of the wilderness that smoothes out the night.

And of course, any sound that you personally find relaxing/soothing/etc. is probably going to also help you sleep.

Dear Mark,

In an effort to make Primal living more cost effective, we are in the process of purchasing some beef in bulk through a local farm found through Eat Wild. We also eat a fair amount of pork, and I looked at the couple of local farms that produce pork, and they both mention supplementing the pigs’ feed with corn and soy. I don’t know enough about modern pig farming to know whether this is standard practice even within the non-commercial farming arena, or if I just need to keep looking for another source. Is the organic, no hormone, no antibiotic pork I buy now supplemented with corn and soy?

Does it really matter?



I’d say it does matter, especially if you’re going to be forking over a large amount of money for a large amount of pork. The fatty acid distribution of pig meat is extremely sensitive to the fatty acid content of the pig’s diet. If the feed is high in polyunsaturated fat, particularly the linoleic acid predominant in corn and soy, the pork fat will reflect that. And there’s clear evidence that due to the proliferation of cheap corn and soy products (including meal and oils) in pig feed, the typical PUFA content of pork fat has been grossly underreported. As Chris Masterjohn reports, the “new” pork fat has less saturated fat, less monounsaturated fat, and nearly twice the amount of linoleic acid as before, while Tokelauan pigs – given tons of coconut – end up with just 3% of fat as PUFA.

Although you probably won’t be able to get coconut-fed pork, you can do better by looking for pigs given other types of grains, like barley, oats, or even wheat. Pigs fed on these “small grains” tend to have higher quality (read: more firm and less polyunsaturated) fat than corn or soy-fed pigs (PDF). And you probably won’t be able to totally avoid soy and corn; that’s okay as long as the pigs get other types of feed, too. “Supplemented with” is probably okay (but try to find out what else the pigs eat and just how much the “supplement” really is). What you don’t want is a factory-farmed or “pastured” pig that gets the bulk of its nutrition from corn, soy, and vegetable oil.

If you absolutely can’t get a full breakdown of the pig’s feed, before you commit to a bulk order, try to get your hands on some bacon. If the bacon is stiff, firm, and tries to maintain its shape and solidity when held at one end (it doesn’t droop down like a limp noodle), the pig’s diet was likely fairly low in corn and soy and the fatty acids in the bacon are mostly monounsaturated and saturated – as they should be. I’ll sometimes get pastured pork that’s fed on produce trimmings and leftovers plus forage, barley, and oats, and the bacon is pretty darn firm and stiff, even at room temperature. I’ve never run a fatty acid analysis on it, but it certainly passes my subjective taste analysis with flying colors.

That’s all I’ve got for today, folks. Since I’ve mentioned bacon (twice!), I imagine today’s comment section will provide a rollicking good time, so go ahead and have at it. Thanks for reading!

TAGS:  dear mark

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending more than three decades educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates flavorful and delicious kitchen staples crafted with premium ingredients like avocado oil. With over 70 condiments, sauces, oils, and dressings in their lineup, Primal Kitchen makes it easy to prep mouthwatering meals that fit into your lifestyle.

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