Healthy Bread Test: Shocking Results Are In

July 13, 2011   34 Comments

Back on June 29th, Snack Girl began healthy bread research WITHOUT government or industry funding. The experiment was simple.

Healthy Bread Test

At the beginning of the experiment (see: Which Bread Is The Healthiest?), I placed 3 slices of bread into Ziploc freezer bags and left them on my bookshelf at room temperature. The bread I tested was homemade bread, Wonder Bread, and Arnold 12 Grain bread.

Each day, I checked to see if any visible mold, fungus, or bacteria had grown on the slices of bread. My hypothesis was that the homemade bread was going to mold first because it didn't have any preservatives.

Other than that, I decided to let the bread speak for itself. The photos above and below were taken July 12th - 15 days after I started the test. Above the homemade bread is on the left and the Wonder bread is on the right.

This is the Arnold 12 grain bread:


Do you see any mold? No? After 15 days at room temperature in a bag - NOTHING?


Here are my results so far:

  • Homemade bread - 10 days
  • Wonder bread - 11 days
  • Arnold Bread - ?????

Maybe the Arnold bread has more preservatives in it or, perhaps, it is made with SUPER grain that never rots (not likely).

So, my homemade bread did mold before Wonder bread - if only a day before. But, it lasted 10 days before it molded which begs me to ask the question - do bread manufacturers really need to put preservatives into bread?

I know you guys are going to get grumpy if I mention Whole Foods (since many of you don't live close to one), but I do buy some bread at Whole Foods. And, get this, their Whole Foods Organic Wheat Bread has ZERO preservatives and costs 28 cents less a loaf than the Arnold 12 grain.

My guess is that Whole Foods bakes the bread in a central location and then HUSTLES it out to stores so that they don't need to add anything for freshness.

Hey, if a slice of freshly baked bread can last 10 days in a bag at room temperature - how long can bread last that was made in a (I hope) much more sanitary kitchen?

The bread product that will have zero preservatives will be bread that you can find in the freezer! This is a great option for those of us who want healthy bread and don't want to bake it.

Check out the "Natural Foods" freezer part of your supermarket for bread that costs the same as many other commercial breads and doesn't have preservatives.

Why do you think the Arnold bread hasn't molded after 15 days?

Want to read about snacks?
CLIF BAR Vs. SNICKERS: Are They BOTH Candy Bars?
Why Watermelon Makes Us Feel Good
Can You Get A Healthy Meal Here?
A Fruit You Just Gotta Try

Get Free Email Updates! Yes please!


Wow, that's interesting! Certainly making me re-think my bread choices at the grocery store! I was just saying to my husband last night how cheap it would be to make our own bread. Maybe it's time to start!

The only bread I eat is Ezekiel. Most people recommend keeping it in the freezer (no preservatives), but I don't.

And I purchase it at Trader Joe's because it's a lot cheaper there!

And using the Cinnamon Raisin version you can make an incredibly delicious and healthy French Toast - not too many calories.

If you haven't tried Ezekiel bread before, here's a pic ...


Ken Leebow

I'm guessing that Arnold bread has a lot more artificial preservatives in it. It's amazing what they can do nowadays. I like Rudi's organic bread. We don't eat much bread but we do buy their hamburger buns. We keep them in the freezer and take out what we need. I got them on sale last time. :)

I have always loved white bread (Brownberry Country White was my favorite) and never really cared for wheat bread or any bread that seemed somewhat healthy for me. However, after reading through this blog, I have decided to change some of the unhealthy things that I eat. One of these changes includes my precious white bread. I went to the freezer aisle of my local Pick n Save and decided to try Rudi's Organic Honey Whole Wheat bread. I've only eaten it for the last few days, but I'm surprised and delighted with how great it tastes! Yay! One step closer to a healthy lifestyle!

I am interested in finding out what is the different between white growth and blue growth. I bake lots of different kind of bread at home, even hamburger and hot dog buns, all of it so much better than mass produced baked goods. The Arnold bread scares me even more than the moldy breads.

Thanks for posting

Christine Hanlon

Umm, well, now I'm really hating the fact that I've been buying Arnold breads - the Thins for the adults & the whole grain wheat for the kids - for a while now from Sams since it was so affordable & somewhat "healthy".

The fact that it isn't molding at room temp in a sealed concerning. Real food goes bad. Fake food lives on & on.

Sigh, I need to rethink my bread choices.

Darn it. Darn it. Darn it.

Thanks for the eye opener!

darn! I always get those Arnold Thin rolls...need to find another at Stop & Shop - any ideas?

I keep all my bread in the freezer until I'm ready to use it. Guess I don't need to.

I simply stopped buying and eating bread. This way, there's no need to try and guess what's in it or how long it will keep. My "breadless" life suits me just fine.

Microbial and mold growth is dependant on the food source, moisture and the environment. It may not be the amount of preservatives in the Arnold bread that is affecting the mold growth but the amount of water used when making it. Perhaps the amount of water in the other two breads is greater than that of the Arnold bread and that is what triggered sporulation.

Danielle, I think you are on to something. There are a lot of things that could affect when the bread molds in addition to the preservatives present in the bread.

Lisa, I am not sure whether your test really addresses your question of "Which bread is the healthiest?" I think looking at the ingredients would be a better test for that question. You only really addressed the question of which bread molds the fastest, which is interesting and would certainly contribute to my choice of bread, but maybe not in the direction you are hoping. I know you know about how to test scientific hypotheses (since we learned the same place!), so I am not sure why you went with this as a test of healthiness. I love your blog though and think it is a wonderfully worthwhile endeavor!

@Shanna - hey, girl! My assumption - which I realize now is not explicit - is that the more microbes that exist - the healthier the food. As you know, we have gut microbes that interact with food microbes and a LACK of food microbes has been attributed to an inability to digest food.

I guess what I am really testing here is "Will microbes eat it?" and that is not necessarily a test for healthiness. It is more an attribute that can contribute to healthiness. Interesting, though, isn't it?

I'm all about Ezekiel bread. I agree with Ken above - it's cheaper at Trader Joe's so that's where I tend to buy it. I buy several at a time for home & work. Keeps well in fridge & freezer. The cinnamon raisin is the BEST!


It is interesting! And thanks for the clarification. Sorry for the science-geekiness. I'm not even a biologist anymore (not professionally, anyway), but apparently I play one online. ;)

I buy my bread from Great Harvest. No preservatives and all natural ingredients. But the Whole Foods brand sounds great too!

What's the white stuff on the Arnold bread? looks like mold to me.

@Michelle: I think it's just the Ziploc bag, looks like it.

That's such a great idea! Look in the freezer section! I try to avoid it though >.< ice cream takes up half of the freezer section at where I got to. I'm going to have to go look there, thanks Snack-Girl~!

i've all but given up bread, but if i do, then the really heavy german style rye bread is amazing. so filling, flavoursome and nutritious. great with cheese or peanut butter.

Currently, we buy local bread at $5.50/loaf from Whole Foods. It lasts 4-9 days without molding.

We love the bread we buy and tried many before buying it regularly; however, I'd like to make our own. I'm going to test a couple of recipes in my Mum's bread maker and, if they turn out well, buy one of our own.

What recommendations do you all have for a good bread maker? Out budget is 70-200 USD.

The white stuff is probably Rhizopus and the green is probably a Penicillium species. Both are common bread molds and can also be opportunistic pathogens. Neither is likely to hurt you unless you are immunocompromised or allergic.

Well this is interesting! My daughter and I did this recently with a piece of Nature's Own Honey Wheat bread, and some other food from our kitchen. We were looking for decay and mold and just wanted to see what these things look like in and out of baggies. The disturbing thing is that all the other food got super nasty a LONG time ago, and the jury is still out on the Honey Wheat bread because it STILL hasn't grown any mold or anything! It still feels like it just came from the grocery store! yikes.

Snack Girl, have you tried Julian Bakery's Bread? I was in search of a healthier, smart carb bread and a friend suggested I check Julians out. It's so delicious. They have a smart carb bread with 12g of fiber, 12g of protein, and only 13 carbs. They also have a purity bread which is all gluten-free. I was expecting it to be dry and tasteless, but it's so moist and so tasty when you toast it. Their cinnamon raisin is my favorite!

If you are searching for a new bread to try, here is their website: Let me know what you think!



Interesting that the Arnold bread did not mold. I am doing an accidental experiment myself with Dave's Good Seed Bread...No preservatives and USDA Organic Certified. It was placed in a baggy in Sept 2011 - Fell under the seat of my pickup. December I found it with no mold. It is hanging in my cubie at work now waiting for it to mold. On January 8th 2012 I opened the baggy to expose it to some fresh air. Sealed it back up and to this day 1/25/2012 still no signs of mold on the bread. I tell scares me that I have been eating that bread. And it does state no preservatives and certified Organic. Hmmmmm - something to make you wonder!

Interesting experiment!

Regarding your comment..."So, my homemade bread did mold before Wonder bread - if only a day before. But, it lasted 10 days before it molded which begs me to ask the question - do bread manufacturers really need to put preservatives into bread?"

Your homemade bread lasted 10 days, and the Wonder Bread lasted 11 days from the beginning of YOUR experiment. In actuality, the Wonder Bread lasted a lot longer than 11 days since the time it was made. After being made, the Wonder Bread had to be packaged, shipped, and stocked on the shelves before ever coming home with you. So, at minimum, it probably lasted at least a week longer than the 11 days you recorded, and maybe more. From the perspective of the Wonder Bread corporation, it is mandatory that they load their bread with preservatives otherwise they would have way too much wasted bread (and lost sales) that couldn't make it all the way. Obviously, this doesn't mean it's good for us to eat bread loaded with preservatives, it just means the preservatives are (unfortunately)probably not going anywhere.

Thanks again for the info! Great article!

My mom noticed that thing about Arnold bread not growing mold, so she left a piece out on her shelf to see what would happen. No bag, just sitting on a plate in the open air. It has been there for a couple years now with no mold. We'll never eat it, but every now and then we sniff it or poke it. It doesn't even feel stale. Creepy.

I now live in an apartment with a mold problem, so I think i'm going to see if Arnold will resist mold even here. If so, it seems like we should be able to treat paint and carpet with whatever is in the bread to prevent mold.

I would recommend trying the bread at your local grocery store that is baked in the bakery. In my local grocery they have both fresh baked wheat and white- no preservatives. Both breads only have 6 natural ingredients and I only pay $1.50 a loaf.

White bread has more sugars than whole grain breads, which is an easier environment for fungi to develop. I am not familiar with these fancy types of breads, but there is a lot of known variance between how long certain grains keep before spoiling, and some that have anti-fungal properties, which is another variable to consider. Also, as someone else mentioned moisture is a huge factor in mold growth, if something dries out then fungi does not have an appropriate environment for growth (think about croutons).

But, in terms of your comparison to store bought and home-made bread.. you have to also remember that you do not know the exact day the bread was made, which could have been a week before you purchased it.

I inadvertently did this test with Dave's Killer Bread, 21 grain, leaving the whole loaf out for 15 days while away visiting with a friend. This was during the summer in California, yet when I returned expecting to see a load of moldy bread, it was like pristine with NO mold at all and a good smell, to boot? I had used part of the load and so had opened it up to receive spores, but no mold? What is really in Dave's Killer Bread, I wonder. Give it a test with one slice in a ziplock bag and after 2 weeks post your results. Maybe my results were a fluke?

My husband has had a loaf of Arnold's Whole Grain 12 Grain bread sitting in his office since March 2015 (best by date was 3/19/15). It is now 8/6/15 and no sign of any mold. I googled "why Arnold bread doesn't get moldy" and came upon this site. Unbelievable and scary.

I have left bread out for over 2 years now!!!! No mold!!! I have started with Wonder bun, organic wheat and Elevation Burger bun. No mold on any of them after a month and I kept them in the hot closet wrapped loosely in a napkin. My home made bread went bad after 3 days. There's definitely an agenda people and it ain't good.

I purchased a bread from harvest gold and kept it in a bag for seven days at room temperature no change seen at all even after seven days.

your experiment appears to be very biased because without even trying to test how long Bread last. I purchased Wonder Bread last July 5th and went on a trip to South America for two weeks the 15th and upon return July 25th I find that my bread has no mold and was amazed that wonder bread could last a full month with not a trace of mold, me being a single person living alone I waste a lot of bread and since I've started using Wonder Bread I have yet to waste one piece of bread it definitely is worth a little extra money.

I used to live in a house with mold issues -- at least in one room. I easily kept store-brand bread with preservatives on the counter for two weeks with no spoilage.(Different room, of course.) Now I live in a place without known mold issues and the same exact bread will mold within a week. So I keep all the bread refrigerated -- preservatives or not. I wonder how long your Arnold bread will last at my place?

arnold bread label: "NO Artificial Preservatives"

(read label, rather than assuming what you don't know.)

Add a comment:


(required, never published)

© 2024