Do I *really* need to refrigerate…? (The frosting edition)

Posted on July 6, 2015 in Icings, Frostings, Toppings, Oh My!/ The Sugary

I hope everyone had a wonderful July 4th holiday and got to see some amazing fireworks! I’ve been working the weekend away, and sadly not baking nearly as much as I need to to feed my sugary addiction. Although, I did make some adorable Minnie Mouse cupcakes for a friend… take a look đŸ™‚

And… I may have eaten all of the leftover Oreos…😳 But, we’re not here to talk about my inability to say no; we’re here to talk science! Don’t get scared though, I’m not going to get too nerdy on you. I’m going to share a few things that I’ve learned from personal experience when it comes to buttercreams and how you are supposed to store them, versus what’s best for flavor, texture, and structure. First we are going to break down a few ingredients and determine whether we need to refrigerate them.


Soft to the touch

  • USDA guidelines suggest refrigerating butter. They actually go as far as suggesting you freeze any butter you don’t plan to use soon, and state that it can be frozen for up to 2 months. Butter will not go bad this quickly, but rather it may become rancid, or develop and “off” taste and smell if left out too long, or even pick up the taste of other strongly flavored foods that it is stored with. Rancid butter is not dangerous to eat, it just tastes awful.
  • Most butter is made from milk that has been pasteurized, has low water content, and often times has salt added – all of which inhibit bacteria growth.
  • If you take a look at many online conversations
  • There are storage containers made specifically to keep butter spreadable at room temperature for up to 2 weeks! Check out Butter Bell crocks – they use water and an airtight seal to keep air out and keep the butter cool to prevent bacteria growth but also perfectly spreadable.
  • BOTTOM LINE: For personal use, butter will be just fine if left out at room temperature for several days if covered. Butter crocks will keep butter fresh for 1-2 weeks. I personally have left butter out overnight and it was just fine, but of course, monitor your butter and make sure it is not rancid. For commercial/business use, never play with your customers safety. Follow FDA/USDA guidelines and refrigerate your butter and allow it to come to room temperature before using.



  • The USDA recommends using eggs within 30 days of the packing date, however, many cartons only have a sell by date. Using your eggs within 3 weeks of the sell by date will usually ensure optimum freshness. Eggs do not “go bad” after this date but will start to dry up, or lose mass, inside the shell. Because they lose mass, you can use a water test to determine if your eggs are fresh. Put an egg in a bowl or glass of water, if it sinks its fresh, if it floats, its older and has started to dry up.
  • A cold egg left out at room temperature will “sweat” and the water on the outside of the shell may possibly grow bacteria. It is important to refrigerate eggs to keep new bacteria growth down and inhibit any bacteria already present. But fresh eggs from vendors or farms may arrive for sale at room temperature. If you think about it, eggs may sit in their “nests” for several days or longer before being gathered and will be at room temperature if not warmer.
  •  In Europe, salmonella is battled by vaccinating the hens, so eggs are sold at room temperature and customers are encouraged to refrigerate after purchasing. In the US, hens are not vaccinated, thus salmonella and bacteria are a concern. Instead the eggs are washed and sprayed with chlorine, thus removing their natural protective barrier and requiring refrigeration to prevent any present bacteria from multiplying.
  • Your eyes, nose, and mouth are the best indicators of whether an egg is safe to eat. A rotten egg will have a horrible smell. If your eggs taste, smell, or look strange (pale, loose, too runny), play it safe.
  • BOTTOM LINE: Refrigerate your eggs to slow/inhibit bacteria growth and try to consume them within 3-5 weeks of the date of purchase for best quality and taste. From personal experience, I have left an egg out for a day or two at room temperature, and it was fine each time – but that is a risk I choose to make for myself. If using eggs to bake or cook for a customer, always make sure your eggs are refrigerated and fresh.



  • Sugar does not go bad or grow bacteria itself. Sugar will only change texture, harden, or clump over long periods of time but will still be ok to use/consume.
  • Sugar naturally inhibits bacteria growth and has been used to preserve food for a long, long time. Bacteria needs water to grow, and sugar “binds,” or absorbs, water from whatever it is added to, effectively reducing its ability to grow bacteria through dehydration.
  • BOTTOM LINE: When added to jams, jellies, frosting, etc, sugar can act as a natural preservative and assist in inhibiting bacteria growth.



  • The FDA recommends milk be refrigerated at all times and if it has been left out for longer than two hours to throw it away, unless it is left out in a high temperature setting – in which case they recommend throwing it away after an hour.
  • Milk and cream contain pathogenic organisms that can cause illness when consumed -refrigeration is important to slow their growth. Bacteria do not thrive in cold conditions, but will grow quickly in a warm environment.
  • Some milk sold at the grocery store may be unrefrigerated – this is because it is Ultra-Pastuerized – which means it is heated to a very high temperature thus killing 99.9% of the bacteria present in the milk. This type of milk would be more forgiving if left out at room temperature but must still be refrigerated once opened.
  • BOTTOM LINE: Always be safe and refrigerate your milk. The more you leave it out, and the more you open it, the greater the presence of bacteria. Consume your milk and cream by the expiration date or a few days after. If your milk has a sour smell, throw it away.

 Now, lets get to the buttercreams!


  1. American Buttercreams are made from butter, powdered sugar, and either water, milk, or cream – cream being my own personal favorite!
  2. We now know that sugar does not grow bacteria, and can act as a preservative. Most butter is made from pasteurized milk, has low water content, and salt, meaning it is very difficult for bacteria to grow and thrive.
  3. The amount of liquid added to these two ingredients is scant, and the high amount of sugar absorbs it as well as the moisture from the butter. Water is a better choice as it does not have the pathogens that milk or cream may contain but once again, the sugar is acting as a preservative and limiting bacteria growth. Be careful if using well water that it does not contain bacteria. Ultra Pasteurized milk or cream would be a wonderful addition to minimize pathogens.
  4. BOTTOM LINE: American Buttercream can be left out at room temperature for a week…officially, that is what I recommend. BUT… for personal consumption, and to satisfy my own curiosity, I have left an American Buttercream out for two weeks and it was perfectly fine, and didn’t taste a bit different from the day I made it.


  1. Meringue Buttercreams get insanely hard when refrigerated, so this is where I really want to concentrate my efforts. It’s such a shame to lose that fluffy, light texture – you either have to frost your cake immediately, refrigerate, and let it sit out at room temperature for 1-2 hours before serving to thaw… or you refrigerate your frosting, and then let it thaw when you need it and re-whip it. Why can’t I just leave it out for a day or two, at least until all of it is completely scarfed down?? Let’s find out đŸ™‚
  2. We have learned that eggs in the US need to be refrigerated, but what about once they are used to make a meringue? My French and Swiss Meringue Buttercreams have meringues that are pasteurized, or cooked, to at least 160 degrees (sometimes I go a lil over to be safe) thus killing any present bacteria/salmonella.
  3. French and Swiss meringues are meringue, which is cooked eggs and sugar, and butter. Based on what we know about meringues, sugar, and butter, it would be safe to assume that they can stay out at room temperature…right? Well, I did my own test and its safe to say, that frosting lasted OVER a week at room temperature. The texture was divine, it was still light, buttery, and amazing. The only difference towards the second week was it started to lose some of its sweetness.
  4. Italian Buttercreams are made by adding a very hot sugar syrup to uncooked egg whites. One would think that a sugar syrup that reaches about 240 degrees would then cook the eggs right? EH! WRONG! When taking the temperature of the final meringue at its hottest, it barely reaches 130 degrees. To be honest, we really can’t test it to determine just how hot the egg whites get with our home equipment and there’s no way I’m taking a risk with anyone’s health but my own.
  5. BOTTOM LINE: French and Swiss Meringue Buttercreams can last at room temperature for a few days to a week and still maintain optimal taste and texture. Italian Meringue…while I have left it out for several days before for my own consumption, I would recommend leaving it out for a day at the most before refrigerating.


  1. Whipped cream frosting is not made with any cooked ingredients. Any bacteria that may be present in the cream will still be present in the final product.
  2. The amount of sugar added is not nearly enough to inhibit bacteria growth.
  3. Refrigerating whipped cream does not change its texture or flavor, so really…why not?
  4. BOTTOM LINE: Whipped creams MUST be refrigerated. I have left cupcakes out for 1-2 hours frosted with whipped cream, but I KNEW they would be eaten within those 1-2 hours. After that, they went back into the fridge.


  1. We haven’t talked chocolate yet, but there really isn’t much we don’t know about it. Considering that chocolate is always sold at room temperature, from bars to chips, I think its safe to say that it requires no refrigeration 😉.
  2. The heavy cream is brought to a boil, effectively killing the bacteria present in the cream.
  3. BOTTOM LINE: Ganache can be left out at room temperature for 1-2 weeks before it *should* be refrigerated. My own diabolical experiments have seen ganache last a month at room temperature, but really…. who has chocolate sitting around that long without eating it with a spoon?


  1. The milk is boiled, thus killing the remaining bacteria.
  2. The flour added to the milk absorbs a lot of the moisture.
  3. The butter doesn’t grow bacteria well, and the sugar absorbs the rest of the moisture left in the flour/milk mixture.
  4. BOTTOM LINE: Ermine frosting is pretty damn good at warding off that pesky bacteria! I leave mine out for up to a week, just like my Swiss and French buttercreams and it’s just fine. But honestly, it’s so darn good it never lasts that long.

******Thanks for joining me in the partly scientific, partly common sense adventure đŸ™‚ . You’ll notice that I always recommend the least amount of time on my actual recipes on other posts. This is because I do not know who you are baking for, and who will be consuming the goods so I tend to play it safe – which is what you should do as well. If you are making desserts for business, always, always, always, follow Food Safety guidelines – it’s not worth your job and your livelihood if you aren’t 100% sure your food is safe to consume. The same can be said if you are planning on feeding elderly individuals, pregnant women, and small children. This post was created so that we would know more about our food, and get a good idea of what makes it safe at room temperature or shelf stable. This suggestions should be particularly helpful for those of us who have accidentally left something out overnight on the counter đŸ˜‰ . *******




You Might Also Like

No Comments

Leave a Reply

Back to top