Should Sour Cream and Cottage Cheese Be Stored Upside Down?

"Is this true?" my daughter emailed me, attaching the following from myfridgefood.com: "Bacteria is what causes cottage cheese and sour cream to go bad. If you store them UPSIDE DOWN it creates a vacuum in the container which stifles the growth of bacteria and they last much longer... science lesson over." 

I wondered whether a science lesson had, in fact, ever begun. I promptly turned the question over to this site's Advisory Board members, all scientists. While waiting for their responses, I checked Google and discovered that this "fact" quoted above had been widely discussed online.  I found it on cbsnews.com, facebook.com, lifehacker.com, messsage.snopes.com, pinterest.com, and answers.yahoo.com.  Most of the sites (including CBS) recommend upside down storage.  But before you do that, read the following comments from the Shelf Life Advice Board scientists:

Dr. Timothy Bowser, food process engineer: "I'm no expert on cottage cheese, but my impression is that the comment about a vacuum is nonsense. If a vacuum did form, it would be so low as to be inconsequential. Other factors--such as pH (acidity), storage temperature, and a good tight package--are much more important for the preservation of cottage cheese than the iffy possibility of a vacuum."

Dr. Joe Regenstein, food scientist: "Actually, if you stored the cartons upside down, you'd get a very short-term vacuum, but then the gases would pass through as they go for equilibrium.  So it might help a little but not much." 

Dr. Catherine Cutter, food scientist: "I posed your question to our dairy expert, Dr. Bob Roberts, Professor and Department Head, Department of Food Science at Penn State University.  He's our dairy-processing expert. Here was his response:  'While yeast and molds are important spoilage issues, gram-negative psychrotrophs (cold-loving bacteria) often spoil cottage cheese.  I don¹t see how inverting the carton minimizes spoilage. It will hide whey synersis (liquid in the carton), but I don¹t see any reason to think it would enhance shelf life.'"

Dr. Clair Hicks, food scientist: "It's false.  Both cottage cheese and sour cream are lactic fermentations and have a low pH so, if manufactured correctly and refrigerated, they will have a pretty good shelf life.  So lactic bacteria are what makes these products.  Yes, other bacteria such as psychrotrophic bacteria can grow in these products over a few weeks.  Turning the carton upside down or not will not affect their growth.  The difference in pressure due to this action is not significant. They certainly did not check their facts. 

We often package fresh meats in vacuum packaging, but, to make this work, there must be a barrier film which excludes oxygen, and the package must be skin tight. In this case, you have to create a strong vacuum and then shrink the film around the product."

Our Board scientists have all given you permission to keep your sour cream and cottage cheese right side up.  However, it's clear that a lot of internet readers believe that upside down is better for many foods and even paint.  If you don't believe me, click below: http://message.snopes.com/showthread.php?t=45824''

Let's end this discussion with a comment from Yahoo!: "Storing upside down will have no effect on spoilage.  [Boldface mine.] But a lot of people open old cottage cream or sour cream and see liquid on top and think it has spoiled. When you store it upside down, the liquid will be at the bottom and thus not visible when you open the container. Maybe this is what your friend is experiencing. It is just separated liquid, not spoilage, and can be mixed back into your cottage cheese or sour cream."

https://answers.yahoo.com/question/index?qid=20080916151717AAmCDpn

How long can you expect cottage cheese and sour cream to last, whether refrigerated upside down or right side up?

Shelf Life Advice info on cottage cheese is listed here: http://shelflifeadvice.com/dairy/cheese/cottage-cheese

It says opened cottage cheese (refrigerated of course) will last about a week, unopened 45-60 days, frozen for 3 months. 

For info about the shelf life of sour cream, click here: http://shelflifeadvice.com/dairy/cream-and-cream-products/sour-cream.  You'll see that the shelf life of this product varies depending upon the fat content and brand.  In general, you can expect sour cream to last 1-2 weeks, 7-10 days, or until the use-by date.  For more information about the shelf life of sour cream, go to "How long will sour cream be 'good' once it's opened?"

Reminder:  Shelf life information is about spoilage (what makes food look, taste, or smell bad), not about contamination that can make the person who eats it sick.

Source(s):

Robert F. Roberts, Ph.D., Pennsylvania State University, Department of Food Science 

Members of the Shelf Life Advice Advisory Board:

Timothy J. Bowser, Ph.D., Oklahoma State University, Dept. of Biosystems and Agricultural Engineering

Catherine Nettles Cutter, Ph.D., Pennsylvania State University, Department of Food Science

Clair L. Hicks, Ph.D., University of Kentucky, Dept. of Animal and Food Sciences

Joe Regenstein, Ph.D., Cornell University, Dept. of Food Science

myfridgefood.com "Keep Your Cottage Cheese Longer"

http://myfridgefood.com/tips/keep-your-cottage-cheese-longer/