ANSWER: Freezable lunch bags such as the Playtex Fridge-To-Go and the PackIt Freezable Lunch Bag keep food at safe temperatures for 4-6 hours. Just putting an ice pack in a regular insulated bag usually
doesn't keep food cold enough.
I know what you are thinking. "When I was a kid, I took a ham sandwich every day in a brown bag for lunch with no ice and I never got sick." I wish I could explain why that is but I can't. The fact is that perishable food sitting out at room temperature WILL GROW bacteria. If you are lucky, the bacteria will be good bacteria and will not make you sick. Sometimes, however, the food will contain bad bacteria such as Staphylococcus aureus, Bacillus cereus, or listeria, and then people can get sick if the food sits at unsafe temperatures. 50% of healthy people carry the Staph bacteria on their skin, hair, nasal passages, and throats1 . Staph bacteria can grow in temperatures as low as 44.6°F1 and bacteria can double every 30 minutes! If you are going to the trouble to pack healthy lunches for your children to take to school, than you might as well pack them so the food stays at safe temperatures. According to the FDA, refrigerators should all be set below 40°F and perishable food should not stay at room temperature (or above 40°F ) for more than 2 hours. But does packing your child's lunch in an insulated bag with an ice block keep it at safe temperatures until lunch? I did an experiment to find out.
About the Scientist
If you are new to my website, let me tell you a little about myself. My name is Annie Pryor. I have a Ph.D. in biochemistry from The Ohio State University. After a few years working in a research lab, I "retired" to be a stay-at-home mom. When my first baby got a terrible stomach virus that required a trip to the ER, I decided to research the subject and created this website dedicated to reducing the prevalence of the stomach "flu" in the world. My 3 little kids keep me busy, but I still get a hankering to do experiments now and then. I've tested cleaning products, hand sanitizers, produce washing techniques, essential oils, Norwex Cloths, SteriPens, laundry, lunch box coldness, the Phone Soap, sponges, and even sunlight. I also happen to be the inventor of a really useful drying rack. I invented it because I needed a convenient place next to the kitchen sink to hang baby bibs up to dry between meals. It is also perfect for drying sports water bottles, dish cloths, food-storage bags, cleaning cloths and many other items. I have a shorter drying rack (12.5 inches tall) and a taller 15 inch rack. The Mommy Genius® Drying Racks are manufactured in the USA and are available on Amazon. If you would like to be informed when new experimental results are posted, please like my Facebook page.
I am also very proud of my daughter, Katie Scarlett. At age 8, she has written, illustrated, and published the first 3 books in a delightful series! Princess Katie and the Fairy Tea Party , Princess Katie and the Mermaid Lagoon , and Princess Katie and the Kitty Club are available on amazon. The stories are so sweet and teach about kindness, forgiveness, including others, and doing the right thing. I think every little girl would love them! Please consider buying them for a little girl that you love. Katie gets about a $2 royalty from amazon for each book sold that is getting deposited into her college savings account.
First, I tested my meat thermometer in ice water and boiling water to make sure it was accurate. My thermometer read 32°F in the ice water and 212°F in the boiling water as it should. Next, I put 1 cup of milk into 4 small ziplock containers and took the temperatures. The milk started out at 36°F. I put the containers of milk into 4 different lunch boxes. The PackIt and the Playtex Fridge-to-go bag are freezer bags. They are kept in the freezer and contain built in ice blocks. (The Fridge-to-go bag was made for baby bottles but is a perfect lunch bag.) The other two bags were regular insulated bags that do not go in the freezer. One bag is a Marvel Superhero bag that I bought for my son at Walmart. The other was a pink striped insulated bag that someone gave my daughter. The ice blocks that I used in these bags were Cool It Fit and Fresh Ice Packs. I put the lids on the milk and put one container of milk into each bag. I put one frozen ice block into each of the 2 lunch bags that needed them. I did not put ice blocks into the 2 freezer bags. Then I sealed the bags and left them on my kitchen countertop for the afternoon. I checked the temperatures at 4 hours and 6 hours. I did this experiment twice on 2 separate days. For the Marvel and the pink lunch boxes, I put the ice blocks NEXT TO the container of milk in the first experiment. In the second experiment, I put the container of milk directly ON TOP of the ice block. There was no difference in the two days of experiments for the The Pack It and the Playtex Fridge-to-go and they both performed equally well on both days.
The Playtex Fridge-to-go bag and the PackIt Freezable Lunch Bag Pack It, both kept the milk at 40°F or below for 4 hours. The Pack It was slightly above 40°F at 6 hours. That is still okay because it is safe to leave food above 40°F for up to 2 hours. I doubt there is more than 6 hours between the time you pack the lunch and the time your child eats the lunch. The regular insulated lunch bags with just one ice block did not keep the milk at safe temperatures even for 4 hours. If the milk was directly ON the ice block, it was better but still above 40°F. Since stuff slides around in lunch boxes while the child is carrying it, keeping the perishable items in direct contact with the ice block may be difficult. These ice blocks were completely melted at the 4 hour time check. I continued the test for the Playtex Fridge-to-go bag and the milk had only risen to 42°F at 8 hours. That is a really great bag! However, the Pack It has been improved since I did these experiments. The Pack It now has a zipper closure which will help it keep food colder longer.
The Playtex Fridge-To-Go bag and the PackIt Freezable Lunch Bag are both great SAFE choices for packing lunch. If you use any other insulated bag with ice packs, you probably aren't keeping the food below 40°F. It is possible that you are doing a good job if you are putting multiple ice packs in. Consider doing an experiment of your own to determine if your packing methods are keeping food cold enough.
The Playtex Fridge-To-Go bag is a bit smaller than the PackIt. The inside packing space of the Playtex Fridge-to-go is about 6 inches by 8 inches by 2.5 inches. It could hold a sandwich and a juice box and that is it. The inside packing space of the Pack It is about 7 inches by 4 inches by 7 inches. The PackIt is bigger and would fit a sandwich box, a drink, and a few other items. So, if you pack a drink, I'd go for the PackIt Freezable Lunch Bag. A new model of the PackIt Freezable Lunch Bag came out since I did these experiments. It has a zipper closure and a shoulder strap. I highly recommend this PackIt with the zipper and that is what I've been using to pack my kids' lunches for the past year.it. No one has gotten food poisoning. I pack preservative free lunch meat sandwiches so keeping the food cold is even more important than if you are just packing peanut butter and jelly.
There is also a fabulous new lunch box container called the Zak Designs Lunch box. It is a 2-story box with dividers. The top fits a whole sandwich. The bottom has 3 compartments for other foods. It fits perfectly into the Pack-It (sideways). I use these for my kids. This is my 9 year old son's lunch.
I also use these fabulous Reduce Waterweek Kids Waterbottles to put milk or juice in for my kids. The Pack-It fits the Zak lunch box and a water bottle perfectly with plenty of room left for a Zylast Hand Sanitizer (which kills norovirus). This is how I pack my kids' lunches. The Zak Lunch boxes and the water bottles go in the dishwasher, and there are no plastic bags to throw away!
If you decide not to put the bottles in the dishwasher and need a good, sturdy bottle drying rack, I recommend this Mommy Genius Drying Rack available on amazon. It is great for heavy sports water bottles, those little plastic "Reduce Water Week" water bottles shown above, food-storage bags, dish towels, and baby bibs.
Too many school children are not given the opportunity to wash hands before lunch. If you children are not given time to wash hands, consider packing a hand sanitizer in their lunch. But not just any hand sanitizer. If you are going to bother using a hand sanitizer, it ought to be one of the few that actually kills norovirus. Norovirus is the most common and terrible stomach virus that causes vomiting and diarrhea. Most people HATE those illnesses, but most hand sanitizers don't kill it. The main reason to use a hand sanitizer is to protect you from stomach bugs like norovirus. (Colds are spread primarily through the air so hand sanitizer doesn't make a big difference in the number of colds you get. Stomach viruses are generally spread by putting dirty fingers in your mouth or on your food, so hand sanitizer can make a big difference.) Here are my two favorite hand sanitizers that have been tested and shown to kill norovirus. Zylast Antiseptic and Clorox Hand Sanitizer Spray. If you would like more information on these, please read my hand sanitizer page.
If you have any personal experience with these or any lunch boxes that you'd like to share, please e-mail me at phd.annie at gmail.com. I have many more experiments to do! I'll be posting all of my dishwasher results soon. I have tested the PureWash Pro laundry system and will be posting those soon. I am also working on experiments testing many more cleaning products including Honest Company and Better Life. If you would like to suggest a product or experiment, please e-mail me firstname.lastname@example.org. If you would like to be informed when new results are posted, please like my facebook page. I always post on there when new results are up. If you would like to help support my work, please use my Amazon links when you shop on amazon. I have an Amazon affiliate account. If you use any of my Amazon links when you shop on Amazon, I get a small percentage of the sale. For example, you can click to Amazon using the link for my daughter's book and buy something. It doesn't matter what you buy, but I will get a small percentage of the sale. I use that Amazon money to buy agar plates and all the supplies that I need to do these experiments. If you don't want to bother using amazon links, you are welcome to send me a small donation through paypal. If you really want to brighten my day, please buy one of my daughter's books. They are excellent! If you don't have a little girl to give them to, buy a copy for your local elementary school library or children's hospital.
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If you want to read more of my experiments, please check out this list.
Lastly, before you leave, please brush up on your knowledge of stomach bugs so you can help decrease their spread by reading this page of my website. Thank you!
--Annie Pryor, Ph.D.