Christine Bruhn, PhD is the Director of the Center for Consumer Research at the University of California, Davis where she earned her doctorate. Dr. Bruhn has a special interest and passion for safe food handling practices. Her major area of research is in consumer attitudes and perceptions of food quality, safety and wholesomeness. Dr. Bruhn travels widely and is a sought after speaker at both academic and government conferences on food safety and food handling and food processing technologies . She currently serves on several education and advisory panels including the Food and Drug Administration's Risk Communication Advisory Group. In addition, she is often contacted by members of the media when questions of food safety make the news, especially in her home state of California. Along with her interest in making sure everyone knows “How to determine when your food had gone bad,” she is an avid cook and enjoys sharing practical food safety tips with her family and friends. For more information on food safety and nutrition questions, please visit IFIC.org.
How to Tell if Your Frozen Foods Have Gone Bad
Christine Bruhn, Center for Consumer Research at UC Davis, explains how to know if your frozen foods need to be trashed.
Christine Bruhn: I am Christine Bruhn, University of California, Department of Food Science and Technology. We have been talking about how you can tell if your food has gone bad. Today we are going to be looking at the freezer. So freezing is a wonderful way to make your food life more convenient. You can put things in there, pull them out without having to go to the grocery store and if you over-buy, you can have things waiting for you in the freezer until you are ready to eat it. A bread is a really good example of that. If you have had a good deal at your grocery store and you have got a bunch of bread, you are stocking up for the summer time and you can buy a number of things to stick them in the freezer, the shelf life is pretty long. It goes from three months to about a year depending on the product. Bread, I guess I would feel comfortable just putting in their original bags as long as you use it pretty soon. Your main problem with bread is it is going to draw moisture, the freezing is going to draw moisture out of the product and you are going to see froth accumulating outside. The top of the product will get a little bit dry, but you can freshen it up by just sticking it in the oven for a few minutes, so maybe 10 or 15 minutes at a 200 or 250 degree oven and it becomes more fresh like. So it is a good way to make it ready for eating. If you are going to buy frozen foods, it is a best way to stock up on your fruits and vegetables. Buy products that are already frozen such as frozen vegetables, corn, peas, green beans and so forth. Don't choose the vegetables and just chop them up and put them in the container like this. You can see it is frozen because the frost has come up. Vegetables have enzymes and the enzymes will slowly act while they are in the freezer and it is going to lead to a major deterioration of flavor. These Brussel Sprouts are going to probably taste like hay by the time they are eaten. It is just because the vegetables have been broken down. If you have got a lot of vegetables, maybe you have got a whole garden or again, a good buy, you blanch them first and that means dropping them for a few seconds maybe 20 seconds in boiling water and that destroys the enzyme activity and allows you to freeze these products safely. There is a lot of information on how to freeze on the web, just follow the guidelines there. Something like fruit, you can freeze. You don't have to blanch the fruit. So strawberries, blackberries, blueberries, I would wash them, I would remove the stem and either drop them whole in a bag or you can slice them with sugar whatever way you are going to be using them in the future and they can be frozen just fine. In the area of meat and poultry, you really have a higher quality product if you buy it already frozen as opposed to freezing your own. For example, this chicken, look how good it looks. It has got a little bit of a sauce, but you can really see the color of the meat there and it is all nice and firm and that's opposed to the freezing in your own bag from home. The chicken breast is beginning to lose some of its moisture. You see the frost across the top there? In the freezing process, the moisture on the surface is going to be drawn out of the chicken and it is going to accumulate on the package and if you have a freezer that is a frost-free, this action will take place even more rapidly. The way they make it frost-free, is every few days, the temperature fluctuates, it warms up a little bit which makes the frost on the outside of the freezer melt, but it also warms up the product. Then it gets cold again. So with the frost on the outside, they are always melting that frost which is convenient for you, but they are also zipping out moisture from the frozen products every time it fluctuates. So longer shelf-life and better quality, if you have maybe a chest freezer then you have to defrost it yourself, because it will maintain that cold, cold temperature uniformly for a longer period of time and that keeps the quality of your product longer. So this is home freeze, the good thing, you have got the date down here, use it within, 3-5 months, something like that for better quality, but even better if you have a heavier plastic that has been shaped to the product. Here is similarly ground beef, commercially frozen. Look how nice and smooth that is. No spots for the moisture to come up as opposed to this very lightweight, little bag that's got the hamburger and you see all the moisture coming up and that's going to have a dry surface. It is not going to be as higher quality as this commercial product and here with the meat package, I guess, the worst thing you can do is just stick the meat in, in its own container because this is a very, very lightweight plastic. That product is going to lose moisture right away and that white, chalky appearance of the dried-out flesh, that's called freezer-burn and it is dry and not as pleasant. We have got an even another example with these little sausages. You can see there is a lot of frost in here. These products are still edible. I will drop them in a soup or put them in some sort of sauce so that the moisture from the sauce helps to overcome that dryness in the surface. Equip yourself with heavy-duty plastic, heavy-duty freezer bags or you can also use aluminium foil and make it tight and close to the product so you are minimizing any opportunity for the moisture to come in and move away from the product into the packaging. You don't want that. So freezing helps make our life easier. It is convenient whether we have a lot of our own food that we are storing or whether we have food we have purchased already that is frozen and we can quickly prepare a meal from it. That's a great way to go. Just be sure to watch the date and make sure your freezer stays nice and cold and then follow all the normal sanitation practices. You have got to keep this food cold, so when you are defrosting it, don't put it on the counter, you might forget about it. Defrost it in the refrigerator where it is still cold or defrost it in the microwave and then cook it right away. That way, you maintain the safety as well as maintaining the quality.
Next, we are going to talk about the pantry and how can you tell if the food in your pantry has gone bad.