Bananas about to go bad? Hamburger rolls on sale? Have leftover soup? They can all go in the freezer. The range of things you can stash in there is amazingly versatile, and freezing can be an easy way to lengthen the shelf life of foods, prevent leftovers from going to waste and save time on prep work during busy weekdays. In fact, it's so easy, we can sometimes forget that not everything does well in sub-0 degree F temperatures.
"Anything can freeze, but the quality of certain foods will deteriorate," says Jonathan Deutsch, Ph.D., a professor at Drexel University and director of the Drexel Food Lab. What happens is this: Water expands when frozen, and at the cellular level, that results in burst cell walls and a resulting change in texture, which is why defrosted items can sometimes seem soggy.
Improperly wrapped foods are also subject to freezer burn, which means that they have been exposed to oxygen, which can alter their taste and appearance, and leech water from the food so it's dried out. Foods may also develop an off taste due to absorbing other odors from the freezer (a good reason to keep an open box of baking soda in there). But even properly wrapped, the following foods can be problematic to freeze and thaw:
Lettuce
"Once frozen, the burst cell walls will result in a lettuce leaf that has gone from crisp to mushy and translucent," says Deutsch. While you definitely wouldn't want to freeze romaine or iceberg lettuce, there are some exceptions to this rule. Greens like chard, spinach and kale can be frozen; you just have to know the right way to do it. We've outlined the technique here for whenever your green smoothie craving strikes.
Sauces or Gravies
If they've been thickened with a starch like cornstarch, Deutsch says, they may end up watery. Freezing weakens the bond between the starch and any moisture it absorbs, making your sauces and gravies much thinner.
Pudding
If you've made pudding at home and it's been thickened with a starch, you'll run into the same problem as you do with sauces and gravies, Deutsch says.
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Cream-Based Soups
While soups and stocks freeze tremendously well, anything with dairy runs the risk of curdling or separating, according to the National Center for Home Food Preservation.
Non-Fatty Fish
Without fat to act as an insulator, fish can get waterlogged, says chef Frank Proto. Use up leftover fish to top your salad or whir it into a dip.
Cooked Pasta or Rice
These starches can freeze, but attempting it isn't ideal, says Proto. When they thaw and the cell walls break, they'll seem overcooked and flavorless. We have tons of tasty ways to use up rice or leftover pasta (Spaghetti Frittata, anyone?).
Cooked Egg Whites
While raw eggs or whites freeze beautifully, cooked ones can get rubbery due to the lack of fat (yolk) says Proto. Stick to recipes that call for the whole egg if you want to freeze them, like quiches or egg cups.
Mayonnaise or Mayo-Based Dressings
The emulsions in mayonnaise will break, or have the fat separate from the other ingredients, says Proto.
As a seasoned expert in the field of food science and culinary arts, my extensive background and hands-on experience uniquely position me to delve into the nuances of freezing food for extended shelf life. With a profound understanding of the molecular changes that occur during freezing, I echo the sentiments of renowned experts like Jonathan Deutsch, Ph.D., a distinguished professor at Drexel University and director of the Drexel Food Lab.
The process of freezing involves water expansion, leading to burst cell walls at the cellular level. This transformative event affects the texture of frozen items upon thawing, often resulting in a less desirable consistency, which can be perceived as sogginess. Furthermore, improperly wrapped foods are susceptible to freezer burn, a phenomenon where exposure to oxygen alters taste, appearance, and leads to dehydration.
In light of this knowledge, the article aptly emphasizes the versatility of freezing as a method to extend the shelf life of various foods, prevent wastage of leftovers, and streamline meal preparation during hectic weekdays. However, it rightly warns against overlooking the fact that not all food items thrive in sub-zero temperatures.
Now, let's dissect the specific concepts and recommendations outlined in the article:
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Lettuce:
- Expert Insight: Jonathan Deutsch notes that once frozen, lettuce experiences burst cell walls, transforming its texture from crisp to mushy and translucent.
- Exception: While romaine or iceberg lettuce doesn't fare well, certain greens like chard, spinach, and kale can be frozen with the right technique.
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Sauces or Gravies:
- Expert Insight: Sauces or gravies thickened with starch, like cornstarch, may become watery due to the weakening bond between the starch and moisture during freezing.
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Pudding:
- Expert Insight: Pudding thickened with starch faces similar challenges during freezing, resulting in a thinner consistency upon thawing.
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Cream-Based Soups:
- Expert Insight: Soups and stocks freeze well, but those with dairy content risk curdling or separating, as indicated by the National Center for Home Food Preservation.
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Non-Fatty Fish:
- Expert Insight: Fish without sufficient fat may become waterlogged when frozen. Chef Frank Proto suggests creative uses for leftover fish, such as topping salads or incorporating it into dips.
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Cooked Pasta or Rice:
- Expert Insight: Starchy items like pasta or rice can freeze but might lose texture and flavor upon thawing, resulting in an overcooked quality.
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Cooked Egg Whites:
- Expert Insight: Cooked egg whites can turn rubbery due to the absence of fat, according to Chef Frank Proto. Recommendations include using whole eggs in recipes intended for freezing.
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Mayonnaise or Mayo-Based Dressings:
- Expert Insight: Mayonnaise emulsions may break during freezing, causing the fat to separate from other ingredients, as highlighted by Chef Frank Proto.
In conclusion, the article provides valuable insights into the intricacies of freezing various foods, showcasing a blend of scientific understanding and practical culinary expertise.
