A healthy dilemma: fresh or frozen?

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Biology / Health / Myths

In the modern world of refrigerators and freezers we are able to keep our food lasting longer than ever before. But is there a nutritional difference between fresh and frozen produce? Which should you be eating?

Share the love: this post was written by science communication student Brendan Ma.

Is fresh always best? Image credit: leibolmai [CC BY-NC-ND 2.0] via Flickr.

Is fresh always best? Or does frozen food have ‘goodness’ too? Image credit: leibolmai [CC BY-NC-ND 2.0] via Flickr.

How fresh is ‘fresh’?

Your immediate response may be to shout “of course fresh is better, it’s fresh!”, and you may be right, but it depends on the circumstances. In most cases, the produce you see on the shelves of the supermarket has been harvested under-ripe to avoid being damaged during transit to the store. This means that the produce had not had time to reach its ‘peak nutrition’ before being harvested.

The moment the produce is picked, its nutritional content immediately begins to deteriorate. The act of picking a piece of fruit from its stem, or pulling a vegetable out of the ground essentially removes it from its nutrient source. As a living organism, the produce requires a source of energy to sustain life, and it finds these calories in its own stored nutrients.

After the produce is harvested, it is loaded onto a truck, boat or plane to travel for days (or even weeks) to the shops. It then sits on the shelves at the store for some time before you decide to buy it and take it home. Once it reaches your home, chances are it will sit in your refrigerator for a few more days before you eat it. Over this time, the food loses large amounts of its nutritional value.

Frozen alternatives

Frozen foods, on the other hand, are harvested at peak nutrition and snap frozen to −18 ºC. This process of rapidly freezing produce locks in many of the vitamins and nutrients. While this harsh freezing may degrade some vitamins, the fact that it is harvested and frozen at peak nutrition results in frozen produce containing more nutrition than their ‘fresh’ counterparts. This difference in nutrition is further increased when the fresh produce is not locally in season and needs to be imported from interstate or overseas.

A series of studies have been performed which compared the nutritional content of frozen and fresh produce from supermarkets. Frozen broccoli had consistently higher levels of vitamin C and A. Frozen ‘super foods’ such as blueberries were much higher in anti-cancer nutrients and vitamins. A group of scientists from the Centre for Food Innovation at Sheffield Hallam University highlighted that green beans lost 77% of their vitamin C within seven days of being harvested, while frozen brussels sprouts scored higher on all nutrient measurements versus their fresh counterparts.

Of course, the rates at which nutrients degrade are not equal. Some vitamins last longer and do not degrade as rapidly as others. Water-soluble vitamins such as B and C remain high in frozen produce while rapidly lost in fresh. Fat-soluble vitamins (A and D), on the other hand, are much hardier and stable, and studies have shown no distinct difference between fresh and frozen.

Of course, if you pick a fresh vegetable from your garden or a local farmers’ market and consume it on the day of purchase, nothing can compare to the nutrition (or the taste), but unless you’re willing to shop daily, frozen produce may be a great nutritional alternative. In fact, it might be time to throw out the preconceived notion that ‘fresh’ is always best, and consider some frozen alternatives.

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