At a time when people throughout the world are forced to limit shopping due to COVID-19, I think it poignant to take a closer look at how these processes affect the nutritional content of fruits and veggies that may soon be in limited supply.
The quality of a fruit or vegetable begins to deteriorate the moment it is harvested. Nutrition degradation is slowed with refrigeration, but it all depends on the type of nutrients and the type of produce.
Spinach, for example, loses vitamin C incredibly quickly. The cause is twofold: vitamin C is particularly vulnerable to light and oxygen and spinach is thin and lacks the ability to retain moisture.
According to a 2007 study conducted by food scientist Diane Barrett, fresh spinach will lose 100% of its vitamin C content in one week without refrigeration and 75% with refrigeration. Carrots, a more dense vegetable, will lose 27% of their vitamin C content in one week without refrigeration.
The same study suggests that frozen vegetables are able to hold on to vitamin C for longer (this is because freezing pauses the natural process of oxidization). When frozen, spinach lost just 30% of its vitamin C content.
The widespread belief that frozen foods contain fewer nutrients than fresh produce likely stems from a time when this process took days. With today’s technology, most fresh vegetables can be harvested, washed, blanched, and frozen in a matter of hours.
“Compare that to fresh vegetables, most of which are harvested, sent to a packing plant, packed, graded, shipped to retailers, then put in the consumer baskets,” notes Richard Harrow, Chief Executive of the British Frozen Food Federation.
The only caveat here is blanching, which involves heating food for a few minutes to inactivate unwanted enzymes that degrade texture and color. Blanching reduces nutrient content, but not to the extent that canning does.
Canned foods go through an intense heat treatment that has a significant impact on nutrient content.
In her study, Barrett determined that foods with fat-soluble nutrients (such as vitamins A and E) fared better during this heat treatment than foods with water-soluble nutrients (such as B vitamins and vitamin C).
Canned foods also tend to include added salt or sugar, which makes them less nutritious than frozen foods.
“The good thing about canned foods is the process used to sterilize them,” notes Barrett. “It results in greater nutrient loss, but once the produce is in the can it can be pretty stable for years, and you can be sure it’s safe because it’s gone through a process that kills all microorganisms.”
What is most important to your health, adds Barrett, is to maintain a balanced that includes lots of fruit and vegetables - no matter how they are prepared.
“You should eat fruit and vegetables whether they’re fresh, frozen, or canned, or dried or fermented; any one of these forms is nutritious,” says Barrett. “The most important thing is to not stop eating fruit and vegetables.”
Have you been forced to change your shopping or cooking habits due to COVID-19? Share your thoughts in the comments section below!