There's nothing more delicious than eating freshly picked fruits or vegetables. However, we are not all that lucky, or able to, so most of our fruits and vegetables are stored fresh or frozen.
Fresh food of course starts to deteriorate the longer it is stored, and on that basis frozen options may be just as good.
Here's a couple of studies looking at some similarities and differences.
The first one focusses on nutrients in fresh and frozen produce after cooking, and the second one looks at nutrients in fresh and frozen products over time.
S = similar
Fresh vs Frozen Antioxidants (AO) Fresh vs Frozen Ascorbic Acid
Peas Higher AO in fresh S
Carrots S S
Broccoli S S
Spinach Higher AO in fresh S
Green beans S S
So, in this study, FRESH peas and spinach have higher levels of total antioxidants than frozen, after cooking, but the rest of the findings are similar (Simpson, 2013).
Now taking a closer look at the vitamin content, here's info. from Bouzari et al., (2015). They've chosen eight commonly frozen foods and looked at the difference between nutrients at three time points. After 3 days, 10 days and 90 days.
I've simplified this to show best results for fresh or frozen foods under each nutrient.
Ascorbic acid (Vit C) | Riboflavin (B2) | a-tocopherol (Vit E) | Beta-carotene
Sweetcorn HIgh in frozen S High in frozen Low in frozen
Carrots S S S Low in frozen
Broccoli S High in frozen S S
Spinach S S High in frozen Low in frozen
Peas S Low in frozen 2 x more in frozen Low in frozen
Green beans High in frozen S 2 x more in frozen S
Strawberries S S S Low in frozen
Blueberries High in frozen S High in frozen Low in frozen
To summarise this study then, ascorbic acid levels (Vitamin C), and riboflavin (B2) are either similar or higher in frozen foods. Alpha-tocopherol (Vitamin E) is extremely susceptible to oxidation and frozen products seem here like a much better option. On the other hand if you're looking for beta-carotene then fresh is clearly best. Most of the produce maintained its nutrient level relatively well to the 10-day mark, although of course when buying foods from a supermarket we don't generally know how long it has been stored for. If you want more details then the graphs in the study make an interesting read.
Like everything, there's a balance between pro's and con's with the foods you choose to buy and eat. Fresh is fabulous, especially if you've grown your own, imagine freshly picked peas, tomatoes or berries! Also, many box schemes and farmers markets pride themselves on their efficiency at getting produce from the farm to the consumer. Yet frozen fruits and vegetables are at times more nutrient dense, more convenient to store, often cheaper, save time and usually reduce food waste.
Here's to fruits and vegetables, both fresh and frozen!
Simpson (2013) Nutritional comparison of cooked fresh and frozen vegetables.
Bouzari et al., (2015) Vitamin Retention in Eight Fruits and Vegetables. A Comparison of Refrigerated and Frozen Storage