Frozen produce holds same nutritional value as fresh

The researchers behind a study comparing the nutrients value in fresh and frozen fruits and vegetables have published their results in a paper featured in the Journal of Food Composition and Analysis. In the majority of comparisons between nutrients within the categories of fresh, frozen and “fresh-stored,” the findings showed no significant differences in assessed vitamin contents.

The findings of this study do not support the common belief of consumers that fresh food has significantly greater nutritional value than its frozen counterpart, the paper’s authors wrote.

Produce was stored in three different ways (fresh, frozen and “fresh-stored”) and analyzed for their concentrations of L-ascorbic acid (vitamin C), trans-b-carotene (provitamin A), and total folate. The third “fresh-stored” categorization was intended to mimic typical consumer storage patterns of produce following purchase (five days of refrigeration).

The fruits and vegetables used in the study include broccoli, cauliflower, corn, green beans, green peas, spinach, blueberries and strawberries of all three categories of freshness.

During the two-year study, the produce was analyzed in six time frames: (1) Summer to Fall Year 1, (2) Fall to Winter Year 1, (3) Winter to Spring Year 1, (4) Summer to Fall Year 2, (5) Fall to Winter Year 2, and (6) Winter to Spring Year 2.

In the cases of significant differences, frozen produce outperformed “fresh-stored” more frequently than “fresh-stored” outperformed frozen. The study found there were no statistically significant differences for L-ascorbic acid (vitamin C) contents in fresh, fresh-stored and frozen produce for broccoli, cauliflower and corn.

In its trans-b-carotene (provitamin A) analysis, the study found that frozen broccoli was lower and statistically different from its fresh counterparts. Fresh broccoli stored at 4 C for 5 days after purchase did not show a significant reduction in trans-b-carotene. Different packaging may resultin
differences on the retention of total carotenoids during transport after processing and storage. Another study found that modified atmosphere packaging prevent any loss of carotenoids of broccoli florets stores at 5 C for 6 days, while unwrapped florets or florets wrapped in perforated film lost 50 percent of their carotenoid content under the same conditions.

Of all of the fruits and vegetables examined, spinach contained the highest content of trans-b-carotene. As with green beans, the authors found the fresh spinach had a statistically significant greater content of trans-b-carotenethan the fresh-stored and frozen produce, which themselves were not statistically different.

There was a generally consistent observation of five days of refrigerated storage having a negative association with nutrient concentration in the cases of significant differences. The findings suggest that the time a consumer stores their fresh produce prior to consumption is an important factor in determining comparative nutritional value, according to the authors.

The study was supported by a grant from the Frozen Food Foundation.