Selected nutrient analyses of fresh, fresh-stored, and frozen fruits and vegetables

This two-year study compared the status of targeted nutrients in selected fresh and frozen fruits and vegetables. In addition, a novel third category was examined—a “fresh-stored” categorization intended to mimic typical consumer storage patterns of produce following purchase.

Broccoli, cauliflower, corn, green beans, green peas, spinach, blueberries, and strawberries of all three categories of freshness were analyzed for their concentrations of l-ascorbic acid (vitamin C), trans-β-carotene (provitamin A), and total folate. Analyses were performed in triplicate on representative samples using standardized analytical methods and included a quality control plan for each nutrient. 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.

In the cases of significant differences, frozen produce outperformed “fresh-stored” more frequently than “fresh-stored” outperformed frozen. When considering the refrigerated storage to which consumers may expose their fresh produce prior to consumption, 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.

In principle, the freezing of fruits and vegetables could serve to provide a highly beneficial mitigation of the problems of spoilage and/or degradation, and provide consumers increased access to nutritious fruits and vegetables. The aim of this study was to determine and compare the status of targeted nutrients in selected fresh, frozen, and “fresh-stored” fruits and vegetables. The “fresh-stored” storage parameter was developed by the researchers for the purpose of approximating typical consumer storage patterns.

The frozen green beans possessed a mean L-ascorbic acid level significantly (p < 0.05) greater than both the fresh and fresh-stored samples. The Database also reports a mean content of vitamin C for fresh green beans being lower than that of its frozen counterpart,but this difference in the Database is not statistically significant and is of lower magnitude than the difference observed in our study.In this study, fresh-stored green beans showed a 13% lower value of L-ascorbic acid than for fresh green beans, but this difference was not determined to be statistically significant. Fresh-stored green beans showed an Lascorbic acid value 40% lower than that of frozen green beans, a difference determined to be statistically significant. Other researchers have reported marked L-ascorbic acid loss with extended storage. Martins and Silvafound that the beans’ quality held well during frozen storage.

In our comparisons of the levels of L-ascorbic acid, transb-carotene, and folate found in fresh, fresh-stored, and frozen fruits and vegetables, we determined that the majority of comparisons yielded no significant difference. In the cases of significant differences, there was a generally consistent observation of five days of refrigerated storage having a negative association with nutrient concentration.

Corresponding to this observed negative association, our study found frozen produce samples to have significantly higher nutrient contents than freshstored more frequently than the inverse. Overall, our findings suggest that the time a consumer stores their fresh produce prior to consumption is an important factor in determining comparative nutritional value, and one that we believe merits more consideration from investigators when making nutritional comparisons. When accounting for a storage period that mimics that employed by consumers, our findings do not support the common perception that fresh produce is nutritionally superior to frozen produce.

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