Nutritional comparison of fresh, frozen and canned fruits and vegetables. Part 1. Vitamins C and B and phenolic compounds

TLDR

Freezing and canning can preserve nutrients, but initial thermal treatment often depletes water‑soluble, oxygen‑labile vitamins and phenolics, though these compounds remain relatively stable during canned storage due to low oxygen, with variability across commodities. The review aims to assess how nutrient loss in fresh, frozen, and canned fruits and vegetables during storage and cooking is often underestimated, and to recommend expressing nutrient data on a dry‑weight basis to improve comparisons. The review finds that frozen foods initially retain more nutrients than canned, yet accrue losses during storage, that moisture changes can distort nutrient assessments, and that focusing solely on fresh produce overlooks the nutritional advantages of canned and frozen options. © 2007 Society of Chemical Industry.

Abstract

Abstract The first of a two‐part review of the recent and classical literature reveals that loss of nutrients in fresh products during storage and cooking may be more substantial than commonly perceived. Depending on the commodity, freezing and canning processes may preserve nutrient value. The initial thermal treatment of processed products can cause loss of water‐soluble and oxygen‐labile nutrients such as vitamin C and the B vitamins. However, these nutrients are relatively stable during subsequent canned storage owing to the lack of oxygen. Frozen products lose fewer nutrients initially because of the short heating time in blanching, but they lose more nutrients during storage owing to oxidation. Phenolic compounds are also water‐soluble and oxygen‐labile, but changes during processing, storage and cooking appear to be highly variable by commodity. Further studies would facilitate the understanding of the changes in these phytochemicals. Changes in moisture content during storage, cooking and processing can misrepresent changes in nutrient content. These findings indicate that exclusive recommendations of fresh produce ignore the nutrient benefits of canned and frozen products. Nutritional comparison would be facilitated if future research would express nutrient data on a dry weight basis to account for changes in moisture. Copyright © 2007 Society of Chemical Industry