Global warming potential and nutritional content of fresh and frozen roots : a study on carrots and turnips

Sammanfattning: Environmental impact originating from food production is of great concern since it is related to every single customer in the world. Food is cultivated, transported, stored and processed in different ways, and every step in the life cycle has an impact on the environment whereas the nutritional value of food is altered in many of the steps. Waste of food is also an important aspect. A majority of the food waste in households and large-scale catering establishments is related to vegetables and it may be assumed that fresh vegetables have a higher waste than frozen at consumer stage. Further on, whether fresh or frozen vegetables provide consumers with most nutrients for every g of CO2-equivalent (eq) generated during production of the vegetables may be a concern. This study aimed to answer whether there is any difference in nutritional value of fresh and frozen coarse vegetables and if the production of these has different global warming potential. The vegetables investigated were carrots and turnips. Nutritional content was measured by nutrient index score, NRF9.3 (Nutrient Rich Food). Global warming potential was investigated by Life Cycle Assessment. Cultivation, storage, processing, packaging and transportation were investigated; from harvest to processing plant, wholesaler and restaurants and large-scale catering establishments, including storage losses and preparation waste. The results show that frozen root products has a lower nutritional content than fresh before cooking but after cooking the difference in nutritional content between fresh and frozen is decreased due to increased solubility and extractability of nutrients, and disrupted cell membranes. Fresh carrots provide consumers with the highest nutritional value for every g CO2-equivalent generated during production of these products, followed by (in descending order) frozen carrots, fresh turnips and frozen turnips, independent of cooked or uncooked state. Thus, from an environmental and nutritional perspective (bioavailability disregarded)) fresh carrots are the best choice of the products examined in current study. Complementary research on vegetables that are more easily spoiled during time of storage is needed in order to investigate whether fresh or frozen vegetables in general are the best choice from an environmental and nutritional perspective.