In recent years, Life Cycle Assessment (LCA) has been rapidly developed as an environmental assessment tool in food product systems. However, new methodologies need to be introduced for the application of LCA to the food product systems.
The authors revisited the mass–based, economic value–based & multiple (caloric value, protein, carbohydrate, fibre, saturated fat, 5 minerals, 6 vitamins) quality–based Functional Units (FUs) in food product LCAs, responding to the research question of which ones are appropriate for proper environmental benchmarking.
Based on the research, the authors have drawn that the Mass–based FU(MFU) considering the water content and the Economic value–based FU(EFU) could be appropriate for food LCAs.
Additionally, the authors have drawn that the definition of Quality–based FUs(QFUs) in food product LCAs has some limitations.
Firstly, the dietary quality indexes/scores (e.g., NRF9.3, NRF9, LIM3, NQI, NRV, FNIprot7) suggested by former practitioners ignore the contributions of individual nutrients and minerals (i.e., carbohydrate, fibre, saturated fat, protein, Ca, Fe, Mg, K, Na, Zn, vitamins A, B, C, D, E) to the QFUs: the practitioners calculated the dietary quality indexes/scores using arithmetic mean, while ignoring the importance of individual nutrients and minerals.
Secondly, the environmental performance of food products could be significantly affected by the dietary contexts when using dietary dependent QFUs. The choice of QFUs should be based on the regions' dietary situation, but most studies was conducted in western–type dietary contexts.
Fig. Comparative analysis of 12 complementary FUs: MFUs (MFUwet and MFUdry), EFU (EFUpri), Multiple QFUs (QFUcal, QFUpro, QFUcar, QFUfib, QFUmin5, QFUvit6, QFUnrf14, QFUlim2, QFUnrf14.2)
Therefore, further researches should reconsider the importance (i.e., weight factors) of individual nutrients in the definition of the QFUs integrated with the multiple qualities. The weight factors of individual nutrients need to be calculated by the nutritional proportions based on daily recommended intake and/or the fuzzy sets theory.
Besides, the further researches need to develop the relevant product category-specific indexes/scores to different product categories, while the choice of QFUs are based on the regions' dietary situation.
The results were published in "International Journal of Environmental Science and Technology" under the title of "Revisiting mass, economic value, quality‐based functional units in life cycle assessment of foods towards environmental benchmarking" (https://doi.org/10.1007/s13762-023-05115-0).
