Indices for food classification systems: A perspective from food technology, nutrition, and beyond

Abstract

Background: Classification systems (FCSs) are widely used to categorize foods based on selected indices and to derive dietary guidelines. Recently, there has been controversy over the robustness of FCSs and the NOVA classification of ultra-processed foods (UPFs). Scope and approach: This review presents and discusses indices within a framework comprising fresh or natural foods, prepared and processed foods (PFPs), and UPFs. Indices were grouped by formulation, processing, or socio-economic and environmental factors. Key findings and conclusions: Indices based on food composition databases and nutrient content are influenced by data quality, food variability, analytical imprecision, and the absence of matrix-effect considerations. Processing indices, usually associated with unit operations, require additional criteria to assess their relevance and weight within the overall process. Indicators for «natural processing» are introduced to account for storage, spontaneous fermentations, and post-cooking events at the time of consumption. It was confirmed that some indices behind UPFs are often ill-defined (e.g., palatability). Nutrient bioavailability and the glycemic index of starchy foods provide valuable insights into the effects of formulation and processing. It is proposed that current FCSs be attentive to emerging trends in sustainability and people’s well-being by incorporating indices for food security, socio-cultural conditions, and food waste, thereby adopting a more holistic approach. Developing scientifically based and validated indices to classify foods would guide consumers in making sustainable, healthy food choices and provide policymakers with robust information for their dietary recommendations.