Nutritional, phytochemical, and microbial changes in leafy greens across developmental stages

Leafy greens are vital dietary components due to their rich nutritional and phytochemical profiles and are consumed at various developmental stages, from sprouts and microgreens to baby and mature leaves. This review synthesizes current knowledge on the ontogenic changes in nutritional composition, bioactive compounds, and microbial safety across these stages. Early developmental forms, especially microgreens, exhibit superior concentrations of vitamins, antioxidants, and phytochemicals like polyphenols and carotenoids, whereas mature leaves contribute more fiber and structural carbohydrates. Phytochemical content fluctuates significantly with growth, with microgreens often showing peak antioxidant potential. However, microbial safety varies inversely; sprouts, due to moist and warm growth conditions, pose the highest contamination risk, while mature leaves tend to host more diverse but less pathogenic microbial communities. Importantly, certain phytochemicals have antimicrobial properties, suggesting synergies between nutritional quality and food safety. The review emphasizes the influence of genotype, environment, and cultivation practices, including controlled-environment agriculture on quality and safety outcomes. It highlights the need for integrated research on underexplored species and stages, and calls for standardized protocols to better inform harvest timing, breeding strategies, and regulatory frameworks. This holistic understanding is essential for producing safe, nutrient-dense, and functionally beneficial leafy greens for modern diets.