Impact of different thermal treatments on heavy metals, aroma-active compounds, and protein-related nutritional quality of edible green seaweed Ulva reticulata.

Ulva reticulata, an edible green seaweed, holds promise as a functional food ingredient but is limited by heavy metal contamination and a strong fishy odor. This study evaluated hot water, steam, microwave, and ultrasound processing methods to improve safety, sensory quality, and retention of essential amino acids. Microwave and ultrasound treatments significantly (P < 0.05) reduced heavy metals-arsenic, cadmium, tin, mercury, lead, nickel, and chromium-to within FSSAI limits, with microwave processing achieving up to 88 % reduction. Headspace-GC-MS/MS analysis identified 46 volatile compounds, and key fishy odor contributors-hexanal, (E,E)-2,4-heptadienal, and (E)-2-octenal-were notably reduced by microwave and ultrasound treatments. In contrast, hot water and steam processing increased hexanal levels. Microwave processing also preserved essential amino acids better than other methods. Overall, microwave and ultrasound technologies enhance the safety, sensory profile, and nutritional quality of U. reticulata, supporting their potential for functional food development.