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The application of ultra high pressure homogenisation (UHPH) treatments is useful to obtain fine and stable soymilk emulsions. Changes of isoflavones, protein digestibility and lysine availability during 4 months of storage at 20 ± 2 °C in soymilk treated by UHPH (300 MPa and 75 °C of inlet temperature) were studied in comparison to UHT-sterilised soymilk (142 °C, 6 s). Results indicated that although there was a significantly higher extractability of isoflavones in UHT (about 38%) than in UHPH-treated samples (about 15%), similar total contents were found at the end of storage. The interconversion of isoflavones into β-glucosides was faster in UHT than in UHPH-treated soymilk. Similar evolution of protein digestibility in both UHPH and UHT-treated soymilks was found, being slightly higher in the initial UHT (88.4%) than in UHPH-treated samples (83.3%). No great differences were observed in the % of blocked lysine among samples after treatments, neither in their evolution throughout storage. [ABSTRACT FROM AUTHOR]