How high pressure pre-treatments affect the function and structure of hen egg-white lysozyme

A comparative study between high pressure homogenization (HPH, 40–120 MPa) and high pressure processing (HPP, 300–600 MPa) with respect to their effects on lysozyme structure and functionality was carried out. The results showed that high pressure processing induced: (i) activity increase in the presence of NaCl (≤0.6 M), especially for samples processed by HPH (up to 6 times at pH 4.5), (ii) thermal resistance reduction up to 34 and 40% for HPP and HPH, respectively, (iii) higher resistance to low pH, with consequent activity increase at pH 5.5 (up to 40% for HIP samples) and at pH 4.0 (up to 110% for HPH samples) and (iv) activity recovery up to 21 days of storage at 5 °C, indicating a molecular reorganization after processing. Structurally, only discrete and transient alterations were observed by X-ray crystallography. Therefore, the results highlighted that HPP and HPH reversibly changed the lysozyme functionality in different ways and is an interesting alternative to improving lysozyme performance, if carried out immediately before enzyme usage. Industrial relevance HPP and HPH are generally described as technologies able to increase the activity of several enzymes and are suggested as tools to improve the performance of commercial enzymes. The results showed that both processes improved lysozyme functionality, but the structural alteration was slight and probably transient, possibly indicating the need for processing the lysozyme immediately before using it to ensure functional gains.