The effect of high pressure treatment on the functional and rheological properties of Mozzarella cheese

Low-moisture Mozzarella cheese (LMMC) was high pressure (HP) treated at different stages of storage at 4 °C and analysed immediately post HP treatment. Confocal laser scanning microscopy of the unheated cheese indicated that HP treatment enhanced the development of age-related swelling of the paracasein matrix. This microstructural change coincided with a reduction in the level of serum expressed on centrifugation and suggests that HP results in an increase in the water holding capacity of the paracasein matrix. Proteolysis, as measured by urea polyacrylamide gel electrophoresis (urea-PAGE), pH 4.6 water soluble nitrogen and total levels of free amino acids (FAA), was largely unaffected by HP treatment of LMMC. HP treatment resulted in an increase in the flowability and a reduction in the melt time on heating at 280 °C, especially at storage times ≤ 15 days. Dynamic measurement of the viscoelastic changes on heating the cheese from 20 to 82 °C showed that HP treatment resulted in an increase in the fluidity of the heated cheese, as measured by phase angle, especially in 1-day-old cheese. Thus, accelerated ripening of LMMC was induced by HP treatment, which may lead to the development of an industrial process if cost effective commercial HP equipment were available.