A Comparative Study of the Effects of High Hydrostatic Pressure and Ultraviolet Light on Stability, Health Related Constituents and Quality Parameters of Tiger Nut Milk
Tiger nut milk is classified as a low acid beverage characterized by having a high starch and protein content. In the following, a comparative study was performed to: 1) determine the efficacy of thermal Long Time Low Temperature treatment (LTLT), high hydrostatic pressure (HHP) and ultraviolet light at 254 nm (UV-C) to pasteurize tiger nut milk; 2) To evaluate thermal, HHP and UV-C effects on physicochemical properties, nutrients and bioactive constituents. Thermal (60ºC for 30 min), HHP (500 MPa and 600 MPa for 90, 120 and 180s), and UV-C (18.4 mJ/cm2) at 254 nm treatments achieved 5-log reduction of target bacteria. On the other hand, HHP decreased the measured protein, vitamin C and the antioxidant contents. In comparison, UV-C treatment did not result in significant changes in protein, vitamin C or antioxidant content of tiger nut milk. However, despite the microbial reduction supported by UV-C treatment the shelf-life of tiger nut milk under refrigerated conditions was not improved compared to non-treated controls. In conclusion, UV-C treatment would be the preferred approach for pasteurizing tiger nut milk to ensure adequate pathogen reduction whilst retaining nutrients content of the beverage.