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

Abstract

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.