High pressure homogenization combined with pH shift treatment: A process to produce physically and oxidatively stable hemp milk

Abstract

Hemp milk, an emerging beverage with high nutritional value and low allergenicity, is an attractive alternative to dairy, soy, and nut milks. To obtain a non-thermally processed, physically and oxidatively stable hemp milk, high pressure homogenization (HPH) combined with pH shift treatment was investigated. For hemp milk (4% protein, 5% fat) without pH shift, increasing the homogenization pressure (up to 60 MPa) resulted in a more uniform distribution of emulsion droplets (2.2–2.7 μm). When pH shift was applied prior to HPH, large clusters and aggregates of oil droplets (3.5–8.2 μm) were formed. Interestingly, hemp milk with such interactive structures was remarkably stable, showing negligible phase separation within 3-day storage at 4 °C. Moreover, hemp milk made by combined pH shift and HPH exhibited delayed hydroperoxides (expressed as peroxide value, PV) and malondialdehyde (expressed as thiobarbituric acid-reactive substances, TBARS) production, suggesting the resistance of such emulsion cluster structures to radicals. On the other hand, a significant reduction of microbial population was observed in hemp milk prepared by pH shift combined with HPH. The results indicate that the pH shift + HPH combination treatment may potentially be employed for the production of non-thermally processed hemp milk.