Distribution of almond polyphenols in blanch water and skins as a function of blanching time and temperature

The distribution of polyphenols in blanched almond skins and blanch water, as a function of time and temperature, was quantified using negative ion electrospray time-of-flight mass spectrometry (ESI TOF MS). Almonds were blanched in 25 degrees (RT) and 100 degrees C (HW) water for up to 10 min. At 10 min, similar to 30% (25 degrees) and 90% (100 degrees C) of the polyphenols quantified had leached from the skins into the blanch water. Many of the compounds precipitated from the blanch water due to limited water solubility, as evidenced by a logarithmic fit to kinetic data (1st order kinetics). The rate of procyanidin degradation into smaller polymeric units (e.g., catechin and epicatechin) also increased as a function of time and temperature. Finally, hydration in RT water increased the extraction efficiency of phenolics by 25%. This work shows that the blanch water, in particular the 100 degrees C blanch water, was rich in polyphenols and supports exploration of alternative uses for blanch water. (C) 2011 Elsevier Ltd. All rights reserved.