Polyphenols and antioxidant activity of skins from California almonds subjected to roasting, pasteurization, and storage were determined by LC-MS quantification, total phenols (TP), and ferric reducing antioxidant power (FRAP). Pasteurization did not significantly change TP, FRAP, or flavonoids and phenolic acids (FP). Roasted almonds had 26% less TP and 34% less FRAP than raw, but equivalent FP (n = 12). Storing almonds at 4 and 23°C for 15 mo resulted in gradual increases in FP, up to 177 and 2%, respectively (n = 13). At 4°C and 15 mo, polyphenols increased 18-fold for p-hydroxybenzoic acid, while others were 45 to.