In the US, 0.2% children and 0.5% adults are suffering from tree nut allergies while almond allergy ranks the third among tree nut allergies. Several allergenic proteins are identified in almond. The major protein in almond, amandin, which accounts for ~65% of soluble proteins, is highly thermal stable. In liquid system, fifteen phenolic compounds (1) tannic acid (2) tannin (3) ellagic acid (4) (+)-catechin (5) phenol (6) grape skin extract (7) grape seed extract (8) red wine concentrate (9) tea tannins (10) coffee (11) coffee tannins (12) pinto bean tannins (13) almond skin tannins (14) walnut tannins (15) small red bean tannins were mixed with whole almond extract with a concentration (2 mg/ml) ratio 1:1. Only grape skin tannins and tea tannins can reduce immunoreactivity of almond proteins in room temperature incubation while after 100ºC heating, different phenolic compounds had different effects on immunoreactivity. Among the 15 polyphenols, tannic acid, tannin, ellagic acid, grape skin, red wine, tea tannins and walnut were able to retain or even increase the immunoreactivity. On the other hand, addition of coffee tannins, small red bean tannins, phenol, grape skin tannins, coffee, and pinto bean tannins can further reduce the immunoreactivity significantly compared to cooked whole almond (WA) extract without any phenolics. In solid system, almond flours were subjected to dry roasting, microwaving, autoclaving, and blanching. Among these processing methods, autoclaving and blanching managed to destroy 4C10 reactive epitope while others cannot. After most of the thermal processing tested, amandin immunoreactivity can recover and remain unchanged. Maillard reactions between sugars and almond proteins can significantly reduce immunoreactivity in presence of 20% sugars, especially corn syrup with higher aw, compared to processing alone. Moreover, adding of phenolics (e.g. ellagic acid and grape seed tannins) showed the similar effect as adding sugars. In conclusion, the loss of amandin immunoreactivity was most likely due to the chemical modifications of these matrix constituents such as sugars and phenolics instead of thermal processing alone. Nonetheless, during processing with a more intensive Maillard reaction (dry roasting with 20% sugar or corn syrup or microwaving 3 min), ellagic acid can hinder the effect of Maillard reaction by anti-glycation and decreasing system pH.
