First of all,what is amygdalin?

It is the active ingredient of bitter almond extract.

Why bother with amygdalin at all?

This is the main issue–there’s really no reason to buy natural almond extract.  Benzaldehyde is easy to make synthetically without ever bringing it near cyanide. And ethanol suspensions of benzaldehyde are sold (more cheaply than natural almond extract) as imitation almond extract.  It’s a more strongly-flavored product, and there’s no risk of poisoning.  But as consumers, most of us assume “natural” must be better than "imitation".  But don’t buy into the hype!  This is one instance where imitation might be more cost-effective and marginally safer.

Extra nitty gritty: How an almond ends up sweet or bitter

Although a weaker (or, if you’d like to be euphemistic about it, “more delicate”) version of almond extract can be made by soaking chopped sweet almonds in vodka, the reality is that sweet almonds just don’t make enough amygdalin to yield a high proportion of benzaldehyde.  A recent article in Plant Physiology may help explain how this came to be.  The precursor of amygdalin is prunasin.  There are similar amounts of prunasin in both almonds, and similar amounts of the enzyme that converts prunasin into amygdalin.  So why isn’t there amygdalin in sweet almonds?

In this article, the authors focused on  the enzyme that breaks prunasin down: the glycosidase prunasin hydrolase (PH).  If most of the prunasin is broken down by PH, it won’t be available to make into amygdalin, with the outcome that the almond will be sweet and not bitter. The authors set out to determine whether differences in PH (not pH, mind you) might account for the differences in sweet and bitter almond fruits.  They found that in both species, there were two PHs: PH691 (identical in both species) and PH692, which contains a polymorphism resulting in an arginine residue in sweet almonds but a cysteine in bitter almonds.  This difference in PH692 might result in a different activity: perhaps the sweet almond version of PH692 is more active.

What’s more, the authors found that the localization of PH was different in the two species: while PH started out in the symplast (inside the cell membrane) and moved to the apoplast (outside the cell membrane) in sweet almonds, in bitter almonds the localization was reversed, moving from apoplast to symplast. Although the authors did not directly investigate the consequence of this differential localization, one could well imagine that if the localization of PH better coincided with prunasin accumulation in sweet almonds than bitter almonds, the result would be little remaining prunasin to turn into amygdalin in the mature sweet almond.   Further characterization of these differences may influence the breeding of sweet almonds, where avoiding amygdalin content is the primary goal.

#BitterAlmondExtract #Amygdalin