English to German Science Chemistry; Chem Sci/Eng amino acids

The relatively high levels of pH and FAN are conducive for Strecker Degradation of the residual amino acids in the beer. No wonder why some consumers perceived the beer with such widely different flavor profile from that of the brewer at beer release.

Residual amino acids in fermented wort
The amount of FAN in malt specified is required to be high enough to provide adequate level of assimilable nitrogen for yeast fermentation but not too high to render excessive residual amino acids in the beer to cause flavor instability concerns.

In addition, the residual S-containing amino acids can turn into highly flavor-active aldehyde. For example, the threshold for methional (from methionine) is around 4.2 ppb, and forced aging was shown to increase the level of methional by several folds [7]. Some varieties like CDC Copeland, Explore and Genesis appear to give relatively lower residual amino acids in the beer, in general.

ATTENTION: the article is Chinese English

Not sure what's meant here: Rückstände? Reste? Or something completely else?

TIA