Treatment of fruit juices with β-glucosidase for release of aroma precursors

Β-glucosidase can diversify flavour by releasing aroma precursors from monosaccharide glucosides but is not yet applied in fruit juice processing. Here, we compare β-glucosidase A (BglA) from the extremophile Halothermothrix orenii H168 expressed in Escherichia coli to a commercial product containing β-glucosidase (Rapidase® Revelation Aroma) in enzymatic activity and effect on fruit juice aroma composition (apple, apple-mango, apple-raspberry, grape; identified via SPME GC–MS). While BglA demonstrated a higher tolerance against sugars (fructose, glucose, sucrose), Rapidase® demonstrated a higher tolerance against low pH. Juice treatment with Rapidase® led to a significant release of new aroma compounds, likely due to the presence of additional enzymes (arabinofuranosidase, rhamnosidase, apiosidase) which transferred disaccharide glucosides into monosaccharide glucosides. Only eugenol, chavicol, and 2-methyl butyric acid were released in all apple-based juices following both enzymatic treatments, indicating that only they are present as potential aroma precursors bound in monosaccharide glucosides in untreated apple juice.