Comparative effects of bacterial proteases on the physicochemical stability of cream liqueur
Loading...
Files
Published Version
Date
2026-10-01
Authors
Chen, Yuetong
Sinha, Aritra
Kelly, Alan L.
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier B.V.
Published Version
Abstract
Heat-stable microbial proteases secreted by psychrotrophs in raw milk can survive pasteurisation and compromise dairy emulsion stability, yet their behaviour in complex matrices such as cream liqueur is poorly understood. This study compared three bacterial proteases (AprX from Pseudomonas fluorescens and HhoA from two Bacillus cereus strains) and evaluated their effects on a commercial Irish cream liqueur during 20 d of ambient storage, alongside reconstituted skim milk. Stability was assessed by viscosity, colour, particle size distribution, and casein hydrolysis. Protease activity was matrix-dependent: HhoA was most active in skim milk (rapid gelation at 37°C), whereas AprX predominated in cream liqueur. By Day 20, AprX caused 67.1% casein hydrolysis, increased Dx90 from 0.193 to 0.340 μm, broadened the size distribution (span >3.0), and shifted colour (ΔE = 12.8). A biphasic viscosity response suggested significant hydrolysis of caseins followed by aggregation. Overall, ethanol–fat–caseinate interactions modulated protease behaviour and identified AprX-producing Pseudomonas as a key enzymatic risk to cream liqueur stability.
Description
Keywords
Age gelation , AprX metalloprotease , Bacillus cereus , Cream liqueur , Heat-stable protease , Pseudomonas fluorescens , [FoodNutritionalSciences] , [SEFSOffice] , [CUBS]
Citation
Chen, Y, Sinha, A & Kelly, A L 2026, 'Comparative effects of bacterial proteases on the physicochemical stability of cream liqueur', International Dairy Journal, vol. 181, 106725, pp. 1-10. https://doi.org/10.1016/j.idairyj.2026.106725