Impact of Vacuum Roasting Conditions on Water Dynamics, Polyphenol Retention, and PLA₂ Enzyme Inhibition in Cocoa Beans

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Author:
Bhattacharyya, Rik
Area of Honors:
Chemical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Ramaswamy C Anantheswaran, Thesis Supervisor
Ali Borhan, Thesis Honors Advisor
Joshua D Lambert, Faculty Reader
Daniel Edward Ciolkosz, Faculty Reader
Keywords:
Cocoa
Vacuum Roasting
Moisture Dynamics
Polyphenol
Phospholipase A2
Abstract:
Vacuum roasting of cocoa beans represents a potentially valuable alternative to conventional hot air roasting, offering a controlled environment that will minimize oxidative degradation and enhance bioactive compound retention. This study evaluated the impact of vacuum roasting on moisture dynamics, polyphenol retention, and phospholipase A₂ (PLA₂) enzyme inhibitory activity in cocoa beans compared to conventional hot-air roasting. Beans were roasted under atmospheric and vacuum conditions at two temperatures and roasting times. Moisture analysis indicated significantly enhanced drying efficiency under vacuum conditions, demonstrated by increased effective water diffusivity, particularly at the higher temperature along with consistently lower water activity values than conventional roasting. Total polyphenol content analysis showed significantly higher retention in vacuum-roasted samples compared to conventionally roasted beans, with statistical significance observed in three out of the four tested roasting conditions. These results indicate that vacuum roasting may provide a protective effect against polyphenol oxidation and degradation under moderate roasting conditions. Furthermore, the PLA₂ inhibitory activity assays showed that at especially at lower concentrations, cocoa extracts from vacuum roasting treatments exhibited markedly stronger PLA₂ inhibition compared to conventional roasting. At a higher extract concentration, PLA₂ inhibition increased substantially across all treatments, exceeding 75%, but the differences between vacuum and conventional roasting diminished. These findings suggest that vacuum roasting of cocoa beans can be used to develop chocolate products with improved functional properties, but further studies are warranted to optimize commercial vacuum roasting parameters for sensory quality.