Thermal treatments extend the shelf life of processed products however, they may modify their qualities. This study examines the effects of processing and storage (4 ◦C during 60 days) on phenolic compounds and cell walls in strawberry nectar. Under microbial inactivation standardization, conventional thermal treatment (TT) was compared to Ohmic Heating (OH), High Pressure Processing (HPP), and Pulsed Electric Field (PEF). HPP resulted in the least colour variation after processing. After storage, colour decreased significantly after PEF, while TT preserved colour most effectively. Immediately after processing HPP-and OH- samples exhibited the highest total phenolic compounds (no reduction and a 4% reduction). However, after 60 days of storage TT better preserved phenolic compounds (a 7% reduction). Proanthocyanidins and anthocyanins degraded over time (a 14% (HPPsamples) and 42% (PEF-samples) reduction respectively). Cell wall components such as neutral sugars and galacturonic acid uniformly degraded after storage. Pectin degree of methylation significantly decreased after storage especially after PEF and HPP treatments which probably failed to achieve complete enzyme inactivation. Storage had a more significant impact on nectar quality attributes than processing.
Rincon et al. (Wed,) studied this question.