Effect of sequential multi-frequency ultrasound washing processes on quality attributes and volatile compounds profiling of fresh-cut Chinese cabbage

The objective of the current investigation was to assess the microbial quality, physicochemical parameters, volatiles profile and sensory quality of fresh-cut Chinese cabbage samples exposed to dual frequency ultrasound (DFU1: 20–40 kHz; DFU2: 20–60 kHz; and DFU3: 40–60 kHz) and triple frequency ultrasound (TFU: 20–40–60 kHz) washing processes. The natural microbiota (total bacteria, yeasts and molds), physicochemical quality (instrumental colour, texture, electrolyte leakage, and microstructure), volatile compounds and sensorial quality (texture, colour, odour, appearance and general acceptability) were determined. Counts of total bacteria, yeast and molds were significantly reduced (P < 0.05) with TFU, which in general reduced 3.1 and 2.8 decades respectively. However, the results indicated that TFU washing of Chinese cabbage brought about undesirable changes in physicochemical and volatile compounds attributes whereas the DFU preserved or enhanced these attributes. Forty-three (43) volatile compounds were identified and quantified by HS-SPME-GC-MS analysis, six (6) of which had odour activity values greater than 1 (OAVs > 1) and were considered as aroma active compounds (AACs) contributing substantially to the core aroma profile of the Chinese cabbage. Finally, DFU washing according to an affective sensory tests on treated samples, presented positive sensory characteristics with better general acceptability compared to TFU washing.