Effect of ultrasound pre-treatment on the physical, microbiological, and antioxidant properties of calçots

Abstract

The effect of ultrasound (US) treatment (40 kHz, 250 W) for 0, 10,25 and 45 min on the physical and microbiological quality, total antioxidant capacity (TAC) and total phenolic content (TPC) of calçots (Allium cepaL.) was evaluated. Moreover, the effect of roasting (270 °C, 8 min) and in vitro simulated digestion on the antioxidant properties was studied. Overall, US treatment had no effect of the physical quality and antioxidant properties of calçots regardless the treatment time, while thermal processing produced an increase on the TAC and maintenance in TPC. Furthermore, the digestion process caused a remarkable decrease on the TAC and TPC, but that decrease was higher in roasted than in fresh samples. The microbial load of all US-treated fresh samples was below 6 log (cfu g−1) and a decrease of 1-log reduction was observed after treating for 45 min. Those results indicated that US pre-treatment had no negative effects on the quality of calçot while produced a decrease on the microbial load at high processing times.

This work was supported by ACCIÓ (Generalitat of Catalonia, RD14-1-004), Sociedad Agrícola i Secció de Crèdit de Valls S.C.C.L., Cooperativa of Cambrils, and PGI ‘Calçot de Valls’. This work was also supported by the ‘Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement’ (FI-2017-B2-00164, L. Zudaire) and CERCA Programme of Generalitat de Catalunya. T. Lafarga is in receipt of a ‘Juan de la Cierva’ contract awarded by the Spanish Ministry of Economy, Industry, and Competitiveness (FJCI-2016-29541). I. Aguiló-Aguayo thanks the National Programme for the promotion of talent and its employability of the ‘Ministerio de Economía,Industria y Competitividad’ of the Spanish Government and to the European Social Fund for the Postdoctoral Senior Grant ‘Ramon y Cajal’ (RYC-2016-19949).