Changes in the structure and antioxidant properties of onions by high pressure treatment

• Published in: Food & function 2013, Vol.4 (4), p.586-591
• Main Authors: Vázquez-Gutiérrez, José Luis, Plaza, Lucía, Hernando, Isabel, Sánchez-Moreno, Concepción, Quiles, Amparo, de Ancos, Begoña, Cano, M. Pilar
• Format: Article
• Language: English
• Subjects: Allium cepa; Antioxidants; Antioxidants - chemistry; Antioxidants - isolation & purification; Ascorbic acid; Cell Membrane - chemistry; Cell Wall - chemistry; Cell walls; Diffusion; Flavonoids - chemistry; Flavonoids - isolation & purification; Fluorescence recovery after photobleaching; Food Handling - instrumentation; Food Handling - methods; Membrane permeability; Onions - chemistry; Permeability; phenolic compounds; Phenols; Phenols - chemistry; Phenols - isolation & purification; Plant Extracts - chemistry; Plant Extracts - isolation & purification; Plasma membranes; Pressure; Scanning electron microscopy; Tonoplasts
• ISSN: 2042-6496; 2042-650X
• DOI: 10.1039/c3fo30253a

Onions have antioxidant properties and they are an important source of bioactive compounds such as phenols. The aim of this work was to study the effect of high hydrostatic pressure (HHP) (100-600 MPa/1-3 min/25 °C) on the microstructure and antioxidant properties of onions (cv. Doux) and its relationship with changes in the extractability of potential health-related compounds. Cryo scanning electron microscopy was used to study the microstructure. Vitamin C, total phenolic content and antioxidant activity (DPPH&z.rad;, ABTS&z.rad; + , FRAP) were also analyzed. Tonoplast, plasmalemma and cell walls were affected by the HHP treatment and it favored the diffusion of the cellular content to the intercellular spaces. Vitamin C did not show significant changes, whereas the extracted phenolic content and antioxidant activity increased at pressures of 300 or 600 MPa. Therefore, it could be concluded that HHP produced changes in membrane permeability and disruption of cell walls favoring the release of phenolic compounds from tissue and, in consequence, improving their extractability. HHP produces changes in cell wall and membrane permeability favoring the release of phenolic compounds, therefore, improving their extractability.