Impact of high hydrostatic pressure on the structure, diffusion of soluble compounds and textural properties of persimmon 'Rojo Brillante'

Abstract

[EN] The use of high hydrostatic pressure (HHP) provides a reliable way of obtaining high quality food. The aim of this work was to analyze the effect of high pressure treatments on the microstructure and textural properties of astringent and non-astringent (95-98% CO 2, 24h, 24°C) persimmon 'Rojo Brillante'. Samples were submitted to different HHP treatments (200MPa and 400MPa during 1, 3 and 6min). The microstructural changes observed by Low Temperature Scanning Electron Microscopy and Light Microscopy were related to the improvement in the diffusion and extractability of tannins and acid compounds of this fruit. Some textural properties (firmness and cohesiveness), pH and titratable acidity were also analyzed. Cell wall disruption and migration of the cell content to the intercellular spaces took place when 200MPa was applied. Precipitated tannins could be observed in the intercellular spaces of the astringent samples, while they remained inside the tannic cells of the non-astringent ones. The cellular degradation was more obvious and the concentration of solutes in the intercellular spaces increased when 400MPa was applied. In this way, HHP favored the diffusion of tannins and other soluble components to the intercellular spaces, which could be related to a higher extractability of these nutritional compounds in persimmon 'Rojo Brillante'. The tissue from non-astringent samples was more affected by HHP treatments. Despite the greater diffusion of soluble compounds, the application of HHP provoked undesirable effects on texture, such as a decrease in flesh firmness and cohesiveness in both astringent and non-astringent samples. pH increased in both astringent and non-astringent samples when 200MPa was applied due to the insolubilization of tannins, while titratable acidity decreased for the same reason. According to the pH values obtained, extractability of acid compounds could be improved when 400MPa is applied. © 2011 Elsevier Ltd.