Effect of high-pressure/high-temperature processing on chemical pectin conversions in relation to fruit and vegetable texture
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- 作者：Ans De Roeck ; Thomas Duvetter ; Ilse Fraeye ; Iesel Van der Plancken ; Daniel Ndaka Sila ; Ann Van Loey ; Marc Hendrickx
- 关键词：Pectin ; Texture ; Demethoxylation ; β ; -elimination ; High-pressure sterilization
- 刊名：Food Chemistry
- 出版年：2009
- 出版时间：1 July 2009
- 年：2009
- 卷：115
- 期：1
- 页码：207-213
- 全文大小：1057 K
文摘
Heat sterilization of plant derived food products entails considerable organoleptic and nutritional quality losses. For instance, texture loss of fruits and vegetables occurs, next to turgor pressure losses, mainly due to chemical changes in the cell-wall pectic polysaccharides. High-pressure sterilization, i.e. the combination of high temperature (90 °C) with high pressure (500 MPa), could present a positive alternative assuring safety while minimizing quality losses. In this study, the potential of high-pressure sterilization in preserving fruit and vegetable texture was evaluated by investigating the effect of combined high-pressure/high-temperature (HP/HT) treatments on two texture related chemical pectin conversions in model sytems. First, a protocol was developed to perform reproducible kinetic studies at HP/HT under constant processing conditions. Subsequently, apple pectin solutions at pH 6.5 were subjected to different HP/HT combinations (500, 600 and 700 MPa/90, 110 and 115 °C) and the extent of chemical demethoxylation and β-eliminative depolymerization was determined. At atmospheric pressure, both zero-order reaction rate constants increased with increasing temperature. At all temperatures, demethoxylation showed a higher rate constant than β-elimination. However, a temperature rise resulted in a stronger acceleration of β-elimination than of demethoxylation. When combining high temperature with high pressure, β-elimination was retarded or even stopped, whereas demethoxylation was stimulated. These results are very promising in the context of the texture preservation of high-pressure sterilized fruits and vegetables, as β-elimination is accepted to be one of the main causes of thermal softening and low methoxylated pectin can enhance tissue strength by forming cross-links with calcium ions present.