Comparison of physical and chemical properties of high pressure- and heat-treated Lychee (Litchi chinensis Sonn.) in syrup

Abstract

Lychee usually has white flesh, but its flesh is very sensitive to thermal and enzymatic impairment and ultimately changes in color. This investigation was intended to study the magnitude of color change in lychee by high pressure and thermal processing. The lychee was packed in syrup prior to being processed. Pressurized lychee was performed at 600MPa at 30°C or 50°C for 20min, while the pasteurized sample was heated at 90°C for 3min. It was found that pressurization induced lower color L*, a* and b* values, including low anthocyanin content. For enzymatic activities, high pressure could reduce the activity of polyphenoloxidase by 33-51%, whereas pasteurization markedly reduced that activity by 90%. © 2012 Taylor & Francis.