Use of image analysis to evaluate the effect of high hydrostatic pressure and pasteurization as preservation treatments on the microstructure of red sweet pepper

• Pasteurization and high pressure cause structural changes in pepper tissue.
• The lower the pressure, the greater the structural changes in pepper tissue.
• Structural changes cause variations in the morphometric and image texture parameters.
• Image analysis can quantitatively describe microstructural changes in pepper tissue.

The aim of this work was to evaluate the effect of HHP treatment and PAST on the microstructure of red Lamuyo-type sweet peppers using image analysis and to determine the parameters that allow characterizing the changes observed on the structure using different magnifications (100 ×, 200 ×, and 350 ×). The results show that all the preservation treatments evaluated caused structural modifications on the microstructure of red sweet pepper, but HHP at 500 MPa and PAST had less impact. Fractal dimension texture, contrast, inverse difference moment, and entropy are texture features that are appropriate for characterizing the effect of HHP and PAST on red pepper texture. In this context, it is important to consider the magnification at which red pepper texture is evaluated because cell damage caused by treatments is best observed at low magnification. Consequently, image analysis could be used in future studies to relate microstructure to the functionality of products subject to HHP.Industrial relevanceRed sweet peppers (Capsicum annuum) are an excellent source of essential nutrients and bioactive compounds. High hydrostatic pressure (HHP) applied during food processing can improve the retention of food quality attributes and nutritional and organoleptic properties better than pasteurization (PAST). Image analysis is a non-invasive technique that allows to provide objective evaluations from digitalized images. There are no studies that quantify the effect of HHP and PAST using image texture parameters and that evaluate the effect of the magnification used on these texture features. These features are critical factors that determine food acceptance or rejection by the consumers. Thus, texture measurement has gained much attention from food science and industry. Therefore, it would be interesting to study the effect of these treatments on the microstructure of red sweet pepper tissue using image analysis. Thereby, it would be possible to relate the image information to structural modifications and to the extractability of bioactive compounds or acceptance of preservation processes by consumers.