Impact of the industrial freezing process on selected vegetables — Part I. Structure, texture and antioxidant capacity

Effect of different cooking methods on structure and quality of industrially frozen carrots

“…Moreover, some cells showed the evidence of the onset of separation in the middle lamella regions; the cell separation was due to the breakage of chemical bonds among the pectic components of middle lamellae of adjacent cells and/or to the hydrolysis of some other components of the cell wall (i.e., pectin, hemicelluloses, cellulose). Similar effect of thermal treatment was confirmed by several authors for different vegetable structures (Sila et al 2005;Paciulli et al 2015;Xu et al 2015). In our study, the cells separation after cooking might be ascribed to a decrease in the strength of cell-cell interactions in the middle lamella adjacent to the intercellular spaces.…”

“…The decrease of the slope of the rising portion of the curve and the broaden curve profiles of the cooked carrots were probably in relation with the softening and the increased deformability of the structure, due to heat, that caused plasmolysis and cell separations (Fig. 1c-f), as previously observed in other vegetables (Canet et al 2004;Paciulli et al 2015). Among cooking practices, R B and R S samples exhibited very similar forcedistance curves, with narrower shapes than R MW that presented instead a broader curve with a more complex profile ( Fig.…”

“…Freezing leads to major modifications as compared to blanching because it induces the formation of ice crystals that mechanically stress and damage the tissue (Van Buggenhout et al 2006). Frozen vegetables exhibited the weakening of the cell wall with the depolymerisation of the pectic materials, and a loss of turgor with softening effects (Prèstamo et al 1998;Paciulli et al 2015). Moreover, the storage of frozen products induced a further tissue softening (Neri et al 2014).…”

Effects of freezing, freeze drying and convective drying on in vitro gastric digestion of apples

“…Samples were fixed in formaldehyde (10%), followed by dehydration, embedding in paraffin (60°C for 3 h), and sectioning into 4-5 lm slices with a microtome (model Finesse 325, Thermo Shandon, Cheshire, UK). The slices were stained with acid Schiff and haematoxylin to visualize cell walls (Paciulli et al, 2014). Images were obtained using a light microscope (Olympus BX60FS, Japan) at 100Â magnification.…”

Influence of freezing on the bioaccessibility of beetroot (Beta vulgaris) bioactive compounds during in vitro gastric digestion

“…According to Bourne, the texture of foods is derived from their structure. Many studies have focused on the effects of freezing on textural quality of vegetables –including green asparagus stems, zucchini and green beans and carrots – through mechanical and/or sensorial measurements of frozen/thawed vegetables or through microscopic measurements . Some workers have investigated chemical modifications during freezing that are responsible for pH, soluble solid, water content or color changes of frozen/thawed fruits and vegetables.…”