Texture and structure of glucose-infused melon

The effect of glucose and calcium infusion on texture characteristics and u ltrastructure of melon was studied using an Instron Universal Testing Machi ne and optical and transmission electron microscopy. Resistance to puncture was significantly greater when treatment was perform ed under vacuum or when Ca2+ was present during atmospheric and vacuum gluc ose infusion. Atmospheric treatment produced a smaller resistance to punctu re than the one shown by raw fruit. Processing reduced residual relaxation force and relaxation time, showing, the high internal fracture suffered by the fruit during treatment. There was a good correlation between textural c hanges detected through instrumental measurement and structural alterations of flesh tissues. Vacuum-treated samples showed cell walls with good optic al density and a middle lamella still visible. Atmospheric impregnation cau sed very much reduced staining and disruption of cell walls as well as rupt ure of membranes. Addition of Ca2+ during both infusion procedures resulted in more electron-dense cell walls as compared with those impregnated witho ut Ca2+ (C) 2000 Society of Chemical Industry.