In this research, the use of hydrocolloid constituted of pectin (1%), carboxymethylcellulose (CMC) (0.5%) and gelatinized starch (5%), added to sucrose (15%), was tested to evaluate the influence of these compounds on the quality parameters of frozen melons under various cooling rates. The evaluation parameters were soluble solids, loss of cellular fluid by exsudation and water holding capacity after thawing. Tissue disruption due to ice crystal growth was determined by optical microscopy and the physical distribution of gels on the cell wall was examined by Scanning Electron Microscopy (SEM) on frozen and freeze-dried materials. Evaluation parameters and microscopic analyses of cellular structure, permitted to detect the existence of interactive effects between hydrocolloid systems and the cell wall, which appears responsible for less damaged fruit structures. In addition, histological studies by optical microscopy permitted the verification of a possible increase of the wall resistance. Treatments with pectin and gelatinized starch added of sucrose and calcium ions presented the best results in the maintenance of the structure, minor loss of cellular fluid and better texture of the material after thawing. The treatments with calcium appeared to be responsible for the maintenance of the fruit firmness.
frozen foods; quality; microstructure
