EFFECT OF SWEET SOLUTES ON THE QUALITY OF A PUMPKIN PUREE (CUCURBITA MOSCHATA DUCHESNE EX POIRET) PRESERVED BY THE HURDLE TECHNOLOGY

The effect of glucose and xylitol on the quality of a pumpkin puree preserved by the hurdle technology was studied. It was demonstrated that the addition of glucose or xylitol to depress water activity (A(w)) to 0.98 was necessary to assure 3 weeks of microbial stability at 25C of a pH 4.00 pumpkin puree, containing potassium sorbate and submitted to vapor heat treatment. A decrease in a and b color parameters was observed during storage for both humectants. However, the use of a low oxygen permeability packaging such as polyvinyl chloride-polyvinylidene chloride copolymer instead of polyethylene protected the color. From a rheological point of view, xylitol diminished yield stress and consistency coefficient independently of storage time. The results obtained emphasize the advantage of the use of glucose as well as the importance of an appropriate choice of solutes to depress A(w) in order to improve the quality of pumpkin puree. PRACTICAL APPLICATIONS Fresh pumpkins are very sensitive to microbial spoilage and to physiological and biochemical changes; thus, a preservation process is necessary to extend shelf life. In this study, a development of a minimally processed pumpkin puree was proposed and the color stability and rheological behavior were evaluated to improve the quality. The results obtained demonstrated that the addition of glucose (10.00% w/w) to a pH 4.00 pumpkin puree containing potassium sorbate (0.0120% w/w), steam cooked and packed in polyvinyl chloride-polyvinylidene chloride copolymer bags, assures the microbiological and color stability and prevents changes in the rheological behavior during a storage of 3 weeks at 25C.