Improved shelf-life of Nabulsi cheese wrapped with hydrocolloid films

Abstract

Chitosan- and bitter vetch protein-based films were prepared, characterized and applied as wrapping films of Nabulsi cheese, to improve the shelf-life of such dairy product widely consumed in the Middle East. Unsalted cheese wrapped with these hydrocolloid films was found to maintain the pH value of the fresh product during storage, whereas the pH of unwrapped samples was shown to progressively decrease. These findings were confirmed by the decrease in titratable acidity detected in the wrapped unsalted cheeses at 9th day of storage. Conversely, no effect was observed at different storage times in the weight loss of wrapped samples, compared to the unwrapped ones, stored both in the absence and presence of salts. However, chitosan films proved to be the most effective wrapping material in hindering microorganism growth in unsalted cheese. Hardness, chewiness and gumminess of the wrapped unsalted samples increased during storage, whereas no significant difference in springiness was observed between the wrapped and unwrapped cheeses, except for the protein-wrapped salted samples in which the springiness was observed to decrease slightly from the 3rd day onward. The proposed wrapping is suggested as an innovative packaging system of Nabulsi cheese to preserve over time its quality without brining.