The Effect of adjusting PH on Stretchability and Meltability to White Brined Nabulsi Cheese

Abstract

Problem statement: Boiled white brined (Nabulsi cheese) is the mostly consumed in Jordan; this cheese should show meltability and high stretchability in order to fit in the production of high quality Kunafa and other popular local sweets and pastries.The most outstanding characteristic of Nabulsi cheese is the long keeping ability (more than one year) without cooling, since it is preserved in concentrated brine (up to 25%). Approach: This work was based on the hypothesis that it would be possible to imply meltability and stretchability to the cheese by adjusting pH to the original brine that may specifically act on cross linking bonds of casein. A new apparatus for measuring the actual stretchability was designed and constructed; measurements on different cheeses proved its validity and reliability to measurement stretchability up to 80cm. Detailed treatments revealed the success of the proposed assumption in inducing meltability and stretchability to cheese processed and preserved according to the traditional methods. Results: The following results were obtained: It is possible to imply a low but acceptable level of stretchability and meltability through adjustment of the pH in the range of 5.4-5.8 by adding calculated amount of citric acid considering the buffering capacity of the cheese and storing it for few weeks to reach equilibrium. Conclusion: Conformational experiments proved the applicability of the new method on commercial Nabulsi cheese samples. Sensory evaluation revealed the superiority of pH adjusting treatment specifically at pH 5.4 and 5.8 as well as commercial Mashmouleh cheese that has high meltability and stretchability when used in Kunafa making.