Production of plant proteinase from jack fruit (Artocarpus integrifolis) and its influence on rheological and sensory characteristicsof low fat yogurt [electronic resource].

Includes references.

Adding a proteolytic enzyme extraction from Jack fruit (Artocarpus integrifolis) in combination of fermentation process in yogurts manufacture was tried to improve yogurt flavour and rheological properties. Experimental yogurts milk contained . control, 3.9 (T1), 7.8 (f2) and 11.7 (f3) units/ml millk .from crude extracts of plant proteinase. The pH of the product treated with plant ptoteinase was lower than the control. However, The rate of acidity development during storage slightly increased with increasing the addition of plant proteinase level and progress of storage period of yogurt. The proteolytic activity of all yogurts gradually increased until the end of storage period (15 days). Yogurts made from milk treated with plant proteinase preparations were less firm compared with control at all storage periods, where T3 showed more less firm after 15 days of storage being 20.17 g/ 100g. Generally, increasing units of plant proteinase preparations decreased the finnness. On the other hand, yogurt made from milk pretreated with plant proteinase had higher syneresis, and apparent viscosity than the untreated product. The greatest viscosity was found in T2 and T3 of 433 and 479 mPa.s respectively, compared with control of 299 mPa.s at 15 days storage. The results indicated that there is an inverse relationship between the amount of units of plant proteinase preparations and susceptibility of yogurt to syneresis. The T2 gained the highest scores (85 points) followed by the control (81.5 points) after 15 days of storage, while yogurt of T3 showed a low scoring being 75. From the foregoing results, it is recommend to use Jack fruit (Artocarplls integrifolis) as a source of plant proteinases and utilize it to develop a high quality yogurt at a level of 7.8 units of plant proteinases / ml milk.

Summary in Arabic.

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