Effect of acidifying agents and storage temperature on ripening of ricotta cheese

الملخص EN

The effect of storage period and acidifying agent on ripening of Ricotta cheese was investigated.

The acidifying agents used were white vinegar, lemon juice and grapefruit juice added during heat treatment of the whey at 90˚ C.

The curd accumulated at the surface was extracted and squeezed for overnight.

The curd was then cut into pieces, 10 % of salt was added and packed into plastic bags (polyethylene).

The cheese was stored for two months, at cold temperature (4 ± 2˚C) and room temperature (30 ± 11˚C).

Tire analysis was carried out at 0, 15, 30, 45 and 60 days intervals.

The total solids of cheese increased significantly (P = 0.05) due to the loss of moisture content.

The increase was more 33.09 % when white vinegar was used compared to 32.65 % and 31.95 % increasing for lemon and grapefruit cheese, respectively.

Soluble nitrogen (SN), soluble nitrogen to total nitrogen ratio (SNYTN), formula (FRI) and Shilovish (SRI) ripening indices showed increasing trend as the storage period progressed.

The pH value decreased significantly (P = 0.05) in samples with white vinegar than those with lemon and grapefruit juices.

The total volatile fatty acids (TVFA) increased during storage period.

White vinegar cheese stored at room temperature produced the highest TVFA (20 mls 0.1 N Na OH), which was significantly (P = 0.05) higher than respective values of lemon cheese (15mls 0.1 N Na OH) and grape fruit cheese (14mls 0.1 N Na OH).

The samples stored at room temperature had a good score till 15 days of storage and had a shelf life of 30 days, while those Stored at cold temperature had a good score till 30 days of storage arid still better till the end of the storage period.

Samples stored at cold temperature were significantly (P = O.05) better than samples stored at room temperature.