EFFECT OF REINFORCEMENT RICOTTA CHEESE BY SKIM MILK POWDER AND MILK PROTEIN CONCENTRATE POWDER ON THE QUALITY OF THE CHEESE TARGET DURING STORAGE

Ricotta cheese was made from acidified skim milk by yogurt starter at pH 5.8- 5.9 and adding different concentration of skim milk powder and milk protein concentrate. Acidity ,Fat, Protein, Ash, Total solids and the yield% of cheese were increased with increasing of skim milk powder and milk prote in concentrate while pH values were decreased .The cheese made by yoghurt starter coagulant with adding 2% skim milk powder had a higher values for the rheological properties Hardness, adhesiveness, Cohesiveness (g), Springiness (mm), Gumminess(g) and Chewiness (g.mm) which were 5777(g) , 4318.9(g) ,0.56(g),9.34(mm),2656(g) and 24820.28 (g.mm) respectively, while aading 4% skim milk powder had the lowest rheological properties for Hardness and adhesiveness which were (2712(g)-3391.8(g) respectively .The rheological properties in treatment (6% skim milk powder) as follows, Cohesiveness (g),Springiness (mm), Gumminess(g) and Chewiness(g.mm) were 0.45(g),7.81(mm), 1219(g) and 9520.01(g.mm) respectively. On the other hand, Ricotta cheese made by yoghurt starter coagulant with 4% milk protein concentrate powder showed the highest properties .Hardness(g), Cohesiveness (g), Springiness (g), Gumminess(g) and Chewiness(g.mm) were 6119(g),0.62(g),10.63(mm),3778(g) and 43466.59(g.mm) ,respectively while , adding 6% milk protein concentrate powder gave the highest value for adhesiveness [4127.91(g)] .but the same treatment had the lowest value for the Hardness(g), Cohesiveness (g), Springiness (mm), Gumminess(g) and Chewiness(g.mm) values being 4377(g),0.39(g),7.95mm,1709 (g)and 13595 g.mm ,respectively.The microbiological tests showed that, the control samples contained the lowest of total bacterial counts (7x10^4 cfu/g), protolytic bacteria (6x10^3 cfu/g) and lipolytic bacteria(1x10^3 cfu/g),All samples were free from coliform bacteria and staphylococcus. spp. Addition of 2% skim milk powder and milk protein concentrate showed the highest total score points for Sensory evaluation (83.5 and 82.8% )., adding 6% skim milk powder and milk protein concentrate showed the lowest total score points for Sensory evaluation (77.8 and 78.8 %).Generally , this work was carried out to study the effect of use skim milk and milk protein concentrate by different percent on the composition and the quality of Ricotta cheese.