Effect of Adding Black Rice Flour on Properties of Processed Cheese Spread

THE effect of adding black rice flour (Oryza sativa L. indica) (BRF) on properties of spread type processed cheese (STPC) was the aim of this study. BRF contained rich amount of antioxidants (anthocyanin’s, total phenols and total flavonoids), protein, crude fiber, total carbohydrates and minerals.    Six treatments of STPC were performed by substituting cheese-base with BRF at the ratio of (the control) nil, 5,10,15,20 and 25% on the dry basis. Chemical composition and Organoleptic properties were determined after processing and during storage periods for three months. Significant differences p>0.05 were found between STPC treatments as affected by the substitution ratio of BRF. The results showed that the BRF contained anthocyanin’s (4874.8 mg cy-3- glc/100gm dry weight), total phenols (695.4mg GAE/100 gm dry weight), total flavonoids (112.6mg quarstine/100 gm dry weight) and DPPH (76.85%). Although DM, fat/ DM and ash/DM contents of STPC were not influenced by adding BRF, the total nitrogen (TN)/ DM percentage significantly tended to decrease when the level of cheese base substitution with BRF exceeded 25%. The soluble nitrogen (SN)/TN percentage of all treatments of STPC was higher than that of the mature Ras cheese itself, used as cheese-base, and decreased significantly as the portion of BRF instead of cheese base increased. The gradual substitution of cheese base with BRF in STPC making was associated with the proportional increment in the fibers/ DM percentage and decrement in the titratable acidity %, in spite of the stability of pH value at 5.8. Hardness, cohesiveness, gumminess and chewiness exhibited proportionally higher values, while, springiness property behaved opposite trends as the BRF was used instead of cheese base in STPC recipes. Whether the proportional replacement of cheese base with BRF or the prolonging of cold storage period was associated with the gradual increase in the oil separation index and decrease in the meltability % as well as in the penetration (mm) of STPC. The use of BRF instead of cheese base did not lead to any significant differences in the score of all organoleptic attributes of STPC. Moreover, the BRF flavour was accepted and favorably preferred in STPC and improved the stability of sensory quality of STPC along the cold storage period, especially when the substitution level of cheese base with BRF was more than 5%. The blends prepared by using 5, 10, 15, and 20% BRF showed higher acceptability compared to the control or 25% blend.