Relationship between chemical and rheological characteristics of ras cheese

RAS cheese samples, produced by the Misr Milk and Food Company, Siclam, were chemically analyzed and the nitrogenous compounds soluble at pH 4.6 fractionated by gel filtration. The rheological properties of the cheese were expressed as hardness, elasticity, hysteresis, and toughness. Statistical analysis of chemical composition of cheese, clearly showed greatest differences in the nitrogenous compounds < 5000dalton followed by moisture content, while the amino nitrogen followed by salt content showed lowest differences. pH and protein content were positively correlated with hardness, hysteresis and toughness and negatively with elasticity. Fat content was negatively correlated with hardness and positively with the other measured textural characteristics. Salt and moisture level in cheese had marked effect on rheological properties; both were negatively correlated with hardness and toughness and positively with elasticity. Also, the statistical analysis revealed that hardness of Ras cheese was affected by pH, protein%, moisture%, nitrogenous compounds <5000 dalton and amino nitrogen, but the most variable was found to be the amino nitrogen followed by the protein content in cheese. Whereas the elasticity of cheese was affected mainly by soluble nitrogen followed by the pH. The major factor affect on hyteresis was amino nitrogen followed by the pH and protein%. The toughness in Ras Cheese was mainly affected by the amino nitrogen, pH, moisture and protein content

Production of bacteriocins by streptococci

Production of inhibitory substance [s] was investigated by using 8 strains of Streptococcus lactis ssp. lactis and 6 strains of Streptococcus lactis ssp. cremoris isolated from Domiati cheese samples. Among the strains tested, Streptococcus lactis spp. lactis 5 and 7 were found to inhibit the growth of S. lactis spp. lactis 1, 3 and 6, S. lactis spp., cremoris 11, 14, 19, 20 and CNRZ 117, Leuconostoc mesenteroides ssp. mesenteroids 1, Lactobacillus delbrueckii ssp. bulgaricus CNRZ 1188, 1183 and Lactobacillus plantarum 19. In contrast, strains of S. lactis ssp. cremoris tested did not inhibit the growth of indictor strains used. The inhibitor substance [s] was completely inactivated by alpha chemotrypsin, but it was less sensitive to trypsin and pronase. The optimum pH for the activity of antibacterial agent was 4.5-5. Addition of 4% NaCl to the growth medium of the producer strain reduced the titer of bacteriocin

Michael condensation of B- [2tetroyl] -acrylic acid and hetero-ring formation via reaction of 3- [2-tetralyl] -6-acetyl-5-oxo-3-cyclohexene-1carboxylic acid with some nucleophelic reagents

In continuation to our recent study Beta-[2-tetroyl]-Acrylic acid [I] reacts under Michael conditions with acetylacetone to give 3-[2-tetralyl]-6-acetyl-5-oxo-3-cyclohexene-l- carboxylic acid [II]

Synthesis and some reactions of new 3, 1 nbenzosazine-4- one derivatives

2[2,5-Dimethylbenzoyl vinyl]-4H -3, j-benzoxazin-4 -one [II] can be obtained via reaction of B-[2,5-dimethylbenzoyl]-acrylyl chloride with anthranilic acid followed by cyclization of the anilide [I] formed by the action of Ac2O. The action of amines, hydrazines, hydroxylamine hydrochloride, urea and thioureas on the benzoxazone has been investigated