Improvement of camel milk-clotting: Usefulness of crude extract from green pods of carob (Ceratonia siliqua. L) as a substitute for commercial rennet.

Camel milk transformation into cheese remains an objective to be improved today. This study aimed to improve camel milk clotting using a crude extract from green pods of carob as a substitute for commercial rennet. The composition of the crude carob extract was determined for dry matter and protein content. Milk clotting conditions were studied at different temperatures, pH and CaCl2 concentrations. Milk clotting properties were assessed by milk clotting activity, specific activity and proteolytic activity. Enzymatic hydrolysis of camel milk caseins by crude carob extract and its inhibition were demonstrated by SDS-polyacrylamide gel electrophoresis. Crude carob extract analysis showed a protein and dry matter content of 23.26±0.5 mg/ml and 30.66±0.5 g/l, respectively. Optimal milk clotting activity was observed at 53.6 °C, pH 4.5, and 0.09 M CaCl2. The crude carob extract showed a high milk clotting activity (4.97 U/ml) and a low proteolytic activity (0.04U/ml) with camel milk. The cheese yield of curd produced from camel milk using crude carob extract was the highest (23.95%) compared with that of Camel chymosin (20.5%). The high ratio of milk-clotting to proteolytic activity shows the potential of this extract as a substitute for commercial rennet in the dairy industry.

Effect of heat treatment on the antioxidant activities of camel milk alpha, beta and total caseins.

This study aimed to evaluate the effect of various heating temperatures on the antioxidant activities of camel milk caseins. The samples were processed with three different heat treatments: Pasteurization at low and high temperatures and boiling. Fresh camel milk (unheated) was used as a control. Camel milk caseins were separated by fast ion exchange liquid chromatography (FPLC) and identified by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS page). The antioxidant activities of caseins were measu- red by three different in vitro methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, 2, 2'-azino-bis (3-ethylbenzthiazoline-6-sulfonate) (ABTS) radical scavenging activity and ferric reducing power assay (FRAP). The antioxidant activity evaluated by the DPPH assay decreased significantly (p<0.05) with the increase in heat treatment of caseins. However, there was no significant difference in ABTS radical scavenging activity and Ferric Reducing Antioxidant Power assay (FRAP) of heat-treated camel caseins compared to unheated onesStill, a decrease was observed in those activities by the increase of temperature in the different casein concentrations. Besides, whatever the concentration tested and the methods applied, the antioxidant activity of beta-casein (ß-CN) was more pronounced than the alpha-casein (α-CN). Therefore, camel milk casein could be used as a natural source of antioxidants which may have a potential application in the food and nutraceutical industries. Throughout the different heat treatments applied, pasteurization at low temperature could be the most suitable alternative to preserve the antioxidant properties of camel milk.

Association of cytokine Th2 gene polymorphisms with autoimmune thyroid diseases in Tunisian population.

Autoimmune thyroid diseases (AITD) including Graves' disease (GD) and Hashimoto's thyroiditis (HT) are complex genetic diseases. Th2 cytokines act on the development of AITD. This study was conducted on Tunisian patients with AITD to investigate the association of Th2 cytokine gene polymorphisms and haplotype combination with GD or HT risk. A total of 156 controls, 160 patients with HT and 88 patients with GD were genotyped for IL-4 rs2243250, IL-5 rs2069812, IL-6 rs1800796 and IL-13 rs1800925 polymorphisms by PCR-RFLP. The AITD risk was assessed by a logistic regression analysis using the SNP stats statistical program. False-positive report probability (FPRP) was estimated to evaluate significant findings. IL-13 rs1800925 was associated with GD, after adjustment for age and gender, in codominant, dominant and allele genetic models (p = .0072; p = .0018; p = .012, respectively). Significant association of the IL-6 rs1800796C/G genotype with GD was also detected (p = .025). Furthermore, increased risk of HT was still found for IL-13 rs1800925T allele (p = .039, OR = 1.39) and for IL-4 rs2243250T/T genotype both in codominant (p = .033, OR = 2.59) and recessive (p = .011, OR = 2.73) models after adjustment for age and gender. Interestingly, haplotype analysis performed on the IL-4, IL-5 and IL-13 genes revealed a high risk of HT with CTT haplotype (p = .008, OR = 2.12). However, the CCT haplotype is a protective factor (OR = 0.36). Patients carrying the CT haplotype with only one minor allele had a moderate risk of HT (OR = 1.56). The FPRP analysis showed that the association of IL-13 rs1800925 polymorphism with GD and HT and the association of CTT haplotype with HT were noteworthy. In conclusion, the IL-4, IL-5, IL-6 and IL-13 polymorphism may play a role in susceptibility to GD and HT in the Tunisian population. Furthermore, gene-gene interaction between the IL-4, IL-5 and IL-13 significantly increases the risk of AITD. Further studies with larger numbers of individuals are needed to confirm the results.