The influence of breed on the organoleptic characteristics of Zamorano sheep’s raw milk cheese and its assessment by instrumental analysis

The aim of this study was to investigate the effects of three different somatic cell count (SCC) values on the sensory characteristics of sheep’s milk cheeses from the Castellana and Churra breeds (allowed for Protected Designation of Origin Zamorano cheese manufacture) and the Assaf breed (foreign), determined by typical consumers and instrumentally. The results show that the sensory characteristics of hardness, intensity of taste, and pungency reflect a significant influence of the SCCs of the original milk whereas breed significantly affects colour intensity and hardness (Warner‐Bratzler maximum shear force; WBSF). The instrumental parameters most closely related to the assessments of the typical consumers were WBSF and the value of a*, for hardness and colour respectively.     

Pressure Induced Inactivation of Selected Food Enzymes

Pectinesterase, lipase, polyphenol oxidase, lipoxygenase, peroxidase, lactoperoxidase, phosphatase and catalase have been examined at distinct conditions within a pressure range of 0.1 to 900 MPa, temperatures from 25°C to 60°C, pH 3 to 7, and time of treatment of 2 min to 45 min. Results in model buffers made it possible to rank the enzymes according to their pressure induced inactivation in the following order: lipoxygenase, lactoperoxidase, pectinesterase, lipase, phosphatase, catalase, polyphenol oxidase, peroxidase. A combination of pressure with moderate temperature increased the degree of enzyme inactivation. Pressure treatment of real food systems showed a protective effect of food ingredients on the pressure inactivation of most enzymes evaluated. For example sucrose protected pectinesterase from inactivation by pressure while lactoperoxidase and lipoxigenase were as stable in milk as in buffer.     

RHEOLOGY OF SUCROSE-CMC MODEL SOLUTION

The rheological behavior of an aqueous solution composed of 65% sucrose and 0.1% CMC was experimentally determined from -10C to 50C using a rotational viscometer equipped with coaxial cylinders. The model solution behaved as pseudoplastic fluid, represented by the power-law model. Flow behavior and consistency indices determined at -10.1, 0.5, 9.8, 19.0, 30.1 and 50. OC, showed values between 0.79 to 0.86 and 0.15 to 10.22 Pa. sⁿ, respectively. The effect of temperature on the rheological parameters was represented by Arrhenius-type relationships, with R²≥ 0.97. They were compared to the rheological behavior of a concentrated orange juice with 65° Brix and 7% pulp content. The comparison of separate rheograms for both fluids showed that the model solution can be used to represent concentrated orange juice.     

OSMOTIC DEHYDRATION OF KIWIFRUIT (ACTINIDIA CHINENSIS): FLUXES AND MASS TRANSFER KINETICS

Pulsed‐Vacuum‐Osmotic‐Dehydration of kiwifruit (Actinidia chinensis) was studied using two kinds of osmotic solution: sucrose (65 Brix) and concentrated grape juice (63 Brix), three temperatures (25, 35 and 45C) and four vacuum pulse times (0, 5, 10 and 15 min). Experimental results enabled the mass transfer kinetics for water and solutes to be studied (compositional changes of the liquid fraction and changes in the liquid fraction/solid matrix ratio). The impregnation of samples, because of the vacuum pulse, was higher when concentrated grape juice was used as the osmotic solution, probably due to its lower viscosity. The effective diffusivity (D_e) was obtained for each experimental condition and the results show higher diffusivities for vacuum‐pulsed treatments, although differences between treatments with different vacuum‐pulse time could not be observed. D_e values were slightly greater for treatments with concentrated grape juice. The activation energies (E_o) were obtained by fitting the data to the Arrhenius equation.     

Metastability of Tetragonal Zirconia Powders

The formation of metastable t -ZrO₂ by thermal treatment was studied in a systematic way on two different samples: a gel (G) and zirconyl acetate (A). The results show that initially nucle-ation of t -ZrO₂ is favored by creation of anionic vacancies with trapped electrons. At higher temperatures the electronic defects disappear, the crystallites grow, and the m -phase can nucleate. This evolution is observed perfectly on sample A because of its special morphological characteristics.     

RELATIONSHIP BETWEEN FOODBORNE BACTERIAL PATHOGENS AND THE REACTIVE ARTHRITIDES

Certain individuals suffer complications after diarrheic episodes caused by Campylobacter, Salmonella, Shigella, or Yersinia. One of these complications may be a sterile arthritis such as reactive arthritis, Reiter's syndrome and anklylosing spondylitis. Reactive arthritis and Reiter's syndrome have been shown to have a bacterial etiology; however, such etiology, while suspected, has not been definitely confirmed for ankylosing spondylitis. These arthritides show a strong familial assocation and here, reactive arthritis, Reiter's syndrome and ankylosing spondylitis are characterized and the relationship of the diseases to the major histocompatility complex antigen, HLA-B27, is described. Studies have indicated that there may be molecular mimicry between certain microbial antigens and HLA-B27. Molecular mimicry is discussed in terms of its possible explanation of the etiology of the reactive arthritides. The roles of antibodies, lymphocytes, bacterial antigens, and stress proteins in the symptomology of the arthritides are reviewed .