Granulomatous enteritis and lymphadenitis in Iberian pigs naturally infected with Lawsonia intracellularis.

Intestinal samples and/or lymph nodes of two Iberian pigs from two different farms were submitted for histopathologic examination. Both pigs had proliferation of ileal and/or cecal crypts with almost complete absence of goblet cells. Infection by Lawsonia intracellularis was demonstrated by immunohistochemistry and polymerase chain reaction assay. The mesenteric lymph node of one pig had moderate lymphocyte depletion with granulomatous inflammation of the lymph node parenchyma. Histiocytes and multinucleated giant cells from the lymph node of one pig contained L. intracellularis antigen within the cytoplasm. This pig had also porcine circovirus type 2 (PCV-2) infection, but nucleic acid and antigen of this virus were not demonstrated in the lymph node. The second pig had lymphocyte depletion and marked granulomatous inflammation in Peyer's patches. Histiocytes and multinucleated giant cells in areas of granulomatous inflammation contained L. intracellularis antigen; no PCV-2 nucleic acid or antigen was detected in the tissues of this pig. This is the first description of granulomatous ileitis and lymphadenitis associated with L. intracellularis infection.

Microbial study of farmhouse ewe cheese during storage in olive oil.

The effect of storing farmhouse ewe cheese in oil and in vacuo over long periods of time on physicochemical properties (water activity and pH) and the microbiota of the cheese was investigated. The storage conditions were found to scarcely influence the sample pH. Also, the initial water activity (a(w) = 0.961) and its value after 9 months of storage (0.927) were both very similar to those for naturally ripened cheese. The incidence of pathogenic microbial groups was found to decrease with storage time (counts fell below 1 log CFU/g). The flora that effects proteolytic changes in cheese consisted of lactic microorganisms (viz. lactococci and lactobacilli), in addition, after 6 months of storage, of enterococci. The last are responsible for the formation of large amounts of soluble nitrogen (SN), non-protein nitrogen (NPN) and aminoacid nitrogen (NH2-N), which provide this type of cheese with very special sensory features while preventing dehydration and thus lengthening its shelf life.

Chemical and microbiological characteristics of ewes' milk cheese manufactured with extracts from flowers of Cynara cardunculus and Cynara humilis as coagulants.

The chemical and microbial characteristics as well as the flavor and aroma of Los Pedroches cheese made using aqueous extracts of Cynara cardunculus L. flowers were compared with those of cheeses manufactured with extracts of Cynara humilis L. throughout ripening. The two thistle species assayed were found to have no appreciable effect on the moisture, fat, protein, and NaCl contents of the cheese or on its water activity, flavor, and aroma; however, the use of C. humilis resulted in reduced lactic acid content (p < 0.001) and higher pH values (p < 0.05) relative to those of cheese specimens produced with C. cardunculus. The protein breakdown of the cheeses was assessed in terms of soluble nitrogen (SN), nonprotein nitrogen (NPN), and amino acid nitrogen (AAN). Proteolysis was more marked and rapid in cheese containing C. cardunculus as coagulant, the SN and NPN contents of which were significantly higher (p < 0. 01) than those of the cheese obtained with the species C. humilis; AAN contents were similar in both species of Cynara throughout ripening. Although total viable, coliform, and lactobacilli counts were similar in cheeses produced with both types of plant coagulant throughout ripening, enterobacteria and yeasts counts (p < 0.01) and molds counts (p < 0.05) were higher in cheese produced with C. humilis than in cheese obtained with C. cardunculus.

Changes in water activity and some microbial groups during storage of pet feed.

The effect of exposure of different pet feed samples to the typical temperature and moisture conditions of many months of the year (9 degrees C and 80% RH) on water activity (aw), pH and growth of various microbial groups (mesophilic aerobic bacteria, fungi and yeasts) was studied. The storage conditions were found to scarcely influence the samples pH, with no significant changes relative to the initial values (the standard deviation was 0.04 and the coefficient of variation 0.85%). By effect of exposure to the temperature and moisture conditions tested, the initially stable feeds reached moisture contents close to 20% and aw values near those of equilibrium with the ambient relative humidity during storage. Microbial counts increased with increasing aw, with final means of 8.44, 9.16 and 8.71 log CFU/g for mesophilic aerobic bacteria, fungi and yeasts, respectively. The risk of mycotoxin production at these aw values is discussed. Careful control of moisture is recommended in order to preserve the quality of pet feed throughout its scheduled shelf life.

Water activity of Spanish intermediate-moisture meat products.

On the basis of considering foods with water activity from 0·600 to 0·910 to be intermediate-moisture foods (IMF), we determined the water activity, pH, and some chemical parameters for 70 samples from 17 different selected types of Spanish intermediate-moisture meat products. Even though the salt content is the main water-activity depressor, the sodium chloride molality in the overall amount of water of the product cannot be used to calculate the a(w) value of these types of meat products of intermediate moisture.