Lactobacillus casei strains isolated from cheese reduce biogenic amine accumulation in an experimental model

Tyramine and histamine are the biogenic amines (BAs) most commonly found in cheese, in which they appear as a result of the microbial enzymatic decarboxylation of tyrosine and histidine respectively. Given their toxic effects, their presence in high concentrations in foods should be avoided. In this work, samples of three cheeses (Zamorano, Cabrales and Emmental) with long ripening periods, and that often have high BA concentrations, were screened for the presence of BA-degrading lactic acid bacteria (LAB). Seventeen isolates were found that were able to degrade tyramine and histamine in broth culture. All 17 isolates were identified by 16S rRNA sequencing as belonging to Lactobacillus casei. They were typed by plasmid S1-PFGE and genomic macrorestriction-PFGE analysis. Two strains (L. casei 4a and 5b) associated with high degradation rates for both BAs were selected to test how this ability might affect histamine and tyramine accumulation in a Cabrales-like mini-cheese manufacturing model. The quantification of BAs and the monitoring of the strains' growth over ripening were undertaken by RP-HPLC and qPCR respectively. Both strains were found to reduce histamine and tyramine accumulation. These two strains might be suitable for use as adjunct cultures for reducing the presence of BAs in cheese.     

Identification of staphylococci and dominant lactic acid bacteria in spontaneously fermented Swiss meat products using PCR-RFLP

Pathogenic, spoilage, and technologically important microorganisms were monitored in 21 spontaneously fermented Swiss meat products manufactured with meat from wildlife or animals grown in natural habitat. Thereby, PCR-restriction fragment length polymorphism (RFLP) on rpoB and 16S rRNA gene sequences provided a powerful tool for fast and accurate identification of the main microbial population. Lactobacillus sakei and Lactobacillus curvatus dominated in fermented meat products followed by Staphylococcus species, which constituted 88.2% of all Gram-positive, catalase-positive cocci (GCC⁺) with cell counts varying from 2.6 to 7.0 log cfu/g during maturation. Staphylococcus equorum was prevalent in frequency and cell counts during maturation (18.0%; 5.0-7.3 log cfu/g) and in the end products (28.4%; 1.8-6.2 log cfu/g) implicating a new presumptive starter species for meat fermentation. Nine out of 14 end products indicated safety risks to consumers due to the high incidence of Staphylococcus saprophyticus or Staphylococcus epidermidis combined with cell counts of 7.4 and 4.9 log cfu/g, respectively. This fact was supported by the detection of Staphylococcus aureus and Enterobacteriaceae in ready-to-eat products strongly exceeding the tolerable limit of 2 log cfu/g. Spontaneously fermented meat products produced from wildlife or animals grown in natural habitats not only gave rise to hygienic and safety concerns but also provided new presumptive starter strains.     

Volatile constituents of palm wine and palm sap

Palm wine and pasteurised palm sap volatiles were collected, concentrated on a Tenax GC and analysed by gas chromatography and gas chromatography-mass spectrometry. Eighty-two components were identified: 47 esters, 9 alcohols, 5 acids, 6 carbonyls, 2 acetals, 4 terpenes and 9 hydrocarbons. These had all been found previously in conventional wines. Odour evaluation of the separated palm wine components as they eluted suggested that no one compound is responsible for the characteristic palm wine odour. The acetates of higher alcohols and the ethyl esters of straight-chain aliphatic C₆-C₁₀ acids seemed to be important and may play a big role in imparting the fruity nuances of characteristic palm wine odour. Their association with alcohols seemed also to be necessary for the expression of typical palm wine odour. The qualitative difference between palm sap aroma and palm wine aroma appeared to be due mainly to the presence of these esters and alcohols in palm wine and their apparent absence from palm sap, as well as to the presence of some low-boiling esters and alcohols in palm sap and their apparent absence from palm wine.     

STUDY OF GLAZE PENETRATION AND ITS EFFECT ON GLAZE FIT: I-III*

A method for determining glaze penetration was developed and the effect of glaze penetration on glaze fit studied. The effects of twenty-four fluxes on penetration of a base glaze into semivitreous, hotel china, terra cotta, cordierite, pyrophyllite, wall tile, and steatite bodies were determined. The result shows that glaze penetration affects glaze fit and that penetration varies greatly, depending on glaze composition and the character of the body.     

Analysis of extractables from one euphorbia

Chemical analyses have been made of the heptane extractable material ofEuphorbia lathyris, a plant which has been proposed as an “energy farm” candidate. The heptane extract is 4–5% of the dry plant weight and has a heat value of ≈18×10³ BTU/Ib. This reduced photosynthetic material consists almost entirely of polycyclic triterpenoids.     

N- Vs. C- Tricyanovinylation of Ring-Substituted Dimethylanilines. The Spectral Properties of the Products.

Methods for changing the selectivity in the N- vs. C- tricyanovinylation are discussed. In acetonitrile, 2,3-, 2,4-, 3,4- and 3, 5-dimethylanilines are N-tricyanovinylated, 2,6-dimethyl- and 2, 6-diethylanilines are p-tricyanovinylated, and 2,5-dimethyl- and 2-ethylaniline give mixtures of N- and p-tricyanovinyl derivatives. The UV, IR, NMR and mass spectra of the products are discussed in relation to the position of the tricyanovinyl group and to electronic and steric effects.     

Neutral lipid transfer protein does not regulate α-tocopherol transfer between human plasma lipoproteins

Vitamin E has no known plasma carrier protein and is transported by plasma lipoproteins. The site of association of vitamin E in the lipoprotein particle and the mode of transfer of vitamin E between plasma lipoproteins have not been ascertained. Since neutral lipids (triglycerides and cholesterol esters) exchange between plasma lipoproteins by processes mediated by neutral lipid transfer protein, we questioned that if vitamin E, a hydrophobic molecule, is carried in the core of the lipoprotein particle then its transfer between plasma lipoproteins may be mediated by neutral lipid transfer protein. Transfer of D-α(5-methyl-³H)tocopherol from in vitro-labeled human plasma lipoprotein fractions to other plasma lipoproteins was measured under incubation conditions that were designed to yield markedly differing degrees of neutral lipid exchange. Despite the presence of the d>1.21 g/ml lipoprotein-poor plasma fraction or purified lipid transfer protein that resulted in up to a 10-fold increase in neutral lipid transfer, vitamin E transfer between very low density lipoproteins, low density and high density lipoproteins remained constant. Even excess amounts of lipid transfer protein, which caused triglyceride transfer between very low density and high density lipoproteins to reach saturation, failed to affect significantly vitamin E transfer. Vitamin E distribution between lipoprotein fractions did correlate with lipoprotein mass ratios. Vitamin E transfer was higher as the protein ratio of acceptor lipoproteins to donor lipoproteins increased. We conclude that vitamin E transfer between lipoproteins is not dependent primarily on neutral lipid transfer protein and is not mediated via neutral lipid transfer.     

Liver and thymus lipid composition in AKR mice with and without lymphomas

Lipid composition of liver and thymus in controls, early stage lymphoma, and advanced stage lymphoma-bearing AKR mice was studied. There was a significant decrease in the liver total lipid content in mice with advanced lymphoma, whereas in the early stages, no quantitative change was seen. In livers of mice with advanced stage lymphoma, there was a significant decrease in the nonpolar fraction. The decrease was in triglyceride, whereas the cholesterol fractions were relatively increased though highly variable. There was an increase in the polar lipid/nonpolar lipid ratio in the advanced lymphoma livers and a very large increase in the polar lipid/triglyceride ratio, indicating that the decrease in total lipid in these livers was largely in the triglyceride fraction. Similar changes were seen in the thymus, in which the lipid composition reflected the transformation from normal to malignant cells.     

Liquid-crystallization induced reactions. Microstructure and morphology of copolyesters synthesized by transesterification of PET with some LCP monomers

The transesterification of poly(ethylene terephthalate) (PET) with a mixture of sebacic acid (S), 4,4′-diacetoxybiphenyl (B) and 4-acetoxybenzoic acid (H), carried out under conditions expectedly favoring the formation of a p(ET-SBH) random copolyester, produces biphasic materials with an isotropic matrix and a highly fibrous, liquid-crystalline dispersed phase. Spectroscopic, calorimetric, microscopic and diffractometric characterization of the fractions separated by solvent extraction has shown that the two phases consist of practically random copolyesters having different average composition. Interestingly, the degree of aromaticity of the matrix is even lower than that of PET, whereas that of the minor phase is appreciably higher than that calculated for the SBH copolyester that would be produced from the monomer mixture in the absence of PET. This unexpected result is interpreted on the basis of an enthalpy-driven progressive diffusion of aromatic-rich material toward the mesophase which segregates at an early stage of the polycondensation within the isotropic mixture of low molar mass oligomers initially produced by the PET acidolysis. Thus, an increasing differentiation, rather than an equilibration, of the composition of the two phases takes place. It is noteworthy that, despite the strong compositional difference, the two phases of these products show fairly good compatibility and interfacial adhesion.