Physico-chemical changes during storage and sensory acceptance of low sodium probiotic Minas cheese added with arginine.

The partial substitution of sodium chloride by potassium chloride (0%, 25%, and 50%) and addition of arginine (1% w/w) in probiotic Minas cheese was investigated. Microbiological (Lactococcus lactis and Lactobacillus acidophilus counts, and functionality of the prebiotics L. acidophilus), physicochemical (pH, proteolysis, organic acids, fatty acids, and volatile profiles), rheological (uniaxial compression) and sensory (hedonic test with 100 consumers) characterizations were carried out. The sodium reduction and addition of arginine did not constitute a hurdle to lactic and probiotic bacteria survival, with presented values of about 9 log CFU/g, ranging from 7.11 to 9.21 log CFU/g, respectively. In addition, lower pH values, higher proteolysis, and a decrease in toughness, elasticity and firmness were observed, as well as an increase in lactic, citric, and acetic acid contents. In contrast, no change was observed in the fatty acid profile. With respect to the sensory acceptance, the probiotic low-sodium Minas cheese presented scores above 6.00 (liked slightly) for the attributes flavor and overall acceptance. The addition of arginine can be a potential alternative for the development of probiotic dairy products with reduced sodium content.

Analysis of sibutramine metabolites as N-trifluoroacetamide and O-trimethylsilyl derivatives by gas chromatography-mass spectrometry in urine.

A method for identifying the metabolites of sibutramine 1-(4(chlorophenyl)-N,N-dimethyl-alpha-(2-methylpropyl))cyclobutanemethanamine) in urine, utilizing a double derivatization strategy, with N-methyl-N-(trimethylsilyl)-trifluoroacetamide and N-methyl-bis-(trifluoroacetamide), in gas chromatography/mass spectrometry is proposed. This methodology results in mass spectra with at least three fragments in abundance superior to 20%, attending the World Anti-Doping Agency identification criteria for qualitative assays. The characterization of the derivatives was obtained through two ionization modes: Chemical Ionization and Electron Impact ionization, both in full scan mode. Sibutramine was administered to 5 (five) volunteers and the excretion profile followed for 92h. Routine analytical, hydroxy-cyclobutane-bis-nor-sibutramine which becomes the more abundant metabolite in the first 10h and hydroxy-isopropyl-bis-nor-sibutramine which becomes the most abundant after 40h, were proposed for doping monitoring.