The aim of this study was to evaluate the production of the vasoactive amines, histamine and tyramine, and of other biogenic amines (putrescine, cadaverine, spermidine, and spermine) during the ripening of pecorino Carmasciano cheese, a traditional Italian cheese produced with raw sheep milk. Vasoactive amines, which may pose health risks for consumers, showed relatively low levels near the end of Carmasciano ripening (136.41 mg/kg tyramine and 65.5 mg/kg histamine). The other biogenic amines were also detected and showed increasing levels with time. Results demonstrated that the concentrations of the vasoactive amines were always below the limits established for other foods. However, the data concerning raw materials and the increasing trend of certain biogenic amines highlight the need to control indigenous bacterial populations responsible for amine production, including the implementation of Good Manufacturing Practices and adequate training of staff.
Typhoid
fever is a major cause of morbidity and mortality in developing
countries. Vaccines based on the Vi capsular polysaccharide are licensed
or in development against typhoid fever. Vi content is a critical
quality attribute for vaccines release, to monitor their stability
and to ensure appropriate immune response. Vi polysaccharide is a
homopolymer of α-1,4-N-acetylgalactosaminouronic
acid, O-acetylated at the C-3 position, resistant to the commonly
used acid hydrolysis for sugar chain depolymerization before monomer
quantification. We previously developed a quantification method based
on strong alkaline hydrolysis followed by High Performance Anion Exchange
Chromatography-Pulsed Amperometric Detection analysis, but with low
sensitivity and use for quantification of an unknown product coming
from polysaccharide depolymerization. Here we describe the development
of a method for Vi polysaccharide quantification based on acid hydrolysis
with concomitant use of trifluoroacetic and hydrochloric acids. A
Design of Experiment approach was used for the identification of the
optimal hydrolysis conditions. The method is 100-fold more sensitive
than the previous one, and specifically, resulting in the formation
of a known product, confirmed to be the Vi monomer both de-O- and
de-N-acetylated by mono- and bidimensional Nuclear Magnetic Resonance
spectroscopy and mass spectrometry. Accuracy and precision were determined,
and chromatographic conditions were improved to result in reduced
time of analysis. This method will facilitate characterization of
Vi-based vaccines. Furthermore, a similar approach has the potential
to be extended to other polysaccharides containing 2-amino uronic
acids, as already verified here for Shigella sonnei O-antigen, Streptococcus pneumoniae serotype 12F,
and Staphylococcus aureus types 5 and 8 capsular
polysaccharides.
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