Histamine poisoning is a significant public health and safety concern. Intoxication from ingestion of food containing high amounts of histamine may cause mild or severe symptoms that can even culminate in cardiac arrest. Nonetheless, although histamine levels in dairy products are not subject to any regulation, important outbreaks and severe adverse health effects have been reported due to intake of dairy products with a high histamine content, especially ripened cheeses. Histamine, a biogenic amine, can accumulate in dairy products as a result of the metabolism of starter and nonstarter lactic acid bacteria, as well as yeasts that contribute to the ripening or flavoring of the final product, or even as a result of spoilage bacteria. The aim of this review is to describe the microbiological causes of the presence of histamine in fermented milk products, and to propose control measures and potential methods for obtaining histamine‐free dairy products. Thus, this manuscript focuses on histamine‐producing microbiota in dairy products, highlighting the detection of histamine‐producing bacteria through traditional and novel techniques. In addition, this review aims to explore control measures to prevent the access of histamine‐producing microbiota to raw materials, as well as the formation of histamine in dairy products, such as a careful selection of starter cultures lacking the ability to produce histamine, or even the implementation of effective food processing technologies to reduce histamine‐producing microbiota. Finally, the removal of histamine already formed in dairy products through histamine‐degrading microorganisms or by enzymatic degradation will also be explored.
Three different procedures for the quantitative assessment of free and metal complexed volatile sulfur compounds (VSCs) and for the determination of truly free SO2 have been developed, taking advantage of a GC-sulfur chemiluminescent detector system (GC-SCD) with cryotrapping. The inertness of the inlet systems, together with the column used (SPB-1 sulfur) makes it possible to obtain a non-saturated perfectly Gaussian peak for SO2, well resolved from H2S. In the main procedure, the injection of 1 mL of the headspace of a sample prepared in complete anoxia and equilibrated at 30°C makes it possible to get highly sensitive signals for all VSCs and free SO2. Detection limits are 3, 35 and 60 ng/L for H2S, MeSH and EtSH, 13 g/L for truly free SO2 (at pH=3.4, or 0.46 g/L for molecular SO2), and better than 1 g/L for other relevant sulfur volatiles. Method precision is also satisfactory and linearity covers the whole range of occurrence of these compounds. A second procedure, not making use of the cryotrapping unit, gives also satisfactory results, although with higher detection limits (0.03, 0.25 and 0.37 µg/L for free H2S, MeSH and EtSH, respectively). For the analysis of free plus metal-complexed forms, it has been demonstrated that the headspace injection of the vapors on a 1:10 brine dilution of the sample heated at 70°C for 25 min, gives good estimates of the free + metal-complexed forms of H2S and wine mercaptans.
The
aim of this work was to study the physicochemical changes of
eight red wines stored under conditions differing in O2 exposure and temperature and time under anoxia. The methods used
to analyze the wines included the measurement of volatile sulfur compounds,
color, tannin (T) polymerization, and liquid chromatography–mass
spectrometry untargeted metabolomic fingerprint. After 3 months, the
color of the oxidized samples evolved 4–5 times more intensively
than in wines stored under anoxia. The major metabolomic differences
between oxidative and anoxic conditions were linked to reactions of
acetaldehyde (favored in oxidative) and SO2 (favored in
anoxia). In the presence of oxygen, the C-4 carbocation of flavanols
delivered ethyl-linked tannin–anthocyanin (T–A) and
tannin–tannin (T–T) adducts, pyranoanthocyanins, and
sulfonated indoles, while under reduction, the C-4 carbocation delivered
direct linked T–A adducts, rearranged T–T adducts, and
sulfonated tannins. Some of these last reactions could be related
to the accumulation of reduced species, eventually ending with reductive
off-odors.
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