Biogenic amines (BAs) represent a considerable toxicological risk in some food products. Putrescine is one of the most common BAs in food. Its increased occurrence in food may lead to alimentary poisoning, due to enhancement of the toxic effects of other BAs, and also to lower quality of food, this amine is potentially carcinogenic. Increased occurrence of putrescine in food is mainly due to the bacterial metabolism of the Gram-negative as well as Gram-positive bacteria present. The bacterial metabolism of putrescine is very specific due to its complexity (in comparison with the metabolism of other BAs). There are 3 distinct known pathways leading toward the formation of putrescine, in some splices involving up to 6 different enzymes. The existence of more metabolic pathways and the possibility of their simultaneous use by different bacteria complicate the specification of the best conditions for food production and storage, which could lead to a lower content of putrescine. This review provides a summary of the existing knowledge about putrescine production and detection (mainly detection of specific genes for different enzymes using polymerase chain reaction) in both starter and contaminating microorganisms. Thus, this comprehensive review gives a useful overview for further research.

The formulation, characterization, and anticipated antibacterial properties of hemp seed oil and its emulsions were investigated. The oil obtained from the seeds of Cannabis sativa L. in refined and unrefined form was characterized using iodine, saponification, acid values, and gas chromatography, and was employed for the preparation of stable oil-in-water emulsions. The emulsions were prepared using pairs of non-ionic surfactants (Tween, Span). The effects of the emulsification method (spontaneous emulsification vs. high-intensity stirring), hydrophilic lipophilic balance (HLB), type and concentration of surfactant, and oil type on the size and distribution of the emulsion particles were investigated. It was found that the ability to form stable emulsions with small, initial particle sizes is primarily dependent on the given method of preparation and the HLB value. The most efficient method of emulsification that afforded the best emulsions with the smallest particles (151 ± 1 nm) comprised the high-energy method, and emulsions stable over the long-term were observed at HBL 9 with 10 wt % concentration of surfactants. Under high-intensity emulsification, refined and unrefined oils performed similarly. The oils as well as their emulsions were tested against the growth of selected bacteria using the disk diffusion and broth microdilution methods. The antibacterial effect of hemp seed oil was documented against Micrococcus luteus and Staphylococcus aureus subsp. aureus. The formulated emulsions did not exhibit the antibacterial activity that had been anticipated.

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The aim was to monitor production of eight biogenic amines (BAs) (histamine, tyramine (TYR), tryptamine, putrescine, cadaverine (CAD), phenylethylamine, spermine and spermidine) by selected 81 lactic acid bacteria (LAB) strains: Lactobacillus, Lactococcus, Leuconostoc, Enterococcus, Pediococcus, Tetragenococcus and Bifidobacterium. The tested LAB and bifidobacteria were isolated from dairy products and beer. The decarboxylase activity of the micro-organisms was studied in growth medium after cultivation. The activity was monitored by HPLC after the pre-column derivatisation with dansylchloride. Fifty LAB showed decarboxylase activity. Thirty-one strains produced low concentrations of CAD (£10 mg L )1 ). Almost 70% of beer isolates generated higher amounts of TYR (£3000 mg L )1 ). Most of the tested LAB demonstrated decarboxylase activity. The above micro-organisms can contribute to the increase of content of BAs in dairy products or beer and thereby threaten food safety and health of consumers. Production of BAs even by the representatives of some probiotic strains (Bifidobacterium and Lactobacillus rhamnosus) was detected in this research. This study has also proved that contaminating LAB can act as sources of higher amounts of CAD and TYR in beer.

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