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This study aimed to design high-quality and safe spreadable processed cheese with a prolonged shelf life appropriate for logistic support in emergency/crisis situations, foreign missions, and/or state material reserves. Samples with dry matter content (DM) of 30–55 g/100 g and fat in dry matter content (FDM) of 30–50 g/100 g were produced, hermetically sealed and sterilised at 120 °C for 40 min. The microbiological, chemical, textural, viscoelastic, and organoleptic parameters of unsterilised and sterilised processed cheese were compared. The effect of the products' dry matter and fat content on the sterilised samples' properties was also evaluated. The sterilisation regime applied was sufficient to ensure the microbiological safety of processed cheese. A significant decrease in pH values and increased rate of the complex of Maillard reactions and lipid oxidation processes (P > 0.05) was detected due to sterilisation. These processes were more intense with increasing dry matter and fat content (P > 0.05). A deterioration in the appearance, colour, and aroma of processed cheese and an increase in the firmness of the products (P > 0.05) were also observed as a result of sterilisation. For the quality and safety of sterilised processed cheese, combinations of 40 g/100 g DM and 50 g/100 g FDM were recommended for spreadable products. • Non-sterilised and sterilised processed cheeses were produced. • Sterilisation at 120 °C for 40 min was sufficient to ensure food safety. • Sterilisation process induced increased Maillard reactions intensity. • Sterilisation process increased the hardness of processed cheeses. • Optimal combination of dry matter and fat content was recommended. [ABSTRACT FROM AUTHOR]

The aim of the study was to compare nutritional parameters (contents of fat, protein and the individual amino acids), biogenic amines (histamine, tyramine, phenylethylamine, tryptamine, putrescine, cadaverine, spermidine and spermine) content, selected functional properties (colour and textural properties) and pH values of six parts of crocodile carcass (tail dorsal – TD, tail ventral – TV, neck – N, shoulder – S, leg – L and cheek – C). The individual parts of the crocodile carcass showed different values of nutritional parameters. TD and C had the highest values of Essential Amino Acid Index (104–126). Valine, threonine and leucine were determined as limiting amino acids in individual parts of the crocodile carcass. The content of biogenic amines was very low. These results will provide crocodile meat producers as well as consumers with new and useful information about the nutritional value of this meat and its relevance for nutrition. [ABSTRACT FROM AUTHOR]

Ternary mixtures consisting of phosphate and citrate emulsifying salts were studied for their impact on selected textural properties (especially hardness) of processed cheese spreads over a 30 day storage period at 6 ± 2 °C. Two different groups of samples were manufactured, one with pH adjustment (target values within the interval of 5.60–5.80) and one without pH adjustment. When binary mixtures with trisodium citrate (TSC) and tetrasodium diphosphate (TSPP) were used (with zero content of the other salts tested in the ternary mixture), the products consisting of TSC and TSPP at a ratio of approximately 1:1 were the hardest. Increasing the content of TSC, TSPP and/or sodium salt of polyphosphate and decreasing that of disodium hydrogen phosphate (DSP) in ternary mixtures resulted in the increasing of the hardness of processed cheese. The absolute values of processed cheese hardness significantly changed as a result of pH adjustment. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this work was to compare selected properties (hardness, cohesiveness, adhesiveness, characteristics of fat globules, pH, meltability and sensory characteristics – homogeneity, rigidity and flavour) of processed cheeses (dry matter content 40 g/100 g; fat in dry matter content 50 g/100 g) made with traditional emulsifying salts (sodium salts of phosphates) and products in which the traditional emulsifying salts were replaced with 1 g/100 g κ-carrageenan. The development of the above-mentioned properties was studied in dependence on the maturity level of cheese (raw material; 1–16 weeks' maturity). The samples made without the use of traditional emulsifying salts were nearly five times as hard as the products with phosphates regardless of the maturity level of cheese. In both types of samples, hardness was decreasing and adhesiveness was rising with the increasing maturity level of cheese. Meltability of the samples without traditional emulsifying salts was very low and remained practically unchanged with the increasing maturity level of cheese. On the other hand, in the processed cheeses with phosphates, meltability was increasing with the rising maturity level of cheese. [Copyright &y& Elsevier]

The aim of the presented study was to evaluate the microbiological, chemical, physical and organoleptic properties of sugar-based foods (apricot-apple jam, flower meadow honey, sweetened hazelnut cocoa spread) stored at four different temperatures (−18, 5, 23 and 40 °C) for a period of 24 months. In addition, critical combinations of storage temperature and time were determined for maintaining food quality and food safety. Storage of all samples ≤23 °C appeared to be safe from a microbiology perspective, while in the case of storage at 40 °C it was not recommended to exceed a storage period of 6 or 12 months. The pH-values decreased and the dry matter, ammonia, TBARS content increased most intensively during the first 6 months of storage (P < 0.05). The amino acid content of sweetened hazelnut cocoa spread decreased significantly at 40 °C (P < 0.05). With the prolonged storage time, the organoleptic properties of the samples deteriorated. The changes were more intensive when an elevated storage temperature was used (P < 0.05). Moreover, under the above-mentioned conditions a marginal decrease of the total saccharide content in all samples was observed. In addition, the apparent viscosity of the honey and the firmness of the jam increased significantly at elevated temperatures of 40 °C (P < 0.05). • Quality of sugar-based foods was monitored during a storage period of 24 months. • The pH-values decreased and the dry matter, ammonia, TBARS content increased. • Decline of the amino acid content of sweetened hazelnut cocoa spread was observed. • The organoleptic properties deteriorated especially at elevated storage temperature. • Increase of the apparent viscosity (honey) and the firmness (jam) was detected. [ABSTRACT FROM AUTHOR]

The aim of the study was to reduce the concentration of biogenic amines (BAs) in Dutch-type cheese by the activity of the added culture. The reduction of BAs was caused by the use of the selected strains of Lacticaseibacillus casei and Lactiplantibacillus plantarum over a three-month period (at 12 ± 1 °C). The results indicated that the use of different microbiological strains does not have a significant influence on the basic chemical parameters of the model cheese samples. The lowest BA concentrations were determined in model cheese with Lacticaseibacillus casei CCDM 198. These samples contained fewer total BA content than the control samples: after 28 days of ripening by 32%, after 56 days by 37% and after 84 days by 32%. The adjunct culture demonstrated high efficacy of reduction of putrescine, phenylethylamine and tyramine in real conditions of the model Dutch-type cheese samples. • Dutch type cheese samples were produced with different adjunct culture. • The applied strains did not have an effect on the basic chemical parameters. • Differences between batches in concentration of free amino acids were observed. • The most effective BA reduction was caused by Lacticaseibacillus casei CCDM 198. • Reduction of phenylethylamine, putrescine and tyramine was demonstrated in cheese. [ABSTRACT FROM AUTHOR]

Tyramine is one of the most toxic biogenic amines and it is produced commonly by lactic acid bacteria in fermented food products. In present study, we investigated the influence of selected nisin-producing Lactococcus lactis subsp. lactis strains and their cell-free supernatants (CFSs) on tyramine production by four Lactobacillus and two Lactiplantibacillus strains isolated from cheese and beer. Firstly, we examined the antimicrobial effect of the CFSs from twelve Lactococcus strains against tested tyramine producers by agar-well diffusion assay. Six Lactococcus strains whose CFSs showed the highest antimicrobial effect on tyramine producers were further studied. Secondly, we investigated the influence of the selected six Lactococcus strains and their respective CFSs on tyramine production by tested Lactobacillus and Lactiplantibacillus strains in MRS broth supplemented with 2 g.L−1 of l -tyrosine. Tyramine production was monitored by HPLC-UV. The tyramine formation of all tested Lactobacillus and Lactiplantibacillus strains was not detected in the presence of Lc. lactis subsp. lactis CCDM 71 and CCDM 702, and their CFSs. Moreover, the remainder of the investigated Lactococcus strains (CCDM 670, CCDM 686, CCDM 689 and CCDM 731) and their CFSs decreased tyramine production significantly (P < 0.05) – even suppressing it completely in some cases – in four of the six tested tyramine producing strains. • Effect of nisin-producing lactococci and their CFSs on tyramine production was studied. • Tyramine production could be reduced by the presence of nisin-producing lactococci and their CFSs. • The level of tyramine reduction differed between tyramine producers. • Nisin-producing lactococci and their CFSs could enhance safety of fermented food. [ABSTRACT FROM AUTHOR]

The microbiological, chemical, physical and organoleptic changes of white brined cheese stored under four different temperatures (−18; +6; +22 and + 40 °C) for a period of 6 months were evaluated. The samples were stable from microbiological point of view when stored up to +22 °C. The growth of microorganisms was significant after 1-month storage at +40 °C (P < 0.05). The dry matter, fat and protein contents increased and the pH-values decreased during 6-months storage (P < 0.05) and the rate was affected by the temperature used (P < 0.05). The ammonia content, TBARS-value (a marker of oxidation stability) and free amino acid content of white brined cheese significantly increased due to the prolonging of the storage time (P < 0.05) and elevating temperature (P < 0.05). The corrected stress and elongational viscosity increased (P < 0.05) with the extended storage time and higher temperature. [ABSTRACT FROM AUTHOR]

The aim of the work was to compare κ-carrageenan and ι-carrageenan (in concentrations 0.025–0.150 g/100 g) application to cream desserts (dry matter content 44 g/100 g and fat content 38.5 g/100 g) and evaluate their viscoelastic properties and sensory quality. Sample properties were monitored during 28 d (6 ± 2 °C). During storage a slight decrease in the pH of the samples was monitored. Furthermore, the increasing addition of κ- and ι-carrageenan resulted in complex modulus (G*) and gel strength (A F) values increase (P < 0.05). In all samples, regardless of the type and concentration of carrageenan, a significant increase in the values of firmness was observed during storage. In general, the G* and A F were higher in the samples with κ-carrageenan compared to products to which ι-carrageenan was applied (P < 0.05). Moreover, all samples were characterised as homogenous and no water release and no off-flavour (P ≥ 0.05) were detected. The suggested concentration of both tested carrageenans in order to obtain products with desired properties lies in the range of 0.050–0.125 g/100 g. • Kappa-carrageenan was evaluated as a more effective thickening agent. • Significant increase in the firmness of cream desserts was observed during 28 d of storage. • Firmness of cream desserts was higher in products with κ-carrageenan addition. • Iota-carrageenan cream desserts presented a more viscous-like character. • Higher concentration of applied carrageenans resulted in firmer products. [ABSTRACT FROM AUTHOR]

The aim of the study was to investigate the dependence of selected textural, rheological and mechanical vibration damping properties of restructured chicken breast ham (RCBH) on the concentration of furcellaran (FRC1 or FRC2) or κ-carrageenan (KC) during a 14-days storage period (at 4 ± 2 °C). The above-mentioned polysaccharides were used in concentrations of 0.25 g/100 g, 0.50 g/100 g, 0.75 g/100 g and 1.00 g/100 g. Control sample (CS) without any polysaccharide addition was also produced. The textural, rheological and mechanical vibration damping properties of RCBH samples were affected by the type and concentration of the polysaccharide used (p < 0.05) and the storage period (p < 0.05). Samples prepared with KC and FRC1 at a concentration level of 1.00 (g/100 g) presented the highest values of hardness, G′, G″ and G*. Values of G* and δ (in all tested frequency ranges) indicated a solid-like behavior for all the samples over the experimental range. It was found that the first resonance frequency peak position increased with an increase in the RCBH stiffness leading to lower vibration damping properties of the samples (p < 0.05). • Restructured chicken breast hams with κ-carrageenan and furcellaran were developed. • The hardness of the samples increased with the rising level of added polysaccharides. • The use of polysaccharides resulted in higher G* values during the cooling stage. • The samples exhibited a solid-like character over the experiment. • The polysaccharides used influenced samples displacement transmissibility and stiffness. [ABSTRACT FROM AUTHOR]

Spreadable processed cheese (SPC) samples, with 30 and 40% (w/w) dry matter (DM) and 30, 40 and 50% (w/w) fat in dry matter (FDM), were produced with nine individual melt holding times (between 0 and 10 min) and stored for 30 days. Milk fat droplet size and viscoelastic properties were determined. In general, longer holding times resulted in decreased diameter of the milk fat droplets in all tested SPC samples. Furthermore, the size of the milk fat droplets decreased with increasing DM content and decreasing FDM content. Furthermore, for most of the produced SPCs, with the progress of the storage time, the G∗ values decreased over the first 2 or 3 min (of the applied holding time). In addition, prolonging the holding time and storage period resulted in an increase of the samples G∗ values. Increased DM content and decreased FDM content in SPC samples resulted in increased G∗ values. [ABSTRACT FROM AUTHOR]

This study focussed on the dependence on different emulsifying salt ternary mixture composition [disodium hydrogenphosphate (DSP), tetrasodium diphosphate (TSPP), sodium salt of polyphosphate (P20; number of phosphate units in the chain ≈20), trisodium citrate (TSC)] of hardness and gel strength of spreadable processed cheese (PC) manufactured from Cheddar and white brined cheeses. All PC samples were stored for 60 days (6 ± 2 °C). The hardest PC and samples with the highest gel strength were those produced from DSP and TSPP in a ratio 1:1. The hardness of all examined samples increased with the extending storage period, whilst their hardness and gel strength decreased with the rising maturity degree of the raw material utilised. Furthermore, higher values of gel strength were reported for the PC samples produced with Cheddar cheese in comparison with those made from white brined cheese. [ABSTRACT FROM AUTHOR]

The objective of the current study was the evaluation of 8 biogenic amines (BA) occurrence in beer samples (115 samples in total) manufactured in microbreweries of the Central Europe region in relation to the progress of the storage period (at 20 ± 2 °C). The examined beer samples were divided into 3 main groups according to their extract of original wort value (EOW): (i) Light craft beer (EOW ≤ 10; 12 samples in total), (ii) Lager craft beer (11 ≤ EOW ≤ 12; 65 samples in total), (iii) Special craft beer (EOW ≤ 13; 38 samples in total). The tested craft beer samples were analyzed immediately after purchase and at the end of the best before date. Furthermore, the most frequently detected BA was tyramine. In addition, other abundant monitored BA were putrescine and cadaverine. Moreover, concentrations of histamine above 20 mg/l were detected in lager craft beer and special craft beer samples (at the end of the best before date). On the whole, with the progress of the storage time the BA concentration increased. Thereafter, more than 30% of the tested samples presented total BA content in the range of 50–100 mg/l. However, 18% of the examined craft beer samples had a total amount of BA higher than 100 mg/l. • Biogenic amine occurrence in Czech craft beers was monitored. • With the progress of the storage the biogenic amine content increased. • The most frequently detected biogenic amine was tyramine. • 18% of the beers presented biogenic amine values higher than 100 mg/l. [ABSTRACT FROM AUTHOR]

The scope of the study was the evaluation of Chios mastic gum (CMG) addition (0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45 and 0.50%, w/w) on the rheological, textural and meltability properties of spread-type processed cheese (PC; with 40%, w/w, dry matter and 50%, w/w, fat in dry matter) during a 60-day storage period (at 6 ± 2 °C). The hardness of the evaluated PC samples was affected by the amount of CMG applied and by the storage period. Hence, from a concentration 0.05% (w/w) of CMG up to 0.20% (w/w) the hardness of the samples decreased, followed by an increase (up to 0.40%, w/w) and a rapid decrease in hardness was again recorded. With the prolonging of the storage period the hardness of all samples increased. Furthermore, the results obtained by the rheological analysis and meltability were analogous to those of hardness analysis. [ABSTRACT FROM AUTHOR]

The aim of the study is to model concentrations of selected biogenic amines in various fish species (Atlantic salmon, Atlantic cod, striped catfish) bought in retail stores in Central Europe. Since the data contains non-detectable values, statistical methods for left-censored values from the exponential and Weibull distributions are applied and used to evaluate and compare the amount of biogenic amines in fish samples. Moreover, a risk of exceeding certain limits of biogenic amine concentrations to protect human health is determined. There are relatively high concentrations of putrescine, cadaverine and histamine in almost all fish species. Moreover, there was a significant difference in mean concentrations (distributions of concentrations, respectively) of histamine, tyramine and spermidine among the species. • Use of censored distributions for modelling data with non-detectable values. • High concentrations of putrescine, cadaverine and histamine in almost all species. • Significant difference in concentrations of histamine, tyramine and spermidine. • High probabilities of exceeding specified limit values of putrescine concentration. [ABSTRACT FROM AUTHOR]

The scope of the study was the evaluation of selected physicochemical parameters and organoleptic properties of Czech-type lager beer [11.00% (w/w) original wort extract; 4.60% (v/v) ethyl alcohol content] during a 12-month storage period (25 ± 2 °C), in relation to the applied type of packaging [glass bottle, aluminum can, polyethylene terephthalate (PET) bottle and stainless steel beer keg]. The examined beer samples organoleptic characteristics were off-flavors, carbonation level, fullness, bitterness intensity and overall rating. Furthermore, the examined physicochemical parameters during storage were CO 2 concentration, color, turbidity (haze) and foaming stability. Generally, the type of packaging significantly influenced the physicochemical and organoleptic properties of the examined samples (P < 0.05). The more intensive changes were observed in the CO 2 content, color and turbidity of the examined samples. The aluminum can and stainless steel keg were evaluated as the most suitable types of packaging for beer storage. On the contrary, the PET bottle was evaluated as the least appropriate for long-term storage period. • Czech-type lager beer was evaluated during a 12-month storage period. • Four types of beer packaging were examined. • The best packaging type were the aluminum can and the stainless steel keg. • PET bottle was evaluated as the least appropriate for long term storage of beer. [ABSTRACT FROM AUTHOR]

The novelty of this study is the investigation of the effect of different heat treatments and, simultaneously, the effect of different fat levels on the quality of pork liver pâtés. Hence, this study aimed to evaluate the effect of heat treatment and fat content on selected properties of pork liver pâté. For this purpose, four batches of pâtés with two different fat contents (30 and 40% ( w / w )) and two different heat treatments (pasteurisation: target temperature 70 °C, holding time of 10 min; sterilisation: target temperature 122 °C, holding time of 10 min) were manufactured. Chemical (pH, dry matter, crude protein, total lipid, ammonia, and thiobarbituric acid reactive substances (TBARS)), microbiological, colour, textural, rheological, and sensory analyses were performed. Both different heat treatment and fat content affected most of the parameters observed. Sterilisation ensured the commercial sterility of the manufactured pâtés, resulting in elevated TBARS values, hardness, cohesiveness, gumminess and springiness, and increased rheological parameters (G', G″, G*, and η*), as well as colour changes (decrease in L* and increase in a*, b*, and C* values) and deterioration of appearance, consistency, and flavour also being detected ( p < 0.05). Higher fat content caused similar variations in the textural and viscoelastic properties, i.e., the increase in hardness, cohesiveness, gumminess and springiness, and also in G', G″, G*, and η* ( p < 0.05). However, the colour and sensorial parameters changed in different ways compared to the changes induced by the sterilisation effect. Overall, the observed changes might not be desirable for some consumers and further research would be appropriate to improve especially the sensorial attributes of sterilised pork liver pâtés.

The decarboxylation of the corresponding amino acids by microorganisms leads to the formation of biogenic amines (BAs). From a toxicological point of view, BAs can cause undesirable physiological effects in sensitive individuals, particularly if their metabolism is blocked or genetically altered. The current study aimed to monitor and evaluate the content of eight biogenic amines (BAs) in 232 samples of wines (white, rosé, red) produced in the Central European region (Zone B). White wines (180 samples), rosé wines (17 samples), and red wines (35 samples) were analyzed. High-performance liquid chromatography equipped with a ultraviolet-visible diode array detector (UV/VIS DAD) was applied to identify and quantify the BAs present in wines. In general, histamine (HIS), tyramine (TYM), putrescine (PUT), cadaverine (CAD), phenylethylamine (PEA), spermine (SPN) and spermidine (SPD) were detected in all tested wine samples. Tryptamine (TRM) was not present in any of the samples examined. In white and red wines, SPD, TYM, and PUT were most often detected. Regarding rosé wines, the three major BAs were SPN, TYM, and CAD. The BA content in red wines was generally higher than in rosé and white wines. However, HIS concentrations above the recommended limit of 10 mg/L were detected in 9% of the red wine samples. In addition, alarming levels of PUT, HIS, TYM, and PEA, with serious potential impact on consumer health, were recorded in two red wine samples. On the whole, the presence and concentrations of BAs in wine should be constantly evaluated, primarily because alcohol intensifies the hazardous effects of BAs.

Modern food technology research has researched possible approaches to reducing the concentration of biogenic amines in food and thereby enhance and guarantee food safety. Applying adjunct cultures that can metabolise biogenic amines is a potential approach to reach the latter mentioned goal. Therefore, this study aims to study the crucial factors that could determine the decrease in biogenic amines concentration (histamine, tyramine, phenylethylamine, putrescine and cadaverine) in foodstuffs using Bacillus subtilis DEPE IB1 isolated from gouda-type cheese. The combined effects of cultivation temperature (8 °C, 23 °C and 30 °C) and the initial pH of the medium (5.0, 6.0, 7.0 and 8.0) under aerobic and also anaerobic conditions resulted in the decrease of the tested biogenic amines concentration during the cultivation time (another factor tested). Bacillus subtilis was cultivated (in vitro) in a medium supplemented with biogenic amines, and their degradation was detected using the high-performance liquid chromatography equipped with UV-detector. The course of biogenic amines degradation by Bacillus subtilis DEPE IB1 was significantly influenced by cultivation temperature and also the initial pH of the medium ( p < 0.05). At the end of the cultivation, the concentration of all of the monitored biogenic amines was significantly reduced by 65-85% ( p < 0.05). Therefore, this strain could be used for preventive purposes and contributes to food safety enhance.

The scope of the study was the evaluation of the selected physicochemical (O 2 and CO 2 contents, bitterness, color, total polyphenol content (TPC), turbidity, foaming stability) and sensory properties of Czech lager beer with different original wort extract (OWE) values (OWE of 10.0; 11.0; 11.5; 12.0% w / w ) during a cold storage period of 6 months (4 ± 2 °C). The length of the cold storage period did not influence the values of dissolved O 2 and CO 2 , bitterness, color and foam stability of the samples. Contrarily, the TPC, turbidity, and sensory attributes of the samples were affected by the course of cold storage. The OWE values did not affect the development of the parameters tested. All beer samples stored until the 5th month presented "very good" sensory characteristics. Cold storage of beer is advantageous in order to maintain its freshness and sensory attributes at the highest level for the final consumer.

This study reports the development of selected indicators affecting changes in food quality and safety of selected long-life canned (Szeged goulash, canned chicken meat, pork pâté, canned tuna fish) and dehydrated (instant goulash soup) food during a two-year storage experiment at four different temperatures. The storage temperatures were selected to represent Arctic (−18 °C), temperate (5 °C), subtropical (25 °C) and tropical (40 °C) climatic zones where such food is likely to be stored during, for example, humanitarian and military missions. Microorganism amounts below the detection limit (p < 0.05), regardless of the storage temperature (p ≥ 0.05), were monitored in canned samples. The contents of dry matter, fat and proteins did not change during storage, regardless of the storage temperature (p ≥ 0.05). During the 24-month storage, all food showed an increase in the level of ammonia (p < 0.05) and the TBARS-value (p < 0.05), whereas the rate of increase in both parameters was significantly higher at higher storage temperatures (p < 0.05). The losses of individual amino acids during storage ranged from 5% rel. calculated on the amino acid contents in Month “0” up to 15% rel. (p < 0.05). With storage temperatures above the freezing point, the hardness values decreased with the increase in the storage temperature (p < 0.05) and prolongation of the storage period (p < 0.05). Moreover, with temperatures of −18 °C, the development of hardness, measured as the “decrease rate”, was significantly higher compared to the absolute values.

Degradation of undesirable biogenic amines (BAs) in foodstuffs by microorganisms is considered one of the most effective ways of eliminating their toxicity. In this study, we design two sets of primers for the detection and quantification of the amine oxidase gene ( yobN ) and endogenous (housekeeping) gene ( gyrB ) in Bacillus subtilis. Moreover, these sets can be used for relative quantification of yobN by real-time PCR (qPCR). We also tested the degradation of BAs by three bacterial strains ( B. subtilis strains: IB1a, CCM 2216, CCM 2267) in a mineral medium over a two-day period. Their degradation abilities were verified by high performance liquid chromatography with UV detection (HPLC/UV). According to the results, two strains significantly ( P  < 0.05) reduced histamine, tyramine, putrescine, and cadaverine. Moreover, our results indicate that the degradation ability of B. subtilis strains could be limited by sporulation because the gene encoding amine oxidase (yobN) is no longer expressed in the spores., Competing Interests: Conflict of interestThe authors declare no conflict of interest., (© Association of Food Scientists & Technologists (India) 2021.)

Tyramine is one of the most toxic biogenic amines and it is produced commonly by lactic acid bacteria in fermented food products. In present study, we investigated the influence of selected nisin-producing Lactococcus lactis subsp. lactis strains and their cell-free supernatants (CFSs) on tyramine production by four Lactobacillus and two Lactiplantibacillus strains isolated from cheese and beer. Firstly, we examined the antimicrobial effect of the CFSs from twelve Lactococcus strains against tested tyramine producers by agar-well diffusion assay. Six Lactococcus strains whose CFSs showed the highest antimicrobial effect on tyramine producers were further studied. Secondly, we investigated the influence of the selected six Lactococcus strains and their respective CFSs on tyramine production by tested Lactobacillus and Lactiplantibacillus strains in MRS broth supplemented with 2 g.L -1 of l-tyrosine. Tyramine production was monitored by HPLC-UV. The tyramine formation of all tested Lactobacillus and Lactiplantibacillus strains was not detected in the presence of Lc. lactis subsp. lactis CCDM 71 and CCDM 702, and their CFSs. Moreover, the remainder of the investigated Lactococcus strains (CCDM 670, CCDM 686, CCDM 689 and CCDM 731) and their CFSs decreased tyramine production significantly (P < 0.05) - even suppressing it completely in some cases - in four of the six tested tyramine producing strains., (Copyright © 2021. Published by Elsevier Ltd.)

Out of six samples of wastewater produced in the dairy industry, taken in 2017 at various places of dairy operations, 86 bacterial strains showing decarboxylase activity were isolated. From the wastewater samples, the species of genera Staphylococcus, Lactococcus, Enterococcus, Microbacterium, Kocuria, Acinetobacter, Pseudomonas, Aeromonas, Klebsiella and Enterobacter were identified by the MALDI-TOF MS and biochemical methods. The in vitro produced quantity of eight biogenic amines (BAs) was detected by the HPLC/UV-Vis method. All the isolated bacteria were able to produce four to eight BAs. Tyramine, putrescine and cadaverine belonged to the most frequently produced BAs. Of the isolated bacteria, 41% were able to produce BAs in amounts >100 mg L -1 . Therefore, wastewater embodies a potential vector of transmission of decarboxylase positive microorganisms, which should be taken into consideration in hazard analyses within foodstuff safety control. The parameters of this wastewater (contents of nitrites, nitrates, phosphates, and proteins) were also monitored.

Degradation of undesirable biogenic amines (BAs) in foodstuffs by microorganisms is considered one of the most effective ways of eliminating their toxicity. In this study, we designed two sets of primers for the detection and quantification of the multicopper oxidase gene (MCO), which encodes an enzyme involved in BAs degradation, and endogenous (glyceraldehyde-3-phosphate dehydrogenase) gene (GAPDH) in Lactobacillus casei group by real-time PCR (qPCR). We tested 15 Lactobacillus strains in the screening assays (thus, MCO gene possessing assay (PCR) and monitoring of BAs degradation by HPLC-UV), in which Lactobacillus casei CCDM 198 exhibited the best degradation abilities. For this strain, we monitored the expression of the target gene (MCO) in time (qPCR), the effect of redox treatments (cysteine, ascorbic acid) on the expression of the gene, and the ability to degrade BAs not only in a modified MRS medium (MRS/2) but also in a real food sample (milk). Moreover, decarboxylase activity (ability to form BAs) of this strain was excluded. According to the results, CCDM 198 significantly (P < 0.05) reduced BAs (putrescine, histamine, tyramine, cadaverine), up to 25% decline in 48 h. The highest level of relative expression of MCO (5.21 ± 0.14) was achieved in MRS/2 media with cysteine., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The aim of the study is to model concentrations of selected biogenic amines in various fish species (Atlantic salmon, Atlantic cod, striped catfish) bought in retail stores in Central Europe. Since the data contains non-detectable values, statistical methods for left-censored values from the exponential and Weibull distributions are applied and used to evaluate and compare the amount of biogenic amines in fish samples. Moreover, a risk of exceeding certain limits of biogenic amine concentrations to protect human health is determined. There are relatively high concentrations of putrescine, cadaverine and histamine in almost all fish species. Moreover, there was a significant difference in mean concentrations (distributions of concentrations, respectively) of histamine, tyramine and spermidine among the species., Competing Interests: Declaration of competing interest All authors declare that they have no conflict of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The aim of this work was to add various amounts of rework (0.0 to 20.0% wt/wt) to processed cheeses with a dry matter content of 36% (wt/wt) and fat with a dry matter content of 45% (wt/wt). The effect of the rework addition on the viscoelastic properties and microstructure of the processed cheeses was observed. The addition of rework (in this case, to processed cheese with a spreadable consistency) in the amounts of 2.5, 5.0, and 10.0% (wt/wt) increased the firmness of the processed cheese. With the further addition of rework, the consistency of the processed cheeses no longer differed significantly. The conclusions obtained by the measurement of viscoelastic properties were supported by cryo-scanning electron microscopy, where fat droplets in samples with added rework of over 10.0% (wt/wt) were smaller than fat droplets in processed cheeses with lower additions of rework., (Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The basic raw materials for the production of processed cheese are natural cheese which is treated by heat with the addition of emulsifying salts. From a point of view of the melting temperatures used (and the pH-value of the product), the course of processed cheese production can be considered "pasteurisation of cheese." During the melting process, the majority of vegetative forms of microorganisms, including bacteria of the family Enterobacteriaceae, are inactivated. The melting temperatures are not sufficient to kill the endospores, which survive the process but are often weakened. From a microbiological point of view, the biggest contamination problem of processed cheese is caused by gram-positive spore-forming rod-shaped bacteria of the genera Bacillus, Geobacillus, and Clostridium. Other factors affecting the shelf-life and quality of processed cheese are mainly the microbiological quality of the raw materials used, strict hygienic conditions during the manufacturing process as well as the type of packaging materials and storage conditions. The quality of processed cheese is not only dependent on the ingredients used but also on other parameters such as the value of water activity of the processed cheese, its pH-value, the presence of salts and emulsifying salts and the amount of fat in the product.

The aim of this work was to examine the effect of a different dry matter (DM) contents (35 and 45% wt/wt) and fat in DM contents (40 and 50% wt/wt) on the textural and viscoelastic properties and microstructure of model processed cheeses made from real ingredients regularly used in the dairy industry. A constant DM content and constant fat in DM content were kept throughout the whole study. Apart from the basic chemical parameters, textural and viscoelastic properties of the model samples were measured and scanning electron microscopy was carried out. With increasing DM content, the rigidity of the products increased and the size of the fat globules in the model samples of the processed cheeses decreased. With increasing fat in DM content, the rigidity of the processed cheeses decreased and the size of the fat globules increased., (Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Background: The present study examined the influence of eight selected strains of Penicillium nalgiovense as secondary culture on the ripening of soft mould cheese. Ion-exchange chromatography, SDS-PAGE and sensory analysis were used for comparison of P. nalgiovense with common secondary mould culture (Penicillium camemberti)., Results: Proteolytic activity was more intensive in the case of the strains of P. nalgiovense in comparison with the control strains of P. camemberti. Some differences in the proportion and amount of free amino acids were observed between the strains of P. nalgiovense during ripening. Lower proteolytic activity of P. nalgiovense was more desirable for sensory properties of cheese, especially in case sample N2., Conclusion: This study provides information on the usability of selected strains of P. nalgiovense that could support the development of sensory properties of mould-ripened soft cheese. The cheese with the culture N2 had the best flavour after 35 days of storage. Moreover, this strain showed the lowest bitterness in comparison with the other used P. nalgiovense cultures. The intensity of bitterness of sample N2 was comparable to that of the control sample with P. camemberti. © 2015 Society of Chemical Industry., (© 2015 Society of Chemical Industry.)

The aim of this study was to compare the biogenic amine production of two starter strains of Lactococcus lactis subsp. cremoris (strains from the Culture Collection of Dairy Microorganisms - CCDM 824 and CCDM 946) with decarboxylase positive activity in a model system of Dutch-type cheese during a 90-day ripening period at 10°C. During ripening, biogenic amine and free amino acid content, microbiological characteristics and proximate chemical properties were observed. By the end of the ripening period, the putrescine content in both samples with the addition of the biogenic amine producing strain almost evened out and the concentration of putrescine was >800mg/kg. The amount of tyramine in the cheeses with the addition of the strain of CCDM 824 approached the limit of 400mg/kg by the end of ripening. In the cheeses with the addition of the strain of CCDM 946 it even exceeded 500mg/kg. In the control samples, the amount of biogenic amines was insignificant., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The aim of this work is to evaluate the effect three different storage temperatures (6, 23 and 40 °C) on the sterilized processed cheese quality during 24-month storage. Sterilized processed cheese (SPC) is a product with extended shelf life (up to 2 years). The samples of SPC were subjected to basic chemical analyses, i.e. pH-values, dry matter, fat, crude protein and ammonia content, and microbiological analyses, i.e. total number of microorganisms, number of coliforms, colony forming units of yeasts and/or moulds and spore-forming microorganisms. Furthermore, amino acid content (ion-exchange chromatography), protein profile (SDS-PAGE) and fat globules size (image analysis of microscopic technique) were monitored and sensory analysis (scale test and pair comparative test) was implemented, too. Increasing storage temperature and length evoked decrease of total amino acid content and protein nutrition value, increase of ammonia amount, protein changes, enlargement of fat globule size and deterioration of sensory properties of SPC. All the changes grew expressive with increasing storage temperature and time.

Results of inverse gas chromatography adsorption/desorption experiments using selected probes on skimmed milk, whey and demineralised whey powder materials are presented. The dispersive component of surface energy was found to be dominant, indicating a low polarity character. Surface energy profiles of demineralised whey and skimmed milk showed a characteristic steep exponential decrease from approximately 170 mJ/m(2) to 60 mJ/m(2) and 140 mJ/m(2) to 45 mJ/m(2), respectively, whereas whey powder exhibited a constant (non-exponential) surface energy at approximately 45 mJ/m(2). The dispersive surface energy of demineralised whey and skimmed milk powder showed a broad distribution ranging from 40 mJ/m(2) to 120 mJ/m(2) and 175 mJ/m(2), respectively. In contrast, the dispersive surface energy distribution for whey was very narrow, ranging from only 42.8 mJ/m(2) to 45 mJ/m(2). The determined yield locus and Mohr's circles indicated that demineralised whey exhibited free flowing powder characteristics, whereas skimmed milk and whey exhibited cohesive powder flow behaviour., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The aim of this study was to evaluate the combined effect of temperature (10, 20 and 37°C), pH (4, 5, 6, 7 and 8), and NaCl content (0, 1, 3, 4, 5 and 6% w/v) on the growth and putrescine and cadaverine production of Serratia marcescens CCM 303 under model conditions. The decarboxylase activity of S. marcescens was monitored in broth after cultivation. The cultivation medium was enriched with selected amino acids (ornithine, arginine and lysine; 0.2% w/v each) serving as precursors of biogenic amines. Levels of putrescine and cadaverine in broth were analysed by high-performance liquid chromatography after pre-column derivatisation with o-phthalaldehyde reagent. S. marcescens produced higher amounts of putrescine (up to 2096.8 mg L(-1)) compared to cadaverine content (up to 343.3 mg L(-1)) in all cultivation media. The highest putrescine and cadaverine concentrations were reached during cultivation at 10-20°C, pH 5-7 and NaCl content 1-3% w/v. On the other hand, the highest BAs production of individual cell (recalculated based on a cell; so called "yield factor") was observed at 10°C, pH 4 and salt concentration 3-5% w/v as a response to environmental stress.

Highly undesirable microbial contaminants of processed cheese are endospore-forming bacteria of the genera Bacillus and Clostridium. Survival of Bacillus subtilis, B. cereus, Clostridium butyricum and C. sporogenes was examined in model processed cheese samples supplemented with monoacylglycerols. In processed cheese samples, monoacylglycerols of undecanoic, undecenoic, lauric and adamantane-1-carboxylic acid at concentration of 0.15% w/w prevented the growth and multiplication of both Bacillus species throughout the storage period. The two species of Clostridium were less affected by monoacylglycerols in processed cheese samples and only partial inhibition was observed. The effect of milk fat content on microbial survival in processed cheese was also evaluated. The growth of Bacillus sp. was affected by the fat level of processed cheese while population levels of Clostridium sp. did not differ in processed cheese samples with 30, 40 and 50% fat in dry matter., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The aim of the study was the monitoring of six biogenic amines (histamine, tyramine, phenylethylamine, tryptamine, putrescine, and cadaverine) and two polyamines (spermidine and spermine) in 112 samples of dairy products purchased in the Czech Republic, namely in 55 cheeses made in small-scale farms and in 57 fermented dairy products. The products were tested at the end of their shelf-life period. Neither tryptamine nor phenylethylamine was detected in the monitored samples; histamine was found only in four cheese samples containing up to 25mg/kg. The contents of spermine and spermidine were low and did not exceed the values of 35 mg/kg. Significant amounts of tyramine, putrescine, and cadaverine occurred especially in cheeses produced from ewe's milk or in long-term ripened cheeses. In about 10% of the tested cheeses, the total concentration of all the monitored biogenic amines and polyamines exceeded the level of 200mg/kg, which can be considered toxicologically significant. In fermented dairy products, the tested biogenic amines occurred in relatively low amounts (generally up to 30 mg/kg) that are regarded safe for the consumer's health., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Formation of biogenic amines may occur in food due to metabolic activities of contaminating Gram-negative bacteria. Putrescine is assumed to be the major biogenic amine associated with microbial food spoilage. Gram-negative bacteria can form putrescine by three metabolic pathways that can include eight different enzymes. The objective of this study was to design new sets of primers able to detect all important enzymes involved in the production of putrescine by Gram-negative bacteria. Seven new sets of consensual primers based on gene sequences of different bacteria were designed and used for detection of the speA, adiA, adi, speB, aguA, speC, and speF genes. A newly developed touchdown polymerase chain reaction (PCR) method using these primers was successfully applied on several putrescine-producers. Selected PCR products were sequenced and high similarity of their sequences (99-91%) with known sequences of the corresponding genes confirmed high specificity of the developed sets of primers. Furthermore, all the investigated bacteria produced both putrescine and agmatine, an intermediate of putrescine production, which was confirmed by chemical analysis. The developed new touchdown PCR method could easily be used to detect potential foodborne Gram-negative producers of putrescine. The newly developed sets of primers could also be useful in further research on putrescine metabolism in contaminating microbiota., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The aim of the study was to explore production of seven biogenic amines (phenylethylamine, histamine, cadaverine, tyramine, putrescine, spermine and/or spermidine) by selected staphylococci and enterococci. Thirty three enterococcal strains isolated from rabbit meat (Oryctolagus cuniculus f. domesticus) and 21 staphylococcal strains isolated from intestinal content of trout (Salmo trutta morpha fario) were tested. Production of biogenic amines was evaluated after cultivation of the tested microorganisms in the de Man, Rogosa and Sharpe Broth (enterococci) or in the Brain Heart Infusion Broth (staphylococci). Both the above cultivation media were enriched with selected amino acids (histidine, tyrosine, arginine, ornithine and lysine; 2g/L each) serving as precursors of biogenic amines. After cultivation, levels of the monitored biogenic amines in broths were analysed by a high performance liquid chromatography equipped with a UV/VIS DAD detector. Among 21 staphylococci, 18 strains produced tyramine or cadaverine, 13 strains formed putrescine or phenylethylamine and only one strain generated histamine. Two staphylococcal strains produced cadaverine levels above 1000 mg/L. Among 33 enterococcal strains, 27 formed cadaverine, 18 strains produced tyramine, 10 strains generated phenylethylamine, and 2 strains gave putrescine. Most of the tyramine producing enterococci generated more than 1000 mg/L of this biogenic amine. Production of spermine or spermidine by the studied strains was not proved., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The aim of this work was to study, under model conditions, combined effects of the concentration of lactose (0-1% w/v), NaCl (0-2% w/v) and aero/anaerobiosis on the growth and tyramine production in 3 strains of Lactococcus lactis subsp. lactis and 2 strains of L. lactis subsp. cremoris. The levels of the factors tested were chosen with respect to the conditions which can occur during the real process of natural cheese production, including the culture temperature (10 ± 1°C). In all strains tested, tyrosine decarboxylation was most influenced by NaCl concentration; the highest production of tyramine was obtained within the culture with the highest (2% w/v) salt concentration applied. Two of the strains L. lactis subsp. lactis produced tyramine only in broth with the highest NaCl concentration tested. In the remaining 3 strains of L. lactis, tyramine was detected under all conditions applied. The tested concentration of lactose and aero/anaerobiosis had a less significant effect on tyramine decarboxylation. However, it was also found that at the same concentrations of NaCl and lactose, a higher amount of tyramine was detected under anaerobic conditions. In all strains tested, tyramine decarboxylation started during the active growth phase of the cells., (Copyright © 2011 Elsevier B.V. All rights reserved.)