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Twenty-two free amino acid ( FAA) concentrations were observed during manufacture (7 days) and ripening period (42 days follow-up) of Olomoucké tvarůžky ( PGI, smear acid cheese). During the ripening period, the amounts of volatile compounds and selected sensory attributes were also analysed. The free amino acids were determined by means of ion-exchange chromatography, and the volatile compounds were detected and identified using HS- SPME coupled with GC/ MS method. The development of the individual FAA content positively correlated with the ripening period ( r = 0.7734-0.9229; P < 0.01). Forty-six volatile compounds (14 alcohols; 10 esters; 7 ketones; 5 acids; 4 aldehydes; 3 sulphur compounds; 2 phenol compounds; and 1 terpene) were identified. Concentrations of several compounds increased (e.g. 3-methylbutanal, 2-butanol, 2-butanone; P < 0.05) or decreased (e.g. dimethyldisulphide, methanethiol, 2-phenylethylacetate, methylbutyric acid; P < 0.05) over cheese ageing. The results gave information about the development of sensory active substances and its precursors in Olomoucké tvarůžky during ripening. In conclusion, we found that free amino acid concentrations and sulphur compounds are positive with improved flavour. [ABSTRACT FROM AUTHOR]

The aim of the study was (i) to detect changes of dry matter, NaCl and twenty-two free amino acids contents, pH and levels of selected microorganisms in four layers of cheese (from edge to core) during ripening and storage period and (ii) to describe the changes of the above-mentioned parameters caused by early relocation of cheese from optimum ripening conditions to refrigeration temperatures. The number of mesophilic aerobic and facultative anaerobic bacteria and lactic acid bacteria differed significantly ( P < 0.05) during the experiment dependent on the analysed layer and ripening/storage conditions. The free amino acid content differed significantly in individual analysed layers of cheese and also according to individual ripening/storage conditions. The highest content of free amino acids was found in samples stored at optimal ripening temperatures. Cheese hardness was also analysed and the lowest one was detected in samples ripened under optimal temperatures for the whole period. Early release of cheeses into storage rooms with lower temperature significantly affected properties of these products. [ABSTRACT FROM AUTHOR]

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]

Abstract: The aim of this study was to explore the effect of elevated temperature (16°C) on ripening of Dutch-type cheese. Three slices of each cheese block were further divided into three layers. The processes in the control samples of cheese ripening at 10°C were also monitored. The contents of free amino acids in accelerated cheese were two times higher than were those in control samples. The highest contents of free amino acids were observed in the cores of all slices of cheeses ripening at both temperatures. The contents of tyramine, in layers of the studied slices, reached almost 500mgkg−1 during 56days of the experiment. The contents of biogenic amines in the edges grew even higher. Accelerated cheese showed faster equalisation of hardness than did control samples. The increase of temperature by 6°C can reduce the ripening time in cellars by approximately one half. [Copyright &y& Elsevier]

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]

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]