Search

The effect of high pressure processing (300 and 600 MPa) combined with mild heat treatment (55 and 75 °C) on the colour parameters, anthocyanin content, and sensory characteristics of strawberry puree were examined after the treatments and 2 weeks of cold storage at 2 and 15 °C. As on an industrial scale the simultaneous implementation of these treatments remains a challenge, the HHP and heat treatments were carried out consecutively in different sequences. The colour parameters and the anthocyanin content did not change significantly due to the treatments, but decreased during cold storage, at 15 °C storage the changes were more intensive than at 2 °C. Regarding the sensory test results, the different sequence of the 600 MPa-75 °C combined treatments is not detectable even after 2 weeks of storage at 15 °C, but in case of 300 MPa-55 °C, the enzyme inactivation is probably not sufficient enough as differences between the samples were detected.

High hydrostatic pressure (HHP) technology, as a promising alternative of thermal-treatment and chemical preservatives, can be used to produce minimally processed foods. It has the advantage of affecting only non-covalent bonds of macromolecules in foods, and thus preserves nutritional components, taste, and flavour exceptionally well. However, HHP also influences enzymatic reactions of food. Although some of these changes are often beneficial, monitoring the potential effects of high pressure treatments — especially in the field of product and technology development — is essential. The aim of this study was to point out some parameters of high hydrostatic pressure technique (pressure, temperature, build-up time, holding time, number of cycles) that can substantially impact the sensory properties of treated products.

There is an increasing consumer demand for fresh, shelf stable and healthy products with the favourable sensory properties of the original material food. In the beverage industry the appearance of Alicyclobacillus acidoterrestris spp. presents a problem which has to be solved. In this study the effectiveness of combined high hydrostatic pressure and heat treatment was investigated to examine its microbiological reducing ability regarding the A. acidoterrestris DSMZ 2498 in commercial pasteurized apple- and orange juice. In addition it was studied whether the electronic nose is able to show the differences during the 4 weeks storage time regarding the decreasing number of microorganisms which is in connection with aroma changes. It was established that the combined heat- and high pressure treatment caused microbial inactivation of acidoterrestris at different levels dependent on the combination of applied treatment parameters. These differences could be followed also by the electronic nose.

In our tests, we artificially infected liquid whole egg samples with Salmonella enteritidis, Listeria monocytogenes, and Staphylococcus aureus bacteria, and then treated the samples in “Food Lab900” high hydrostatic pressure (HHP) instrument for 3–17 min at 200–400 MPa. Subsequently, the change of the viable cell count of the specific bacteria has been tested. In addition to the samples infected with various bacteria, non-infected samples were also treated in each test and the change in viable cell count, colour and viscosity of the samples upon the effect of the treatment. In summary, it can be concluded that in each test of our investigations, the viable cell count of S. enteritidis critical for egg products is reduced significantly, while the reduction of the total viable cell count was around two magnitudes. Additionally, based on our results, microbial destruction, reduction of enthalpy (denaturation of egg white) caused by the treatment at HPP, and colour change are primarily affected by the pressur...

The consumers have increasing desire towards fresh, long shelf-life and healthy products by consisting favourable sensory properties. As an ambivalent fact appears that the product should meet all these requirements and should be consumable long time. All these demands lead to the importance of the minimal processing methods. The properties of widely common citrus juices (100% orange, – grapefruit, – and tangerine juice) were analyzed by measuring the possible changes in the physical–chemical parameters (pH, Brix°, electric conductivity, colour) respectively the aroma and acid content. The applied technology was pulsed electric field (in furthers: PEF) treatment with the parameters of 28 kV/cm with 50 pulses; respectively high hydrostatic pressure (HHP) technology with the parameter of 600 MPa pressure for 10 min treatment time. The sensory properties of the juices were analyzed with electronic-nose and -tongue to measure the possible changes of the treated juices compared to the untreated (control) samples with the help of these electronic tools, which can serve as a potential detection system for the differentiation of the treatments mentioned above. Industrial relevance Fruit juices are preserved mainly by heat treatment which can change many prosperous flavour- , acid and sensory properties. The present work shows in case of citrus juices the application of pulsed electric field treatment and high hydrostatic pressure techniques as non-thermal preservation possibilities and the use of electronic tongue and – nose as a new method for sensory testing.

High hydrostatic pressure (HHP) processing technology offers the possibility to preserve quality attributes. Objective test methods describing quality in a complex form have an important role in the development of new products and in the quality assurance of different technologies. Therefore, research was performed to compare the effects of HHP treatment and heat pasteurization on visual appearance, volatile composition, taste and texture properties of strawberry purees measured by sensorial and objective methods. Sensory evaluation did not show significant differences between samples. Similar result was obtained from the color measurements. Viscosity of purees changed only slightly as a result of the treatments. Electronic nose and electronic tongue were found to be promising tools for discrimination of strawberry purees treated by different levels of high hydrostatic pressure or thermal treatment. Canonical discriminant analysis showed that control and “600 MPa for 5 minutes” samples were quite similar. Samples treated by 600 MPa for 15 minutes were distinguished from the above mentioned ones. The heat treated samples (80°C for 5 and 15 minutes) were definitely separated from the control samples. Fusion of the data from the electronic nose and tongue showed the same trend and improved the classification of the treated puree samples.

Experiments were performed to study the effects of high hydrostatic pressure (HHP) and gamma irradiation, respectively, from two aspects. The effects of HHP treatments on minced pork meat exposed to 50–800 MPa for 20 min and stored at 4 °C for a period of 1 week were examined. The immediate effects of HHP on egg white samples were compared to that of irradiation. Egg white samples were subjected to irradiation (3 kGy) and HHP treatment (400 MPa, 5 min) and measured immediately after treatments. The recorded electronic nose data and near infrared spectra were evaluated using different methods of multivariate qualitative analyses.

Experiments were performed to study changes caused by irradiation or high hydrostatic pressure pasteurization of liquid egg white by differential scanning calorimetry, spectrofluorimetry, electronic nose measurements and NIR-spectrometry. The non-thermal pasteurization treatments were also assessed in relation to loss of carotenoid content, and lipid- and cholesterol oxidation of liquid egg yolk. Unlike radiation pasteurization, high pressure processing caused protein denaturation in egg white, which manifested in changes of its DSC-thermogram and intrinsic tryptophan fluorescence. Electronic nose testing showed changes of the head-space volatile composition of egg albumen, particularly as a function of radiation treatment. Both treatments caused changes in the NIR-spectrometric “fingerprint” of the liquid egg white. Various chemometric analyses of the results of the latter instrumental methods, particularly statistical techniques developed by the group of one of the co-authors of this article, demonstrat...

In principle, high hydrostatic pressure (HHP) processing offers the possibility to preserve berry products while affecting their volatile components less than heat pasteurization. Therefore, we performed preliminary investigations to compare effects of HHP treatment (600 MPa, 5 min, at ambient temperature) and heat pasteurization (80 °C, 5 min) on volatile composition of raspberry, strawberry and blackcurrant purees measured by ‘electronic nose’ at 25 °C. Changes in the head space volatiles could be monitored by this method. Taking into account the confusion matrix of the discriminant analysis, heat-treatment had a more significant effect on volatile compounds than HHP. So, application of HHP treatment can retain volatiles of berry products.

hereisanincreasingconsumer� demandforhighquality,� minimally- processed,� additive-freeand� microbiologically-safefoods.�The� applicationofnon-thermalfoodprocessing� techniques,�suchasultra-highhydrostatic� pressureandgammairradiation,� inde- velopingrapidly.�Beingnon-thermaltreat- ments,� foodcomponentsinvolvedinboth� sensoryandnutritionalqualityremainlarge- lyunaffected.�Inordertogainexperience� onthefeasibilityofnon-thermalpasteurisa- tionofegg,�theeffectsofultra-highhydro - staticpressure�(uHP)� andgammairradia- tiontreatmentswereinvestigatedonfresh� samplesofliquideggwhite.� Nearinfrared� (NIR)� spectroscopywasusedinorderto� monitorqualitychangescausedbytheap- pliedtreatmentsascomparedtountreated� controlsamples.�ourreportsdescribingthe� treatmentsandotheranalyticaltechniques� havebeenpublishedelsewhereingreater� FluidPowerLtd,� uK)� andgammairradia- tion�(3�kGydose)�(RH-γ-30,� Moscau),�re- spectively.�Thesampleswereanalysedim- mediatelyafterthesetreatmentsbyaNIR� spectrometerinordertoseethedifferences� intheNIRpropertiescausedbythevarious� procedures.�NIRspectrawererecordedon� aMetriNIR�10-17�PRtypeNIRspectrometer� inthewavelengthrangeof�1000-1700�nm� withaspectralstepof�2� nm. Forevaluation,�thefirststepinvolvedap- plicationofthePolarQualificationSystem� (PQS) 3 � usingautomaticwavelengthrange� optimisation.� Subsequently,� aSampleRec- ognitionTool�(SRT)� wasalsousedtodis- criminatebetweenthesamplesandtopro- ducetheclassification�(confusion)� matrices.� ResultsofPQSandSRTanalysiswerethen� comparedwiththeclassicalmathemati- cal-statisticalmethodsofprincipalcom- ponentanalysis�(PCA),� canonicaldiscrimi- nantanalysis�(CDA)� andtheircombination� (PCA�+�CDA),� calculatingthediscriminant� functionsusingthefirstfewprincipalcom- ponents. ThePQSwasintroducedatthe�3 rd �Inter- nationalConferenceonNearInfraredSpec- troscopyinBrussels.�AccordingtoPQS,�a� "qualitypoint"� wasdefinedonatwo-dimen- sional�"qualityplane"� anda�"polardistance"� wasusedtodescribequalitydifferences.� Thequalitypointoftheinvestigatedmaterial� wasgivenonthequalityplanebythecentre� ofitsspectrumrepresentedinapolarco- ordinatesystem. 4