VAAM-Jahrestagung 2011 Karlsruhe, 3.–6. April 2011

FMV005The impact of vacuum foil packaging on the qualitycharacteristics of the surface smear microflora of semihardsmear cheeseM. Schuppler* 1 , L. Amato 1 , J. Ritschard 1 , E. Roth 2 , L. Meile 11 ETH Zurich, Institute of Food, Nutrition and Health, Zurich, Switzerland2 Agroscope Liebefeld-Posieux ALP, Bern, SwitzerlandDue to increasing export markets and advancing consumer behavior, cheesesare increasingly sold as vacuum foil pre-packed cheese wheels or portionsfound in self-service shelves. In recent years, it emerged that vacuum foilpackaging influence on the quality characteristics of smear-ripened semihardcheese. Hitherto, neither the cause for this phenomenon could bedetermined, nor are alternative strategies available that prevent the changesin the quality characteristics of the surface smear. We therefore reassess thehypothesis whether microorganisms of the aerobic surface smear ecosystemmay contribute to this phenomen by a change in composition and/ormetabolism of the surface smear microbiota, due to the switch to anaerobicconditions caused by vacuum foil packaging.The identification of volatile compounds accumulated within the vacuumfoil packs was performed by gas chromatography, in order to provide anindication on the type of microorganisms that might be responsible for thealterations in the quality characteristics of the surface smear. Furthermore,surface smear samples of semi-hard cheeses were investigated by acombination of culture-dependent and culture-independent moleculartechniques in order to analyze the surface smear microbiota prior to and aftervacuum foil packaging, both, on a phylogenetic and a metabolic level. Instorage experiments with vacuum foil packaged cheeses, the succession ofthe smear microorganisms was monitored under storage conditions. For thispurpose, cell counts for relevant bacterial groups were determined on avariety of selective and non-selective culture media. Moreover, isolated purecultures of bacteria and fungi were identified by 16S rDNA or ITS-2 rDNAsequencing. TGGE, TRFLP, ITS-2 FLP and qPCR were applied in order toanalyze the composition of the cheese surface microflora in terms ofbacterial and fungal populations using culture-independent techniques.Preliminary results revealed only slight differences in the overallcomposition of the surface microflora of un-packed versus vacuum foilpacked smear cheeses. Typical smear bacteria such as Staphylococcus spp.,Corynebacterium casei, Microbacterium gubbeenense, Brevibacterium sp.and Arthrobacter casei, as well as typical fungal isolates like Candida spp.,Yarrowia lipolytica and Debaryomyces hansenii were identified in thesurface microflora of the cheeses, both prior to and after vacuum foilpackaging.FMV006Granulation of lactic acid bacteria using the fluidized bedtechnologyM. Wassermann* 1 , S. Weinholz 2 , C. Cordes 2 , M. Peglow 3 , W. Pergande 11 VTA GmbH, Weissandt-Gölzau, Germany2 Institute of Molecular Biology (IMB), Anhalt University of AppliedSciences, Bernburg, Germany3 Institute Process Engineering, Otto-von-Guericke-University, Magdeburg,GermanyThe application of lactic acid bacteria has an economic significance asprobiotic and conserving additives for food industry. Therefore a crucialpoint in the commercialization of lactic acid bacteria is the development of astorable culture which retains the viability of the primary culture. Forpreserving bioactive materials freeze and spray drying are establishedmethods.Freeze drying is a gentle but long term and expensive method which isuneconomical. The benefit of spray drying is the formation of free flowingparticles in a short time but it is disadvantageous that the required hightemperatures reduce the viability of mesophilic microorganisms. Thefluidized bed drying technology is an alternative, gentle and cost savingmethod for the preservation of microorganisms. The present study analysesthe influence of the fluidized bed drying technology on cell viability andstorage stability of the model strain Lactobacillus plantarum. Differentcarrier materials were tested and recent studies have shown that the usage ofmaltodextrin results in the highest viablity of bacteria. Furthermore differentprotectants such as trehalose and sorbitol were added. Using sorbitol is moresuited for the protection of the bacteria cells during fluidized bed drying thantrehalose. For shelf life determination the granulated microorganisms arestored at -20 °C, 4 °C and 20 °C. The storage at room temperature withoutadding a cell protectant resulted in none viable Lactobacillus plantarumcells after three months. In contrast adding the protectants trehalose orsorbitol resulted in viable cells. High recovery of viable cells was achievedat 4 °C and -20 °C regardless of using trehalose or sorbitol.The project is part of the WIGRATEC and was founded by the BMBF (FKZ03WKBQ04B).FMV007Generation of new flavours in wheat doughssupplemented with by-products and fermented with non-Saccharomyces cerevisiae yeastsM. Wieschebrock*, F. Schilling, C. HertelGerman Institute of Food Technologies, Quakenbrück, GermanyConsumer studies show the demand of bread and rolls with good taste andflavour. One way to improve the flavour of wheat based products is the useof fermented doughs. However, during fermentation of doughs the formationof flavour is generally limited by the substrate availability in the wheat flourand the metabolic potential of the baker’s yeast Saccharomyces cerevisiae.To overcome these limitations, we set up a new approach by combining theaddition of new substrates and yeasts to the wheat dough fermentation. Byproductsof the food industry like apple, carrot or grape pomace were chosento increase the availability of substrates involved in flavour formation. Inaddition, non-S. cerevisiae yeasts differing in their metabolic potential wereapplied to obtain new flavours during the dough fermentation. Fermenteddoughs were prepared by using strains of the species Kluyveromycesmarxianus, Torulasproa delbrueckii, Wickerhamomyces anomalus andPichia jadinii as starter culture and wheat flour supplemented with 25% ofpomace and subsequently subjected to microbial and sensory analysis.Analysis of the microbiota revealed that the yeast strains were competitiveand thus belonged to the dominating yeast biota (10 6 to 10 8 cfu/g) at the endof fermentation. Furthermore, the fermentation of wheat flour supplementedwith by-products and the non-S. cerevisiae yeasts resulted in doughs withfruity, flowery and sweet flavours. A strain- and species-specific formationof the flavours and a certain influence of the accompanying lactic acidbacteria biota could be observed. The effect of varying by-productconcentration, dough yield, pH and the time of fermentation wasdemonstrated. Baking of white bread by using 20% of the fermented doughsshowed that some of flavours could be transferred to the bread. With regardto the biochemical background it is tempting to speculate that the Ehrlichpathway (fruity esters) or the conversation of terpenes to terpenoides(flowery and sweet) play a certain role. However, the metabolic pathways ofnon-Saccharomyces yeasts involved in flavour formation are currentlyunknown, demonstrating the further research need.FMV008A novel enzymatic approach for growth inhibition ofundesired wine related microorganismsP. Sebastian*, B. Verena, E. Gasser, H. Claus, P. Pfeiffer, H. KönigInstitute for Microbiology and Wine Research, Johannes-Gutenberg-University, Mainz, GermanyMicroorganisms play an important role in winemaking. In addition to theeukaryotic ethanol producing yeasts also bacteria occur in must and wine.The most important representatives are lactic acid bacteria (LAB) and aceticacid bacteria (AAB). Most of these microorganisms are undesired in mustand wine because of their metabolic activities which can negativelyinfluence the wine quality. For example some strains of Pediococcusdamnosus or Leuconostoc mesenteroides are able to produce exopolysaccharideswhich lead to problems during wine filtration. Furtherundesired byproducts of the metabolism of LAB are biogenic amines. Thesecompounds can cause health problems such as migraine, hypertension anddigestive disorders.To inhibit the growth of these spoilage organisms most winemakers usesulphur dioxide. Studies have shown that the addition of sulphur dioxide canlead to an inhibition of desired wine yeasts and especially malolacticbacteria.Since 2001 the usage of lysozyme for microbiological stabilisation of wineis allowed. This enzyme is isolated from hen-egg and therefore not optimallyadapted to the milieu of wine with its low pH value and high concentrationof ethanol. Also examples of incomplete inhibition caused by the occurrenceof resistant strains are described. Sensitive persons can show allergicreaction to lysozyme. Due to the disadvantages of the current agents forspektrum | Tagungsband 2011