1,721,066 research outputs found
Consiglio scientifico della Biblioteca della Facoltà di Agraria dell'Università degli Studi di Napoli Federico II
No full textConsiglio Scientifico Biblioteca della Facoltà di agraria dell'università degli Studi di Napoli Federico II
No full textDifferential viable count of mixed starter cultures of lactic acid bacteria in doughs by using modified Chalmers medium
No full textThe modified Chalmers medium appeared as quite suitable to counting a mixing population consisting of different species of lactic acid bacteria used as starter in breadmaking. Selected strains of Lactobacillus plantarum , Leuconostoc mesenteroides subsp. mesenteroides , Lactobacillus sanfranciscensis , Enterococcus faecalis together with Saccharomyces cerevisiae could be easily differentiated and counted with an acceptable recovery in comparison with reference media. The modified Chalmers medium has proved to be very satisfactory for differential counts of the main species of lactic acid bacteria occurring in starter for dough leavening proces
Micro-rheological Modeling of Flow Induced Crystallization
No full textThe problem of Flow Induced Crystallization (FIC) of polymer melts is addressed via a micro-rheological approach. In particular, the Doi-Edwards model with the so-called Independent Alignment Approximation (DE-IAA) is used to calculate the flow-induced change of free energy. Subsequently, the crystallization induction time, i.e., the nucleation characteristic time, is calculated in isothermal steady shear and uniaxial elongational flows. Asymptotic, analytical expressions for the induction time are also derived in the limit of low and high Deborah number (the product of the deformation rate and the polymer relaxation time). The DE-IAA model is found to give more realistic predictions than those of simpler, dumbbell-like models already proposed in the literature. When compared to existing FIC experimental data in shear flow, good quantitative agreement is found with the polymer relaxation time as the only adjustable parameter of the model
Differential viable count of mixed starter cultures of lactic acid bacteria in doughs by using modified Chalmers medium
No full textThe modified Chalmers medium appeared as quite suitable to counting a mixing population consisting of different species of lactic acid bacteria used as starter in breadmaking. Selected strains of Lactobacillus plantarum , Leuconostoc mesenteroides subsp. mesenteroides , Lactobacillus sanfranciscensis , Enterococcus faecalis together with Saccharomyces cerevisiae could be easily differentiated and counted with an acceptable recovery in comparison with reference media. The modified Chalmers medium has proved to be very satisfactory for differential counts of the main species of lactic acid bacteria occurring in starter for dough leavening proces
Effect of leavening microflora on pizza dough properties
No full textFourteen different starter cultures containing one strain of Saccharomyces cerevisiae with and without individual or combinations of lactic acid bacteria (Lactobacillus plantarum, Lact. sanfrancisco, Enterococcus faecium, Leuconostoc mesenteroides) were employed to investigate the role of leavening microflora on the properties of pizza doughs. Microbiological, chemical and physical characteristics of doughs prepared with the same flour and under the same processing conditions were determined. Leavening times and acidification properties depended on the microbial association used. The proportions of lactic and acetic acid produced by lactic acid bacteria were consistent with the metabolic properties of the strains employed. The bacteria/yeast ratios arising from microbial counts at the end of the leavening process were always lon-er in comparison to sour- or bread-doughs. The size of the yeast population did not change much, while bacteria showed from one to four duplications. Rheologically, the fermented doughs could only be significantly distinguished from the control dough with regard to the elastic modulus. Principal Component Analysis was applied to the acidimetric data. The scattergram of the two principal components effectively discriminated 13 of the 14 pizza dough types
Effect of leavening microflora on pizza dough properties
No full textFourteen different starter cultures containing one strain of Saccharomyces cerevisiae with and without individual or combinations of lactic acid bacteria (Lactobacillus plantarum, Lact. sanfrancisco, Enterococcus faecium, Leuconostoc mesenteroides) were employed to investigate the role of leavening microflora on the properties of pizza doughs. Microbiological, chemical and physical characteristics of doughs prepared with the same flour and under the same processing conditions were determined. Leavening times and acidification properties depended on the microbial association used. The proportions of lactic and acetic acid produced by lactic acid bacteria were consistent with the metabolic properties of the strains employed. The bacteria/yeast ratios arising from microbial counts at the end of the leavening process were always lon-er in comparison to sour- or bread-doughs. The size of the yeast population did not change much, while bacteria showed from one to four duplications. Rheologically, the fermented doughs could only be significantly distinguished from the control dough with regard to the elastic modulus. Principal Component Analysis was applied to the acidimetric data. The scattergram of the two principal components effectively discriminated 13 of the 14 pizza dough types
Caratterizzazione dei primi stadi della cristallizzazione quiescente di polimeri termoplastici mediante spettroscopia dinamico-meccanica
No full textNel presente lavoro sono studiati i primi stadi della cristallizzazione dal fuso di un polimero termoplastico mediante spettroscopia dinamico-meccanica, adottando una tecnica di "inverse quanching" recentemente sviluppata. In questo modo è infatti possibile eseguire esperimenti che richiedano tempi molto lunghi su un sistema "congelato" dove sia il numero che le dimensioni degli sferuliti formatisi rimangono costant
Dairy products
No full textThanks to the application of methods allowing precise imaging of microbial ecology, the field of food fermentation has experienced exponential growth in the last few years. This has resulted in the availability of new information on the structure and dynamics of the microbial populations during fermented food production. Molecular Methods and Microbial Ecology of Fermented Foods presents the latest findings in microbial ecology as determined by the application of molecular methods, reports the most recent advances in the field, and offers details on primers and protocols most suitable for studying specific food ecosystems. It provides analytical details and suggestions useful in research, as well as evaluation of the criticism of using novel approaches in food fermentation microbiology. This book also discusses new insights drawn from the use of bio-molecular techniques in the microbial ecology of fermented foods
Comparison of different starter systems for water-buffalo mozzarella cheese manufacture.
No full textNatural whey cultures, a thermophilic multiple strain starter (Lactobadllus helveticus and Streptococcus thermophilus) and a more complex multiple strain starter, including both thermophilic and mesophilic bacteria and a yeast (L delbrueckii subsp lactis, S thermophilus, Lactococcus lactis subsp lactis, Lactoc lactis subsp diacetylactis, Enterococcus faecalis, Leuconostoc mesente-oides subsp dextranicum and Kluyveromyces marxianus) and artificial acidification (addition of citric acid) were used for the manufacture of water-buffalo Mozzarella cheese. Whey acidity, fermentation end-products and microbial populations were monitored during cheese manufacture. A scorecard for sensory evaluation of water-buffalo Mozzarella cheese was developed and used to compare the cheeses obtained with the different procedures. The traditional technology (raw milk and natural whey cultures) allowed shorter manufacturing times due to faster acid production during ripening. Cheeses produced with the thermophilic multiple strain starter and citric acid addition obtained the lowest scores in sensory evaluation. When the complex multiple strain starter was used scores were slightly higher and more constant than those obtained using traditional technology
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