Modeli određivanja vremena potrebnog za odmrzavanje hrane ovisno o uvjetima prerade i karakteristikama gotovog proizvoda

Determining thawing times of frozen foods is a challenging problem as the thermophysical properties of the product change during thawing. A number of calculation models and solutions have been developed. The proposed solutions range from relatively simple analytical equations based on a number of assumptions to a group of empirical approaches that sometimes require complex calculations. In this paper analytical, empirical and graphical models are presented and critically reviewed. The conditions of solution, limitations and possible applications of the models are discussed. The graphical and semi-graphical models are derived from numerical methods. Using the numerical methods is not always possible as running calculations takes time, whereas the specialized software and equipment are not always cheap. For these reasons, the application of analytical-empirical models is more useful for engineering. It is demonstrated that there is no simple, accurate and feasible analytical method for thawing time prediction. Consequently, simplified methods are needed for thawing time estimation of agricultural and food products. The review reveals the need for further improvement of the existing solutions or development of new ones that will enable accurate determination of thawing time within a wide range of practical conditions of heat transfer during processing.Toplinska i fizikalna svojstva proizvoda mijenjaju se tijekom odmrzavanja, pa je određivanje vremena odmrzavanja oduvijek predstavljalo problem. Razvijeni su različiti matematički modeli za rješavanje tog problema, počevši od relativno jednostavnih analitičkih funkcija koje polaze od niza pretpostavki, pa sve do raznih empirijskih modela što uključuju složene izračune. U ovom su radu kritički prikazani analitički, empirijski i grafički modeli. Osim toga, raspravlja se o uvjetima potrebnim za rješavanje problema, ograničenju i mogućoj primjeni modela. Grafički i polugrafički modeli izvedeni su iz numeričkih metoda. Numeričke metode nisu uvijek primjenjive jer izračuni oduzimaju puno vremena, a specijalizirani su programi i oprema uglavnom skupi. Zbog toga su za primjenu u inženjerstvu prikladniji analitičko-empirijski modeli. Ovaj revijalni prikaz potvrđuje da ne postoji jednostavna, točna i u praksi lako izvediva analitička metoda određivanja vremena odmrzavanja prehrambenih proizvoda, te da treba razviti jednostavnije metode. Zaključeno je da postojeća rješenja treba poboljšati ili treba razviti nove modele koji će omogućiti precizno određivanje vremena odmrzavanja u različitim uvjetima prijenosa topline prilikom obrade hrane

Effetto della temperatura di conservazione del latte, dalla raccolta all'affioramento, sulla microflora del latte, del sieroinnesto e del formaggio Trentingrana

This PhD research is part of a project addressed to improve the quality of Grana Trentino production. The objectives were to evaluated if milk storage and collection procedures may affect cheese-making technology and quality. Actually the milk is collected and delivered to the cheese factory just after milking in 50 L cans without refrigeration or in tanks cooled at 18 °C. This procedure is expensive (two deliveries each day) and the milk quality is difficult to preserve as temperatures are not controlled. The milk refrigeration at the farm could allow a single delivery to the dairy. Therefore it could be a good strategy to preserve raw milk quality and reduce cheese spoilage. This operation may, however, have the drawbacks of favouring the growth of psychrotrophic bacteria and changing the aptitude of milk to coagulation. With the aim of studying the effect on milk and cheese of traditional and new refrigerated technologies of milk storage, two different collection and creaming technologies were compared. The trials were replicated in three cheese factories manufacturing Grana Trentino. Every cheese-making day, about 1000 milk liters were collected from always the same two farms in the different collection procedures (single or double). Milk was processed to produce 2 wheels of Grana trentino every day. During the refrigerated trials, milk was collected and stored at the farm in a mixed tank at 12 or 8 °C and then was carried to the dairy in truck once a day. 112 cheese making day were followed: 56 for traditional technology and 56 for the refrigerated one. Each one of these two thechnologies lead to different ways of creaming: long time in the traditional one and shorter in the new one. For every cheese making day we recorded time, temperatures and pH during the milk processing to cheese. Whole milk before ceraming, cream and skim milk after creaming, vat milk and whey were sampled during every cheese-making day for analysis. After 18 months ripening we opened 46 cheese wheels for further chemical and microbiological analyses. The trials were performed with the aim of: 1 estimate the effect of storage temperatures on microbial communities, physico-chemical or/and rheological differences of milk and skim milk after creaming. 2 detect by culture dependent (plate counts) and indipendent (DGGE) methodolgies the microbial species present in whole, skimmed milk, cream and cheese sampled under the rind and in the core; 3 estimate the physico-chemical characteristics, the proteolytic activity, the content of free aminoacids and volatile compounds in 18 months ripened Grana Trentino cheeses from different storing and creaming of milk technologies. The results presented are remarkable since this is the first in-deep study presenting microbiological and chemical analysis of Grana Trentino that even if belonging to Grana Padano Consortium, it is clearly different in the milk and in the manufacturing technology

Multiple Determinants Direct the Orientation of Signal–Anchor Proteins: The Topogenic Role of the Hydrophobic Signal Domain

The orientation of signal–anchor proteins in the endoplasmic reticulum membrane is largely determined by the charged residues flanking the apolar, membrane-spanning domain and is influenced by the folding properties of the NH2-terminal sequence. However, these features are not generally sufficient to ensure a unique topology. The topogenic role of the hydrophobic signal domain was studied in vivo by expressing mutants of the asialoglycoprotein receptor subunit H1 in COS-7 cells. By replacing the 19-residue transmembrane segment of wild-type and mutant H1 by stretches of 7–25 leucine residues, we found that the length and hydrophobicity of the apolar sequence significantly affected protein orientation. Translocation of the NH2 terminus was favored by long, hydrophobic sequences and translocation of the COOH terminus by short ones. The topogenic contributions of the transmembrane domain, the flanking charges, and a hydrophilic NH2-terminal portion were additive. In combination these determinants were sufficient to achieve unique membrane insertion in either orientation

Review of thawing time prediction models depending on process conditions and product characteristics

Determining thawing times of frozen foods is a challenging problem as the thermophysical properties of the product change during thawing. A number of calculation models and solutions have been developed. The proposed solutions range from relatively simple analytical equations based on a number of assumptions to a group of empirical approaches that sometimes require complex calculations. In this paper analytical, empirical and graphical models are presented and critically reviewed. The conditions of solution, limitations and possible applications of the models are discussed. The graphical and semi-graphical models are derived from numerical methods. Using the numerical methods is not always possible as running calculations takes time, whereas the specialized soft ware and equipment are not always cheap. For these reasons, the application of analytical-empirical models is more useful for engineering. It is demonstrated that there is no simple, accurate and feasible analytical method for thawing time prediction. Consequently, simplified methods are needed for thawing time estimation of agricultural and food products. The review reveals the need for further improvement of the existing solutions or development of new ones that will enable accurate determination of thawing time within a wide range of practical conditions of heat transfer during processing

Glycosylation Can Influence Topogenesis of Membrane Proteins and Reveals Dynamic Reorientation of Nascent Polypeptides within the Translocon

The topology of multispanning membrane proteins in the mammalian endoplasmic reticulum is thought to be dictated primarily by the first hydrophobic sequence. We analyzed the in vivo insertion of a series of chimeric model proteins containing two conflicting signal sequences, i.e., an NH2-terminal and an internal signal, each of which normally directs translocation of its COOH-terminal end. When the signals were separated by more than 60 residues, linear insertion with the second signal acting as a stop-transfer sequence was observed. With shorter spacers, an increasing fraction of proteins inserted with a translocated COOH terminus as dictated by the second signal. Whether this resulted from membrane targeting via the second signal was tested by measuring the targeting efficiency of NH2-terminal signals followed by polypeptides of different lengths. The results show that targeting is mediated predominantly by the first signal in a protein. Most importantly, we discovered that glycosylation within the spacer sequence affects protein orientation. This indicates that the nascent polypeptide can reorient within the translocation machinery, a process that is blocked by glycosylation. Thus, topogenesis of membrane proteins is a dynamic process in which topogenic information of closely spaced signal and transmembrane sequences is integrated

Evaluation der Ökomassnahmen: Bereich Biodiversität

1993 führte der Bund ökologische Direktzahlungen ein; seit 1999 ist die Erbringung des ökologischen Leistungsnachweises (ÖLN) durch die Landwirtschaftsbetriebe die Voraussetzung zum Bezug von Direktzahlungen. Heute werden 97 % der landwirtschaftlichen Nutzfläche nach den Regeln des ÖLN bewirtschaftet. Die wichtigste Massnahme des ÖLN, welche einen Einfluss auf die Biodiversität hat, ist, dass die Betriebe 7 % ihrer landwirtschaftlichen Nutzfläche (LN) als ökologische Ausgleichsflächen (öAF) auszuweisen haben (bei Spezialkulturen 3,5 %). Weitere Anforderungen des ÖLN (ausgeglichene Nährstoffbilanz, geregelte Fruchtfolge, Bodenschutz, gezielter Einsatz von Pflanzenschutzmitteln, tiergerechte Haltung der Nutztiere) können ebenfalls einen Einfluss haben, stehen jedoch weniger im Vordergrund

Geflüchtete aus der Ukraine in Deutschland: Ergebnisse der ersten Welle der IAB-BiB/FReDA-BAMF-SOEP Befragung

Der gemeinsame Forschungsbericht des Instituts für Arbeitsmarkt- und Berufsforschung (IAB), des Bundesinstituts für Bevölkerungsforschung (BiB), des Forschungszentrums des Bundesamtes für Migration und Flüchtlinge (BAMF-FZ) und des Sozio-oekonomischen Panels (SOEP) am DIW Berlin stellt vertieft zentrale Befunde aus der gemeinsamen Studie "Geflüchtete aus der Ukraine in Deutschland" vor. Im Fokus der bundesweiten Studie stehen das Ankommen, die aktuellen Lebensumstände sowie Zukunftspläne der ukrainischen Geflüchteten in Deutschland. Die Analysen basieren auf rund 11.700 Interviews mit ukrainischen Männern und Frauen, die im Zeitraum vom 24. Februar bis zum 8. Juni 2022 nach Deutschland gekommen sind. Die Interviews wurden deutschlandweit auf Basis standardisierter Fragebögen online (CAWI) oder per Papierfragebogen (PAPI) im Zeitraum von August bis Oktober 2022 durchgeführt. Im Zuge der Stichprobenziehung wurden zunächst anhand des Ausländerzentralregisters (AZR) 100 Gemeinden mit einem hohen Anteil von ukrainischen Geflüchteten ausgewählt. Die ausgewählten Gemeinden wurden dann gebeten, Adressen dieser Zielpopulation zur Verfügung zu stellen. Durch Verwendung von Gewichten ist die Stichprobe repräsentativ für diese Grundgesamtheit. Die Studie ist als Längsschnittbefragung geplant, im Frühjahr 2023 wird eine zweite Befragungswelle durchgeführt. Erste zentrale Befunde aus der ersten Welle wurden bereits im Dezember 2022 im Rahmen einer Kurzanalyse veröffentlicht

Still Red Hot? Postfeminism and Gender Subjectivity in the Airline Industry

This article considers the relationship between postfeminism and gender subjectivity through a critique of the retro-aesthetic encoded into Virgin Atlantic's Still Red Hot advertising campaign. Launched in 2009, and prompting a series of complaints to the Advertising Standards Authority, this high-profile 25th-anniversary campaign featured crowds of people staring in awe at a group of 1980s-styled female cabin crew, and a male pilot, walking through an airport arrivals lounge. As they pass they elicit a number of not only admiring glances but also clearly sexualized responses, albeit portrayed in an exaggerated and, therefore, comedic manner, all set to the sound of Frankie Goes to Hollywood's ‘Relax’. Focusing on the relationship between performativity, materiality and signification, or what Judith Butler (1990) calls ‘the scenography of production’, the analysis presented here reflects on the cooptation process played out in this particular advertisement, arguing that while ostensibly parodying the sexual iconography associated with the airline industry, it can also be read as an example of the organizational appropriation of postfeminist ideas regarding gender, sexuality and subjectivity. The discussion emphasizes how this retro-styled campaign is dependent upon the commodification of a knowing, ironic and playful subjectivity preoccupied with the self as a performative project, one that characterizes postfeminist writing but that is at odds with a critique of the discrimination and disadvantage perpetuated within and by the industry

Aircraft Regional-Scale Flux Measurements over Complex Landscapes of Mangroves, Desert, and Marine Ecosystems of Magdalena Bay, Mexico

Natural ecosystems are rarely structurally simple or functionally homogeneous. This is true for the complex coastal region of Magdalena Bay, Baja California Sur, Mexico, where the spatial variability in ecosystem fluxes from the Pacific coastal ocean, eutrophic lagoon, mangroves, and desert were studied. The Sky Arrow 650TCN environmental research aircraft proved to be an effective tool in characterizing land–atmosphere fluxes of energy, CO2, and water vapor across a heterogeneous landscape at the scale of 1 km. The aircraft was capable of discriminating fluxes from all ecosystem types, as well as between nearshore and coastal areas a few kilometers distant. Aircraft-derived average midday CO2 fluxes from the desert showed a slight uptake of −1.32 μmol CO2 m−2 s−1, the coastal ocean also showed an uptake of −3.48 μmol CO2 m−2 s−1, and the lagoon mangroves showed the highest uptake of −8.11 μmol CO2 m−2 s−1. Additional simultaneous measurements of the normalized difference vegetation index (NDVI) allowed simple linear modeling of CO2 flux as a function of NDVI for the mangroves of the Magdalena Bay region. Aircraft approaches can, therefore, be instrumental in determining regional CO2 fluxes and can be pivotal in calculating and verifying ecosystem carbon sequestration regionally when coupled with satellite-derived products and ecosystem models