Fuer die Beschreibung von Trocknungsprozessen ist die Kenntnis einer Reihe von Stoffdaten, insbesondere des Wasserdampf-Sorptionsverhaltens der Trocknungsprodukte, erforderlich, da diese es gestatten, Verpackungs-, Lager-und Stabilitaetsprobleme richtig einzuschaetzen bzw. loesen zu koennen. Anhand einer umfangreichen Literaturrecherche wurde eine tabellarische Zusammenfassung der fuer den Temperaturbereich von 40 bis 80 Grad C gueltigen publizierten Sorptionsisothermen erstellt. Darueber hinaus werden zwei unterschiedliche Methoden beschrieben, die es gestatten, mit relativ einfachen Labormitteln die Wasserdampfisorptionsisothermen bei hoeherer Temperatur mit hinreichender Genauigkeit experimentell zu ermitteln.

The kinetics of water uptake by food powders (animal and vegetable proteins and starch materials) were studied, and a mathematical relationship developed to describe the results. The water uptake rate was found to be proportional to the square of the amount of water still needing to be absorbed to reach equilibrium. The amount of water uptake was a function of the total water uptake at equilibrium and the time required to absorb half of the total uptake. A specific rate constant for the uptake was determined. (wz)

Ein beachtlicher Teil unserer Lebensmittel wird in der Lebensmittelindustrie, in Gross- und Kleinkuechen mit heisser Luft waermebehandelt. Nahrungsmittel sind oft hitzeempfindlich und veraendern ihre physikalischen, chemischen, stukturellen oder mikrobiologischen Eigenschaften waehrend der Hitzebehandlung. Dies beeinflusst sowohl die Qualitaet als auch den Naehrwert der entsprechenden Lebensmittel. Ferner ergibt sich oft ein Verlust an Wasser oder anderen Lebensmittelinhaltsstoffen. So betraegt der Wasserverlust beim Backen von Brot 15 bis 20 % und beim Kochen von Fleisch bis zu 30 %. Es werden die Mechanismen des Stoff-Transports, die Eigenschaften des Lebensmittels, die in diesem Zusammenhang von Bedeutung sind, sowie einige Beispiele fuer Qualitaets- und Naehrwertveraenderungen, die waehrend der Verarbeitung auftreten, diskutiert.

Popovo polje covers an area of about 4,000 ha of soil and is situated in the region of Herzegovina karst (Yugoslavia) with favourable climate conditions. Like most of the karst terrains it is part of the karst depression, later filled in the course of alluvial-colluvial processes. After the construction of the water-power plant there appeared positive changes of the natural hydrologic regime. This paper also presents the course and the nature of these changes as well as the results of the transformations in agriculture in the observed region.

Time—energy budgets (TEB) of Gambel's Quail (Callipepla gambelii) were compiled during two summers in the Colorado Desert of California. Quail spent 6.77 h/d foraging, 6.2 h/d inactive during daylight hours, and 11.02 h/d inactive at night. Field metabolic rate (FMR) calculated from this activity budget was 81.8 kJ/d. Of this, 47.3 kJ/d was expended during foraging, 12.6 kJ/d in daytime inactivity, and 20.4 kJ/d in nighttime inactivity. Despite the extremely hot thermal environment (maximum ambient temperature °45°C), there was no energy cost above resting levels for thermoregulation. FMR was also measured simultaneously with doubly labeled water (DLW), and averaged 90.8 kJ/d. TEB and DLW values agreed to within 6% when differences in measurement period were taken into account. A laboratory validation study indicated that DLW and balance methods agreed to within 5%. The FMR of C. gambelii was only 40% of that predicted for a bird of its body mass. This low FMR is primarily the result of a low resting metabolic rate (RMR): 51% of the predicted basal rate in 1981, and 70% of predicted in 1982. The basis and significance of this low and variable RMR are unclear. Energy assimilation efficiency, measured in laboratory feeding experiments with a mixed seed and arthropod diet, was 60.3%. An individual quail in the field thus required 150.3 kJ/d in its diet, representing a dry matter intake of 8.1 g/d. A diet of seeds alone provides insufficient water for Gambel's Quail in summer, so they must either incorporate moist food items in their diet or drink free water. It was calculated that over the course of a year, a population of Gambel's Quail consumes seeds with a total energy content °15% as great as that in seeds consumed by a population of desert rodents or harvester ants in the same area. Gambel's Quail thus may be important factors in the competition for resources among desert granivores, particularly because they can eat one of their competitors (harvester ants).