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.

Water is an essential component of food structures and biological materials. The importance of water as a parameter affecting virion stability and inactivation has been recognized across disciplinary areas. The large number of virus species, differences in spreading, likelihood of foodborne infections, unknown infective doses, and difficulties of infective virus quantification are often limiting experimental approaches to establish accurate data required for detailed understanding of virions’ stability and inactivation kinetics in various foods. Furthermore, non-foodborne viruses, as shown by the SARS-CoV-2 (Covid-19) pandemic, may spread within the food chain. Traditional food engineering benefits from kinetic data on effects of relative humidity (RH) and temperature on virion inactivation. The stability of enteric viruses, human norovirus (HuNoV), and hepatitis A (HAV) virions in food materials and their resistance against inactivation in traditional food processing and preservation is well recognized. It appears that temperature-dependence of virus inactivation is less affected by virus strains than differences in temperature and RH sensitivity of individual virus species. Pathogenic viruses are stable at low temperatures typical of food storage conditions. A significant change in activation energy above typical protein denaturation temperatures suggests a rapid inactivation of virions. Furthermore, virus inactivation mechanisms seem to vary according to temperature. Although little is known on the effects of water on virions’ resistance during food processing and storage, dehydration, low RH conditions, and freezing stabilize virions. Enveloped virions tend to have a high stability at low RH, but low temperature and high RH may also stabilize such virions on metal and other surfaces for several days. Food engineering has contributed to significant developments in stabilization of nutrients, flavors, and sensitive components in food materials which provides a knowledge base for development of technologies to inactivate virions in foods and environment. Novel food processing, particularly high pressure processing (HPP) and cold plasma technologies, seem to provide efficient means for virion inactivation and food quality retention prior to packaging or food preservation by traditional technologies.

The thermogravimetry (TGA) and derivative thermogravimetry (DTG) methods have been used to measure the free water in low-moisture foods. In this study, the 2nd derivative thermogravimetry (2nd DTG) method distinguished the free and bound water based on the speed of moisture evaporation, which could be used for both low-moisture and high-moisture foods. First, the key factors related to moisture evaporation were optimized. Isothermal temperature of 30 ~ 50°C, dynamic temperature of 0.033 ~ 0.133°C/min, and flow rate of nitrogen of 20 ~ 40 mL/min were the optimal parameters for the 2nd DTG method. Under these conditions, the repeatability and reproducibility of the 2nd DTG method were enhanced, its applicability was expanded to high-moisture foods, and the accuracy was ± 4.0% of the nuclear magnetic resonance results. Hence, the 2nd DTG method is better suited for the measurement of free water in foods.

In this study, the capability of a natural surfactant, lecithin, and the influence of ionic strength, pH, and temperature on some properties of a food grade microemulsion system were evaluated. For this purpose, the pseudoternary phase diagrams of canola oil/lecithin:n-propanol/water microemulsions in the presence of different salts (NaCl and CaCl2), ionic strengths, pHs, and temperatures were constructed. Our findings showed that the presence of salts slightly increased the W/O areas on the phase diagrams, whereas pH variation was not effective on the microemulsion formation. The expansion of microemulsion areas with temperature indicated the greater triglycerides solubilization capacity of lecithin based microemulsions at higher temperatures. These findings revealed the efficiency of lecithin-based microemulsion system for solubilization of triglycerides which can potentially be used for extraction of edible vegetable oils particularly canola oil.

Water activity of multicomponent food mixture was analysed and measured. Samples of dry fermented sausages with two different starter cultures (Pediococcus pentosaceus + Staphylococcus carnosus and Staphylococcus carnosus + Staphylococcus xylosus + Lactobacillus farciminis) were tested during ripening (21 days) and storing (91 days). The basic raw materials were the same for all samples: lean beef meat, lean pork and pork fat in equal parts, nitrite salt mixture (2.5 %), and sugars (1.0 %). The method used for water activity tests was indirect manometric in a static environment. Moisture content of samples was measured using halogen dryer. The course of water activity and moisture content of sausages was variable during ripening and steady during storage. Diagrams showed gradual decrease of both parameters. Mathematical models of water activity and moisture content for storage of dry fermented sausages were developed and statistically verified. The influence of starter cultures was not significant.

The analysis of water by near infrared spectroscopy (NIRS) was the first successful application of this rapid technology which has been developed over the past 30 years into a routine method for many agricultural commodities and food constituents. Nowadays, NIRS technology offers many advantages because its rapidity allows more frequent measurements at all stages from purchase of raw materials and ingredients to the control of the finished products. NIRS-methods are well suited to in-line use. Nevertheless the two dominant and broad peaks, near to 1440 and 1930 nm in nearly every NIR spectrum due to water, are responsible for some typical complications in this analysis. Effects of hydrogen bonding and sample temperature are found to affect the reliability of NIRS results.

This study has deduced a correlation between points of inflection of water activity and loss factor with respect to moisture content. A point of inflection in loss factor with respect to moisture content was found to coincide with the sorption isotherm point of inflection that defines the transition from multilayer to solution in every instance analysed, with an average difference of just 0.01 kg kg−1. Food can support microbial growth and chemical reactions in water activity levels above this critical transition. This correlation was discovered using published dielectric and sorption data for specific foods at similar temperatures. It was found that low sugar foods containing high levels of hydrocolloids generally exhibited different behaviour from fruits. This shows that microwave heating behaviour will be different in fruits compared to low sugar foods with high hydrocolloid content when drying to achieve a certain water activity and therefore shelf life.

Large quantities of food are wasted globally. Sugars such as monosaccharides and oligosaccharides are valuable carbohydrate compounds that can be hydrolyzed from food waste, particularly from carbohydrate-rich bakery waste. These sugars can be extracted from the waste as a value-added compound for manufacturing other food products. Sub-critical water treatment is a new and emerging extraction technique that is considered as a green extraction technology. Water at high temperature and pressure can be used to hydrolyze and extract the sugars. This paper reviews (1) the general process for producing sugars from food wastes, (2) recovery of sugar (particularly oligosaccharides) from food waste via sub-critical water treatment, and (3) the potential of bakery waste as the resources of sugar recovery.

In this study, 13 types of organic materials were oxidized using H₂O₂in a continuous flow reactor under the condition of supercritical water. The effect of the operational parameters on the conversion of total organic carbon (TOC) and total nitrogen (TN) was investigated, and the resulting quality of treated water was analyzed. It was found that these materials were easily oxidized with a TOC conversion achieving 99 % at temperature of 460 °C and TN conversion reaching 94 % at temperature of 500 °C. Rice decomposition was rapid, with TOC and TN decomposition rates of 99 % obtained within residence of 100 s at temperature of 460 °C. At temperature of 460 °C, pressure of 24 MPa, residence time of 100 s, and excess oxygen of 100 %, the quality of treated water attained levels commensurate with China’s Standards for Drinking Water Quality. Reaction rate equation parameters were obtained by fitting the experimental data to the differential equation obtained using the Runge–Kutta algorithm. The decrease of the TOC in water samples exhibited reaction orders of 0.95 for the TOC concentration and 0.628 for the oxygen concentration. The activation energy was 83.018 kJ/mol.

Water is a major component of drinking water, beverages, and most foodstuffs. In this study, an effort has been made to employ selected properties of water for: (1) evaluation of interactions of water with other food components; (2) discussion on the effects of water properties on food and beverage products; (3) applications of water properties in food technology; and (4) comparison of water properties with corresponding properties of similar substances. This study provides the following major conclusions: (i) unusual properties of water are mostly due to its high permanent dipole moment, partial ionic character of O–H covalent bonds, and extensive hydrogen bonds; (ii) different properties of many foodstuffs are strongly related to various properties of water; (iii) the properties of food products change depending on water availability and temperature; (iv) preparation of drinking water is a prerequisite for production of any safe drinks and foodstuffs; (v) water contributes important roles in quality, flavor, and shelf-life of foods; and (vi) water is used in food industries as a fluid for heat transfer; as a medium for temperature moderation in food processing; as a solvent for sugars, salts, water-soluble vitamins, and acids; as a dispersing agent for hydrophilic food components; as a dispersed phase for emulsified products; or as a reactant for several reactions in food processing.