Investigation of Consequences of High-Voltage Pulsed Electric Field and TGase Cross-Linking on the Physicochemical and Rheological Properties of Pleurotus eryngii Protein

This study aimed to evaluate the effects of high-voltage pulsed electric fields (HPEF) and transglutaminase (TGase) cross-clinking on the physicochemical and rheological properties of Pleurotus eryngii protein (PEP). The results showed that HPEF increased α-helixes and β-turns but decreased β-folds. A HPEF at 1500 V/cm maximized the free sulfhydryl content and solubility of PEP. TGase formed high-molecular-weight polymers in PEP. TGase at 0.25% maximized the free sulfhydryl groups, particle size, and solubility; shifted the maximum absorption wavelength from 343 nm to 339 nm and 341 nm; increased α-helixes and β-turns and decreased β-folds; and showed better rheological properties. Compared with TGase cross-linking, HPEF-1500 V/cm and 1% TGase significantly reduced the free sulfhydryl groups, particle size, and solubility, produced more uniform network structures, and improved the rheological properties. These results suggest that HPEF can increase the cross-linking of TGase and improve rheological properties of TGase-cross-linked PEP by affecting the physicochemical properties.

Health issues and technological aspects of plant-based alternative milk

A growing number of consumers opt for plant-based milk substitutes for medical reasons, like cow's milk protein allergy (CMPA), lactose intolerance (LI), or as a lifestyle choice. Plant-based milk substitutes, or plant extracts, are water-soluble extracts of legumes, oilseeds, cereals or pseudocereals that resemble bovine milk in appearance. It is produced by reducing the size of the raw material, extracted in water and subsequently homogenized, being an alternative to cow's milk. They are considered cow's milk replacers due to similar chemical composition and can also be used as a substitute for direct use or in some animal milk-based preparations. On the other hand, these substitutes exhibit different sensory characteristics, stability and nutritional composition from cow's milk. They are manufactured by extracting the raw material in water, separating the liquid, and formulating the final product. Others process like homogenization and thermal treatments are indispensable to improve the suspension and microbiological stabilities of the final product so that can be consumed. However new and advanced non-thermal processing technologies such as ultra-high pressure homogenization and pulsed electric field processing are being researched for tackling the problems related to increase of shelf life, emulsion stability, nutritional completeness and sensory acceptability without the use of high temperatures. Some pre-treatments such as peeling, bleaching or soaking can be performed on the raw material in order to improve the final product. The nutritional properties are influenced by the plant source, processing, and fortification. The addition of other ingredients as sugar, oil and flavorings is done to the plant-based milk substitute to make them more palatable and be more acceptable to consumers. Thus, the aim is to review the main reasons for the consumption of plant-based milk substitute as well as the raw materials used and the technological aspects of its production.

Effects of High-Pressure, Microbial Transglutaminase and Glucono-δ-Lactone on the Aggregation Properties of Skim Milk

The object in this study is to investigate the effects of high pressure and freezing processes on the curdling of skim milk depending on the presence of transglutaminase (TGase) and glucono-δ-lactone (GdL). Skim milk was treated with atmospheric freezing (AF), high pressure (HP), pressure-shift freezing (PSF) and high pressure sub-zero temperature (HPST) processing conditions. After freezing and pressure processing, these processed milk samples were treated with curdling agents, such as TGase and GdL. Pressurized samples (HP, PSF and HPST) had lower lightness than that of the control. In particular, PSF had the lowest lightness (p<0.05). Likewise, the PSF proteins were the most insoluble regardless of whether they were activated by TGase and GdL, indicating the highest rate of protein aggregation (p<0.05). Furthermore, the TGase/GdL reaction resulted in thick bands corresponding to masses larger than 69 kDa, indicating curdling. Casein bands were the weakest in PSF-treated milk, revealing that casein was prone to protein aggregation. PSF also had the highest G' value among all treatments after activation by TGase, implying that PSF formed the hardest curd. However, adding GdL decreased the G' values of the samples except HPST-treated samples. Synthetically, the PSF process was advantageous for curdling of skim milk.

Ultrasonic evaluation of thermodynamic parameters of liquids under high pressure

In many technological processes (e.g., in the chemical, petrochemical, food, and plastics industries), liquids are subjected to high pressures and temperatures. Therefore, knowledge of their thermodynamic properties is essential for understanding, design, and control of the process technology. Direct evaluation of the thermodynamic parameters of liquids under high pressure, using conventional methods, is very difficult. Therefore, the application of these methods in industrial conditions, particularly in on-line control of the technological parameters of liquids, is practically impossible. Ultrasonic methods (e.g., sound speed measurements) are very suitable for this purpose because of their simplicity and accuracy. The sound velocity is closely related to numerous thermodynamic properties of liquids. The objective of this paper is to address the influence of temperature and pressure on the thermodynamic parameters of liquids, using the example of diacylglycerol (DAG) oil, employing ultrasonic methods. In this paper, we present ultrasonic velocity and density measurements (performed by the authors) in DAG oil over a range of pressures and temperatures. On the basis of experimental results (the sound velocity and liquid density versus pressure and temperature) a series of DAG oil thermodynamic parameters such as specific heat ratio, intermolecular free path length, Van der Waals constant b, surface tension, and effective Debye temperature were evaluated as functions of pressure and temperature.

Mitigation of greenhouse gas emissions in the production of fluid milk

Global climate change, driven by the buildup of greenhouse gas (GHG) emissions in the atmosphere, is challenging the dairy industries in the United States and throughout the world to develop sustainable initiatives to reduce their environmental impact. The U.S. dairy industry has committed to lowering the GHG emissions, primarily CH(4), N(2)O, and CO(2), in each sector of the fluid milk supply chain which extends from the farm, to the processing plant, and to distribution of the packaged product, where it is refrigerated by the retailer and then the consumer. This chapter provides an overview of the life cycle analysis (LCA) technique and its use in identifying the GHG emissions in each sector of the fluid milk supply chain, from cradle to grave, and the best practices and research that is currently being conducted to reduce or mitigate GHG emissions in each sector. We also discuss the use of on-farm and off-farm process simulation as tools for evaluating on-farm mitigation techniques, off-farm alternative processing scenarios, and use of alternative energy management practices.

Ultra-High Pressure Homogenization-Induced Changes in Skim Milk: Impact on Acid Coagulation Properties

The effects of ultra-high pressure homogenization (UHPH) on skim milk yogurt making properties were investigated. UHPH-treated milk was compared with conventionally homogenised (15 MPa) heat-treated skim milk (90°C for 90 s), and to skim milk treated under the same thermal conditions but fortified with 3% skim milk powder. Results of the present study showed that UHPH is capable of reducing skim milk particle size which leads to the formation of finer dispersions than those obtained by conventional homogenisation combined with heat treatment. In addition, results involving coagulation properties and yogurt characteristics reflected that, when increasing UHPH pressure conditions some parameters such as density of the gel, aggregation rate and water retention are improved.