Water Activity Prediction in Sugar and Polyol Systems Using Theoretical Molecular Descriptors

The Role of Cosolvent-Water Interactions in Effects of the Media on Functionality of Enzymes: A Case Study of Photobacterium leiognathi Luciferase

A complex heterogeneous intracellular environment seems to affect enzymatic catalysis by changing the mobility of biomolecules, their stability, and their conformational states, as well as by facilitating or hindering continuously occurring interactions. The evaluation and description of the influence of the cytoplasmic matrix components on enzymatic activity are problems that remain unsolved. In this work, we aimed to determine the mechanisms of action of two-component media with cosolvents of various molecular sizes on the complex multi-stage bioluminescent reaction catalyzed by bacterial luciferase. Kinetic and structural effects of ethylene glycol, glycerol, sorbitol, glucose, sucrose, dextran, and polyethylene glycol on bacterial luciferase were studied using stopped-flow and fluorescence spectroscopy techniques and molecular dynamics simulations. We have found that diffusion limitations in the presence of cosolvents promote the stabilization of flavin substrate and peroxyflavin intermediate of the reaction, but do not provide any advantages in bioluminescence quantum yield, because substrate binding is slowed down as well. The catalytic constant of bacterial luciferase has been found to be viscosity-independent and correlated with parameters of water-cosolvent interactions (Norrish constant, van der Waals interaction energies). Crowding agents, in contrast to low-molecular-weight cosolvents, had little effect on peroxyflavin intermediate decay and enzyme catalytic constant. We attributed specific kinetic effects to the preferential interaction of the cosolvents with enzyme surface and their penetration into the active site.

Characterization of eutectic mixtures of sugars and sugar-alcohols for cryopreservation

Natural Deep Eutectic Systems (NADES) composed of sugar and sugar alcohols have been studied and applied in a variety of biological applications. Understanding their interaction with water across dilution and temperature is inherently important for maximizing the utility of NADES. Herein a wide range of sugar:sugar-alcohol molar ratios were synthesized and characterized by viscosity, molar excess volume, differential scanning calorimetry, water activity, and confocal Raman cryomicroscopy. NADES were found to have greater viscosity, reduced heat of fusion, greater absolute molar excess volume, lower water activity, and stronger hydrogen bonding of water than non-NADES mixtures. This is hypothesized to be due to cumulatively stronger hydrogen bonding interactions between components in pure and diluted NADES with the strongest interactions in the water-rich region. This work provides useful data and further understanding of hydrogen bonding interaction strength for a wide range of molar ratios in pure to well-diluted forms.

The Impact of the Water Evaporation Rate and Saccharide Excipients on the Oxidative Degradation of Polysorbates During Oven Drying and Spray Drying

In recent years, many fast drying techniques such as spray-drying are being explored as alternatives to biopharmaceutical freeze-drying. Thus, it is essential to understand how the processability of commonly used excipients will be affected when these new techniques are employed. This study reports a series of observations outlining how the thermally-induced oxidative degradation of polysorbates (PS) evolves in liquid to solid transitions, such as those expected in spray-drying. Firstly, the impact of different evaporation rates on the oxidative degradation of aqueous solutions of two different PS types namely, PS20 and PS80, were screened via evaporative solvent casting. The latter revealed that the evaporation rate could critically impact the rate-limiting steps of PS thermal oxidation. In addition, the potential of saccharides as excipients to mitigate the thermal oxidation of PS80 under slow and fast evaporation conditions was investigated. Five different saccharide excipients were screened, i.e., trehalose dihydrate, maltodextrin, hydroxypropyl-β-cyclodextrin, and Dextran 40. Under slow evaporation conditions, only trehalose dihydrate seemed to be beneficial in avoiding the thermal oxidation of PS80. For fast evaporation conditions, hydroxypropyl-β-cyclodextrin prevented the oxidative degradation of PS80. This implies that distinct strategies to mitigate PS oxidative degradation might be necessary depending on the drying process and rates.

Use of Olive and Sunflower Oil Hydrogel Emulsions as Pork Fat Replacers in Goat Meat Burgers: Fat Reduction and Effects in Lipidic Quality

Diversified strategies to incorporate healthier lipids in processed meat products are being developed. Alternative fat sources to replace animal fat associated with the reduction of fat content are some of the methods used to obtain healthier meat products well recognized by consumers. In order to create a healthier product that can also be consumed in the Halal and Kosher consumer markets, an experimental study was developed to assess the effects of replacing the pork fat (4%) with the same amount of hydrogel emulsion incorporating olive oil or sunflower oil. Three burgers were randomly selected from each lot manufactured and analyzed in triplicate. Burgers were physicochemical analyzed for pH, water activity, composition, fatty acid profile, color, yield, texture, oxidative stability, and volatile compounds and compared according to the fat source. Burgers with hydrogel emulsions can be considered reduced-fat meat products with a healthier fatty acid profile than pork fat burgers. The use of hydrogel emulsions did not negatively affect the quality characteristics assessed in the product and improved the oxidative stability during the storage of cooked burgers. By the characteristics and formulations evaluated, the replacement of pork fat with olive oil hydrogel emulsion proved to be the most effective strategy for obtaining a healthier goat meat product.

Continuous Flow Glycolipid Synthesis Using a Packed Bed Reactor

Glycolipids are a class of biodegradable biosurfactants that are non-toxic and based on renewables, making them a sustainable alternative to petrochemical surfactants. Enzymatic synthesis allows a tailor-made production of these versatile compounds using sugar and fatty acid building blocks with rationalized structures for targeted applications. Therefore, glycolipids can be comprehensively designed to outcompete conventional surfactants regarding their physicochemical properties. However, enzymatic glycolipid processes are struggling with both sugars and fatty acid solubilities in reaction media. Thus, continuous flow processes represent a powerful tool in designing efficient syntheses of sugar esters. In this study, a continuous enzymatic glycolipid production catalyzed by Novozyme 435® is presented as an unprecedented concept. A biphasic aqueous–organic system was investigated, allowing for the simultaneous solubilization of sugars and fatty acids. Owing to phase separation, the remaining non-acylated glucose was easily separated from the product stream and was refed to the reactor forming a closed-loop system. Productivity in the continuous process was higher compared to a batch one, with space–time yields of up to 1228 ± 65 µmol/L/h. A temperature of 70 °C resulted in the highest glucose-6-O-decanoate concentration in the Packed Bed Reactor (PBR). Consequently, the design of a continuous biocatalytic production is a step towards a more competitive glycolipid synthesis in the aim for industrialization.

A Simulation Analysis of a Microalgal-Production Plant for the Transformation of Inland-Fisheries Wastewater in Sustainable Feed

The present research evaluates the simulation of a system for transforming inland-fisheries wastewater into sustainable fish feed using Designer® software. The data required were obtained from the experimental cultivation of Chlorella sp. in wastewater supplemented with N and P. According to the results, it is possible to produce up to 11,875 kg/year (31.3 kg/d) with a production cost of up to 18 (USD/kg) for dry biomass and 0.19 (USD/bottle) for concentrated biomass. Similarly, it was possible to establish the kinetics of growth of substrate-dependent biomass with a maximum production of 1.25 g/L after 15 days and 98% removal of available N coupled with 20% of P. It is essential to note the final production efficiency may vary depending on uncontrollable variables such as climate and quality of wastewater, among others.