No abstract

Enzymes require a certain level of water in their structures in order to maintain their natural conformation, allowing them to deliver their full functionality. Furthermore, as a modifier of the solvent, up to a certain level, water can modify the solvent properties such as polarity/polarizability as well as the solubility of the reactants and the products. In addition, depending on the type of the reaction, water can be a substrate (e.g., in hydrolysis) or a product (e.g., in esterolysis) of the enzymatic reaction, influencing the enzyme turnover in different ways. It is found that regardless of the type of reaction, the functionality of enzyme itself is maximum at an optimum level of water, beyond which the enzyme performance is declined due to the loss in enzyme stability. Furthermore, mass transfer limitations caused by pathway blockage and/or by reduced solubilities of the reactants and/or products can also affect the enzyme performance at higher water levels. Controlling water content of ingoing CO2 and substrates as well as precise management of enzyme support and salt hydrates are important strategies to adjust water level in reaction media, especially in supercritical environments.

In the present study, chemical and sensory qualities of fish burgers prepared from deep flounder (Pseudorhombus elevatus Ogilby, 1912) with and without coating (Group A and Group B, respectively) or batter and breading materials were determined during frozen storage at )18°C for 5 months. According the statistical results, Total volatile base nitrogen of two groups increased significantly (P < 0.05) but a significant decrease (P < 0.05) was observed at the third month for Group A. Thiobarbituric acid value of Group A decreased significantly (P < 0.05) with the storage time from 1.01 to 0.22, whereas a significant increase (P < 0.05) was observed for Group B from 0.15 to 0.62 at the end of storage time. There were significant differences of pH in either the Group A or Group B between the beginning and end of the storage periods (P < 0.05). Parameters of colour, texture, taste and general acceptability for two groups decreased (P < 0.05) but Group B indicated better scores than Group A at the end of the storage period.

No abstract

The primary objective of this study was to investigate the pyrolytic conversion of crude tall oil, a byproduct from the Kraft process in the pulping industry, to hydrocarbon products for use as renewable hydrocarbons and fuels. Abietic acid, the main resin acid in crude tall oil, and tall oil fatty acids, the main distillate fraction of crude tall oil, were pyrolyzed separately using a batch micro reactor at 370, 410, and 450°C for 2 h. The gas and liquid reaction products were identified and quantified using gas chromatography equipped with a flame ionization detector, a thermal conductivity detector, and mass spectrometry. At all temperature regimes, the pyrolysis of abietic acid resulted in the formation of aromatic compounds characterized by up to three benzene rings. While the pyrolysis of tall oil fatty acids at lower temperatures resulted in alkanes and alkenes and negligible amounts of aromatic compounds, higher temperatures promoted the formation of relatively shorter chain alkanes and alkenes and detectable amounts of aromatics. The presence of both CO and CO 2 in the gas fractions suggested that deoxygenation of the initial compounds proceeded through decarbonylation and decarboxylation, but the favored mechanism is dependent upon the structure of the initial substance. This work demonstrates the feasibility of producing renewable hydrocarbons through the pyrolysis of the fatty-acid-rich distillate fraction of crude tall oil.