Recovery of casein-derived peptides with in vitro inhibitory activity of angiotensin converting enzyme (ACE) using aqueous two-phase systems

Peptides inhibiting the activity of angiotensin converting enzyme (ACE) were obtained by trypsin-catalyzed hydrolysis of bovine milk casein, performed at 37 °C, during 1, 2, 5, 8 and 24 h. Results of in vitro inhibitory activity ranged between 13.4% and 78.5%. The highest ACE inhibitory activity was evidenced for hydrolysates obtained after 2 h of reaction. Aqueous two-phase systems (ATPS) formed by polyethylene glycol of 1500 g mol−1 (PEG 1500) + sodium phosphate or potassium phosphates were produced and evaluated, in terms of partition coefficients (K) and extraction yields (y), to recovery the casein hydrolysates at room temperature. In ATPS containing sodium phosphate, the peptides showed a slightly greater affinity toward the bottom salt-rich phase (0.1 ≤ K ≤ 0.9; 5.7% ≤ y ≤ 47%). In the case of ATPS containing potassium phosphates, these molecules showed substantially greater affinity toward the top polymer-rich phase (137 ≤ K ≤ 266; y ≥ 99%). These results point out extraction using PEG 1500/potassium phosphate ATPS is an efficient technique to recover casein hydrolysates containing ACE inhibitors peptides. Outlined data will be helpful in integrating such unit operation to larger scale processes

Proteases: Importance, Immobilization Protocols, Potential of Activated Carbon as Support, and the Importance of Modifying Supports for Immobilization

Although enzymes have been used for thousands of years, their application in industrial processes has gained importance since the 20th century due to technological and scientific advances in several areas, including biochemistry [...

Thermal diffusivity and specific heat of bovine milk affected by temperature and composition

The sizing of equipment used in food processing, particularly heat exchangers and other equipment that require pumping of products, requires accurate data of thermophysical properties. Milk is one of the most processed liquid food fluids in the world and currently data on its thermophysical properties are limited. In a previous paper (Alcântara et al., 2010) density and dynamic viscosity data of bovine milk were presented and how these properties are affected by temperature and composition, in ranges commonly encountered in food processing. Here the thermal diffusivity and specific heat data for milk are presented, evaluating the effect of composition (moisture, fat, lactose, protein and minerals contents) and temperature (only for thermal diffusivity). Linear regression was used and the best models were selected based on the determination coefficient (R2), lack of fit, significance parameters and root mean square error (RMSE) values. Predictive ability of fitted models was compared with Choi and Okos (1986) correlations. Thermal diffusivity ranged from (1.00 to 9.03) × 10-7 m2•s-1 and specific heat from (3.078 to 4.121) kJ•kg-1•K-1. Thermal diffusivity presented a polynomial quadratic behavior affected by temperature and composition, except for lactose concentration which showed no significant effect (p>0.05). For specific heat, increase in the moisture content led to an increase in the specific heat while elevations in fat, protein, lactose and mineral contents promoted a decrease of this property. In both cases the fitted models showed satisfactory R2 values, non- significant lack of fit (p>0.05) and significant parameters (p<0.05), with RMSE values lower than Choi and Okos (1986) correlations. From the properties presented here and in the earlier paper, accurate calculations can be made for correct sizing and adaptation of equipment, as well as provide information of other thermophysical properties such as thermal conductivity and thermal expansion coefficient

Current advances in obtaining novel cyclodextrin glycosyltransferases for optimizing the synthesis of cyclodextrins

The cyclodextrins (CDs) market has increased due to their numerous applications, especially in the food and pharmaceutical industries. The high cost of synthetizing one unique form of CDs, mainly the α- and γ- forms, hinders their use in certain processes. Since CDs are exclusively produced by the enzymatic conversion of starch or starch derivates using cyclodextrin glycosyltransferase (CGTase), enhancing this enzyme production means feasible CD synthesis. Recent discoveries of novel CGTase producers and strategies for optimizing fermentation processes and immobilization techniques have expanded its applications. However, the low yield arising from wild strains remains an obstacle. Studies focused on overexpressing CGTase through heterologous expression and improving their catalytic properties by altering protein structure using protein engineering approaches have been explored to enable upscaling the applications of CGTase. This review surveys recent approaches employed in CGTases production aiming at industrial scale. Overall, the importance of advances in biotechnology for cost reduction in upscale processes and perspectives for future research were highlighted.</p