Production and evaluation of enzyme-modified cheese adding protease or lipase to improve quality properties.

Enzyme-modified cheese (EMC) produced by enzyme hydrolysis is a natural, cost-effective, and flexible alternative to using natural cheese in industrial applications. The modification of cheese by enzymes can increase their benefits for consumer acceptance and health, and intensify the specific cheese flavor. We evaluated the properties of cheese with added protease (Ep) or lipase (El), including texture, sensory, organic acids, volatile compounds, and free amino acids. As results, the hardness and gumminess of the cheese reached their maximum values when the concentration of protease and lipase was 0.1% and 0.6%, respectively. Interestingly, the bitterness and astringency of the cheese was reduced. The highest scores for odor, taste, and overall acceptability were observed on 0.08% protease in Ep and 0.8% lipase in El. Compared with the anchor cheese, eight new compounds were produced after the addition of protease and nine new compounds were produced after the addition of lipase. Irrespective of the type of enzyme, the content of free amino acids decreased slightly with the increase in enzyme content. From the point of view of adding enzyme species, the free amino acids content of Ep was generally higher than that of El, and glutamic acid and proline contents were high. Acetic acid concentrations (aroma-active compounds) of enzyme-modified cheese using protease and lipase were 482-931 mg/100 g and 30-36 mg/100 g, respectively, which were significantly increased. According to the results obtained in this study, a cheese with higher sensorial and textural acceptability was obtained by adding the appropriate protease or lipase.

Effectively Promoting Activity and Stability of a MnCo2O4-Based Cathode by In Situ Constructed Heterointerfaces for Solid Oxide Fuel Cells.

The development of multiphase composite electrocatalysts plays a key role in achieving the efficient and durable operation of intermediate-temperature solid oxide fuel cells (IT-SOFCs). Herein, a self-assembled nanocomposite is developed as the oxygen reduction reaction (ORR) catalyst for IT-SOFCs through a coprecipitation method. The nanocomposite is composed of a doped (Mn0.6Mg0.4)0.8Sc0.2Co2O4 (MMSCO) spinel oxide (84 wt %), an orthorhombic perovskite phase (11.3 wt %, the spontaneous combination of PrO2 additives and spinel), and a minor Sc2O3 phase (4.7 wt %). The surface of the (Mn0.6Mg0.4)0.8Sc0.2Co2O4 phase is activated by the self-assembled nanocoating with many heterogeneous interfaces. Thence, the ORR kinetics is obviously accelerated and an area-specific resistance (ASR) of ∼0.11 Ω cm2 is obtained at 750 °C. Moreover, a single cell with the cathode shows a peak power density (PPD) of 1144.1 mW cm-2 at 750 °C, much higher than that of the cell with the MnCo2O4 cathode (456.2 mW cm-2). An enhanced stability of ∼120 h (0.8 A cm-2, 750 °C) is also achieved, related to the reduced thermal expansion coefficient (13.9 × 10-6 K-1). The improvement in ORR kinetics and stability can be attributed to the refinement of grains, the formation of heterointerfaces, and the enhancement of mechanical compatibility.