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Enzymatic tenderization is extensively applied in the meat industry, whereas its influence on meat flavor has seldom been evaluated. Proteinase K, papain, bromelain and Flavourzyme® were used to treat beef muscle, and the changes in volatile compounds and odors were subsequently analyzed. Proteolysis by proteinase K was found to elevate the average bitterness of the identified peptides by generating peptides with high Q values, whereas proteolysis by papain generated the highest level of amino acids. Enzymatic treatment by Flavourzyme and bromelain significantly elevated the levels of ketones and odors, whereas excessive proteolysis by papain and proteinase K largely reduced the levels of esters and aldehydes. The level of amino acids and degree of hydrolysis were found to be predominant factors that regulated the level of volatiles and odors. These results highlighted the huge influence of enzymatic tenderization on meat flavor, depending on degree of hydrolysis and cleavage pattern of applied proteases.

The dependency of photocatalyst on light limits the large-scale application of photocatalysis technology. Thus, it was explored that the feasibility of the blue long afterglow phosphor and g-C3N4 for constructing a light-storing assisted photocatalytic composite with sustained activity in this study. The g-C3N4/Sr2MgSi2O7:(Eu,Dy) composite was prepared by a simple thermal polymerization method and the photocatalytic removal of NO under illumination and dark was studied. The experimental phenomena were explained from the aspects of optical properties, afterglow brightness and photoelectrochemical results. For the first time, the concept of cumulative pollutant degradation concentration(SC) was defined, which could be used as a quantitative index to evaluate the photocatalytic effect under illumination and dark. The results revealed that g-C3N4/Sr2MgSi2O7:(Eu,Dy) exhibited an enhanced photocatalytic activity under illumination due to the reduced recombination rate of carriers and the improved light absorption capacity. The existence of Sr2MgSi2O7:(Eu,Dy) as an internal light source endowed the composite with the ability to degrade pollutants continuously in the dark. The duration of photocatalysis in the dark was related to the brightness of afterglow and the photocatalytic activity. This study is helpful to promote the development of photocatalytic system with sustained activity.