Actinidin: A Review from Molecular Mechanisms to Biotechnological Applications

Actinidin is a cysteine protease recognized as the predominant protease in kiwifruit. It possesses distinctive catalytic and structural properties that determine its specificity and behavior with different substrates. This, along with its plant origin, has made it one of the most prominent plant-derived proteases. This review offers a comprehensive overview of the available knowledge on this enzyme, addressing its molecular and biochemical characteristics, its production, extraction, purification, and technological optimization. The main biotechnological applications of actinidin are also presented and discussed, with particular emphasis on its use in the processing of food proteins in diverse matrices such as meat, milk, and gluten proteins, its role in digestion, and its antigenic relevance. The available information suggests that actinidin is effective in the hydrolysis of multiple proteins, but its activity clearly depends on the substrate and reaction conditions, which explains its advantages and limitations compared to other enzymes. The diverse range of studies conducted on actinidin reflects the versatility of this enzyme. However, compared with other proteases, relatively few studies have investigated its immobilization or its application in the production of bioactive peptides. Thus, there are significant technological and academic gaps and a need for further studies on actinidin so that its catalytic properties may be fully understood and exploited, on par with other proteases such as papain and bromelain.