## 1 Introduction
Enzymatic-based exfoliation represents a gentler alternative to traditional physical and chemical exfoliation, providing effective skin renewal without compromising the skin barrier. Enzyme peels are a relatively new category of exfoliating treatment employing naturally occurring enzymes, like bromelain, ficin, and papain. Enzymatic reactions take place in order to hydrolyze proteins like keratin, leading to the removal of corneocytes from the _stratum corneum_ and the shedding of dead skin cells. This method provides effective exfoliation, resulting in a smoother, toned, more radiant complexion and an enhanced skin texture and appearance [8; 11; 17; 18]. Unlike chemical exfoliants which dissolve the intercellular matrix via pH-dependent desquamation, enzymatic exfoliation is less aggressive. Since they minimize the risk of irritation, they are suitable for several skin types, i.e., sensitive, dry, oily, problematic, or combined ones, and for individuals with acne-prone skin, rosacea, or inflammatory conditions [8; 11; 17; 18]. Additionally, enzymatic exfoliants do not require extreme pH levels to function, and thus, they are easily incorporated into mild, skin-friendly cosmetics; however, they are easily influenced by several factors, like temperature, enzyme concentration, and formulation stability. When they are extracted from fruit by-products, they may require additional stabilization techniques to maintain their bioactivity. Advances in eco-friendly extraction methods, nanoencapsulation, and product stabilization techniques have notably improved the longevity, bioactivity, and possibility of integrating these alternative sources in cosmetic formulations (i.e., peels, masks, and cleansers) [19; 20; 21]. Such natural peeling factors are not new; the concept of using natural enzymes regarding traditional skincare practices dates back to many centuries ago. During the late 20 th century, as cosmetic industries began to prioritize natural alternatives to traditional exfoliants, enzyme peels gained increasing attention. For the past 50 years, the scientific understanding of enzymes has grown remarkably due to their ability to offer effective exfoliation without causing irritation [1; 5; 15]. Scientists and cosmetic formulators recognized their potential not only for their exfoliating properties, but also for their anti-inflammatory, anti-melanoma, antioxidant, and soothing effects [18; 22; 23; 24; 25; 26]. Initially, enzyme peels were a luxury, found primarily in high-end spas and professional skincare treatment. Over time, their growing popularity created a demand for more accessible formulations, leading to the introduction of enzyme peels in over-the-counter products. Modern formulations provide the benefits of enzyme peels in innovative cosmetic products [1; 8; 15; 27]. Despite the increasing use of enzyme-based exfoliants in cosmetics, the current literature remains limited in several key aspects, including the lack of comparative analyses of bromelain, ficin, and papain's cosmetic benefits, their fruit by-products' potential as alternative sources in skincare formulations, and the consolidated literature regarding enzyme formulation techniques, innovations, and cost-effectiveness in the cosmetic science domain. This review aims to bridge such knowledge gaps by integrating an all-inclusive comparison and the latest research findings considering these proteolytic enzymes [1; 5; 15]. The principal aim of this research is to investigate the proteolytic function of these enzymes used in cosmetic formulations, namely bromelain, ficin, and papain, which are widely known for partaking in skin exfoliation. A comprehensive evaluation and comparative analysis of each enzyme's proteolytic activity, biochemical mechanisms of action, optimal conditions, effectiveness in skin exfoliation and rejuvenation, and their extraction from fruit by-products as a sustainable alternative will be provided.