## 8 Bromelain, Ficin, and Papain Peels By-Products-Based Cosmetic Applications
Oily and acne-prone skin can benefit from bromelain's antimicrobial and anti-inflammatory properties [23; 133], as well as fiction's soothing effects [70]. For dry and aging skin, papain's ability to break down collagen and fiction's influence on the extracellular matrix contribute to improved hydration and skin renewal [198; 199]. Additionally, hyperpigmented skin may come across enhancement through the exfoliating and anti-melanogenic effects of both papain and fiction, promoting a more even skin tone [25; 121]. At this point, it is interesting to add that although allergic reactions to bromelain, fiction, and papain are rare, they should still be considered, especially for individuals with sensitivities to certain plant-based allergens. Bromelain, which is derived from pineapple, may cause skin rashes, itching, or swelling reactions in individuals with pineapple allergies, and can also lead to false-positive latex skin pick tests, while cross-reactivity with allergens such as latex, papain, or wheat flour is also possible [42; 46; 196]. Ficin may trigger irritation and allergic reactions, particularly in those sensitive to fig by-products, with a notable link to cross-sensitization with birch pollen allergens [136; 165; 197]. Finally, papain, while widely used in skincare, may cause rashes, itching, contact dermatitis, or hives, and its keratinocyte activity can degrade tight junction proteins, increasing skin permeability. Individuals with sensitive skin are more prone to reactions, making it important to patch-test enzyme-based products before use [154; 197]. Bromelain, fiction, and papain each offer unique benefits for cosmetic applications, with varying degrees of exfoliation, anti-inflammatory properties, and whitening effects. However, bromelain's strong exfoliation and calming properties, ficin's gentle exfoliation profile, and papain's deep cleansing and acne treatment characteristics serve as promising cosmetic agents [18; 22; 44; 158]. The choice of enzyme depends on the desired formulation outcomes, skin type compatibility, and stability considerations. Future research and development may focus on optimizing enzyme delivery, and enhancing stability for more effective skincare solutions [18; 22; 44; 158]. Sustainability and Circular Economy of Bromelain, Ficin, and Papain Enzyme Peel By-Products-Based Cosmetic Applications  
Incorporating enzymes like bromelain, ficin, and papain into cosmetic formulations requires an understanding of the economic aspects of sustainability and market availability. Bromelain is relatively cost-effective and widely available due to the extensive cultivation of pineapples and the use of by-products like stems. Bromelain's strong exfoliating properties and anti-inflammatory benefits are utilized in various skincare products [27]. Ficin is slightly more expensive and less readily available because of figs' limited cultivation and the labor-intensive extraction process. However, ficin is valued in niche markets for its gentle exfoliating action towards sensitive skin types in specialized skincare [200]. Finally, papain is cost-effective and widely used across multiple industries as it is abundant and easily extracted. Papain's exfoliating value, robust market presence, and cost-efficiency contribute to its broad appeal in cosmetic formulations [99]. The use of bromelain, ficin, and papain in cosmetics exemplifies a commitment to circular economy principles and sustainability, via the innovative use of by-products and green methods of extraction. Such plant-derived enzymes that are often discarded represent a strategic shift towards waste reduction and resource efficiency [68; 201]. Bromelain from pineapple waste, such as stems and peels, ficin from fig tree latex, and papain from unripe papaya fruit latex, highlight how agricultural by-products may be repurposed into valuable cosmetic ingredients [41; 68; 181; 201].