Formulation, Stability, and Safety Evaluation of a Facial Wash Containing Yellowfin Tuna (Thunnus albacares) Bone-Derived Marine Collagen Peptide and Light Fraction Patchouli Oil

Yellowfin tuna (Thunnus albacares) bone by-products represent an underutilized, sustainable source of marine collagen for cosmetic applications. This study developed a gel-based facial wash combining tuna bone-derived marine collagen peptide (MCP) with light fraction patchouli oil (Pogostemon cablin Benth.) and evaluated its physicochemical properties, stability, and safety. Acid-soluble collagen (85.2% protein) was extracted and hydrolyzed with pepsin, yielding a low-molecular-weight MCP (<30 kDa) with a degree of hydrolysis of 27.4 ± 1.8%; FTIR confirmed the preservation of characteristic type I collagen amide bands. Four formulations containing xanthan or guar gum were evaluated under freeze–thaw cycling and three-month storage at 30 and 40 °C. The formulation containing 1% guar gum (F4) showed the most favorable profile, maintaining pH 5.60–5.87, viscosity 8884–9223 mPa·s, spreadability 5.36–6.41 cm, and homogeneity across all conditions. F4 met Indonesian regulatory requirements, with microbial counts below 10 CFU/g, absence of pathogens, and trace levels of arsenic (0.0051 mg/kg) and lead (0.0171 mg/kg). Skin testing in 20 volunteers yielded a Primary Skin Irritation Index of 0.1 (negligible irritant). These findings establish tuna bone collagen peptide as a viable rinse-off cosmetic ingredient and demonstrate a practical route for valorizing fisheries by-products.