<![CDATA[This study aimed to determine the effect of utilizing pineapple bromelain extract as a natural coagulant on the coagulation time and lump grade of rubber latex (Hevea brasiliensis). The study was conducted from November 2025 to April 2026 in Block U28, Afdeling 10, PT Bridgestone Sumatera Rubber Estate, Simalungun Regency, North Sumatra. The study used a non-factorial Randomized Complete Block Design (RCBD) with five treatments and five replications. The treatments consisted of P0 = 3 mL formic acid/100 mL latex, P1 = 1.5 mL, P2 = 5 mL, P3 = 10 mL, and P4 = 15 mL pineapple extract/100 mL latex. The observed parameters included coagulation time and lump grade. Coagulation time data were analyzed using analysis of variance (ANOVA), followed by Duncan’s Multiple Range Test (DMRT) at the 5% significance level, while lump grade data were analyzed using the Kruskal–Wallis test at the 5% significance level. The results showed that pineapple extract had a highly significant effect on latex coagulation time, with an F-value of 735.605 and a significance value of 0.000. Treatment P4 resulted in the fastest coagulation time, at 17.56 minutes, while P1 resulted in the longest coagulation time, at 51.28 minutes. For the lump grade parameter, the Kruskal–Wallis test showed an H-value of 12.319 with a significance value of 0.015, indicating differences among treatments. Treatment P4 produced Grade 1 (very good) in all replications. Based on both parameters, P4, with a dose of 15 mL pineapple extract/100 mL latex, produced the best coagulation characteristics in this study. Keywords: bromelain, pineapple extract, natural coagulant, latex, lump grade, rubber ]]>
