This research was done to explore bioactivity of Xylocarpus granatum's stem extract as tyrosinase inhibitor for alternative preventing black spot in Litopenaeus vannamei postharvest. In this research, extraction of bioactive compound from X. granatum stem was done by soaking the stem in 96% methanol for 24h at temperature 29°C. The methanol was evaporated by using rotary evaporator at temperature 50°C. The extract was dilute with distillate water at series of dilutions (10%, 30%, 50%, 70%, 90%, and distillate water as the control), and then immersing L. vannamei into X. granatum's stem extract as much as 10ml for 6h, and finally the data analyzing use the Kruskal Wallis test and the Least Significant Difference (LSD) test with the degree of confident 95%. The result showed that X. granatum's stem extract is able to prevent a black spot of L. vannamei after harvesting process. Furthermore, concentration of 10 % of extract is an effective concentration for preventing a black spot and the control has black spot 0.0360 -0.0373 mm 2 .
Article history:Received 11 Pencegahan black spot secara fisik pada pasca panen yaitu cephalothorax udang dihilangkan sehingga menjadi udang head less. Cephalothorax udang telah diketahui mengandung polifenoloxidase, enzim tersebut mampu aktif pada kondisi optimumnya yaitu pH 6 dan suhu 45°C, aktifnya enzim tersebut mengakibatkan timbulnya black spot (Gimenez, 2004). Penghilangan kepala udang bertujuan untuk mengurangi jumlah dan aktivitas polifenoloxidase selama proses pasca panen (Benjakul, 2005).Pencegahan black spot secara kimia pada proses pasca panen yaitu penambahan asam askorbat pada udang sebagai antioksidan, perendaman udang ke dalam air es yang mengandung 100 ppm natrium bisulfit (NaHSO 3 )/sodium bisulfit, perendaman udang ke dalam air es yang mengandung 2 ppm metabisulfit/sodium metabisulfit 2 ppm selama 2 menit, serta pencucian udang dengan air yang mengandung klorin 1-10 ppm (Badan Standarisasi Nasional, 1998).Sulfit (metabisulfit maupun bisulfit) merupakan bahan