PENGARUH PENAMBAHAN ASAM ORGANIK TERHADAP PERUBAHAN KUALITAS EKSTRAK DAUN NOJA (PERISTROPHE BIVALVIS) KARENA TERJADINYA REAKSI OKSIDASI

ABSTRAK Noja (Peristrophe bivalvis) adalah tumbuhan sumber pewarna alami yang potensial dikembangkan di Indonesia. Ekstrak daun noja dapat mengalami kerusakan karena teroksidasi selama penyimpanan. Penambahan asam tanat, asam tartarat, dan asam sitrat diharapkan dapat menghambat terjadinya hal tersebut. Penelitian ini bertujuan untuk mengetahui pengaruh penambahan asam tanat, asam tartarat, dan asam sitrat terhadap kecepatan kerusakan ekstrak daun noja akibat oksidasi. Indikator kerusakan dinyatakan sebagai perubahan absorbansi ekstrak terhadap waktu. Pengamatan pada penelitian ini dipercepat dengan menambahkan hidrogen peroksida. Asam tanat, asam tartarat, dan asam sitrat pada berbagai variasi konsentrasi ditambahkan ke dalam larutan ekstrak daun noja, diikuti dengan penambahan 1% (v/v) hidrogen peroksida 30%. Pengukuran absorbansi dilakukan setiap 30 menit. Hasil yang diperoleh menunjukkan bahwa penambahan asam tanat, asam tartarat, dan asam sitrat, memberikan kenaikan nilai absorbansi larutan terhadap waktu sebesar 2 - 3%; 20 - 26% dan 23 - 26%, sedangkan tanpa penambahan asam (blangko) memberikan kenaikan sebesar 24%. Hasil tersebut menunjukan bahwa penambahan asam tanat dan asam tartarat dapat menghambat reaksi oksidasi. ABSTRACT Noja (Peristrophe bivalvis) has the potential to be developed in Indonesia as a natural dyes source. During storage, noja leaves extract was degraded due to oxidation. The addition of tannic acid, tartaric acid, and citric acid expected to inhibit the degradation. This study aims to determine the effect of tannic acid, tartaric acid, and citric acid addition toward the degradation rate of the oxidation. The extract degradation indicator was expressed as the change in absorbance value. In order to shorten the observation time, the oxidation was accelerated by adding hydrogen peroxide. Tannic acid, tartaric acid, and citric acid at various concentrations were added to the noja leaves extract solution, followed by the addition of 1% (v/v) hydrogen peroxide 30%. The absorbance of the sampel was measured every 30 minutes. The results showed that the increase absorbance value of the extract without the addition of organic acid (blank) was about 24%, while the addition of tannic acid, tartaric acid, and citric acid were 2 - 3%; 20 - 26% and 24 - 34% respectively. Thus, it can be concluded that tannic acid and tartaric acid addition inhibits the oxidation.