PENGHAMBATAN AKTIVITAS ENZIM α-GLUKOSIDASE OLEH EKSTRAK KASAR ANTOSIANIN UBI JALAR UNGU SEGAR DAN PRODUK OLAHANNYA (Inhibition Activity of α-Glucosidase by Anthocyanin Crude Extract from Purple Sweet Potato and Its Products)

Abstract

Purple sweet potato is one of the anthocyanin sources that potential to normalize blood sugar levels in diabetics because it can inhibit α-glucosidase. Since it easily damaged, processing into flour or chips is an alternative to extend the shelf life. This study aimed to determine the content of total phenol, total anthocyanin and inhibition of the α-glucosidase enzyme by crude anthocyanin extract from fresh purple sweet potato, conventional and modified flour and chips. Testing of total phenol, anthocyanin and inhibition of α-glucosidase enzyme activity were carried out using the spectrophotometric method. The results showed that total phenol, anthocyanin and inhibition of α-glucosidase enzyme activity from crude anthocyanin extracts using acid solutions in fresh purple sweet potato were respectively 291.7 mg GAEs/100g, 122.1 mg/100 g; 41.73%; sweet potato flour at 212.1 mg GAEs/100 g, 171.3 mg/100 g; 37.61%; purple sweet potato flour rich in resistant starch  of 182.5 mg GAEs/100 g, 141.1 mg/100 g; 65.59%; purple sweet potato flour partially gelatinized of 193.5 mg GAEs/100 g, 139.4 mg/100 g; 39.91%; and purple sweet potato chips of 299.5 mg GAEs/100 g, 203.6 mg/100 g, 44.73%. The ability of anthocyanin to inhibit the activity of the α-glucosidase enzyme could be increased through the retrogradation of starch and frying into chips. Keywords: α -glucosidase, anthocyanin, diabetic, purple sweet potato ABSTRAK Ubi jalar ungu merupakan salah satu sumber antosianin yang berpotensi menormalkan kadar gula darah penderita diabetes karena dapat menghambat enzim α -glukosidase. Ubi jalar ungu segar mudah mengalami kerusakan, sehingga pengolahan dalam bentuk tepung atau keripik merupakan suatu alternatif untuk memperpanjang masa simpan. Penelitan ini bertujuan untuk mengetahui kandungan total fenol, total antosianin serta penghambatan enzim α-glukosidase oleh ekstrak kasar antosianin dari ubi jalar ungu segar, tepung ubi jalar ungu konvensional dan yang termodifikasi secara fisik serta keripik ubi jalar ungu. Pengujian total fenol, antosianin dan penghambatan aktivitas enzim α -glukosidase dilakukan dengan menggunakan metode spektrofotometri. Hasil penelitian menunjukkan bahwa total fenol, antosianin dan  penghambatan aktivitas enzim α-glukosidase dari ekstrak kasar antosianin menggunakan larutan asam pada ubi jalar ungu segar  berturut-turut sebesar 291,7 mg GAEs/100 g, 122,1 mg/100 g; 41,73%; tepung ubi jalar sebesar 212,1 mg GAEs/100 g, 171,3 mg/100 g; 37,61%; tepung ubi jalar ungu kaya pati resisten (TP) sebesar 182,5 mg GAEs/100 g, 141,1 mg/100 g; 65,59%; tepung ubi jalar ungu tergelatinisasi parsial (TG) sebesar 193,5 mg GAEs/100 g, 139,4 mg/100 g; 39,91%; dan keripik  ubi jalar ungu (KU) sebesar 299,5 mg GAEs/100 g, 203,6 mg/100 g; 44,73% . Kemampuan antosianin dalam menghambat aktivitas enzim α-glukosidase dapat ditingkatkan melalui proses retrogradasi pati dalam ubi dan penggorengan ubi jalar ungu menjadi keripik. Kata kunci: α-glukosidas, antosianin, diabetes mellitus, ubi jalar ungu