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Pengaruh Ion-ion Logam terhadap Aktivitas Pektinase dari

Aspergillus niger pada Penjernihan Sari Buah Jambu

Dian Puspita Anggraini 1)*, Anna Roosdiana1), Sasangka Prasetyawan1), Diah Mardiana1)

1) Program Pasca Sarjana Kimia, Universitas Brawijaya, Jl. Veteran No.1 Malang, 65123

Diterima 25 Februari 2013, direvisi 15 April 2013

ABSTRAK

Enzim pektinase dapat digunakan pada penjernihan berbagai jenis minuman sari buah, namun

kinerjanya dapat dipengaruhi oleh ion-ion logam yang terkandung dalam buah-buahan. Tujuan

penelitian ini adalah untuk mengetahui jenis inhibisi ion logam Zn2+

, Mg2+

dan Ca2+

terhadap aktivitas

pektinase dari Aspergillus niger dan potensinya pada penjernihan sari buah jambu. Uji aktivitas

dilakukan pada pH 5, temperatur 50oC selama 55menit dengan konsentrasi masing-masing ion 2–10mM.

Kadar asam galakturonat, sebagai produk hidrolisis substrat pektin, digunakan sebagai dasar penentuan

aktivitas dan dianalisis secara spektrofotometri visibel. Hasil penelitian menunjukkan bahwa mulai

konsentrasi 4mM ion Zn2+

; Mg2+

menjadi inhibitor untuk aktivitas pektinase sedangkan untuk ion Ca2+

mulai konsentrasi 6mM. Nilai KI untuk ion logam Zn2+

; Mg2+

dan Ca2+

saat konsentrasi 6mM berturut-

turut adalah 176,99; 326,09 dan 280,37mM. Pektinase dari Aspergillus niger mampu mengurangi kadar

pektin dari sari buah jambu sebesar 18%.

Kata kunci: Pektinase, Aspergillus niger, KI, Asam Galakturonat, Penjernihan.

.

ABSTRACT

Pectinase can be used on various fruit juices clarification, however the activities can be affected by

their metal ions content. The purpose of this study was to determine the type of metal ions inhibition i.e.

Zn2+

; Mg2+

and Ca2+

on the pectinase activity of Aspergillus niger, and its potential application in guava

juice clarification. Activity assays performed at pH 5, temperature 50°C during 55minutes and each ion

concentration were 2-10 mM. Galacturonic acid concentration, as the product of pectin substrate

hydrolysis, used as the basis for determining its activity and analyzed by visible spectrophotometry. The

results showed that the ions concentration of Zn2+

and Mg2+

more than 4 mM were inhibitor for pectinase

activity while Ca2+

ion concentration was 6mM. KI values for the metal ions Zn2+

; Mg2+

and Ca2+

at

concentrations of 6mM were 176.99; 326.09 and 280.37 mM respectively. Pectinase from Aspergillus niger

were able to reduce 18% of pectin of guava juice.

Key word: pectinase, Aspergillus niger, KI, galacturonic acid, clarification.

NATURAL B, Vol. 2, No. 1, April 2013

D. P. Anggraini, dkk. : Pengaruh Ion-ion Logam terhadap Aktivitas Pektinase dari Aspergillus niger 67

pada Penjernihan Sari Buah Jambu

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