Pengaruh Konsentrasi dan Jenis Larutan Perendaman terhadap Kecepatan Ekstraksi dan Sifat Gel Agar-agar dari Rumput Laut Gracilaria verrucosa

https://doi.org/10.22146/jrekpros.549

Sperisa Distantina(1*), Devinta Rachmawati Anggraeni(2), Lidya Eka Fitri(3)

(1) 
(2) 
(3) 
(*) Corresponding Author

Abstract


Rumput laut jenis Gracilaria penghasil agar-agar banyak tumbuh di Indonesia, tetapi studi pengolahannya belum banyak. Penelitian ini bertujuan mempelajari proses transfer massa pada ekstraksi agar-agar dari rumput laut Gracilaria verucosa (pantai Pekalongan) secara bacth menggunakan pelarut air. Pengaruh penggunaan alkali NaOH (1,5 N dan 3,75 N) dan asam asetat (0,2 N, 0,6 N, dan 0,8 N) pada tahap perendaman terhadap koefisien transfer massa (kca) dan sifat gel agar-agar (gel strength, melting dan setting temperature) juga dipelajari. Rumput laut direndam menggunakan larutan alkali atau asam selama 15 menit. Setelah dicuci menggunakan air sampai pH netral, rumput laut diekstraksi menggunakan pelarut air. Ekstraksi dijalankan di dalam gelas beker yang dilengkapi motor pengaduk. Cuplikan sampel diambil setiap interval waktu tertentu. Cuplikan dibekukan semalam dalam freezer, kemudian diangin-anginkan sehingga air mencair dan terpisah dari agar-agar. Agar-agar yang dihasilkan dikeringkan mengunakan oven (70C) sampai berat konstan. Hasil penelitian menunjukkan bahwa perendaman dengan alkali menghasilkan kecepatan ekstraksi yang lebih lambat, rendemen lebih rendah tetapi sifat gel agar-agar yang lebih baik dibandingkan perendaman menggunakan larutan asam.

Kata kunci: Alkali, Asam Asetat, Perendaman, Ekstraksi, kca

Seaweeds of Gracilaria species are abundantly cultivated in Indonesia. However, studies related to its extraction process are still rare. In the present work, the mass transfer process on a batch extraction of agar was studied by extracting seaweeds in hot water solvent. The effect of alkali (NaOH) and acetic acid (CH3COOH) in the soaking process on the volumetric mass transfer coefficient (kca) and the quality of gel agar were investigated. Seaweeds (Gracilaria verrucosa) from Pekalongan coast were soaked in aqueous NaOH (1.5 N and 3.75 N) or in aqueous acetic acid solution (0.2 N, 0.6 N, and 0.8 N). After being washed, the seaweeds were extracted in hot water of 98C and neutral pH. Some of the extract samples at various times were freezed, thawed, dried and weighed. The evaluation of experimental data showed that the mass transfer coefficient kca decreased and the gel strength of agar increased with the increase of alkali concentration. Meanwhile, the value of kca increased and the gel strength of agar decreased with the increase of acetic acid concentration.

Key words: Alkali, Acetic Acid, Soaking, Extraction, Volumetric Mass Transfer Coefficient (kca), Gel strength

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DOI: https://doi.org/10.22146/jrekpros.549

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