Isoterm Sorpsi Lembab Beras Berkalsium

https://doi.org/10.22146/agritech.9708

Chatarina Wariyah(1*), Supriyadi Supriyadi(2)

(1) Program Studi Teknologi Hasil Pertanian Fakultas Agroindustri Universitas Mercu Buana Yogyakarta Jl. Wates Km 10, Yogyakarta 55375
(2) Jurusan Teknologi Pangan dan Hasil Pertanian, Fakultas Teknologi Pertanian, Universitas Gadjah Mada, Jl. Sosio Yustisia, Bulaksumur, Yogyakarta 55281
(*) Corresponding Author

Abstract


Calcium-fortified rice is a dried product that is vulnerable to moisture sorption. The storage condition and the deterioration rate during storage could be evaluated by its moisture sorption isotherm. Moisture sorption isotherm of rice and calcium-fortified rice of three rice varieties i.e. low - (Memberamo), medium - (Ciherang) and high amylose rice (IR-42) were determined by static gravimetry method at temperature 25 oC. Samples were equilibrated at control temperature during 14 days in the desiccators adjusted at water activity (a ) between 0.076 – 0.930. GAB equation was used to evaluate water adsorption isotherm curve. The research showed that these curves were sigmoid and the aof monolayer of calcium-fortified rice tended lower than normal rice. The higher amylose of rice led to the lower a  ofcalcium-fortified rice.

ABSTRAK

Beras berkalsium merupakan produk kering yang rentan terhadap uap air. Untuk menentukan kondisi penyimpanan yang tepat dan kecepatan kerusakan beras berkalsium selama penyimpanan perlu dievaluasi pola penyerapan air atau isoterm sorpsi lembabnya. Isoterm sorpsi lembab beras berkalsium dari tiga varietas beras yaitu amilosa rendah (Memberamo), sedang (Ciherang) dan tinggi (IR-42) ditentukan menggunakan metode gravimetri statis pada suhu 25 oC. Sampel disimpan dalam desikator yang berisi garam jenuh dengan aktivitas air (a ) antara 0,076 – 0,903 yang ditempatkan dalam ruangan pada suhu terkendali selama 14 hari atau sampai mencapai kadar air seimbang. Model yang digunakan untuk mengevaluasi kurva adsorpsi lembab beras berkalsium adalah persamaan GAB (Guggenheim Anderson de Boer). Hasil penelitian menunjukkan bahwa kurva isoterm sorpsi lembab beras berkalsium berbentuk sig- moid dan a monolayer cenderung lebih rendah daripada beras normal dengan adanya penambahan kalsium. Aktivitas air beras berkalsium semakin rendah dengan semakin tinggi kadar amilosa.


Keywords


Sorption isotherm; calcium-fortified rice; GAB equation

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DOI: https://doi.org/10.22146/agritech.9708

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agriTECH (print ISSN 0216-0455; online ISSN 2527-3825) is published by Faculty of Agricultural Technology, Universitas Gadjah Mada in colaboration with Indonesian Association of Food Technologies.


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