and Takada (2001). The FT-IR spectr

and Takada (2001). The FT-IR spectra were obtained from samples in KBr pellets using a Nicolet 200 FT-IR spectrophotometer
(Nicolet, Madison, WI, USA). Apparent viscosity, optical rotation
and texture profile analysis (TPA) of sample gels were made as
described by Braudo, Muratalieva, Plashchina, and Tolstoguzov
(1991), Plashchina, Muratalieva, Braudo, and Tolstoguzov (1986)
and Lau, Tang, and Paulson (2000) respectively. Thermogravimetric
analyses (TG) were carried out on a thermal analyzer Perkin–Elmer
TG7 using the temperature program 30–600
◦
C at a heating rate
of 5
◦
C/min in a nitrogen atmosphere. The drying gel samples,
removed water by a vacuum freeze dryer, were sputtered with a
layer of gold and examined by scanning electron microscopy (JSM-840, Jeol, Japan).
4. Results and discussion
4.1. Physicochemical properties
Table 1 showed that the apparent molecular weight, sulfate content and 3,6-AG content of agar were all slightly reduced after
oxidation, and the gelling temperature, gel melting temperature
and gel strength of oxidized agar were all decreased with the
increase of carboxyl content. The results indicated that the molecular chain of agar was less broken after oxidation under the chosen
reaction conditions, and the introduction of carboxyl group in little
quantity could affect the gelling properties of agar.
4.2. Analysis of IR and Cryo-SEM
Fig. 1 indicated that the IR spectra of agar before and after oxidation were almost the same. This result meant that the introduction
of carboxyl content into agar molecule was small. Fig. 2 indicated
that the gel skeleton structures of agar before and after oxidation
were all of the porous network structures, and the pores of gel
skeleton structure became smaller and denser after oxidation. This
result meant that the gel skeleton structure of oxidized agar would
have much higher capillary force to hold the water in gels than that

Hasil (Bahasa Indonesia) 1:

dan Takada (2001). Spektrum FT-IR Diperoleh dari sampel di KBr pelet menggunakan spectrophotometer Nicolet 200 FT-IR(Nicolet, Madison, WI, Amerika Serikat). Viskositas jelas, rotasi optisdan tekstur analisis profil (TPA) sampel gel dibuat sebagaidijelaskan oleh Braudo, Muratalieva, Plashchina, dan Tolstoguzov(1991), Plashchina, Muratalieva, Braudo, dan Tolstoguzov (1986)dan Lau, Tang dan Paulson (2000) masing-masing. Thermogravimetricanalisis (TG) dilakukan pada thermal analyzer Perkin-ElmerTG7 menggunakan suhu program 30-600◦C pada tingkat Penghangat Ruangan5◦C/menit dalam suasana nitrogen. Sampel gel pengeringan,air dihapus oleh membekukan vakum pengering, telah tergagap denganlapisan emas dan memeriksa dengan memindai mikroskop elektron (JSM-840, Jeol, Jepang).4. hasil dan diskusi4.1. secara fisikokimia propertiTabel 1 menunjukkan bahwa berat molekul jelas, sulfat konten dan konten 3,6-AG agar semua sedikit berkurang setelahoksidasi, dan suhu gelling, gel temperatur lelehdan kekuatan gel teroksidasi agar-agar menurun denganmeningkatkan kandungan carboxyl. Hasilnya mengindikasikan bahwa rantai molekul agar-agar adalah kurang rusak setelah oksidasi di bawah pilihankondisi reaksi, dan pengenalan karboksil di littlekuantitas dapat mempengaruhi sifat gelling agar-agar.4.2. analisis IR dan Cryo-SEMGambar 1 menunjukkan bahwa spektrum IR agar sebelum dan sesudah oksidasi hampir sama. Hasil ini berarti bahwa pengenalancarboxyl konten ke dalam agar-agar molekul adalah kecil. Gambar 2 menunjukkanbahwa gel kerangka struktur agar sebelum dan sesudah oksidasiSemua struktur jaringan pori, dan pori-pori gelkerangka struktur menjadi lebih kecil dan lebih padat setelah oksidasi. Inihasil dimaksudkan bahwa gel kerangka struktur teroksidasi agar-agar akanmemiliki banyak kekuatan kapiler yang lebih tinggi untuk menahan air di gel dari itu