Judul: Identifikasi Komponen Pembentuk Gel (KPG) dan Potensi Antioksidan Daun Kacapiring (Gardenia jasminoides Ellis)
Abstrak: Leaf of Kacapiring (Gardenia jasminoides Ellis) is a part of plant which has hydrocolloid component and can form gel. The aims of this research were (1) to evaluate physical and chemical properties of leaves and gel, (2) to extract, isolate, fractionate and identify gel forming component (GFC), and (3) to analyse the potency of antioxidant capacity of its gel. The research was devided into three steps as follows (1) Physical characterization were done for the dimension of leaves, and gel properties by sensory analysis. Chemical components of leaf and gel were quantified by proximat analysis and mineral component was analyzed by atomic absorption spectrophotometer (AAS) such as Cu, Fe, Mg and Ca. Dietary fibre component was analyzed by enzymatic method and estimation of pectic substances was done by spectrophotometer (2) Isolation of GFC was done by extraction using 0.028 M ethylendiamintetraacetate (EDTA). GFC was fractionated by ultrafiltration membrane. Monomers of GFC was identified by paper chromatography, and (3) Bioactive components such as, chlorophyll total was analyzed by spectrophotometer and its derivations of acetone extract (99.9%) by thin layer chromatography (TLC), meanwhile phenolic total and antioxidant capacity were analyzed by spectrophotometer. The results showed that kacapiring leaves contained water, ash, protein, fat, and carbohydrate. The mineral content in leaf and gel consisted of Ca of 19974.70+49.31 and 5429.71+68.98 mgKg-1db, Mg of 4263.15+38.66 and 2800.63+110.96 mgKg-1 db respectively, while Fe and Cu were not detected. The best gel can be obtained by AQ (1:15) treatment. Dietary fibre of leaf and gel contained of 24.98+0.72 and 90.61+1.02 %db respectively. Pectic substances of GFC isolate contained 56.53+0.61 %db galacturonic acid as pectin monomers. Isolate of 0.25% GFC was fractionated by ultrafiltration membrane and 96.78 % of retentate was separated in 5 μm membrane filter. Analysis by paper chromatography showed that GFC isolate contained galacturonic acid and glucose. Bioactive component of kacapiring leaves and gel contained chlorophyll total of 4926.25+190.31 and 1166.86+8.73 mgKg-1db. Both of them had 5 fractions by acetone extract, i.e. chlorophyll a, chlorophyll b, lutein (chlorophyll derivations), feofitine and carotene. Phenolic total in leaves and gel contained 5215.91+2.97 and 2648.16+56.22 GAE/g db, and antioxidant capacity had 1.5 x 10-1+0.00 and 3.1x10-3 +0.00 mM TEAC/mg dw respectively.
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Judul: Effect Of Pre-Treatment And Drying Temperature On The Properties Of Gac Powder
Abstrak: Gac fruit has a high content of antioxidant, especially carotenoids. These carotenoids are currently in special demand as they are natural antioxidants with potential to prevent cancers. The objectives of this research were to study the optimum drying condition to produce gac powder, study the waste utilization from gac skin as a powder, and investigate the physical and chemical properties of dried gac powder. Annova completely randomized factorial design was used to study the effect of different pre-treatment (blanching and adding of ascorbic acid) and dried using tray dryer at different temperature (50 and 60ºC) until moisture content in range of 5.8-6.4%. The results showed that the best dried gac powder was from the ascorbic acid pre-treated, using aril pulp and dried at 50°C due to the less amount of antioxidant loses. Physical properties showed bulk density value 0.65±0.02 g/mL and water solubility index (WSI) 36.42±3.11 %. Color properties showed lightness (23.55±2.43), with redness (a*) (23.48±1.27) and yellowness (b*) (39.72±2.97) (p<0.05). Aril and pulp mixture using ascorbic acid as pretreatment at 50ºC has the highest value in total carotenoid content (TCC) (93.49±11.35 mg β-carotene/100 mL samples),total phenolic compound (TPC) (467.44±7.64 μg GAE/g), DPPH (43.57±1.61 mmol Trolox/100g) and FRAP assay (598.22±18.59 μmol AAE/100g) (p<0.05) compared to other sample (p<0.05). Gac peel sample with blanching and dried at 60°C showed the lowest value of TCC (32.40±2.23 mg β-carotene/100 mL samples), TPC (0.62±0.03 mg GAE/g), DPPH (15.67±1.02 mmolTrolox/100g), and FRAP assay (194.00±7.84 μmol AAE/100g). The aril-pulp mixture showed the highest TCC, TPC, DPPH and FRAP value compared to peel significantly (p<0.05). Peel with ascorbic acid pre-treatment and dried at 50°C had the greatest antioxidant activities among the peel samples.
Keyword: antioxidant, carotene, gac fruits, gac powder supplement, peel, waste utilization

Judul: Pemodelan Nilai Tukar Rupiah Terhadap US Dollar Menggunakan Deret  Waktu Hidden Markov Dua Waktu Sebelumnya
Abstrak: Nilai tukar Rupiah terhadap US Dollar mengalami perubahan setiap waktunya dalam periode yang panjang dan perubahan yang terjadi mungkin terjadi kembali di masa mendatang. Jika penyebab kejadiannya tidak diamati secara langsung dan membentuk suatu rantai Markov maka perubahan nilai tukar Rupiah dapat dimodelkan dengan model deret waktu hidden Markov. Untuk menggambarkan perilaku nilai tukar Rupiah terhadap US Dollar, dalam karya ilmiah ini digunakan model deret waktu hidden Markov dua waktu sebelumnya. Model ini mengasumsikan bahwa nilai tukar Rupiah terhadap US Dollar bergantung pada rantai Markov yang merupakan penyebab kejadian yang tidak diamati dan nilai tukar Rupiah dua waktu sebelumnya.
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