Judul: Fortifikasi Beras dengan Gac Aril (Momordica conchinchinensis) menggunakan Teknik Vakum Impregnasi.
Abstrak: Tujuan dari penelitian ini adalah untuk meningkatkan sifat fungsional beras dengan fortifikasi gac aril menggunakan vacuum impregnation (VI) dengan melihat pengaruh dari varietas padi dan metode preparasi beras serta kondisi VI pada kualitas beras yang difortifikasi dengan gac aril. Hasil penelitian menunjukkan bahwa kedua varietas beras yang tidak disosoh memiliki tingkat kekerasan yang lebih tinggi dan warna yang lebih gelap (nilai L* lebih rendah) dibandingkan sampel yang disosoh. Unpolished Sao Hai (SH) yang diimpregnasi dengan gac aril menunjukkan kadar β-karoten (22,10 mg/g), likopen (8,38 μg/g), dan TPC (0,24 mg GAE/g) tertinggi, sementara aktivitas antioksidan semua sampel yang diimpregnasi gac aril tidak berbeda nyata (p>0,05) (nilai DPPH berkisar 1,39-1,72 mmol TE/g) dan lebih tinggi dari kontrol. Namun, evaluasi sensori menunjukkan bahwa Khaw Dok Mali 105 (KDML 105) yang diimpregnasi dengan gac aril memiliki skor tertinggi dari penerimaan keseluruhan. Berdasarkan karakteristik secara keseluruhan, unpolished KDML 105 dipilih untuk mempelajari kondisi VI yang sesuai pada langkah selanjutnya. Unpolished KDML 105 direndam dalam larutan gac aril 30% di bawah tekanan vakum (0, 300 dan 500 mmHg) dan teknik tekanan (single pressure dan pulse pressure) yang berbeda. Berdasarkan analisis sampel kering, tekanan vakum pada 500 mmHg dengan pulse pressure memberikan kadar β-karoten (41,41 mg/g), likopen (25,07 μg/g), TPC (0,21 mg GAE/g) dan nilai DPPH (2,91 mmol TE/g) tertinggi, sedangkan hasil analisis physical, texture dan sensory menunjukkan hasil yang tidak berbeda nyata (p>95%). Selain itu, indeks glikemik (GI) beras setelah proses VI menurun dari 84,24 menjadi 72,04. Dapat disimpulkan bahwa perlakuan nonpolishing, high vacuum pressure, dan pulse pressure merupakan kondisi yang paling sesuai untuk mempersiapkan beras dengan fortifikasi gac aril. Manfaat kesehatan dari beras ditingkatkan dengan aktivitas antioksidan yang tinggi dan GI yang lebih rendah.
Keyword: aktivitas antioksidan, beras, gac aril, vacuum impregnation

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: Stabilitas Global Model Holling-Tanner Tipe II
Abstrak: Phenomenon of prey predator is a natural phenomenon which is intended to study the impact of the natural balance caused by two interacting species. Therefore, mathematical models were developed to describe the dynamics of prey and predator populations. One of the models studied in this paper is the model of Holling-Tanner type II. The method used in this paper is the analysis of the stability of a fixed point. There are two fixed points obtained in this study i.e. T₁ and T₂. The stability of T₁ is saddle while T₂ depends on the value of the selected parameter. There are three cases analyzed for the fixed point T₂. For one of the cases, the limit cycle is obtained by changing the value of one parameter.
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