Judul: OPTIMIZATION OF PRE-TREATMENTS TOWARDS REHYDRATABLE TORCH GINGER (Etlingera elatior) FLOWER CHARACTERISTICS
Abstrak: Torch ginger (Etlingera elatior) is an indigenous plant found in South-Asian region which is known for its attractive appearance, pink color, and health benefits. The torch ginger flower shows potential for its rehydratable form development to increase added value, convenience, and shelf life. Some of the most important characteristics in the rehydratable torch ginger flower development are moisture content, color difference, rehydration ratio, and antioxidant activity. Cabinet drier has been used widely in the development of dehydrated food due to its affordability, however shows problem in the degradation of quality. On the other hand, pre-treatments such as steam blanching and sodium metabisulphite soaking has been known to retard quality degradation during drying in dehydrated products. In this study, optimization was done using Response Surface Methodology (RSM) in Design Expert v11.0 software with 13 combination runs of steam blanching time (ranging from 30-180 seconds) and sodium metabisulphite soaking concentration (ranging from 0.15%-0.40%). The optimum pre-treatments in the experiment were found to be 180 seconds of steam blanching continued by soaking in 0.331% sodium metabisulphite solution which resulted in moisture content of 7.96%, rehydration ratio of 4.65, color difference of 12.56, and antioxidant activity of 39.36% with the desirability of 0.719.
Keyword: optimization, torch ginger, rehydratable, blanching, sodium metabisulphite

Judul: Shelf Life Estimation of Red Ginger Powder  “Deherbanoer” Using Arrhenius Model Accelerated Shelf-Life Testing (ASLT)  Method
Abstrak: Jahe (Zingiber Officinale) merupakan tanaman rempah-rempah yang memiliki produktivitas tinggi di Indonesia. Kandungan senyawa dalam jahe memiliki beragam manfaat untuk kesehatan manusia, jahe dapat diolah menjadi berbagai macam produk sebelum dikonsumsi. Bubuk jahe merah “Deherbanoer” merupakan salah satu produk olahan jahe dari Kecamatan Bogor Tengah, Kota Bogor, Jawa Barat. Bubuk jahe merah selama proses penyimpanannya dapat mengalami penurunan kualitas yang dipengaruhi oleh kondisi lingkungan, sehingga perlu diketahui informasi mengenai umur simpan produk agar dapat dikonsumsi pada mutu terbaiknya. Penelitian bertujuan untuk mengetahui karakteristik awal, mengidentifikasi penurunan mutu selama penyimpanan, dan melakukan pendugaan umur simpan. Bubuk jahe merah disimpan menggunakan kemasan alumunium foil, metallized, dan polypropylene (PP) dalam kondisi penyimpanan dengan suhu 25, 35, dan 45°C selama 8 minggu. Parameter yang diamati selama penyimpanan adalah perubahan kualitas kadar air, kadar oleoresin, warna, angka kapang dan khamir. Hasil penelitian menunjukkan adanya perubahan mutu berupa peningkatan kadar air, penurunan oleoresin, perubahan intesitas warna, dan cemaran kapang. Penetapan umur simpan didasarkan pada parameter dengan laju penurunan mutu yang besar yaitu kadar oleoresin. Bubuk jahe merah “Deherbanoer” yang dikemas menggunakan alumunium foil memiliki umur simpan yang lama yaitu 11,21 bulan pada suhu 25°C, 9,68 bulan pada suhu 35°C, dan 8,4 bulan pada suhu 45°C., Ginger (Zingiber Officinale) is a high productivity spices plant in Indonesia. The content compounds within a ginger has various benefits for human health, ginger can be processed into various products before being consumed. Red ginger powder "Deherbanoer" is one of the processed ginger products from Central Bogor District, Bogor City, West Java. Red ginger powder, during the storage process, has being decreased in quality which affected by environmental condition, thus it is necessary to know the information about its shelf life so that it can be consumed at the best quality. This research was aimed to determine the initial characteristics, identify quality degradation during storage, and conduct estimated shelf life. Red ginger powder was packaged using aluminum foil, metallized, and polypropylene (PP) packaging in various storage conditions at 25, 35, and 45°C for about 8 weeks. The observed parameters during its storage were the change of water content quality, oleoresin content, color appearance, mold and yeast numbers. The results showed a change of qualities such as an increasing both in water content and color brightness, a decreasing in oleoresin content, and mold contaminated. Determination of shelf life was based on the parameter with a large rate of deterioration, namely oleoresin content. Red ginger powder “Deherbanoer” which packaged using aluminum foil has a best shelf life which are about 11.21 months at 25°C, 9.68 months at 35°C, and 8.4 months at 45°C.
Keyword: Arrhenius, packaging, red ginger powder “Deherbanoer”, shelf  life

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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