Judul: Pengaruh Ekstrak Lengkuas (Alpinia galanga L.Swartz) Terhadap Peningkatan Daya Simpan Buah Salak Pondoh (Sallacca edulis Reinw.)
Abstrak: Pondoh salacca fruit (Salacca edulis Reinw) is an Indonesia tropical seasonal fruit with non-climateric respiratory pattern and naturally perishable with 5 to 6 days of storage at the room temperature (Mahendra et al., 1993). Decrease the quality of fresh fruits generally occurs due to handling during harvest and post harvest inadequate, leading to various forms of mechanical damage, physiological, biological, and microbiological. The damage of salacca fruit especially caused by infection of yeast, the yeast grow in the skin of the fruit, the color of fruit flesh turn into brown, tender, wet, and even rotten, or, the skin of the fruit becomes very dry and hard, and this could caused problems when peeling it. Alpinia galangal (Alpinia galangal L. Swartz) is one of natural rhizome from Zingiberaceae Family that can be used as natural antimicrobes. In this study, to maintain the quality and to extend shelf life of Pondoh salacca fruit, immersion salacca fruit in Alpinia galangal extract, perforation packaging and low temperature storage were performed. The aim of this study is to determine the effect of Alpinia galangal extract to hamper the rotten of Pondoh salacca fruit, analyze physical and chemical conversion during storage and define the best temperature in effort to extend shelf life of Pondoh salacca fruit. This study applies MAP (Modified Atmosphere Packaging). The packages that were used in this study are holed polyethylene (PE) plastic bag sized 25 x 16 cm with 40 μm thickness. Design research that was used is completely randomized design in factorial pattern and four times repetition that were consist of Alpinia galangal concentration factor (consist of 3 levels that were A = 0% (v/v aquadest), B = 5% (v/v aquadest), and C = 10% (v/v aquadest). and storage temperature factor (consist of 3 levels that were T1 = 15oC (RH 85 – 90%), T2 = 22oC (RH 65 – 66%), and T3 = 31oC (RH 67-72%). The study result showed that the best treatment is salacca fruit immersion in 5% (v/v aquades) Alpinia galangal extract during 30 second and storage at temperature 15o C (RH 85-90%) could extend shelf life of Pondoh salacca fruit up to 21 days of storage with 8.33% damage percentage, 0.55% weight loss, 71.56% skin water rate percentage, 80.87% flesh water rate percentage, 17o brix total suspended solid, 0.18% total acid, and 25.83 mg vitamin /100 gram material. The result of organoleptic analysis showed that until the 30th day of storage, hardness, easiness-to-peel, color, flavor, and taste still generally could be accepted, while the black spot at fruit bottom and freshness parameter for salacca fruit that fruit immersion in 0% (v/v aquades) Alpinia galangal extract could not be accepted by panelist on 10 days of storage.
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Judul: Aplikasi Gel Lidah Buaya (Aloe vera L.) sebagai Pelapis Buah Salak Pondoh (Salacca edulis Reinw.).
Abstrak: Pondoh salacca is one type of fruit that damaged quickly during storage. Application of coating as gas barrier could do to prolong the shelf life. Aloe vera gel can used as oxygen barrier that reduce respiration rate of pondoh salacca. This research performed to study the effect of aloe vera gel coating in preventing damage to physical, chemical, and microbiological pondoh salacca during storage. Packaging material used are a plastic polypropylene (PP) and polyethylene terephthalate (PET) that applied in normal (without vacuum) and vacuum condition. Fruits that have been sorted and cleaned, sprayed with a coating solution aloe vera gel : solvent ratio of 0:1, 1:4, and 1:2, then dried with the aid of a fan to dry. Once packed, pondoh salacca stored at cold temperature range 15-20 oC and RH 90-99 %, and observed on accordance with the conditions of the fruit. The parameters observed are of the weight loss, the percentage of damage, Vitamin C, total dissolved solids, and total acidity. The results of the analysis found that the ratio of coating is best able to withstand the decline in the quality of pondoh salacca is aloe vera gel : solvent ratio of 1:2. The type and condition of the best packs to maintain the quality of fruits is a kind of plastic PP and normal conditions (without vacuum). The combination of treatments both can also reduce damage fruits, it is evident that the treatment aloe vera gel : solvent ratio of 1:2 and the type of plastic PP with normal conditions can last up to 26 days of storage the level of damage by 37 % and amounted to 0.61 % weight losses. The content of Vitamin C fruits amounted to 1.84 mg/100 g of fruit, and the amount of total dissolved solids and total acid are 15.5 oBrix and 0.48 %.
Keyword: pondoh salacca, coating, aloe vera gel, packaging, shelf life

Judul: igenvalues and Eigenvectors of Tridiagonal Matrix with Non Constant and Recurrent Diagonal Entries.
Abstrak: Matriks tridiagonal adalah suatu matriks yang mempunyai entri-entri bernilai nol kecuali pada diagonal utama, di bawah diagonal utama (subdiagonal) dan di atas diagonal utama (superdiagonal). Entri pada diagonal utama tidak konstan dan berulang. Setiap entri pada matriks tridiagonal ini adalah bilangan kompleks. Dalam karya ilmiah ini, akan dibuktikan 3 teorema untuk menentukan nilai eigen dengan 2 kasus dan 1 teorema untuk menentukan vektor eigen. Teorema pertama menentukan polinomial karakteristik dari matriks tridiagonal. Polinomial karakteristik dari matriks tridiagonal tersebut digunakan untuk menentukan nilai eigen pada teorema kedua dan ketiga serta menentukan vektor eigen pada teorema keempat
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