Judul: Aplikasi Edible Coating Lidah Buaya dan Suhu Penyimpanan untuk Menjaga Mutu Salak Pondoh (Salacca edulis Reinw.) Terolah Minimal.
Abstrak: Application of edible coating and storage temperature are common to maintain fruit’s quality. A source that can be used as edible coating is aloe vera which contains antimicrobial substance. Unfortunately extra effort is needed to prepare aloe vera to be edible coating (peeling, crushing, and filtering) that causes difficulties in application. Formulation of aloe vera edible coating in powder form could ease the application. This research aimed to know the effect of spray drying process on aloe vera edible coating characteristics and its effectiveness to maintain minimally processed salak pondoh. Furtheremore, this research aimed to get information about the effect of aloe vera edible coating and storage temperature on minimally processed salak pondoh (Salacca edulis Reinw.). Fruits quality parameters in this research were firmness, weight loss, percentage of damage, and visual changes. Statistical analysis used was Completely Randomized Design with twice replications. The result showed that spray drying process decreased aloe vera edible coating viscosity, total soluble solid (TSS), and titratable acidity, while its pH value increased. Aloe vera edible coating color changed to be yellowish from smooth green. Furtheremore storage temperature gave significant (α=0.01) effect on all parameters, while aloe vera edible coating did not give significant effect on all parameters analyzed, but uncoated fruits were contaminated by molds sooner than coated ones.
Keyword: Edible coating, aloe vera, polysaccharides, minimally processed fruit, spray dry

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: Invers dari Matriks Tridiagonal Jacobi
Abstrak: Suatu matriks berukuran n×n dinamakan matriks tridiagonal jika untuk . Karya ilmiah ini memberikan algoritma yang mudah untuk menemukan invers ( dari matriks tridiagonal Jacobi yang simetrik dan nonsimetrik. Setiap elemen pada matriks tridiagonal ini adalah bilangan real. Terdapat 3 lema dan 2 teorema untuk menentukan . Lema pertama menunjukkan persamaan utama dalam membuktikan lema-lema dan teorema-teorema selanjutnya. Invers dari matriks yang simetrik dibuktikan oleh lema kedua yang menunjukkan elemen-elemen baris ke- dari . Selanjutnya, lema kedua dilengkapi dengan teorema pertama yang menunjukkan elemen-elemen dengan . Invers dari matriks yang nonsimetrik dibuktikan oleh lema ketiga yang menunjukkan elemen-elemen dengan dan elemen-elemen dengan dibuktikankan oleh teorema kedua.
Keyword: symmetric, nonsymmetric, matrix