Judul: Stability of Polyphenol in Hermetically Packaged Tea Drink During Storage
Abstrak: Teknologi hot-filling merupakan salah satu teknologi pengawetan yang sering digunakan dalam proses pembuatan minuman teh kemasan. Namun, teknologi tersebut belum cukup untuk menginaktivasi bakteri pembentuk spora yang mungkin mengontaminasi selama proses pembuatan minuman teh, sehingga diperlukan kombinasi pengawetan melalui konsep hurdle untuk menggabungkan teknologi pengawetan (hot-filling) dengan penggunaan pengawet kimia dan senyawa fenolik sebagai pengawet alami yang terkandung di dalam teh. Penelitian ini bertujuan untuk mengkaji stabilitas senyawa fenolik dalam minuman teh dengan metode spektrofotometri yang tervalidasi, serta untuk menganalisis stabilitas dari senyawa fenolik yaitu total fenolik, total tanin, dan individu katekin selama penyimpanan. Minuman teh terbuat dari ekstrak daun teh hijau dengan penambahan sukrosa, kalium sorbat, natrium askorbat, serta natrium bikarbonat yang kemudian dipasteurisasi dan dikemas secara hermetis. Uji stabilitas dilakukan selama 8 minggu pada suhu ruang dengan metode Folin-Ciocalteu untuk total fenolik dan total tanin dan menggunakan metode HPLC untuk individu katekin. Validasi metode total fenolik dan total tanin diperoleh nilai presisi yang lebih besar dari nilai RSD Horwitz, nilai linieritas > 0.990, nilai akurasi sebesar 111.28% (total fenolik) dan 96.92% (total tanin), batas deteksi (LoD) sebesar 10.34 mg/L (total fenolik) dan 11.91 mg/L (total tanin), dan batas kuantifikasi (LoQ) sebesar 31.34 mg/L (total fenolik) dan 33.38 mg/L (total tanin) telah memenuhi kriteria yang dipersyaratkan oleh (AOAC 2013) sehingga dapat dikatakan bahwa metode telah valid dan dapat digunakan sebagai metode untuk mengestimasi nilai total fenolik dan total tanin secara rutin di laboratorium. Selama 8 minggu penyimpanan di suhu ruang, total fenolik mengalami penurunan yang signifikan dari minggu 0, 4, hingga minggu 8. Sementara total tanin dan katekin mengalami penurunan yang signifikan dari minggu 0 ke 4 namun cenderung stabil pada minggu 4 ke 8. Meski demikian, individu katekin yaitu epigalokatekin galat mengalami penurunan yang signifikan dibandingkan katekin lainnya hingga pada minggu ke 8 senyawa ini terdegradasi seluruhnya. Individu katekin yang paling stabil dan jumlahnya paling besar adalah galokatekin. Penelitian ini menunjukkan bahwa komposisi senyawa fenolik dapat berubah selama penyimpanan, sehingga pengujian stabilitas dengan salah satu senyawa fenolik seperti total tanin saja tidak cukup namun perlu diverifikasi dengan pengujian individu katekin.
Keyword: catechin, phenolic, tannin, tea drink, storage

Judul: Pengaruh Jenis Kemasan dan Suhu Penyimpanan Pada Umur Simpan Teh Hijau.
Abstrak: Green tea is the young shoots and leaves of the tea plant (Camellia sinesis) that have been processed without fermentation process. Processing of green tea is a series of physical and mechanical processes without enzymatic oxidation process (fermentation) to the bud using the panning system. The fermentation process is not needed because to maintain content in fresh tea leaves are picked. This makes green tea products have more nutritional and health value compared with black tea. The aim of shelf life prediction is to know the shelf life of green tea on certain conditions. Determination of product shelf life using the ASS method (Accelerated Storage Studies) and the parameters are environmental conditions that can accelerate the deterioration of food products. The proper packaging and storage can reduce the rate of damage and prolong the shelf life of green tea. The purpose of this study was to determine the change of quality, determining shelf life, and get a better packaging to maintain the quality of green tea. In this study, aluminum foil and plastic PP are used as packaging. The storage’s temperature are 25, 35 and 45°C. Time of storage in this study is three months. Analysis performed includes the analysis of water content, pH, levels of tannin, and organoleptic. Based on initial survey results revealed the characteristics of green tea used are: water content 5,61%, ash content 5,64%, fat 4.05%, protein 21.96%, fiber 6.08%, tannin 8,32% and pH 5,14. During the storage period there was an increase of water content on storage temperature 25 and 35C, this is because the storage space RH is greater than the equilibrium moisture content of materials so that the material absorbs water vapor in the environment to reach an equilibrium with the RH of the environment. At a temperature of 45C, green tea water content decreased in both the packaging, this is because the RH of storage space is smaller than the equilibrium moisture content of material that evaporates moisture on the material to reach equilibrium with the RH of the environment. Value of pH during storage period have increased at each temperature of storage and packaging. The increase in pH can be caused by chemical changes in the acid component of tannin to acid tearubigin and teaflavin. In the higher storage temperature, the rate of increase in pH, which showed smaller. The value of tannin content decreased at each storage temperature and type of packaging. In the higher storage temperature, the rate of decline was found that the greater the tannin content. This is because, the higher storage temperature will support the occurrence of tannin oxidation processes that produce tearubigin and teaflavin. Organoleptic test based on color of steeping, the aroma of steeping, and a sense of steeping green tea. During the storage period the level of preference for three attributes was decreased. The decline occurred due to decreased levels favorite green tea tannin content of the oxidized to teaflavin and tearubigin.
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Judul: The Construction of Greedy SVP LLL Algorithm
Abstrak: A lattice is a set of all integer linear combination of a set of linearly independent vectors in ℝ𝑛���. The independent vectors are called bases of lattice. Any lattice can be generated from many bases, and these bases have the same cardinality. In the lattice, the most fundamental and renowned problem is the Shortest Vector Problem (SVP). SVP is a tracking problem of the shortest nonzero vector in a lattice with equivalent bases. In two dimensions, SVP problem has resolved exactly by Gauss’ algorithm. When the lattice dimension is higher than two, A.K. Lenstra, H.W. Lenstra and L. Lovasz gave a LLL algorithm to compute approximation of nonzero shortest vector in the lattice. Reduced bases solution obtained from LLL algorithm still be an approximation and has polynomial running time of arbitrary dimension which large enough. In 1994, Schnoor and Euchner modified this LLL algorithm as a new variant which later was named deep insertion LLL algorithm. This algorithm is a modified version of the LLL algorithm to the terms of the exchange step to improve the accuracy of output of LLL reduced bases and applying it to the subset sum problem. The purpose of this research are: (1) Reconstruct the LLL algorithm and deep insertion LLL algorithm using a geometric approach. (2) Construct a greedy SVP LLL algorithm. (3) Implement the three algorithms in a symbolic programming language, and evaluate them experimentally. A bases ℬ=[𝐛���1,𝐛���2,…,𝐛���𝑛���] in ℝ𝑚��� is called reduced LLL with parameter 𝛿��� if satisfies: (a) |𝜇���𝑗���𝑖���|≤12, for every integer 𝑖���,𝑗��� with 1≤𝑖���<𝑗���<𝑛���. (b)𝛿���‖𝜋���𝑗���(𝐛���𝑗���)‖2≤‖𝜋���𝑗���(𝐛���𝑗���+1)‖2, for 𝑗���=1,2,…,𝑛���−1,where 𝛿��� is a reduced parameter of real numbers with 14<𝛿���<1. The first requirement is the reduced basis 𝛿��� must “nearly orthogonal” and in its computation case, this requirement can be reached out by using the Gram-Schmidt’s orthogonalization. While the second requirement is called exchange step, or used to called as Lovasz condition. By using both of these requirements, then they establish the LLL algorithm. Then, Schnoor and Euchner modify the LLL algorithm based on the requirements of the exchange step called the deep insertion LLL algorithm, where the exchange step is based on the comparison of the projected vector in orthogonal complement [𝐛���1,𝐛���2,…,𝐛���𝑘���−1]⊥ after j-th reduction. To construct greedy SVP LLL algorithm, the requirements of the exchange step is based on purely by comparing norm of lattice 𝐛���𝑗��� with norm lattice 𝐛���𝑖��� for 𝑖���=1,2,3…,𝑗���−1. The process of insertion reduced vector after the exchange step also has done greedily. Then, we calculate the number of arithmetic operation in greedy SVP LLL algorithm for further analysis. The result of our exprimentation for three algorithms on the certain matrix size shows that the running time of the three algorithms increases propotional to the size of the matrix. The result also shows that by using 𝛿���=34 for the LLL algorithm and the deep insertion LLL algorithm, and the greedy SVP LLL algorithm which is a new variant made by using no parameter of 𝛿���, outperform of the other of two previous algorithm in terms of speed with the same output.
Keyword: LLL algorithm, LLL deep insertion algorithm, greedy SVP LLL algorithm