Judul: Polyphenol Extraction from Mangosteen Pericarp (Garcinia mangostana L.) and Its Application in Tea Product
Abstrak: Mangosteen pericarp has high polyphenol content that have disease preventive properties. The objective of this research was to utilize mangosteen pericarp from waste into added value and to evaluate stability on polyphenol content of green tea drink with mangosteen pericarp extract. Mangosteen pericarp was dried at 50ºC using tray dryer and the moisture content reached 7.43±0.10%. Dried pericarp was extracted with distilled water at 1:5 ratio (w/v). Green tea drink was added by mangosteen pericarp extract with seven different concentrations (0.1-0.7%). The extract then was infused into green tea drink which was mixed with three different concentrations of citric acid (0.06, 0.1, and 0.2%). The result showed that mangosteen pericarp extract had total phenolic compound (127.39±1.19 mg GAE/ml sample), DPPH (4491.63±67.52 μmol Trolox/ml sample), and FRAP (21,492±134.50 mM asorbic acid/ml sample). The maximum concentration of mangosteen pericarp extract in the tea drink that can be accepted by panelist was 0.4%. Tea with the highest concentration of citric acid (0.2%) had the lowest pH (2.79), the highest total phenolic compound (25.48±0.38 mg GAE/ml sample), DPPH (57862.08±1248.85 μmol Trolox/100 ml sample), and FRAP (5,681.11±33.39 mM asorbic acid/ml sample) compared with other treatments (p<0.05). Therefore, the study concluded that mangosteen pericarp extract can be applied in tea drink and provided more polyphenol content for the product. In addition, polyphenol was more stable in acid condition.
Keyword: Polyphenol, Antioxidant capacity, Mangosteen pericarp, Tea, Citric acid.

Judul: Karakter Kulit Manggis, Kadar Polifenol Dan Potensi Antioksidan Kulit Manggis (Garcinia mangostana L.) Pada Berbagai Umur Buah Dan Setelah Buah Dipanen
Abstrak: The objective of this study were to know the character of mangosteen rind during development of the mangosteen fruit, studying the total phenol content and antioxidant potential of mangosteen rind. Research was done at Plant Analysis and Chromatoghrapy Laboratory, Deparment of Agronomy and Horticulture, Bogor Agricultural University. This research used Completely Randomized Desain Group (RKLT) single factor wich is harvesting, with continue test Duncan Multiple Range Test (DMRT) at level 5%. Harvesting one month after anthesis (BSA), 2 BSA, 3 BSA, 4 BSA and the rind storage two and four weeks after harvesting were done separately. Mangosteen fruit was harvested from Leuwiliang, Bogor. The result showed that total phenolic at crude extract mangosteen and antioxidant capacity to reach IC50 of harvesting and storage have negative correlation. Harvesting handling have effect to fruit weight, aril weight, wet weight rind and vitamin C content. Total phenolic of Harvesting and storage handling have a negative correlation with antioxidant capacity to reach IC50 which are value about -0.53 and -0.91. Assumed that total phenolic content will increase antioxidant capacity in mangosteen rind. Antioxidants capacity on harvesting and sorage handling of mangosteen have IC50<50 (capability of antioxidant are very strong).
Keyword: 

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