Judul: Aplikasi Plasma Dielectric Barrier DIscharge (DBD) untuk meningkatkan antioksidan dan senyawa fenol pada biji kopi Arabika (Coffea arabica)
Abstrak: Kopi Arabika Toraja merupakan salah satu kopi unggulan di Indonesia yang berasal dari Tana Toraja. Salah satu tahapan kritis kopi yaitu proses penyangraian yang mempengaruhi munculnya aroma dan rasa tetapi proses ini menyebabkan umur simpan pendek dan kandungan antioksidan berkurang. Penggunaaan teknologi plasma Dielectric Barrier Discharge (DBD) dengan menghasilkan ozon dan plasma lainnya yang dapat mempengaruhi sifat fisik dan kimia kopi. Dengan ozon tersebut diharapkan meningkatkan kualitas biji kopi, baik green bean maupun roasted bean melalui peningkatan antioksidan. Dalam penelitian dilakukan analisa pengaruh alat plasma DBD terhadap nilai antioksidan, total phenol content, kadar air, dan warna. Kadar ozon yang digunakan yaitu 5 ppm. Rancangan percobaan yang digunakan yaitu rancangan acak lengkap faktorial, dimana terdiri dari dua taraf, yaitu jenis tingkat roasting biji kopi (green bean, light roasted bean, medium roasted bean, dan dark roasted bean) dan waktu perlakuan (0 menit, 15 menit, 30 menit, 45 menit, 60 menit). Kombinasi antara dua taraf tersebut memiliki perbedaan signifikan terhadap persen inhibisi, TPC, kadar air, dan warna. Peningkatan persen inhibisi yang terjadi mencapai 22,1% dan peningkatan nilai TPC yang terjadi mencapai 19,1%., Toraja Arabica coffee is one of the leading coffees in Indonesia originating from Tana Toraja. One of the critical stages of coffee is the roasting process which affects the appearance of aroma and flavour but this process causes short shelf life and reduced antioxidant content. The use of Dielectric Barrier Discharge (DBD) plasma technology by producing ozone and other plasmas that can affect the physical and chemical properties of coffee. With ozone, it is expected to improve the quality of coffee beans, both green bean and roasted bean through increasing antioxidants. In this study, the effect of DBD plasma device on antioxidant value, total phenol content, moisture content, and colour was analysed. The ozone level used was 5 ppm. The experimental design used is a factorial complete randomised design, which consists of two levels, namely the type of roasting level of coffee beans (green bean, light roasted bean, medium roasted bean, and dark roasted bean) and treatment time (0 minutes, 15 minutes, 30 minutes, 45 minutes, 60 minutes). The combination of the two levels had significant differences in percent inhibition, TPC, moisture content, and colour. The increase in percent inhibition reached 22,1% and the increase in TPC value reached 19,1%.
Keyword: Antioksidan, arabika, plasma DBD, dielectric barrier discharge, total phenol content, fenol

Judul: Comparison of Total Phenol and Total Phenolic Acid of Bogor Arabica Coffee from Different Postharvest and Roasting Processes
Abstrak: Kopi mengandung senyawa fenolik, yang dapat dianalisis dari kandungan total fenolik atau senyawa fenolik tertentu. Komposisi dan konsentrasi fenolik dalam kopi dipengaruhi oleh proses pascapanen dan tingkat penyangraiant. Penelitian ini bertujuan untuk membandingkan rasio asam fenolat (diukur sebagai asam klorogenat) terhadap total kandungan fenolik dalam kopi arabika Bogor, dengan mempertimbangkan perlakuan pascapanen dan tingkat penyangraian yang berbeda. Sampel kopi diberikan perlakuan pascapanen (kering, basah, dan madu) dan penyangraian (ringan dan gelap). Proses penyangraian melibatkan pemanasan kopi pada suhu antara 147,9°C hingga 178,8°C untuk penyangraian ringan, dan 190,2°C hingga 200°C untuk penyangraian gelap (masing-masing selama 10 menit). Biji kopi hijau digunakan sebagai kontrol. Warna biji kopi, konsentrasi asam fenolik dalam ekstrak kopi, dan konsentrasi fenolik total dalam ekstrak kopi dianalisis dengan colorimeter, HPLC, dan spektrofotometer secara berturut-turut. Hasil penelitian menunjukkan bahwa penyangraian secara signifikan memperkuat warna gelap kopi arabika Bogor. Di antara asam fenolat, isomer 5-CQA muncul sebagai yang paling dominan dan juga paling rentan terhadap degradasi selama penyangraian. Seiring dengan peningkatan tingkat penyangraian, konsentrasi asam fenolat secara konsisten menurun. Kandungan total fenolik pada awalnya meningkat pada kopi ringan namun kembali menurun pada kopi gelap. Biji kopi hijau memiliki proporsi asam fenolat tertinggi (83%), sedangkan kopi gelap memiliki proporsi terendah (19%). Meskipun kopi ringan memiliki kandungan total fenolik tertinggi, konsentrasi asam fenolat menurun secara signifikan dibandingkan dengan biji kopi hijau., Coffee contains abundant phenolic compounds, which can be evaluated either collectively as total phenolics or individually as specific phenolic components. The presence and amount of phenolics in coffee are influenced by various factors, including postharvest treatments and the roasting process. This study aimed to compare the ratio of phenolic acid, specifically chlorogenic acid, to the total phenolic content in Bogor arabica coffee, considering different postharvest treatments and roasting levels. The coffee samples underwent different postharvest treatments (dry, wet, and honey) and were subjected to two types of roasting processes (light and dark). Green coffee beans were used as the control. The roasting procedure involved heating the coffee within the temperature range of 147.9°C to 178.8°C for light roasting and 190.2°C to 200°C for dark roasting (each for 10 minutes). The color of the coffee beans, the concentration of phenolic acid in the coffee extract, and the total phenolic content in the coffee extract were analyzed using a colorimeter, high-performance liquid chromatography (HPLC), and spectrophotometer, respectively. The findings revealed that roasting significantly intensified the dark color of Bogor arabica coffee. Among the phenolic acids, the 5-CQA isomer emerged as the most dominant and was also the most susceptible to degradation during the roasting process. As the roasting level increased, the concentration of phenolic acid consistently decreased. Interestingly, the total phenolic content initially increased in light-roasted coffee but decreased in dark-roasted coffee. Green coffee beans exhibited the highest proportion of phenolic acid (83%), whereas dark-roasted coffee had the lowest proportion (19%). Although light-roasted coffee had the highest total phenolic content, its phenolic acid concentration decreased significantly compared to green coffee beans.
Keyword: asam fenolat, kopi arabika, penyangraian, perlakuan pascapanen, total fenolat

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