Judul: Pattern of Chlorogenic Acid Degradation on Arabica Coffee Roasting Process
Abstrak: Arabica coffee (Coffea arabica L.) contains phenolic compounds that have an important role in the formation of flavor and beneficial for health. One of the main phenolic compounds is chlorogenic acid. Chlorogenic acid has a subgroup with the largest content in coffee, namely caffeoylquinic acid (CQA) but this subgroup is very sensitive to heat damage. This study objective is to understand the effect of the roasting on chlorogenic acid concentration in coffee beans. Measurement of physicochemical characteristics (moisture content, density, yield, and color) was carried out to see the effect of roasting process on characteristic of coffee beans. Meanwhile, the analysis and quantification of chlorogenic acid was carried out using the HPLC method. The results obtained showed that there was a degradation of chlorogenic acid content in the arabica coffee after the roasting process. Higher roasting rate will cause greater damage of chlorogenic acid content. Each isomer such as 3-CQA, 4-CQA, or 5-CQA has a certain pattern of damage due to the roasting process. 5-CQA has pattern that is directly proportional to the roasting level. However, the others, 3-CQA and 4-CQA have different patterns due to an increase on concentration level in certain sampels after the roasting process., Kopi arabika (Coffea arabica L.) memiliki kandungan senyawa fenolik yang berperan penting dalam pembentukan sensori dan bermanfaat bagi kesehatan. Salah satu senyawa fenolik utama yang berperan adalah asam klorogenat. Asam klorogenat memiliki subgrup dengan kandungan terbesar dalam biji kopi yaitu asam caffeoylquinic (CQA), namun subgrup tersebut sangat sensitif terhadap kerusakan akibat panas. Penelitian ini bertujuan mempelajari pengaruh proses penyangraian terhadap konsentrasi asam klorogenat pada biji kopi. Pengukuran karakteristik fisikokimia (kadar air, densitas kamba, rendemen, dan warna) dilakukan untuk melihat pengaruh proses penyangraian terhadap karakteristik biji kopi. Sementara itu, analisis dan kuantifikasi asam klorogenat dilakukan dengan metode HPLC. Hasil penelitian yang diperoleh menunjukkan adanya degradasi kandungan asam klorogenat pada kopi arabika setelah proses penyangraian. Semakin tinggi tingkat penyangraian akan menyebabkan tingginya kerusakan kandungan asam klorogenat. Masing-masing isomer asam klorogenat seperti 3-CQA, 4-CQA, dan 5-CQA memiliki pola kerusakan tertentu akibat proses penyangraian. 5-CQA memiliki pola kerusakan yang berbanding lurus dengan tingkat penyangraian. Namun, isomer lainnya yaitu 3-CQA dan 4-CQA memiliki pola kerusakan berbeda yang disebabkan oleh adanya kenaikan konsentrasi pada sampel tertentu setelah proses penyangraian.
Keyword: arabica coffee, chlorogenic acid, damage pattern, hplc, roasting

Judul: Effect of Initial Temperature and Degree of Roasting on Physicochemical Properties and Taste of Solok Arabica Coffee
Abstrak: Kopi merupakan salah satu komoditas ekspor unggulan dari Indonesia. Pengolahan biji kopi menjadi minuman siap saji terbagi menjadi dua yaitu pengolahan primer dan pengolahan sekunder. Proses penyangraian adalah salah satu proses pada pengolahan sekunder. Variabel yang digunakan pada saat proses penyangraian beragam diantaranya adalah suhu awal dan derajat penyangraian. Penelitian ini bertujuan untuk menganalisis sifat fisikomia dan melakukan uji citarasa terhadap kopi Arabika Solok dengan perlakuan suhu awal dan derajat penyangraian yang berbeda. Penelitian diawali dengan melakukan analisis sebelum sangrai, melakukan penyangraian dengan suhu awal 180C, 200C dan 220C pada setiap derajat sangrai ringan (light), sedang (medium) dan gelap (dark) serta melakukan pengujian terhadap sifat fisikomia dan citarasa kopi Arabika Solok. Analisis data yang dihasilkan menggunakan Analisis of Variance (ANOVA) dua arah dan jika menghasilkan pengaruh yang signifikan dilanjutkan dengan uji Duncan’ Multiple Range Test (DMRT). Hasil penelitian menunjukkan bahwa suhu awal penyangraian hanya mempengaruhi sifat rendemen, atribut flavour dan aftertaste, sedangkan derajat penyangraian berpengaruh signifikan terhadap beberapa sifat fisikomia diantaranya rendemen, densitas kamba, kadar air, warna, keasaman (pH) dan beberapa atribut citarasa diantaranya fragrance, flavour, acidity, body, aftertaste, sweetness dan overall dan tidak ada interaksi antara kedua variabel terhadap semua sifat yang diuji. Sifat fisikomia dan citarasa yang tidak terpengaruh suhu awal dan derajat penyangraian adalah kadar abu, aktivitas antioksidan, balance, uniformity, dan clean cup. Kopi dengan perlakuan derajat sangrai medium mendapatkan skor akhir tertinggi yaitu 82,3 (specialty)., Coffee is one of the leading export commodities from Indonesia. Processing of coffee beans into ready-to-drink drinks is divided into two, namely primary processing and secondary processing. Roasting process is one of the processes in secondary processing. Variables used during the roasting process include the initial temperature and the degree of roasting. This study aims to analyze the physicochemical properties and perform taste tests on Arabica Solok coffee with different initial temperatures and roasting degrees. The study begins with the analysis before roasting, then roasting with the initial temperature of 180οC to 200οC and 220οC at any degree of roasting light, medium and dark and for the last, testing of the physicochemical and taste properties of Solok Arabica coffee. Analysis of the resulting data using two-way Analysis of Variance (ANOVA) and if it gives a significant effect, then continued with the Duncan' Multiple Range Test (DMRT). The results showed that the initial roasting temperature only affected the yield, flavor and aftertaste attributes . While the degree of roasting has a significant effect on several physicochemical properties including yield, density of kamba, water content, color, acidity (pH) and several taste attributes including fragrance, flavor, acidity, body, aftertaste, sweetness and overall and there is no interaction between two variables on all tested properties. The physicochemical properties and taste attributes that were not affected by the initial temperature and roasting degree were ash content and antioxidant activity, balance, uniformity, and clean cup. Coffee with medium roasting degree treatment got the highest final score of 82,3 (specialty).
Keyword: Arabic, physicochemistry, roasting, taste, specialty

Judul: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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