Judul: Pengaruh Heat Moisture Treatment terhadap Sifat tekstural dan Retrogradasi Gel Pati Aren dan Tapioka
Abstrak: Heat Moisture Treatment (HMT) is one of physical modification techniques that uses limited moisture where heating process at high temperature is implemented for certain period of time. This research studied the effect of HMT modification on textural properties and retrogradation of aren and tapioca starch gel. HMT modification was done by using autoclaving method at 120 oC in 60 minutes for tapioca and 90 minutes for aren. Before autoclaving process, the water content of starch was adjusted into 20% (b/b, wb). The observation of retrogradation was done on starch gel with water content 10% (b/b, db) and refrigerated at 4 oC for 7 days. Textural analysis was done by doing compression using texture analyzer. Degree of retrogradation analysis was done by analyzing the changes of hardness from starch gel, and analyzing amylose hydrolisis using α-amylase enzyme. The result from textural analysis and degree of retrogradation analysis show that HMT modification could make starch gel become fragile, shown by decreasing breaking strain. From degree of retrogradation analysis, it is known that HMT modification increased hardness and degree of retrogradation of starch gel. According to this research, it can be concluded that HMT modification could make starch gel become fragile, increase hardness, and increase retrogradation of native starch gel.
Keyword: textural properties., retrogradation, heat moisture treatment

Judul: Karakter Fisikokimia dan Kadar Pati Resisten Tapioka Hasil Modifikasi Heat Moisture Treatment (HMT) Menggunakan Oven
Abstrak: Tapioka dimodifikasi dengan heat-moisture treatment (HMT) pada suhu 120ºC dan 140ºC selama 16 dan 24 jam dengan kadar air 20% . Selama HMT, terjadi penurunan kadar air sekitar 73,38 - 85,95 %, sehingga kadar air HMT aktual hanya 3 - 4 % . Proses HMT menyebabkan hilangnya sifat birefringence di tengah beberapa granula tapioka, penurunan kristalinitas (kecuali untuk HMT tapioka 120-24) tetapi tidak mengubah tipe kristalin dari tapioka. Kandungan amilosa, kapasitas pembengkakan dan kelarutan tapioka HMT lebih rendah dari tapioka alami. HMT tapioka memiliki kadar RDS dan SDS yang secara signifikan lebih tinggi dari bentuk alaminya (kecuali tapioka HMT 120-24) sedangkan kadar RS tidak berbeda nyata . HMT menyebabkan perubahan karakteristik pasta pati . Viskositas puncak, suhu pasting dan viskositas breakdown relatif pasta dari tapioka HMT secara signifikan lebih rendah dibandingkan tapioka alami. Secara umum, perubahan dari semua parameter sangat dipengaruhi oleh kondisi proses .
Keyword: tapioka, HMT, karakter fisikokimia, RS, suhu, waktu

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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