Judul: Kajian Pengaruh Suhu dan Waktu Hidrolisis Asam terhadap Sifat Pati Sagu Termodifikasi sebagai Surface Sizing
Abstrak: Sizing atau pendarihan adalah proses penambahan bahan aditif pada lembaran kertas sehingga mampu meningkatkan sifat-sifat ketahanan terhadap penetrasi cairan. Sizing dibagi dua yaitu surface sizing dan internal sizing. Internal sizing dilakukan di stock preparation dan surface sizing dilakukan di mesin kertas. Bahan untuk surface sizing adalah bahan yang dapat membentuk film seperti patio Modifikasi pati bertujuan untuk memperbaiki sifat-sifat pati sehingga dapat diaplikasikan secara lebih luas. Hal ini penting karena sebagian besar penggunaan pati dalam bentuk dilarutkan pada perlakuan temperatur. Modifikasi ini dapat dilakukan dengan cara hidrolisis, oksidasi, esterifikasi dan lain-lain. Sebelum digunakan, pati tersebut terlebih dahulu harus dimasak dalam cairan pada temperatur tertentu.
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Judul: Pengaruh Heat Moisture Treatment terhadap Laju Retrogradasi pada Gel Pati Sagu (Metroxylon sp.) dan Pati Aren (Arenga pinnata)
Abstrak: Starch is a carbohydrate reserves that are found in various plants and is the second largest source of carbohydrates after cellulose. One starch derived from palm. As for example of the palm starch sources is sago (Metroxylon sp) and sugar palm (Arenga pinnata). Native starch usually has a limited functional properties for a specific process. Modification of starch is usually done to improve the functional properties of starch for a particular purpose. Physical modification such as heat moisture treatment (HMT) has the potential to increase the functional properties of native starch. The purpose of this research was to study the effects of HMT on the rate of starch retrogradasi through the rate of sineresys, the changing textural properties, water content and water activity (aw) during storage. Modification of HMT performed with the method of autoclaving at a temperature of 60 minutes 120oC to sago starch and 90 minutes for arenga starch where previously made starch moisture content of 20%. The rate of sineresis was measured by using centrifuge method, whereas the characteristics of the texture was measured by using texture analyzer. Further analysis was the measurement of water content of starch gels using the oven method and measurement of water activity (aw) using the aw meters. Result of RVA measurement show that HMT can increase the gelatinization temperature, lower breakdown and increasing the setback. This research proved that HMT increases the rate of sineresis of sago and arenga starch gel and can make the texture more rigid. In addition, modification of HMT also increases the fragility of the gels and the moisture content was decreases. Decreasing in aw also occur due to the influence of the HMT. The value of the lowest aw occurred at Sagu HMT starch gel although the rate of decline in the value of the highest aw occurs in the sagu alami starch. Based on the results of the study it can be concluded that the Sagu HMT starch sensitive to heat treatment compared to Aren HMT starch, sagu alami and arenga starch. This is apparent from the highest of increasing a rate of syneresis, increasing in the rate of the elastic modulus, the highest of declining the rate of the strains value, and the highest of the rate of gel moisture content decreasing.
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Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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