Judul: Kinetics of Quality Change of Carotenoids-rich Fat Powder Made From Red Palm Oil
Abstrak: Vitamin A Deficiency (VAD) has been a serious problem in Indonesia and the underlying cause is a diet which is insufficient in vitamin A. Food fortification is one of the strategy that can be implemented in Indonesia to reduce the burden of VAD and to improve vitamin A intake. Red palm oil, Indonesia’s abundant natural resource rich in carotenoids, is very potential to be used as food fortificant. Red palm oil can be used by direct addition to food product or by transforming it into carotenoids-rich fat powder before use. This study was to investigate the kinetics of quality changes of carotenoids-rich fat powder during storage and to determine the product shelf life, using Arrhenius accelerated method. Samples of fat powder were stored at 26C (ambient/room temperature) and at elevated temperatures of 35C, 40C, and 55C for 30 days, and samples were taken and analyzed every 5 days. As a reference, samples of fat powder were also stored at refrigeration of 12C. The results showed that fat powder underwent (i) some color changes, (ii) increase in free fatty acid and peroxide value, and (iii) decrease in carotene content and powder flowability. With carotene tolerance 50% of initial carotene, carotenoids-rich fat powder can be stored for 3 months and 11 days at ambient/room temperature with light protection.
Keyword: Bogor Agricultural University (IPB), Arrhenius accelerated method, Spray chilling, Palm Stearin, Red Palm Oil, Fat powder

Judul: Studi kinetika perubahan mutu mikroenkapsulat minyak sawit merah selama penyimpanan
Abstrak: One of the alternatives of red palm oil utilization is to transform it into red palm oil microencapsulate (RPOM). Some indicators for RPOM quality damaged during storage are free fatty acids, peroxide value, total carotenes, and colours. Besides, its angle of repose also becomes main parameter because RPOM used is powdery product. In this research, RPOM had stored for 40 days in incubator with 35 oC, 44 oC, and 55 oC temperatures to analyzed the change of its quality characteristics. The result shows that the higher the temperature of storage, the faster RPOM get physical and chemical damages. Rate of increase of peroxide value and total rate of decrease of total carotenes are following first order reaction with each value of k are 0.0370 day-1 and 0.0067 day-1 respectively, while the rate of increase of free fatty acids and decrease of yellow colours are following zero order reaction with value of k are 0.0039% day-1 and 0.1720 unit day-1. Activation energy value for various quality parameters which derived from this study are 117327.17 J mol-1 for increase of free fatty acid; 27955.825 J mol-1 for increase of peroxide value; 69638.895 J mol-1 for decrease of carotene total; and 66194.405 J mol-1 for decrease of yellow colour.
Keyword: Bogor Agricultural University (IPB), RPOM, palm oil, order reaction, k value, energy activation value

Judul: Keanalogan graf dan matroid pada operasi penghapusan, pengerutan, dual, dan definisi keterhubungan
Abstrak: Teori matroid merupakan teori yang diambil dari konsep matriks dan graf. Matroid terdiri atas koleksi himpunan bagian-himpunan bagian dari suatu himpunan berhingga dan himpunan berhingga itu sendiri. Pada matroid terdapat suatu matroid yang diperoleh dari suatu graf, matroid ini disebut cycle matroid. Dalam cycle matroid, himpunan berhingga yang dimaksud adalah himpunan sisi-sisi pada graf sedangkan himpunan bagian dari himpunan sisi-sisinya adalah himpunan sisi-sisi yang membentuk cvele. Penulisan ini membahas mengenai pembentukan suatu cycle matroid dan keanalogan operasi penghapusan, pengerutan, dual dan definisi keterhubungan pada graf dan matroid. Operasi penghapusan dan pengerutan pada tulisan ini merupakan operasi penghapusan dan pengerutan pada sisi-sisi dari graf. Dalam operasi penghapusan dan pen pengerutan pada graf dan matroid terdapat operasi yang analog yaitu operasi pembentukan cycle matroid dari graf yang mengalami pengerutan atau penghapusan dengan suatu cycle matroid yang mengalami pengerutan atau penghapusan. Operasi penghapusan dan pengerutan pada graf dan matroid dapat dihubungkan dengan operasi lain yaitu operasi dual. Operasi dual adalah operasi yang mengkonstruksikan suatu graf atau matroid yang berbeda dari graf atau matroid asalnya. Pada dual graf dan matroid, terdapat sifat dual graf yaitu (G/e)*=G*\c* yang analog dengan sifat dual matroid (M/T)*=M*\T, dengan e∈ E(G) dan TCE(M). Sedangkan dalam definisi keterhubungan antara graf dan matroid terdapat hubungan keanalogan graf dan matroid pada definisi keterhubungan graf dan matroid menurut Tutte. Keanalogan ini ditunjukkan dengan samanya nilai keterhubungan pada graf dan matroid.
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