Judul: Development of Zinc Rich Yogurt Based on Soy Milk (Glycine max L.), Pumpkin Fruit and Seeds (Cucurbita moschata)
Abstrak: Yogurt, susu kedelai dan labu kuning merupakan bahan pangan fungsional yang memiliki komponen biokimia yang baik bagi tubuh. Tujuan penelitian ini adalah untuk mendapatkan formula terbaik dari yogurt berbahan dasar susu kedelai dengan penambahan sari labu kuning dan susu biji labu kuning sebagai pangan tinggi zink dan β-karoten. Penelitian menggunakan Rancangan Acak Lengkap (RAL) dengan rasio sari labu kuning dan susu biji labu kuning yaitu (%) F1 (50:50), F2 (40:60), F3 (30:70). Nilai pH dan viskositas yogurt formula terpilih F3 adalah 3,85 dan 47,5 cP. Hasil organoleptik menunjukkan ketiga formula dapat diterima oleh panelis dan formula yang paling disukai adalah F3 yaitu yogurt susu kedelai dengan penambahan sari labu kuning 30% dan susu biji labu kuning 70%. Hasil analisis kimia yogurt formula terpilih F3 mengandung kadar air 80,61%, abu 1,67%, lemak 4,21%, protein 3,73%, karbohidrat 9,73%, zink 2,5 mg/100mL, dan β-karoten 144,37 µg/100 mL (28,8 RAE). Produk ini memenuhi klaim gizi tinggi zink 2,5 mg/100 mL dan harga jual produk per takaran saji (240 mL) adalah Rp6.700,00., Yogurt, soy milk, and pumpkin are functional food ingredients that have biochemical components that are good for the body. The purpose of this study was to obtain the best formula of soy milk-based yogurt with the addition of pumpkin juice and pumpkin seed milk as a food high in zinc and β-carotene. The study used a completely randomized design with the ratios of pumpkin juice and pumpkin seed milk, namely (%) F1 (50:50), F2 (40:60), and F3 (30:70). The pH value and viscosity of yogurt in the selected formula F3 are 3.85 and 47.5 cP. Organoleptic results showed that the three formulas were acceptable to panelists and the most preferred formula was F3, namely soy milk yogurt with the addition of 30% pumpkin juice and 70% pumpkin seed milk. The results of the chemical analysis of the selected formula F3 yogurt contained 80.61% moisture content, 1.67% ash, 4.21% fat, 3.73% protein, 9.73% carbohydrate, 2.5 mg zinc per 100 mL, and 144.37 µg/100 mL β-carotene (28.8 RAE). This product fulfills the nutrition claim of high zinc content (2.5 mg/100 mL) and the selling price of the product per serving size (240 mL) is IDR 6,700.
Keyword: provitamin A, pumpkin, soy milk, yogurt, zinc

Judul: Optimasi Formulasi Yogurt Kedelai pada Skala Laboratorium
Abstrak: Functional food trend progress is very rapidly and the majority of the growing functional food claims are intended to create a healthy digestive tract. Therefore, probiotic food products ranked second most popular after energy food and drink products. Yogurt is one type of probiotic food products that much favored by consumers due to having delicious flavor and providing many benefits for human health. Until now the raw materials used in the process of making yogurt is dairy cow, however, soymilk is one of the raw materials that potentially can replace cow's milk in the manufacture of yogurt. The use of soymilk as raw material for making soy yogurt has not been used optimally. This study aims to optimize the use of soymilk and fresh milk in the manufacture of soy yogurt in order to obtain the optimal cost of raw material response, objective responses (pH, viscosity, and total lactic acid bacteria), and subjective responses (texture, aroma, flavor, and color). Soy yogurt was developed using lactic acid bacteria (1:1 mixture of Streptococcus thermophilus and Lactobacillus acidophilus) and fermented for 8 hours at 43-45°C. The recommended optimum formula by design expert version 8 is the formula with the composition of soymilk and fresh milk ratio of 68.384% and 16.416% with a desirability value of 0.450. The optimum formula has a yellowish white color, taste sour and slightly sweet, sour aroma typical of soy yogurt, smooth texture, a bit of liquid viscosity, and no beany flavor in the final product. Soy yogurt optimum formula has 4.47 pH value, viscosity 200 cP, raw material cost Rp 978.0838, water content 84.70%, ash content 0.73%, protein content 3.06%, fat content 0.79%, carbohydrate content 10.62%, total titratable acidity 0.52%, average content of total lactic acid bacteria in the product 1.8x109 CFU/ml or 9.2553 log CFU /ml, there were no molds and yeasts, and the result of coliform test is <3 MPN/g in the final product. Soy yogurt optimum formula is still suitable for consumption up to 25 days of storage in the refrigerator at 10°C and there were no growth of molds and yeasts.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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