Judul: Development of a Process for Producing Red Tea Syrup Using Vacuum Evaporator EVAP-50 Owner Food Machinery
Abstrak: Tea is the most popular beverage next to water. Preparation of tea from dried tea leaves require many steps and is time-consuming. The goal of this research is to make a convenient way to prepare tea syrup with vacuum evaporation process. In the present study the effect of vacuum evaporating condition on the properties of tea syrup and the most suitable condition for making tea syrup were investigated with rating hedonic approach. Dried red tea leaves (Camellia sinenesis var. assamica) were supplied from Boon Rawd Farm Co., Ltd in Chiang Rai. The samples were ground using hammer mill. Samples (1720 grams) were extracted with 43 L boiled water, infused for 5 minutes with stirring. Solids were filtered. Sucrose was added to tea extract until TSS of 26 oBrix was reached. These initial concentration was evaporated until 68 oBrix under vacuum with various pressures (-500 mmHg and -400 mmHg) and temperatures (70 oC and 60 oC). Sensory characteristics were evaluated for tea syrup and tea drink. There was difference in value of sensory characteristics of tea syrup and tea drink of different treatment. Based on panelists, the highest score of both tea syrup and tea drink were at treatment of 70 oC/-400 mmHg/28 h 30’. The shortest time of processing was at treatment of 70 oC/-500 mmHg/8 h 35’. Meanwhile, the treatment resulted in the highest total polyphenol was at treatment of 60 oC/-500 mmHg/35 h 8’. Keeping tea syrup in room temperature for around 3 weeks that had once been opened, the growth of molds was observed. Hence, the addition of preservative is suggested.
Keyword: vacuum evaporation, tea drink, tea syrup, sensory analysis, formulation

Judul: Development of Effervescent Green Tea (Camellia sinensis var. sinensis ).
Abstrak: Green tea has high phenolic compound which gives good impact to body’s health, due to its high phenolic compound the taste is slightly bitter, which decrease consumer acceptance. To overcome this problem, effervescent tea was presented. Effervescent is the reaction of acid and base producing CO2 when dispersed in water resulting a fizzing mouthfeel which covering undesired taste and giving other advantages. Discovering the best formulation based on its physical, chemical and sensory properties to increase the consumer acceptance is the objectives of this research. The quality of green tea powder was analyzed, it had bulk density 0.60 ± 0.03 g/mL, solubility 76.82 ± 0.66 %, and color (L*, a*, b*) 64.28 ± 0.45; 2.05 ± 0.11; 27.24 ± 0.41. The TPC (Total Phenolic Content) and moisture content were 5.56 ± 0.06 (% w/w dry basis) and 1.84 ± 0.11 % (wb). The second study was determination of the best formulation, there were 16 formulas which were developed with mixture design technique. The components including stevia (2%) as fixed ingredient, green tea powder (Camellia sinensis var. sinensis) (15-40%), mixture of sodium bicarbonate and citric acid (50-65%) with ratio 1:1, maltodextrin (10-20%). Based on the physical, chemical, and sensory properties the best formula consists of 56% mixture citric acid and sodium bicarbonate, 29% green tea powder, and 15% maltodextrin. This formula then used to make the final product and its quality was determined. The hardness 115.80±4.96 N, color as 0Hue 86.46±0.09, effervescent time 183.33±2.08 second, for pH 5.65±0.01, moisture content 1.92±0.03% (wb) and TPC 2.34±0.058 (% w/w db). Consumer acceptance test was conducted with 100 participants with different background (gender, age, occupation, and education), the acceptability and buying intention were considered high (87% and 74% respectively). In conclusion this product has met the standard of effervescent product and finely accepted by consumer.
Keyword: Effervescent, Effervescent tea, Consumer acceptance, Green tea

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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