Post-harvest red chili pepper (Capsicum frutescens) has highly capsaicin as bioactive compound and moisture content. However, capsaicin is the responsible bioactive compound in chili for hot sensation that easy to degrade by partial oxidation caused introduction of heat in drying process. The objective of this research was to investigate kinetics of capsaicin degradation in the drying process under blanching-brine-calcium pretreatment and various temperatures. For this purposes, chili provided local farmer was pretreated using blanching-brine-calcium pretreatment. Afterward, they were dried at 40, 50, 60, and 70 o C for 8 hours. Degradation of capsaicin content was observed every 2 hours using Thin Layer Chromatography (TLC). Results showed kinetics of capsaicin degradation was categorized as second order reaction. At the same temperature and time, capsaicin retention of blanching-brinecalcium pretreated chili has highest value. The temperature dependence of the capsaicin degradation rate was analyzed using Arrhenius correlation. The activation energy for degradation rate of capsaicin during drying was around 45.10367 kJ/mol.K. It indicated the degradation rate increased as well as increased the temperature at the same time.

Abstract. Drying is one of conventional processes to enhance shelf life of onion. However, the active compounds such as vitamin and anthocyanin (represented in red color), degraded due to the introduction of heat during the process. The objective of this research was to evaluate thiamine content as well as color in onion drying under different temperature. As an indicator, the thiamine and color was observed every 30 minutes for 2 hours. Results showed that thiamine content and color were sensitvely influenced by the temperature change. For example, at 50 o C for 2 hours drying process, the thiamine degradation was 55.37 %, whereas, at 60 o C with same drying time, the degradation was 74.01%. The quality degradation also increased by prolonging drying time.

This paper discusses the behavior of geopolymer concrete subjected to passive confinement under compression loads. The confinement is induced by the use of lateral hoops, assembled from un-deformed reinforcing bars. To compare the effect of confinement, identical specimens were produced using conventional concrete with the similar concrete compressive strength. The cylinder specimens were 100 mm in diameter and 200 mm in height, and the hoops were placed on the outer most fibers of the cylinders, perpendicular to the line of loading, with no concrete cover. The parameters analyzed in this study were the steel bar to concrete volumetric ratio, the hoop spacings and the steel yield stresses. The experimental results show that unconfined geopolymer concrete were very brittle compared to the unconfined Portland cement concrete. The strength enhancement (K value) of the confined geopolymer concrete was higher than K value of Portland cement concrete. Confined geopolymer concrete also has better deformability compared to the confined Portland cement concrete. The average confinement effectiveness of geopolymer concrete also has a higher value than that commonly used in the Indonesian Concrete Standard (SNI), that is 4.1. The results were further assessed to the most recent experimental test results conducted in this area.

Drying is one of the alternatives to prevent spoilage in red chili pepper by removing moisture content. Red chili pepper (Capsicum frutescens) has complex nutrition components such as vitamins and bioactive compound. However, vitamin B6 content in chili can degrade significantly in drying process by heat. This research studied degradation rate of vitamin B6 in chili drying process under various pretreatments and temperatures. In this study, post-harvest chili before dried was pretreated by blanching, osmotic dehydration with brine, immersing in calcium chloride solution and the combination of all them. They were dried in tray dyer at various temperatures 40°C, 50°C, 60°C and 70°C. Degradation of vitamin B6 content was analyzed every 2 hours by High-Performance Liquid Chromatography for 8 hours. Results showed that blanching-brine-calcium pretreatment was expected to reduce drying time and retain high content of vitamin B6 in red chili pepper. The degradation rate of vitamin B6 in chili followed second-order reaction. The degradation rate was influenced by temperature change referring to Arrhenius equation with activation energy was about 31.97 kJ/ mol K and constant rate (k0) was 3.769. Therefore, the vitamin B6 retention can be estimated at various pretreatments, times and temperatures. Furthermore, the favorable drying conditions can be evaluated.

Roselle (Hibiscus sabdarifa L) contains anthocyanins as the natural colorant and antioxidant. Drying the roselle extract was aims to produce the dry product that easy consumption as antioxidant. The carrier agent was added in roselle extract to improve the drying rate and maintain the nutritional value. This research studied the effect of carrier agent in drying rate and antioxidant activity. The method consists of two step involving roselle extraction using ultrasonic and the drying process. The roselle extraction by ultrasonic use the water as the solvent. The carrier agent (0%,5%,10% of maltodextrin) was added in roselle extract. The mixture was then dried in tray dryer dehumidification using zeolite in drying temperature 50,60, and 70⁰C. As the response, the moisture content was observed by gravimetry every 15 minutes for 150 minutes. The result showed that Page model was fitted to determine the constant of drying rate. Higher concentration of carrier agent enhanced the moisture evaporation process. Based on the DPPH analysis, the degradation of antioxidant activity in temperature 70⁰C was 2.14 times higher than in temperature 50⁰C. As the conclusion, addition of maltodextrin can speed up the drying process and retain the antioxidant activity of.

Abstract. The red chili pepper drying aims to remove moisture content up to 11% (wet basis). Dried chilies can be easy to distribute and have longer shelf life because it can be protected from decaying by enzymatic and microbial activity. Pretreatment in drying is one of alternative to decrease drying time. This present study was carried out on effect of blanchingbrine-calcium pretreatment toward drying kinetics in chili. In this case, chili provided from the local market was pretreated with blanching, dehydrated osmotic with brine, calcium dipping pretreatment and combination of them. The chili products were dried in tray dryer at 40 o C, 50 o C, 60 o C and 70 o C for 8 hours afterward. Result showed that Lewis model is suitable drying model. The blanching-brine-calcium pretreated chili can be well and faster dried with activation energy was 36.4290 kJ/mol and k 0 was 7.8712. At 70 o C, red chili pepper needed 6.467 hours to dry. Thus, the blanching-brine-calcium pretreatment can be potential to reduce the energy cost for drying as well as retain the quality.

In this study, foaming condition of roselle was optimized using response surface methodology (RSM) and the effect of drying characteristic was investigated. Roselle extract was foamed by addition of 1-5% w/w foaming agents (ovalbumin). The foaming stabilizer, glycerol mono stearate (0-1% w/w) was used to remain mechanic and thermodynamic stability of foam. As the response foam density and drainage volume was determined. The optimum foam variable was then dried at various drying temperatures (50-70°C). The moisture content was observed by gravimetry every 10 minutes for 90 minutes. Result showed that optimum formulation was 3.31% egg albumin and 1% GMS. The constant rate of the foam mat drying (temperature 50°C) was 3 times higher than non foam mat drying. Higher drying temperature can speed up the driving force but lead to color degradation.

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