Chemnical Engineering

The application of non-thermal processing for inactivation of yeast (Saccharomyces cerevisiae) in orange juice was investigated and compared with conventional thermal processing. The results showed that less than 1 log of yeast in orange juice could be inactivated during thermal processing at 50 0 C and 15 min treated time. In contrast high pressure treatment at moderate temperature (50 °C) and 100 to 300 MPa resulted in total (up to 6 log) inactivation of yeast in orange juice. Supercritical CO 2 /liquid CO 2 treatment at ≥6 MPa and 50 °C was sufficient to inactive yeast up to 6 log after 15 min treatment time. For high electric field pulses, the field strength used in this study (15 kV/cm) was high enough to reduce the yeast number up to 2 log after 60 pulses in orange juice. Inactivation of yeast in orange juice using ultrasound is possible. Ultrasound amplitude at ≥40% (≥80 W) combined with moderate temperature (50 0 C) resulted in up to 6 log inactivation of yeast in orange juice after 15 min treatment.

The effect of pre-treatment on sugar yield of cassava root as well as application of amylolytic enzymes for conversion of starch to glucose and bioethanol production using yeast were studied. Different pre-treatments, such as ultrasound, sulphuric acid as well as application of technical enzymes (pectolytic/cellulolytic), have effect on starch conversion into glucose. Up to 3% or 8% of free sugar could be observed after ultrasound and technical enzyme treatment, respectively, compared to untreated sample (free sugar 0.5%). Amylolytic enzymes (α-amylase and gluco-amylase) from different companies (Novozymes, Stern, Valley and AB enzymes) investigated in this study were effective to convert starch in glucose. The activity of amylolytic enzymes depended on the concentration of enzymes and treatment time. Up to 100% of starch could be converted in glucose during 3 h saccharification (28.8 g glucose/100 fresh cassava root) and enzyme concentration of 0.1% w/w. Fermentation of enzymatic s...

The effect of physical (subcritical water) and chemical (acid and alkali) pretreatment on conversion of lignocellulose (cellulose, hemicellulose) in water hyacinth (WH) was investigated. The highest sugar content in acid pretreated samples was observed in WH treated with 3% H2SO4 solution (up to 18.16% w/w). Alkali treatment had nearly no effect on conversion of lignocellulose in WH to sugar. Combinations of acid or alkali pretreatments with enzyme treatment resulted in drastic increase of sugar in samples (up to 31.2 and 22.9 % w/w, respectively). In addition, increasing the applied enzyme concentration from 0.8% w/w (on dry WH basis) to 4% further increased the sugar content in the sample (up to 50.5% w/w). Subcritical water (SCW) (200°C and 10 min) and subsequent enzyme treatment resulted up to 17% w/w sugar in samples. Bioethanol concentration during fermentation (at 30°C) of pretreated sample using Saccharomyses cerevisae increased with increasing the fermentation time. After 3...

Roots of Morinda citrifolia (Noni or Yor in Thai) are the source of important compounds, anthraquinones, which have been proven to have anti-viral, anti-bacterial, anti-cancer activities. The most medicinally valuable anthraquinones in the roots of this plant is damnacanthal, which has been used for treatment of chronic diseases such as cancer and heart disease. In this study, subcritical water extraction was investigated as a benign alternative for solvent extraction of damnacanthal from the dried root of Morinda citrifolia. The experiments were conducted in a continuous flow system at a pressure of 4 MPa at different temperature between 150 and 220 • C and water flow rates of 1.6, 2.4, 3.2 and 4 ml/min. The quantitative analysis of damnacanthal was performed using RP-HPLC with UV detection at 250 nm. The results of the study revealed that the highest amount of damnacanthal extracted with subcritical water was obtained at 170 • C. In addition to the effect of temperature, extractions were conducted at various flow rates and the data were fitted with mathematic models to determine the extraction mechanism. The results suggested that the overall extraction mechanism was influenced by solute partitioning equilibrium with external mass transfer through liquid film. Nevertheless, the desorption model could describe the extraction behavior of Morinda citrifolia reasonably at high flow rates.

The application enzymatic pre-treatment for processing of palm fruit mesocarp was investigated. The results of this project have shown that enzymatic treatment is a suitable method for extraction of oil from palm fruit mesucarp. Not only the enzyme concentration and enzymatic treatment time, but also the applied enzyme type (cellulose, pectinase, and mixture of enzymes) were important for oil extraction from palm mesocarp and decreasing the remaining pressed pulp. Increasing the cellulsae enzyme concentration (treatment for 4h, 50 C) from 0.05% to 0.15% (w/w fresh sample) decreased rapidly the remaining pressed pulp from about 18 % to about 13%. In addition, was the oil yield of enzyme pretreated samples higher than untreated or thermal treated samples. Whereas the extracted oil for untreated samples was less than 75% was the extracted oil for cellulase enzyme treated sample distinct higher (88, 89, and 95 % for 0.05, 0.1 and 0.15% cellulase enzyme concentration respectively). Pect...

Einfluss von Kombinationen aus Ultraschall, Hitze und Druck auf Enzymaktivität und Qualitätsmerkmale von Frucht-und Gemüsesäften Pektinesterase (PE) ist das hitzestabilste Enzym in Zitrusfrüchten. Dieses Enzym ist verantwortlich für den Pektinabbau, der zum Verlust an natürlicher Trübung im Saft führt. Die Trübung des Saftes ist ein Indikator für die Frische von Säften und eine korrekte Saftproduktion. Die Inaktivierung von PE wird normalerweise als Indikator für eine ausreichende Pasteurisation herangezogen, da dieses Enzym resistenter gegen Hitze ist als die in Zitronensaft vorkommenden Mikroorganismen. Ultraschallbehandlung ist ein neuartiges Verfahren, das als Alternative zu thermischen Prozessen betrachtet werden kann. Es kann sowohl konvektiven Wärmetransport als auch Kavitation hervorrufen. Dies kann eine Inaktivierung von Mikroorganismen und Enzymen zur Folge haben. Ultraschallbehandlung allein kann die thermoresistente PE auch nach langer Behandlungsdauer nicht inaktivieren. Durch Kombination von Ultraschall und Hitze (TS) kann jedoch die Reduktion dieses Enzyms, abhängig von Behandlungsdauer und Temperatur, geringfügig erhöht werden.

The Effects of high hydrostatic pressure jet (HPJ) on oil droplet size of virgin coconut oil (VCO) during injection of oil in the mixture of emulsifier and water was studied.. Pressure level as well as emulsifier concentration had distinct effect on oil droplet size of HPJ treated samples. Increasing the pressure from 1000 bar to 3000 bar and surfactant concentration (up t0 19% w/w) resulted decreasing of oil droplet size. In contrast, oil concentration between 2 to 10% (v/w) have no or slight effect on oil droplet size in nano emulsion. HPJ application resulted oil droplet size reduction of about 165 nm- 360 nm in very short treatment time (less than 1 min). In addition, the effects HPJ on turbidity, emulsion stability, and viscosity of prepared nano-emulsions were studied.