José da Cruz Francisco

Solubility of three monoterpenes, their mixtures and eucalyptus leaf oils in dense carbon dioxide

The solubility of 1,8-cineole, alpha-pinene, limonene, their mixtures and the extract of eucalyptus leaf oils in supercritical carbon dioxide were determined using the dynamic method at 80, 100, 150, and 250 bar and 40 and 60 degreesC for each pressure. The results showed an increase in the solubility of all oils with an increase in pressure and a decrease with temperature. The mixtures of both pure blends as well as the eucalyptus oil extracts exhibited lower solubility than the pure single oil components in the same conditions. The oil of E. radiata exhibited a better separation of 1,8-cineole at 80 bar and 60 degreesC

Gelatinization of cassava, potato and wheat starches in supercritical carbon dioxide

The gelatinization of cassava, potato and wheat starches in supercritical carbon dioxide was investigated using light microscope. The starch was placed in a stainless steel chamber at atmospheric pressure and high CO2 pressures, 8 and 30 MPa as well as at 8 MPa N-2 and the gelatinization degree observed by light microscopy. The results showed that both pressure and supercritical fluid affected the gelatinization degree. Cassava and potato starches showed a lowering of the gelatinization temperatures at 8 MPa and an increasing at 30 MPa as compared with the gelatinization degree at atmospheric pressure. For wheat starch, the decrease in the gelatinization temperature occurred in the same direction as the pressure increased, in comparison with the atmospheric pressure conditions. However, between the two applied pressures, there was a larger increase of the gelatinization temperature at 30 MPa than at 8 MPa. The effect of hydrostatic pressure component of the CO2 was evaluated by using N-2 at 8 MPa. The replacement of CO2 by N-2 at 8 MPa increased the gelatinization temperature for all the studied starches compared with the atmospheric conditions

Straightforward rapid spectrophotometric quantification of total cyanogenic glycosides in fresh and processed cassava products

In this study, we extend pioneering studies and demonstrate straightforward applicability of the corrin-based chemosensor, aquacyanocobyrinic acid (ACCA), for the instantaneous detection and rapid quantification of endogenous cyanide in fresh and processed cassava roots. Hydrolytically liberated endogenous cyanide from cyanogenic glycosides (CNp) reacts with ACCA to form dicyanocobyrinic acid (DCCA), accompanied by a change of colour from orange to violet. The method was successfully tested on various cassava samples containing between 6 and 200 mg equiv. HCN/kg as verified with isonicotinate/1,3-dimethylbarbiturate as an independent method. The affinity of ACCA sensor to cyanide is high, coordination occurs fast and the colorimetric response can therefore be instantaneously monitored with spectrophotometric methods. Direct applications of the sensor without need of extensive and laborious extraction processes are demonstrated in water-extracted samples, in acid-extracted samples, and directly on juice drops. ACCA showed high precision with a standard deviation (STDV) between 0.03 and 0.06 and high accuracy (93-96%). Overall, the ACCA procedure is straightforward, safe and easily performed. In a proof-of-concept study, rapid screening of ten samples within 20 min has been tested.

Isolation of anacardic acid from natural cashew nut shell liquid (CNSL) using supercritical carbon dioxide.

Solvent extracted cashew nut shell liquid (CNSL), conventionally known as natural CNSL, is a mixture of several alkenyl phenols. One of these alkenyl phenols is anacardic acid, which is present at the highest concentration. In view of anticipated industrial applications of anacardic acid, the objective of this work was to isolate anacardic acid from natural CNSL by supercritical carbon dioxide (scCO 2). In this study, the solubility data for natural CNSL in scCO 2 under a range of operating conditions of pressure (100, 200, and 300 bar), temperature (40 and 50 degrees C), and CO 2 flow rate (5, 10, and 15 g min (-1)) were established. The best scCO 2 working conditions were found to be 50 degrees C and 300 bar at a flow rate of 5 g min (-1) CO 2. Using 3 g of sample (CNSL/solid adsorbent = 1/2) under these scCO 2 conditions, it was possible to quantitatively isolate high purity anacardic acid from crude natural CNSL (82% of total anacardic acid) within 150 min. The anacardic acid isolated by scCO 2 was analyzed by different spectroscopic techniques (UV-vis, FT-IR, and (1)H NMR) and HPLC analysis, indicating that the anacardic acid isolated by scCO 2 has better quality than that obtained through a conventional method involving several chemical conversion steps.

Liquid crystalline properties and extractability of monoolein-water systems by supercritical carbon dioxide

The influence of phase structure on the extraction recovery of monoolein from monoolein-water systems by supercritical carbon dioxide was investigated. Two monoolein-water mi tures at concentrations of 9 wt% water and 18 wt% water, respectively, were studied. H-2-NMR was used to monitor changes of the phase structures in supercritical conditions. The results showed that the phase structure and the water-monoolein interactions play a role on the extraction yield. The monoolein recovery was higher in the 9 wt% water sample in which L-alpha phase was present compared to the 18 wt% water sample in which the L-alpha melted to yield a L-2 phase. When the phase structures were the same in both samples, the extraction recovery was determined by the solubility properties of the components of the system. The changes due to the presence of supercritical carbon dioxide were shown also to depend on the water concentration of the monoolein-water mixture besides the temperature. The 18 wt% mixture showed a L-2 phase structure in all the range of the temperature investigated while the 9 wt% water mixture showed phase changes from L-alpha phase to L-2 phase in the same temperature range

Softening of dried Vangueria infausta (African medlar) using maltodextrin and sucrose

Softening of dried Vangueria infausta using maltodextrin and sucrose was investigated experimentally. The pulp of V. infausta was dried in a convective dryer, the influence of drying temperature as well as relationship between water content and water activity were examined. In this study, 48 samples of V. infausta pulp, with and without maltodextrin or sucrose, were dried at air temperatures of 60 and 80°C, at a constant air velocity of 3 m/s, for 0-240 min, and until constant weight. The water content, water activity, hardness and toughness were evaluated throughout the drying process. Samples dried at 80°C exhibited shorter drying times than samples dried at 60°C. The water activity of fruit dried for 240 min at 80°C varied from 0.633 to 0.759, and the fruit was thus safe regarding microbiological spoilage. The hardness and toughness of the dried fruit pulp increased with the reduction in water content, and it was observed that samples of pure pulp became unacceptably hard and tough, when dried to the level needed to obtain microbiological stability. The addition of sucrose as well as maltodextrin has shown to be able to reduce the hardness as well as the toughness of the dried fruit pulp; which can be considered as a strategy to obtain dried fruit pulp with suitable consistency. (Less)

The use of ScCO2 for the extraction of LPS from S. enterica subsp. PCM 2266

The paper describes a novel extraction procedure for lipopolysaccharides (LPS) from Salmonella enterica subsp. enterica (PCM 2266). Process parameters for the extraction of LPS from bacterial mass were optimized by carrying out a two-level fractional design experiment. Four parameters, namely temperature, CO, flow rate, pressure and co-solvent composition were analyzed. The best crude extract yields were achieved when the CO, flow rate and temperature were kept high (10g/min, 90 degrees C) and pure water was used as a co-solvent. Pressure had no statistically significant effects within the range of the study performed, whereas the other factors were relevant. The recovery of the extracted LPS by scCO(2) was about 3.3% of the biomass used, while in the classical extraction method yield was less than 2%. All isolates were characterized by SDS-PAGE, by the spectra of the thiobarbituric acid reaction products and GLC-MS analysis. (Less)

Trans-2-nonenal During Model Mashing

Abstract A study on trans- 2-nonenal (T2N) production during laboratory mashing of barley malt reveals that during the mashing-in step of kilned malt, an elevated amount of T2N (up to 14 ppb) is produced, and at the mashing-off step, a rapid decrease takes place. The decrease of T2N level observed is independent of the presence of spent grains. At moderate temperature, spent grains have a stabilizing effect on T2N levels. The decreased amount of T2N during mashing-off can be quantitatively determined in a potential test. Reduced levels of T2N have also been observed when the mashing-in liquor was acidified to pH 5.3, or by using coarse ground malt or by making a thicker mash. Increased amounts of T2N have been found in the extracts carried out at 5°C. No correlation between lipoxygenase activity in kilned malt and the corresponding soluble T2N during wort production was found in the study.