PLA纤维超临界CO2染色研究

探讨了PLA纤维分散染料超临界CO2流体染色的可行性。研究了温度、压力、时间等因素对染色效果的影响；用正交试验法确定了最佳染色工艺。结果表明，随着温度升高，纤维的表观染色深度明显增加；升高压力或延长染色时间，K／S值存在一个最大值；试验用分散染料的最佳染色工艺为温度100℃、时间40min、压力20MPa。     

Mathematical modelling of soybean oil solubility in supercritical carbon dioxide

The solubility of soybean oil in supercritical carbon dioxide has been determined in the pressure range of 100–300 bar and in the temperature range of 313–323 K. The obtained values (from 0.0005 to 0.02055 g L^?1) have been correlated using four different empirical equations proposed correspondingly by Chrastil, del Valle and Aquilera, Adachi and Lu and Sparks et al. Since the Sparks et al. equation provided the lowest average absolute relative deviation (AARD) (10.25%) than other models in the examined experimental range, a modified equation of Sparks et al. model was developed for predicting the solubility of soybean oil in supercritical carbon dioxide as a function of temperature and density. An improved equation showed the lowest deviation (2.15%) between experimental data than the other empirical equations considered in this study. The proposed equation was also applied for correlating the solubility of linoleic acid (AARD was 2.40%).     

Quantification of aroma vapours sorbed in polyethene films using supercritical carbon dioxide

Extraction with supercritical carbon dioxide was used to quantity the amounts of seven different aroma vapours sorbed in polyethene films. The method was found to completely extract all aroma compounds from the films. The solution of aroma compounds in the polymer films decreased with increasing polymer density. Monoterpenes were always completely sorbed in the films, whereas aldehydes and ketones had a much lower affinity for the films. The sulphur-containing compound, thiophene, was difficult to analyse due to its adsorption on metal surfaces.     

Enrichment of tocopherols in modified soy deodorizer distillate using supercritical carbon dioxide extraction

Supercritical carbon dioxide (SC-CO₂) extraction of chemically modified Soy Deodorizer Distillate (DOD) at three levels of pressure (180–300 bar) and temperature (40–60 °C) to optimize the conditions for enrichment of tocopherols in the raffinate was carried out. After modification, soy DOD contained about 90% of fatty acid methyl esters (FAME), showed improved solubility in SC-CO₂, and better extraction rate. Since fatty acid methyl esters are more volatile, they are extracted preferentially over tocopherols and other high molecular weight compounds. Higher levels of pressure and temperature resulted in increased solubility of compounds with high molecular weight and tocopherols due to increased density of SC CO₂. So the extraction at higher pressures and temperatures resulted in a better yield of FAME along with tocopherols in the extract and this in turn decreased the degree of enrichment of tocopherols in the raffinate. However, specific level of pressure and temperature of extraction caused the increase in the solubility of FAME due to their volatility and results in enhanced enrichment of tocopherols in the raffinate. It was observed that the enrichment of tocopherols to ten times the original concentration of feed occurred at extraction pressure of 180 bar and temperature of 60 °C of SC-CO₂.     

Inactivation of Saccharomyces cerevisiae in conference pear with high pressure carbon dioxide and effects on pear quality

This work explores the use of high pressure carbon dioxide (HPCD) for the inactivation of Saccharomyces cerevisiae in fresh-cut conference pears. This fruit was chosen as an example of a ready to eat and minimally processed food. Assays were carried out with continuous CO₂ flow at different pressures (6–30 MPa), temperatures (25–55 °C), and exposure times (10–90 min). Heat treatments at similar temperatures and times were compared to the use of HPCD, wherein it was observed that HPCD was more effective. The total inactivation (5 log₁₀ cycles) of the yeast took place at 55 °C with HPCD while it was necessary to reach 70 °C when only heat was applied. Required pressures and exposure times were relatively low (?6 MPa and on the order of minutes) because of the direct contact between the CO₂ and the pear. The pH and °Brix were not affected by the HPCD treatment; however, the pears lost their texture and became darker due to a decrease in vitamin C and enzymatic browning. Peroxidase activity was only partially reduced. The addition of an antioxidant did not help to prevent darkening. Therefore, HPCD could be a low temperature conservation method that is superior to conventional thermal treatments for the preparation of fruit preserves where a firm texture is not essential.