USE OF OZONE TO INACTIVATE MICROORGANISMS ON LETTUCE

When ozone (1.3 mM) was bubbled for 3 min in a mixture of shredded lettuce and water, counts ofmesophilic andpsychrotrophic bacteria decreased 1.4 and 1.8 log₁₀ cfu/g, respectively. Counts of these microorganisms on lettuce, from a different batch, decreased 3.9 and 4.6 log, respectively, during 5 min of ozone treatment. Shredded lettuce was treated with gaseous ozone, or mixed with aqueous solution of ozone (1:20 w/w) with or without bubbles. For effective delivery of ozone, stirring (low and high speed), sonication or stomaching was applied during the ozonation. Washing the lettuce with water only decreased total count on shredded lettuce by 0.74–1.0 log cfu/g. When lettuce in a treatment chamber was flushed with gaseous ozone, the total count decreased 0.85 log cfu/g, but when vacuum was applied before the ozone flush, the total count decreased 0.96 log cfu/g. Bubbling ozone in water-lettuce mixture while sonicating, high-speed stirring, or before stomaching inactivated 1.4, 1.9 and 1.9 log cfu/g, respectively. In conclusion, bubbling gaseous ozone in water is the most effective ozonation method. Efficient ozone delivery to microorganisms on lettuce requires a combination of ozone bubbling and high-speed stir.     

超临界CO_2脱除大豆分离蛋白异味的研究

利用超临界 CO_2脱除大豆分离蛋白异味。研究了不同压力和温度对萃取效率的影响，从而得出了最佳工艺条件为 27.5MPa和 45℃。经分析萃取出的异味物质主要有醇、醛酮和芳香类物质， 经处理后的大豆分离蛋白异味减少，溶解性有所下降，持水性和乳化稳定性增强。     

超临界二氧化碳染色的现状研究

针对传统水染工艺不能从根本上解决印染行业水环境污染严重及资源消耗、浪费大的问题,介绍了一种全新的清洁生产技术———超临界CO2染色,重点论述了超临界流体和超临界CO2染色工艺的特点,对国内外超临界二氧化碳染色技术在合成纤维和天然纤维纺织品染色中的研究现状作了全面分析,并对其发展前景进行了展望。     

INACTIVATION OF MICROORGANISMS BY CARBON DIOXIDE UNDER PRESSURE

Carbon dioxide under pressure killed bacteria, molds, and yeast. The effect was synergistic with raised temperature and acidic pH and antagonized by lowered A_w. Time of exposure was important, and conditions needed for the inactivation of different microbes varied, some organisms being much more resistant than others. The effect was tested on various foods, but disrupted the texture of some. Clostridial spores were very recalcitrant, but could be destroyed by further lowering the pH along with concurrent exposure at 70°C. The pH in media under pressure was measured and theories advanced for the antimicrobial effect.     

超临界CO2萃取玉米胚芽油的研究

讨论了利用超临界CO2萃取玉米油的萃取压力、温度、时间、夹带剂等不同操作参数对萃取结果的影响，从而确定最佳工艺条件为25－30MPa，45℃,3h；并对产品进行了质量分析，比较了超临界萃取与传统压榨工艺的优缺点。     

超临界CO2萃取红松子油的研究

研究超临界CO2萃取红松子油的影响因素，在试验条件下，其影响因素次序为萃取压力、夹带剂、萃取温度、萃取时间。最优条件为35MPa，45℃，240min，5％无水乙醇作夹带剂，CO2流量20L／h～25L／h。45oC时，在15MPa和35MPa两种不同的压力下，对比了加入5％无水乙醇作夹带剂与不使用夹带剂时超临界CO2萃取过程中出油量随时间的变化，使用夹带剂后出油量均有提高。     

超临界CO2纯化辣椒色素的研究

研究了用超临界ＣＯ２流体纯化溶剂法提取辣椒色素的方法．用超临界ＣＯ２流体作萃取剂，从液体或固体物料中实现萃取、分离和纯化物料从而制备高纯度辣椒色素是可行的．使产品符合ＦＡＯ／ＷＨＯ残留溶剂标准要求（已烷含量２５ｍｇ／ｋｇ）的最佳工艺参数是：萃取压力１８ＭＰａ，萃取温度２５℃，萃取剂流量２．０Ｌ／ｍｉｎ，萃取时间３ｈ．     

超临界二氧化碳染色的原理及研究进展

介绍了超临界二氧化碳染色具有染色时间短、匀染透染性好、染后不用还原清洗等优点,且整个染色过程中不会造成任何污染,解决了传统染色工艺使用大量的水造成浪费大,存在环境污染严重及资源消耗和有机溶剂染色的生态、成本、很难工业化应用的问题。同时介绍了超临界二氧化碳染色法的基本原理,对国内外超临界二氧化碳染色技术在合成纤维和天然纤维纺织品染色中的研究现状作了全面分析,并对其发展前景进行了展望。     

SUPERCRITICAL CARBON DIOXIDE SELECTIVITY TO FRACTIONATE PHENOLIC COMPOUNDS FROM THE DRY ETHANOLIC EXTRACT OF PROPOLIS

The global yield and composition of extracts obtained by supercritical carbon dioxide (SC-CO₂) extraction from a dry ethanolic extract of propolis were measured in order to determine the possibility of using SC-CO₂ to fractionate components of interest present in these extracts. The global yield extraction was measured, and also the concentrations of the following phenolic compounds in the resulting supercritical fluid extracts (SFEs): 3,5-diprenyl-4-hydroxycinnamic acid (known as artepillin C), 3-prenyl-4-hydroxycinnamic acid, 4-hydroxycinnamic acid ( p- coumaric acid) and 4-methoxy-3,5,7-trihydroxyflavone (kaempferide), of which artepillin C was the target component of greatest interest. The results showed extraction yields between 3.82 (at 150 bar) and 13.07% (at 350 bar), which could be highly correlated with the density of the SC-CO₂ at a constant temperature of 60C. The resulting concentrations in the SFE indicated that the selectivity of the carbon dioxide could be manipulated, and it was more selective at lower pressures, although with lower extraction yields.

PRACTICAL APPLICATIONS

Supercritical fluid extraction is an interesting process for the production of natural extracts because it is a clean process, and extractions using carbon dioxide (CO₂) as the solvent have been gaining attention in recent years. This study presented important aspects with respect to the fractionation of a dry ethanolic extract of propolis using supercritical carbon dioxide, and it is important to explore the potential applications of propolis extracts and the biological properties of its fractions in the food, pharmaceutical and cosmetic industries, such as in dental hygiene products, wound healing creams and antibacterial soaps.     

A PREDICTIVE MODEL FOR HIGH-PRESSURE CARBON DIOXIDE INACTIVATION OF MICROORGANISMS

The Weibull model, which is commonly used for thermal inactivation of microorganisms in literature, was used to describe microbial inactivation by high-pressure carbon dioxide (HPCD). The number of parameters of the model was reduced from two to one in order to avoid interrelationship of these parameters with a slight loss of goodness-of-fit. A second-order polynomial function fulfilling a number of constraints was proposed for the secondary modeling of the time-constant parameter of the reduced Weibull model. This function consists of both pressure and temperature and therefore can be used for HPCD treatments.

PRACTICAL APPLICATIONS

The application of any new technology in food preservation requires a reliable model that accurately describes and predicts the inactivation data of microorganisms. In principle, the methodology presented here could be used to describe and predict the survival data for high-pressure carbon dioxide inactivation of microorganisms at least for some pressure and temperature ranges if the isobaric/isothermal survival curves of these microorganisms are linear, concave upward or downward.     

EFFECT OF SUPERCRITICAL CARBON DIOXIDE ON MICROBIAL POPULATIONS IN SINGLE STRENGTH ORANGE JUICE1

The effect of supercritical carbon dioxide on aerobic total plate count (TPC) of fresh-squeezed and quick-frozen single strength orange juice from Valencia oranges was studied. Orange juice was treated with SC CO₂ at different temperatures (35° to 60°C) and pressures (8.3 to 33.1 MPa). SC CO₂ treatment at 35°C reduced the TPC by 2 log cycles after 1 h treatment at 33 MPa. At 45°C and 33 MPa 2 log cycles reduction required 45 mins, and 15 mins treatment was sufficient at 60°C. D values of temperature control samples decreased as temperature increased, while that of supercritically treated juice decreased as pressure increased. D values at 35, 45 and 60°C of the supercritically treated juice at 33.1 MPa were calculated as 28, 22.6 and 12.7 min, respectively. The calculated values of z were 180°C, 167°C and 72°C at 8.3 MPa, 20.7 MPa and 33.1 MPa, respectively.     

荷叶超临界CO2萃取物调节动物血脂的作用

研究了荷叶超临界CO2萃取物对高脂血症大鼠调脂作用的影响。结果表明：荷叶超临界CO2萃取物能显著降低高脂大鼠的血清总胆固醇（TC）、总甘油三脂（TG）、低密度脂蛋白（LDL-C）和升高高密度脂蛋白（HDL—C），能显著降低高脂血症大鼠血清和肝脏中丙二醛（MDA）含量及提高超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH—Px）活性。     

超临界CO2提取大果沙棘油的工艺研究

研究了超临界CO2萃取大果沙棘油的提取工艺，分析了萃取温度、萃取压力、萃取时间、分离温度对沙棘油提取率的影响，并通过正交试验得到了最佳的提取条件：提取压力35MPa，萃取温度45℃。提取时间1．5h，分离温度45℃。提油率可达到10．52％。将所得沙棘油按1g1的比例加水进行水化，然后加入3％～5％白土进行脱色，沙棘清油的得率达到75％～81％，且沙棘清油的颜色浅黄透明，香气纯正。     

ANALYSIS of BUTTERFAT EXTRACTION and FRACTIONATION USING SUPERCRITICAL CARBON DIOXIDE

A flow through extraction reactor was used to study supercritical fraction-ation of butterfat. the rate of extraction of butterfat was constant for an initial period followed by a decreasing rate of extraction. DSC and GC analyses showed that more soluble triglycerides extracted preferentially in the initial stages exhibited lower melting behavior. the chemical and physical properties of the fractions changed with extraction time. Residual butterfat concentration in the bed was obtained as a function of distance from the bed entrance. the breakthrough curves had a sigmoidal shape, with the ascent-portion of the curves advancing through the bed with the degree of extraction. At the highest extents of extraction, the lower acyl carbon number triglycerides were totally depleted from the lowest portions of the bed, where fresh CO₂ was introduced.     

SUPERCRITICAL CARBON DIOXIDE PERCOLATION OF SEA BUCKTHORN PRESS JUICE1

Sea buckthorn press juice was subjected to percolation with supercritical carbon dioxide at 13.8 and 27.6 MPa. Control juice was not percolated. Percolation extracted about 81 % of the oil present in the press juice, lightened the orange color compared with the control juice, and changed the character of the juice as perceived by observers. Percolated juices had no visible particulate that adhered to glass surfaces as did the control juice. All juices were perceived by taste panelists as to be very sour, and it was decided to sweeten the juices with 10% sucrose before proceeding with sensory evaluations. Control juice was more yellow and thicker in consistency than the percolated juices which did not differ from each other. Juices prepared by 27.6 MPa percolation were more frequently reported as having citrus and peach‐like quality attributes compared with either of the other two juices. Analytical values for protein, oil, moisture, titratable acidity and pH were reported for the juices. Light microscopy indicated a lower oil content in the percolated juices and that the particle sizes were smaller in the percolated juices. Some morphological characteristics of the particles in both juice types are described.     

超临界CO2提取栝楼籽油的工艺研究

利用正交实验法对栝楼籽油的超临界CO2提取工艺进行了优化.以栝楼籽油的得率为指标,考察萃取压力、温度、时间和粉碎度对栝楼籽油得率的影响,得到最佳工艺条件为:萃取时间5h、原料粉碎度0.42mm、萃取温度45℃和萃取压力30MPa,栝楼籽油提取率可高达56.38%,且栝楼籽油暗红透明,香气纯正.