Prolonged storage of ‘Aledo’ table grapes in a slightly CO2 enriched atmosphere in combination with generators of SO2

The quality of late-harvested (early December) ‘Aledo’ table grapes, during storage at 2±1 °C followed by a period of 4 days at 20 °C in a slightly CO₂ enriched atmosphere in combination with generators of SO₂ in cardboard boxes, was evaluated. The changes in different biochemical parameters indicative of grape quality, such as weight, texture, colour, sugars, organic acids and fungal attacks, was determined. The best quality maintenance was achieved by combining the use of generators of SO₂ with a slightly CO₂ enriched atmosphere. The rates of weight, texture and colour losses were slowed, and both fungal attack and the rachis drying were delayed. During storage at 2 °C, the levels of glucose, fructose and sucrose remained unchanged under all the tested conditions, while levels of tartaric and citric acids showed a sharp increase. However, a slightly CO₂ enriched atmosphere, SO₂ microgenerators and their combination extended the storage period of late-harvested ‘Aledo’ table grapes without relatively affecting their organoleptic characteristics.     

Transfer process limited models for CO2 perception in CO2 hydrate desserts

A CO₂ hydrate dessert is a carbonated frozen dessert in which CO₂ hydrates replace some or all of the ice. When a CO₂ hydrate dessert is eaten, CO₂ perception is very strong due to formation and bursting of bubbles in the mouth as well as dissolution of CO₂ leading to nociceptor stimulation. A preliminary sensory panel indicated that a CO₂ hydrate dessert could be perceived as more carbonated than a freshly opened soda. However, it was also found that a CO₂ hydrate dessert must have a significantly higher CO₂ concentration than is typical in carbonated beverages (including champagne), just to have moderate perception of carbonation. In this work, heat transfer limited and mass transfer limited models for CO₂ hydrate dissociation are compared and the implications for CO₂ perception are discussed. It is suggested that the mass transfer limited model is most applicable to the case of eating CO₂ hydrate desserts. According to this model, a thin ice shell limits the rate of CO₂ hydrate dissociation. After dissociation, CO₂ gas is dissolved in the available aqueous phase. In a CO₂ hydrate there is much more CO₂ present than could be dissolved in the water that is present, so a large fraction of the CO₂ in the dessert may be lost with the breath of the consumer.     

不同季节工况下变转速NH3/CO2复叠制冷系统性能研究

目的：研究在不同季节工况、蒸发温度为25 ℃条件下,高温压缩机转速对NH₃/CO₂复叠制冷系统性能的影响。方法：建立NH₃/CO₂复叠制冷系统模型并验证其可靠性,计算分析高温压缩机转速与系统高温蒸发温度、高温排气温度、中间温度、高温压缩机功率、制冷量、性能系数的变化关系。结果：仿真模型对制冷量的预测与理论值的相对误差小于14.1%。高温压缩机转速从2 300 r/min增至3 300 r/min,春季、夏季、秋季、冬季工况下的制冷量分别提升了31.7%,41.7%,33.9%,25.2%,且在低转速范围内冬季制冷量最高;高温压缩机功率呈两段式上升趋势,提升了40%～45%。结论：存在使得性能系数最大的最佳高温压缩机转速。基于系统对不同季节工况的适应性问题,提出了变转速NH₃/CO₂复叠制冷系统方案,与定转速系统相比每年可减少19.9%耗电量。     

超临界CO2夹带乙醇萃取裂殖壶藻油脂的工艺研究

研究了超临界CO_2夹带乙醇流体从裂殖壶藻Schizochytriumsp.中提取富含DHA油脂的新工艺。基于气液相平衡性质,确定了夹带剂乙醇的添加范围,并对提取过程进行动力学分析,确定了二氧化碳的使用量。通过中心组合设计的响应面优化试验,获得了最佳提取工艺条件:温度52℃、压力38 MPa、乙醇摩尔比0.04。该条件下,微藻油脂的回收率约为88.2%,显著高于纯超临界CO_2萃取的回收率(71.9%)。根据Peng-Robinson方程考察了混合流体的密度变化对油脂溶解度的影响,部分解释了操作条件对油脂回收率的影响。脂肪酸组成分析显示,新工艺得到的油脂中的DHA质量分数约为39.9%,略高于传统工艺。由此可知,超临界CO_2夹带乙醇流体是一种极性范围广、溶解能力强的绿色提取介质,非常适用于中性微藻油脂的提取。     

超临界CO2萃取燕麦油工艺研究

以燕麦切粒为原料,进行超临界CO_2萃取燕麦油工艺研究及燕麦油品质分析。首先,通过单因素试验探讨各因素对燕麦油萃取率的影响;其次,采用响应面法优化超临界CO_2萃取燕麦油的工艺参数;最后用GC-MS分析燕麦油的脂肪酸组成并进行品质分析。结果表明:超临界CO_2萃取燕麦油的最佳工艺参数为装料量50 g、静态萃取时间74 min、动态萃取时间160 min、萃取压力45MPa、萃取温度50℃,在此工艺条件下燕麦油萃取率可达56.99%;超临界CO_2萃取的燕麦油澄清透明,呈金黄色,具有特殊的麦香味,不饱和脂肪酸含量为87.49%。     

Breaking the spores of the fungus Ganoderma lucidum by supercritical CO2

The hard sporoderm of Ganoderma lucidum spores prevents the release of bioactive components such as polysaccharides which have significant anti-tumour activity. In the present study, supercritical carbon dioxide (SC–CO₂) was used for the sporoderm breaking of G. lucidum spores, and polysaccharides were subsequently extracted and determined for evaluating the performances of SC–CO₂. The operating parameters were optimized by orthogonal array design (OAD), and the morphological status of sporoderm was observed by scanning electron microscope (SEM). The optimum operating conditions for SC–CO₂ breaking of sporoderm were as follows: pressure 35 MPa, temperature 25 °C, time 4 h, and CO₂ flow rate 10 kg/h. After SC–CO₂ processing, the extraction yield of polysaccharides reached 2.98%, which was 3-fold to that of the intact ones (0.94%). This method is fast, efficient and advanced enough to break the hard sporoderm of G. lucidum, which may provide a scientific reference for the large-scale processing of spores in the pharmaceutical and food industries.     

Preparation of isoflavones enriched soy protein isolate from defatted soy hypocotyls by supercritical CO2

Soy hypocotyls, the byproduct from soy protein industry, rich in isoflavones, was attempted to develop into a value-added functional food, soy protein isolate (SPI). Soy hypocotyls were defatted by supercritical CO₂ (SC-CO₂) under the following conditions as 35 MPa, 2 h, 45 °C with a constant flow rate of CO₂ at 5 l/min, fed from the bottom of the extraction vessel. Via extraction, the oil contents were lowered from 10.5 g/100 g in original soy hypocotyls to 0.2 g/100 g in defatted soy hypocotyls (DSH) with a Protein Dispersibility Index (PDI) value of 91.2 that contained about 2.18 g/100 g of isoflavones and 63.6 g/100 g of proteins. SPI was then extracted from DSH under the optimized conditions including: the pH of water solution at 6, the ratio of DSH to water solution as 1:10 and the extraction temperature at 30 °C with the extraction time of 30 min. The freeze-dried SPI contained 92.46 g/100 g of the proteins and 640 mg/100 g of isoflavones, where the three major β-glycosides, glycitin, daidzin and genistin accounted for about 83.7% of the total isoflavones. The yields of SPI and isoflavones were about 48% and 30% in terms of their respective total contents in DSH.     

Supercritical CO2 extraction of trans-lycopene from Portuguese tomato industrial waste

Supercritical CO₂ extraction of trans-lycopene from Portuguese tomato industrial wastes (skins and seeds) was carried out in a flow apparatus. The effects of moisture content, feed initial composition, particle size, solvent flow-rate, pressure and temperature on the extraction yield and recovery were evaluated.     

超临界CO_2流体萃取石榴籽油工艺条件的研究

以石榴籽为原料,对超临界CO2流体萃取石榴籽油的工艺条件进行了研究。通过单因素试验,研究了萃取压力、萃取温度和萃取时间对石榴籽油得率的影响。在单因素试验的基础上,通过正交试验确定了超临界CO2流体萃取石榴籽油的最佳工艺条件。结果表明,超临界CO2流体萃取石榴籽油最佳工艺条件为:萃取压力40 MPa,萃取温度55℃,萃取时间80 min,分离釜Ⅰ温度60℃,压力10 MPa,分离釜Ⅱ温度35℃,压力6 MPa。在最佳工艺条件下,石榴籽油得率为18.6%。     

Physical properties of extruded corn grits with corn fibre by CO2 injection extrusion

Corn grits and corn fibre mixed at different ratios (0/100, 15/85 and 30/70) were extruded at different melt temperature (90, 105 and 120 °C) using extrusion with and without CO₂ injection. Increasing melt temperature also significantly improved physical properties of extrudates in both non-CO₂ and CO₂ injection (200 mL/min) extrusion process. The injection of CO₂ in the extrusion process showed similar effect on physical properties of extrudates at the lower melt temperature (90 and 105 °C), whereas it exhibited opposite trend at higher melt temperature (120 °C). At the lower melt temperature, the surface of extrudates with the CO₂ injection was smoother and lower fracturability, and the cross sectional microstructure was more uniform. The addition of corn fibre decreased the expansion index, bulk density and breaking strength on the same extrusion condition. In addition, non-uniform and more broken cross-sectional microstructure was observed by the addition of corn fibre.     

甜杏仁的超临界CO2萃取及产物分析

以新疆产甜杏仁为原料,采用超临界CO₂萃取技术进行萃取并对所得产物杏仁油的理化指标与脂肪酸组成,以及杏仁粉中微量元素与氨基酸组成进行了分析测定。结果表明：在萃取温度45℃,萃取压力33 MPa,萃取时间5.5 h,分离温度48℃的条件下,杏仁油得率为46.44%;杏仁油中富含油酸（70.98%）和亚油酸（22.93%）,不饱和脂肪酸含量达到93.96%;杏仁粉中含有丰富的蛋白质和微量元素,其中蛋白质含量为50.66%,钙含量为2 655 mg/kg,镁含量为3 995 mg/kg,铁含量为127 mg/kg,锌含量为116.5 mg/kg,锰含量为6.24 mg/kg;杏仁粉蛋白质中谷氨酸含量最高,为11.00%。     

Supercritical CO2 cell breaking extraction of Lycium barbarum seed oil and determination of its chemical composition by HPLC/APCI/MS and antioxidant activity

The extraction parameters for oil extraction from Lycium barbarum seed including extraction pressure, temperature and time were optimized using an orthogonal test design. The optimum conditions for supercritical CO₂ extraction were as follows: extraction pressure, 30 MPa; extraction temperature, 45 °C; dynamic extraction time, 60 min; CO₂ flow, 25 kg/h. The oil yield under the conditions proposed was 19.28 g/100 g. The effect of cell wall breakage pretreatment was investigated by supercritical CO₂ rapid depressurization, and results indicated this pretreatment could result in a rapid and efficient extraction. A sensitive fluorescent reagent 2-(11H-benzo[a]carbazol-11-yl) ethyl 4-methylbenzenesulfonate (BCETS) was utilized as pre-column labeling regent to determine fatty acids (FA) from Lycium barbarum seed oils obtained by different extraction methods. The main FA were: C18:2, C18:1, C16, C20:6, C18:3, and C20. The oil from L. barbarum seed exhibited excellent antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl（DPPH）radical scavenging assay and β-carotene bleaching test, and its antioxidant activity compared well with the references ascorbic acid and α- tocopherol.     

超临界CO2萃取甜瓜籽油工艺及其脂肪酸组成分析

采用超临界CO2萃取技术提取甜瓜籽油,在单因素实验的基础上,运用正交实验设计优化工艺条件。结果表明超临界CO2萃取甜瓜籽油的最佳工艺条件为:萃取压力30 MPa,萃取温度45℃,萃取时间5 h,CO2流量8 L/min,甜瓜籽粉碎粒度24目。在最佳条件下,甜瓜籽油得率为29.34%。利用GC-MS对甜瓜籽油脂肪酸组成进行分析,结果表明超临界CO2萃取的甜瓜籽油共鉴定出12种脂肪酸,其中饱和脂肪酸以棕榈酸(10.87%)、硬脂酸(5.57%)为主,不饱和脂肪酸以亚油酸(64.29%)、油酸(16.64%)为主。     

超临界CO2萃取羊肉油脂及其脂肪酸组成的变化

为探究超临界CO₂萃取技术在动物油脂提取中的应用,明确萃取过程中脂肪酸的变化规律,以羊肉为原料,利用超临界CO₂萃取技术提取羊肉油脂,分析油脂提取效果,并采用气相色谱-质谱联用仪对其脂肪酸质量分数和组成进行分析。结果发现,超临界CO₂萃取羊肉油脂的萃取率可达22.04%,与未处理组相比,经超临界萃取后肉中饱和脂肪酸相对含量显著降低了11.37%(P<0.05),超临界萃取的油中饱和脂肪酸无显著变化(P>0.05);超临界萃取后肉中单不饱和脂肪酸相对含量较未处理组显著提高9.20%(P<0.05),其中棕榈油酸相对含量显著增加了61.00%(P<0.05);超临界萃取的油中单不饱和脂肪酸相对含量与未处理组相比无显著差异(P>0.05),但其中棕榈油酸的相对含量显著提高了70.10%(P<0.05);超临界萃取肉和油中均未检出反式油酸,且其中多不饱和脂肪酸相对含量及组成无显著变化(P>0.05)。因此,超临界CO₂萃取技术可应用于羊肉油脂提取,有利于提高超临界萃...     

Effect of suboptimal temperatures and sublethal CO2 levels on multiplication of Tribolium castaneum (Coleoptera: Tenebrionidae), alone or competing with Cryptolestes ferrugineus (Coleoptera: Cucujidae)

Groups of adults of Tribolium castaneum alone, or in combination with adults of Cryptolestes ferrugineus, were exposed to suboptimal temperatures (15°C, 20°C, and 25°C) and sublethal CO₂ levels (2%, 5%, and 10%) in dry (12%, wet mass basis) and damp (15%, wet mass basis) stored wheat in the laboratory, to investigate effects on population size. The mean adult numbers in single- and mixed-species tests were positively correlated with higher temperature and moisture content and negatively correlated with higher CO₂ levels. Adult numbers in single- and mixed-species tests were lower at sublethal CO₂ levels compared to ambient CO₂ levels at all the test temperatures and decreased in dry grain compared to damp grain. Although, a specific trend was not observed in population inhibition between mixed-species and single-species tests, overall the adult populations of T. castaneum were reduced in the presence of C. ferrugineus. A mathematical model was derived to predict the size of adult populations of T. castaneum alone, or in the presence of C. ferrugineus considering all the variables in this study. The model had an R² value of 0.72 but needs to be validated and refined with field data.     

Vitamin D2 stability in milk during processing,packaging and storage

Stability of vitamin D2 in milk was determined in vitamin D2 fortified milk. Reverse phase high pressure liquid chromatography was used to determine the vitamin D₂ loss during processing, packaging and under light. The percentage losses during pasteurization, boiling and sterilization were demonstrated to be statistically insignificant. Milk was stored for seven days in both glass and plastic bottles under refrigerated temperature, non significant loss of vitamin D₂ was observed, whereas, when stored in polyethylene pouches significant loss was observed as vitamin D₂ decreased from 596.66 to 548.04 IU. This clearly indicated that vitamin D₂ was sorbed up by polyethylene material during storage resulting in its loss. Milk samples were stored for 32 h under three different light intensities (14,852,970 and 4455 lux). Non significant loss of vitamin D₂ was observed in glass packaging, whereas significant loss was observed in polyethylene pouches. In milk fortified with both calcium and vitamin D₂, non significant effect of calcium was observed on the loss of vitamin D₂.     

Determination of the CO2 mass diffusivity of egg components by finite element model inversion

With the aim to improve the technological properties and the product freshness maintenance, the conservation of eggs in saturated CO₂ atmosphere has been proposed. In this research, to study the CO₂ diffusion inside the egg, a numerical model was developed. This required a characterization of the involved materials, with particular reference to the mass diffusivity. The present paper proposes a method, based on just simple laboratory determination of average total CO₂ concentration and on the inversion of a finite element model, to estimate the CO₂ mass diffusivity in the thin albumen, thick albumen and yolk of hen eggs. The method does not require complex devices and looks susceptible to extension to other physical problems. The results showed that the values of mass diffusivity determined by inverse method (thin albumen: 1.8E−09 m²/s; thick albumen: 8.5E−10 m²/s; yolk: 1.6E−10 m²/s) are comparable to the data reported in the literature for similar materials.The simulated and experimental values of CO₂ concentration appear to be in good agreement, particularly for the albumen.     

Supercritical CO2 extraction optimization of pomegranate (Punica granatum L.) seed oil using response surface methodology

This study examined extraction of pomegranate seed oil by using supercritical carbon dioxide. Response surface methodology was used to evaluate the effects of the process parameters, namely extraction pressure, temperature and CO₂ flow rate on the yield of pomegranate seed oil. The extraction parameters were optimized with a central composite design experiment. The linear term of pressure, followed by the linear term of CO₂ flow rate, the quadratic terms of pressure, temperature and CO₂ flow rate and the interactions between pressure and temperature, as well as CO₂ flow rate and temperature, had significant effects on the oil yield (p < 0.05). Maximum yield of pomegranate seed oil from the mathematical model was predicted to be 156.3 g/kg dry basis under the condition of pressure 37.9 MPa and temperature 47.0 °C with CO₂ flow rate of 21.3 L/h. The fatty acid composition and the tocopherols' content of pomegranate seed oil extracted using supercritical CO₂ were compared with those obtained by Soxhlet method. Minor difference was found in the fatty acid composition of the oils extracted by the two methods. The content of total tocopherols was about 14% higher in the oil extracted with supercritical CO₂ than that obtained by Soxhlet extraction.     

超临界CO2法萃取树莓籽油的成分分析

采用超临界CO_2技术萃取树莓籽油,利用GC法测定脂肪酸组成,GC-MS联用法测定甾醇组成,HPLC测定生育酚含量,紫外可见分光光度计测定多酚含量。结果表明:超临界CO_2萃取树莓籽油的平均出油率为17.90%±0.3%;共检测到10种脂肪酸,其中亚油酸相对含量(57.44%)最高,其次是α-亚麻酸(26.58%)、油酸(11.94%)和棕榈酸(2.10%);脂肪伴随物中,共检测出7种甾醇,总甾醇含量为861.85 mg/100 g;γ-生育酚、α-生育酚和δ-生育酚含量分别达到799.248、602.996 mg/kg及13.371 mg/kg;多酚平均含量为(341.19±8.94)mg GAE/kg。此研究为树莓籽油及其他蔷薇科植物油的进一步开发利用奠定了基础。     

Phospholipase A2 and antioxidant enzyme activities in normal and PSE pork

In order to reveal the relationship between phospholipase A₂ and antioxidant enzymes and drip loss in pork, the study was designed to examine the effects of phospholipase A₂ and antioxidant enzymes on the water-holding capacity of pork during postmortem chilling. Six PSE and RFN samples (longissimus muscle) were used to determine the activities of phospholipase A₂ (tPLA_2, cPLA₂ + sPLA₂ and iPLA₂), superoxide dismutase (SOD) and GSH-Px, and acid phospholipase. The results showed that pH_1 h and pH_24 h from PSE pork were lower (p < 0.01) than for normal pork (RFN), but the L* value at 1 h and 24 h postmortem, TBARS content, drip loss at 48 h and 96 h, cooking loss, tPLA₂ activity and iPLA₂ were higher (p < 0.01) than of normal pork. Correlation analysis indicated that drip loss at 48 h was negatively related to pH_1 h (p < 0.01) and pH_24 h (p < 0.01) but positively to T_1 h (p < 0.01) and the activities of total phospholipase A₂ (p < 0.05) and calcium-independent phospholipases A₂ (p < 0.01). The tPLA₂ and GSH-Px play important roles in drip loss.