Reaction Behavior of Glucose and Fructose in Subcritical Water in the Presence of Various Salts

Glucose and fructose were treated in subcritical water in the presence of alkali or alkaline earth metal chlorides. All salts accelerated the conversion of saccharides, and alkaline earth metal chloride greatly promoted the isomerization of glucose to fructose. In contrast, alkali metal salts only slightly promoted this isomerization and facilitated the decomposition of glucose to byproducts such as organic acids. The selectivity of the glucose-to-fructose isomerization was higher at lower conversions of glucose and in the presence of alkaline earth metal chlorides. The pH of the reaction mixture also greatly affected the selectivity, which decreased rapidly at lower pH due to the generated organic acids. At low pH, decomposition of glucose became dominant over isomerization, but further conversion of glucose was suppressed. This result was elucidated by the suppression of the alkali-induced isomerization of glucose at low pH. Fructose underwent decomposition during the treatment of the fructose solution, but its isomerization to glucose was not observed. The added salts autocatalytically promoted the decomposition of fructose, and the reaction mechanism of fructose decomposition differed from that of glucose.     

NaCl和葡萄糖对抗性淀粉形成的影响

以高直链玉米淀粉为试材,分别研究了NaCl浓度和葡萄糖浓度对抗性淀粉形成的影响,发现当NaCl浓度提高到10%以上时,抗性淀粉得率从10.2%提高到16.5%。当NaCl浓度达50%时,抗性淀粉得率提高到17.1%,此后,即使NaCl浓度增加到60%,抗性淀粉得率也不再增大。当葡萄糖浓度从20%增加到60%,抗性淀粉得率从10.0%缓慢增加到14.2%,此后,即使葡萄糖浓度增加到70%,抗性淀粉得率仍维持在14.2%。显然,高浓度NaCl或葡萄糖能够促进抗性淀粉的形成,其原因可能是NaCl或葡萄糖降低了水分活度并且使直链淀粉分子更容易相互靠近、联结。     

山茱萸籽粕亚临界水降解动力学及多糖性质研究

本实验以山茱萸籽粕为原料,进行山茱萸籽粕亚临界水降解研究,测定不同降解温度、降解时间下液态产物的还原糖含量,采用Saeman模型模拟分析,建立降解动力学方程,得到降解动力学参数,并对降解物进行理化性质的分析。结果表明,Saeman模型能较好反映山茱萸籽粕亚临界水降解的过程,初步降解的反应活化能E_a1为29.47 kJ/mol、还原糖降解活化能E_a2为22.21 kJ/mol、指前因子K₁₀为101.49 min^-1、K₂₀为20.28 min^-1,在降解温度160 ℃、降解时间20 min条件下,能得到产量较高的还原糖。单糖组成分析表明,山茱萸籽多糖主要由葡萄糖、木糖、半乳糖、半乳糖醛酸组成,其总糖含量高达78.82%;扫描电镜和红外光谱结构分析结果表明,多糖结构呈表面光滑,无规则颗粒状,粒径大小不一的球状结构物,为吡喃型糖苷环骨架;抗氧化活性分析结果表明,山茱萸籽多糖具有较好的自由基清除能力,在质量浓度为1.0 mg/mL时,对DPPH自由基、羟自由基和ABTS自由基清除率分别为85.61%、63.40%、76.20%。本试验结果为山茱萸籽多糖的进一步分离纯化和理化特性、形态结构的分析提供了参考。     

脱脂椰蓉粉亚临界水降解动力学及产物形态研究

以脱脂椰蓉为研究对象,考察了不同亚临界水降解条件对其降解过程的影响,并测定了100~200 ℃,不同反应时间下降解产物中还原糖的含量。采用Saeman模型对实验数据进行模拟,建立脱脂椰蓉粉亚临界水降解反应动力学方程,得到亚临界水降解动力学参数;并对降解物进行形态学分析。结果表明,Seaman模型能较好的反映脱脂椰蓉粉亚临界水降解的过程,初步降解的反应活化能E_a1为35.94 kJ/mol,还原糖降解活化能E_a2为32.12 kJ/mol,指前因子K₁₀为6.50×10² min^-1、K₂₀为3.24×10² min^-1。该降解过程在140 ℃、30 min能得到温度的高还原糖产物。脱脂椰蓉粉在亚临界水中降解过程中,形态随温度、时间变化而变化,随着温度的升高原料的转化率逐渐升高,原料由固态转化为液态部分越多,水解程度越大。扫描电镜结果表明,随着降解温度的升高和降解时间的延长,脱脂椰蓉粉的纤维结构破坏越显著。     

Reducing Sodium Chloride Content in Meat Burgers by Adding Potassium Chloride and Onion

The goal of this paper was to examine the reduction of sodium chloride by partial replacing with potassium chloride and the influence on taste acceptability of meat burgers. Sodium chloride content in burgers produced with 1.5% of salt and half of partial replacement of sodium chloride with potassium chloride in burgers was 0.62-0.67% in fresh and 0.72-0.93% in grilled burgers. The best taste acceptability had burgers with 1.5% of added sodium chloride and burgers with 1.5% salt and 50 g of added onion, in which the partial replacement of sodium chloride with potassium chloride was one half.     

Sodium Chloride and Magnesium Chloride affected by Ripening of Camembert Cheese

Ripening of cheese with three kinds of salt treatment was studied using MgCl₂, NaCl or a mixture of the two. Proteolysis was followed by determination of TCA-soluble nitrogen and quantitative electrophoresis. A rapid one-step method for free fatty acids was used to determine short and long-chain fatty acids. In the presence of magnesium, proteolysis increased, even with NaCl, which seemed to delay the magnesium activation. Lipolysis was retarded by NaCl, which decreased the level of free fatty acids. An imbalance between proteolysis and lipolysis could be responsible for the unpleasant flavor of the cheese containing both MgCl₂ and NaCl.     

亚临界水及超声强化亚临界水提取植物有效成分的动力学模型

本文依据传质理论和质量守恒原理,对天然植物中有效成分从固相向液相转移的传质过程进行合理的假设,以Fick第二扩散定律为基础建立了亚临界水提取(SWE)和超声强化亚临界水提取(USWE)天然植物有效成分的动力学模型;确立了用于估算亚临界水提取和超声强化亚临界水提取植物有效成分得率的方法;并以提取肉桂中代表性成分肉桂醛为例,以影响肉桂醛得率的重要因素---温度为考察指标,进行了不同温度下亚临界水提取和超声强化亚临界水提取肉桂醛的动力学模型验证实验。提取的动力学模型为(1)k tE E e-∞=-,通过模型检验证明了该动力学模型能很好的拟合提取的实验数据,且超声强化亚临界水提取的E∞和k值明显大于亚临界水提取,表明了超声对亚临界水提取过程有强化效应。该模型的建立为亚临界水提取和超声强化亚临界水提取植物有效成分的工业化应用和技术的推广提供了理论依据。     

亚临界水萃取技术在食品工业中的应用

本文综述了萃取温度、萃取压力、萃取时间、夹带剂对亚临界水萃取效果的影响及其在食品工业、农残检测前处理、植物精油提取的研究进展。最后对其在食品工业方面的应用前景进行展望。     

Drying Kinetics of Hydrated and Gelatinized Corn Starches in the Presence of Sucrose and Sodium Chloride

Drying behavior of the hydrated corn starch, hydrated starch/sucrose, and hydrated starch/sodium chloride mixture and their gels were investigated. Drying data were obtained on slabs of samples in a laboratory tunnel dryer at 40 to 70 °C. The rate-of-drying curves for hydrated starches with or without sucrose showed that the moisture movement may be the result of capillary action rather than diffusion. In the hydrated starches containing sodium chloride, case-hardening was the controlling mechanism. In gelatinized samples, however, diffusion was the main mechanism. The effective diffusivity was estimated by the methods of slopes. Gelatinization of starch reduced the moisture diffusivity significantly. The presence of sucrose or sodium chloride decreased the coefficient significantly in hydrated starch, but their effect was small in gelatinized samples.     

光卤石矿冷分解过程中氯化钠对氯化钾收率的影响

本文通过对盐田光卤石矿冷分解过程的相图分析及计算对氯化钠与氯化钾收率变化关系进行了拟合，并给出了数学模型。     

Fermentation of Cucumbers Without Sodium Chloride

Cucumbers were successfully fermented and stored in the absence of sodium chloride (salt) under laboratory conditions, provided the fruit were blanched (3 min, 77°C) before brining in a calcium acetate buffer and the brine inoculated with Lactobacillus planturum. Bloater formation was prevented by blanching even when brines were not purged of CO₂. Firmness of cucumbers was similar in salt-free brines or those containing salt after 1 mo, but firmness of salt-free cucumbers was lower after storage for 12 mos. Under pilot-scale, commercial conditions, however, the cucumbers were severely bloated, and the firmness was unacceptable after storage for 7 mo, due apparently to Microbial recontamination after blanching.     

亚临界水对卵清蛋白起泡性及乳化性的影响

采用亚临界水处理卵清蛋白（ovalbumin,OVA）,研究其对蛋白粒径、自由巯基、表面疏水性、运动黏度、起泡性能、乳化性能的影响。结果表明：亚临界水能显著降低卵清蛋白的粒径、自由巯基含量、运动黏度,增强其表面疏水性;经过亚临界水处理后,卵清蛋白的起泡性显著提高,其中刚升至140 ℃（处理0 min）时样品的起泡性最高,比未处理的提高了2.7 倍,但随着处理时间的延长,起泡性明显下降;处理后的卵清蛋白乳化性显著提高,并随着处理时间的延长先增高后趋于不变,其中160 ℃处理15 min的乳化性最高,比未处理的提高了1.5 倍。     

亚临界水萃取法检测粮谷中24种残留农药

根据亚临界水可以定量萃取基质中绝大部分化合物的特点,借助加速溶剂萃取仪(ASE)将亚临界水萃取与C18填料固相吸附联用,通过萃取温度和萃取时间的优化,建立了芸豆、小米等粮谷基质中异稻瘟净等24种农药的亚临界水萃取-气相色谱/串联质谱检测法。方法的检测限为0.05 mg/kg,当添加量为0.05 mg/kg~0.10 mg/kg时,24种农药的回收率为70.45%~104.8%,RSD小于12%。     

Reducing the Sodium Chloride Content in Chicken Pate by Using Potassium and Ammonium Chloride

The aim of this research was to investigate possibility of chicken pate production with reduced sodium chloride content, as well as to establish changes in sensory characteristics. In the study, six experimental groups of chicken pate were produced with the same basic ingredients, but different amounts of added salts. Sensory evaluation was performed in order to determine general taste acceptability, and of the sodium and potassium levels in the chicken pate. The pate from EI and EII groups in which the amount of added sodium chloride was reduced and/or partially substituted with ammonium chloride had a most acceptable taste.     

亚临界水处理制备低分子柑橘果胶及其性质研究

为了得到低分子柑橘果胶的物理制备方法,本文研究了高压均质法和亚临界水法处理对柑橘果胶分子质量的影响规律,发现两者均可降低果胶分子质量,50 MPa、100 MPa和150 MPa下均质处理后的果胶重均分子质量分别为140 ku、130 ku和120 ku;105℃、120℃和135℃亚临界水处理后的果胶重均分子质量分别达到了50 ku、20 ku和10 ku;综合考虑产品分子质量、得率、品质等因素确定120℃亚临界水处理为制备低分子柑橘果胶的较佳方法。对比了120℃亚临界水改性前后果胶的基本性质,发现:低分子柑橘果胶的单糖组成变化不大;单糖(特别是半乳糖)含量有一定程度下降;半乳糖醛酸含量从改性前的74.23%升高到87.92%;酯化度从70.32%下降到62.47%;重金属含量略有上升,但仍在安全范围内。可见,120℃亚临界水处理是制备低分子果胶的较好方法。     

大颗粒氯化钠的制备研究

研究了井盐卤水中Ca2+,Mg2+杂质对氯化钠结晶速率的影响,Mg2+能促进NaCI生长速率的提高,少量Ca2+对盐晶体的生长有利,浓度增大到0.6 g/L则抑制了晶体生长.讨论了在oslo结晶器中连续结晶以4 h为宜.进一步研究了不同添加剂对NaCl结晶粒度的影响,甘氨酸可促进晶体长大,甘氨酸的最佳添加量是0.8 g/L,90%以上的NaCl晶体达到0.42 mm以上,具有良好的防结块性能.     

氯化钠和三聚磷酸钠添加量对蒸煮火腿品质的影响

研究不同氯化钠或三聚磷酸钠添加量对蒸煮火腿保水性、质构特性及颜色等指标的影响。结果表明：随着氯化钠添加量的减少,火腿的蒸煮损失率和二次杀菌失水率逐渐增大,而氯化钠添加量降低至1.25%以下时,火腿的硬度、咀嚼度、弹性、黏聚性及回复性极显著下降（P＜0.01）;添加0.20%～0.50%三聚磷酸钠对于保持火腿良好的保水性具有重要作用,为保持火腿良好的硬度和咀嚼度,其添加量需要控制在0.35%以上。     

硫酸钠-过氧化氢-氯化钠加合物合成研究

开发了4Na2SO4·2H2O2·NaCl合成的稳定循环新工艺,将少部分母液取出后,加入计算量的硫酸钠、氯化钠和高浓度的双氧水。5次循环后,母液的组成、固相产品质量及产品中H2O2含量基本不变。此循环大部分母液得到较充分的利用,整个过程比较稳定。将样品置于423K的烘箱中,3h的分解率均小于2.3%,产品的稳定性较高。     

超高压对肌球蛋白-海藻酸钠-氯化钙混合凝胶特性的影响

本实验以含有0.5%海藻酸钠（sodium alginate,SA）和0.2%氯化钙（CaCl2）的鸡肉肌球蛋白混合体系（M-SA-CaCl2）为研究对象,考察超高压处理（high pressure processing,HPP）（100～400 MPa）对混合体系凝胶特性（凝胶保水性（water-holding capacity,WHC）和凝胶强度）的影响。通过分析M-SA-CaCl2混合体系表面疏水性、活性巯基含量、流变特性及凝胶微结构的变化,探讨混合凝胶特性的变化机制。结果表明： 1）混合凝胶WHC随着压力的提高（100～400 MPa）而显著增加（P＜0.05）,而凝胶强度随之显著降低（P＜0.05）; 2）HPP能够增加M-SA-CaCl2混合凝胶体系内部的活性巯基含量,强化混合体系内部疏水作用,减弱SA和CaCl2对肌球蛋白凝胶的增强作用,降低肌球蛋白的热凝胶能力以及凝胶网络结构的蛋白质聚集程度,由此导致混合凝胶特性的变化。     

Calcium Chloride and Potassium Sorbate Reduce Sodium Chloride used during Natural Cucumber Fermentation and Storage

Cucumber fermentation characteristics and pickle quality were evaluated in brines containing equilibrium concentrations of 0-0.4% CaCl₂, 0-0.4% potassium sorbate and 0-10% NaCl. Changes in brine pH and acidity, cucumber texture and color, coliforms, lactic acid and total bacteria, yeasts and molds were followed over time. Results indicated that cucumber spoilage would eventually take place if NaCl or potassium sorbate were not present in the brine. The presence of CaCl₂ helped maintain cucumber firmness. A synergistic action between NaCl, CaCl₂ and potassium sorbate was seen, which allowed good quality pickles to be produced when moderate amounts of all three components were present in the brine (5% NaCl, 0.2% CaCl₂, 0.2% potassium sorbate).