Fragmentation of chitosan by microfluidization process

Fragmentation of chitosan in 0.1 M acetic acid (HAc) by microfluidization was investigated. The degree of fragmentation was followed by viscometry and size exclusion chromatography. The chemical structure of chitosan and its fragments was examined by elemental analysis and ¹H NMR spectroscopy. Fragmentation of chitosan was affected by pressure or intensity of turbulence, exposure time, and hydrodynamic parameters such as molecular weight and polymer concentration in solution; but temperature had only a negligible effect. Chain scission increased bi-linearly with pressure, increased with molecular weight of chitosan but decreased with its concentration. Continuous microfluidization appeared to be more effective in fragmentation than volume pass mode. Molecular weight distribution of fragments was narrower than that of the original polymer indicating that large macromolecules were preferentially fragmented. Degree of acetylation of fragments increased when 0.1 M HAc was used as solvent for chitosan but not in 0.04 M HCl. The fragmentation of chitosan by microfluidization process was described by a parametric model relating chain scission to mechanical action and hydrodynamic parameters of the polymer. It was concluded that microfluidization can be a useful method for moderate fragmentation of chitosan.     

Design of fish oil-in-water nanoemulsion by microfluidization

In the last years, the consumption of polyunsaturated fatty acids (PUFAs) has been promoted due to the prevention and treatment of different diseases. When these are marketed as emulsions, their therapeutic efficacy depends on their charge and size. Microfluidization is an emerging technology able to produce smaller droplet sizes. The aim of this study was to evaluate the capacity of mesquite gum to produce fish oil emulsion by microfluidization as a function of pressure and number of passes. Emulsions were produced according to a two factor, three level with two central points: pressure from 34.5 to 206.8 MPa and 1 to 5 passes. The zeta potential and droplet size distributions were evaluated using electrophoretic and dynamic light scattering equipment, respectively. Coarse emulsion produced by high-shear mixer shows a droplet size up to 1.5 μm, while microfluidization process produce smaller droplet size (≥ 200 nm). Also, zeta potential values increased around − 30 ± 2 mV. The optimal conditions were estimated at 144 MPa and two passes of microfluidization. Nanoemulsions with an average droplet size around 200 nm could be used to improve their absorption in the digestive tract.     

Development of gelling properties of inulin by microfluidization

In this paper, we report the impact of a microfluidic device (Microfluidizer^®) on the development of gelling properties of inulin – water systems. Inulin dispersions at a concentration of 2, 7 and 15%, w/w, were subjected to microfluidization treatments at 30 MPa with various numbers of circulations in the apparatus (1, 2 or 5 passes). The high shear stress treatment did not induce a chemical composition change of inulin. However, it allowed an increase of the gel-like behavior of the system as well as the viscosity of the inulin dispersion, transforming a visual aspect of the product similar to milk, to a system similar to yogurt or margarine depending on the concentration and the number of passes in the Microfluidizer^®. The viscosity increased with both the number of passes and the inulin concentration. Granulometry as well as optical and electronic microscopy ascertained the reduction of the particle size and the formation of a network composed of agglomerates which interacted with the solution and thus led to textural modifications.     

超声与高压微射流处理对大豆分离蛋白微细化的影响

研究超声功率与时间和高压微射流操作压力与次数件对乳液温升、加权平均粒径和粒度分布等的影响,以寻找适合不同工艺需求的大豆分离蛋白物理改性方法。结果表明,经超声处理SPI乳液粒径呈现双峰分布,经高压微射流处理SPI乳液粒径呈单峰分布,说明高压微射流比超声处理的乳化均匀一致性好。超声(1200 W)能够提高SPI乳液的均匀一致性和乳化稳定性,但SPI微团尺寸缩减能力有限,处理时间过长则乳液发生再凝聚,出现SPI微团尺寸增大的现象。当乳液粒径较大(10~(-4) m级)时,瞬时(10~(-6) s级)高压微射流(35 MPa以上)处理形成高能量密度能够达到较好的微细化结果,加权平均粒径D_([3,2])和D_([4,3])显著减小。     

Properties of frozen dairy desserts processed by microfluidization of their mixes

Sensory properties and rate of meltdown of nonfat (0% fat) and low-fat (2% fat) vanilla ice creams processed either by conventional valve homogenization or microfluidization of their mixes were compared with each other and to ice cream (10% fat) processed by conventional valve homogenization. Mixes for frozen dairy desserts containing 0, 2, and 10% fat were manufactured. Some of the nonfat and low-fat ice cream mixes were processed by microfluidization at 50, 100, 150, and 200 MPa, and the remaining nonfat and low-fat ice cream mixes and all of the ice cream mix were processed by conventional valve homogenization at 13.8 MPa, first stage, and 3.4 MPa, second stage. The finished frozen and hardened products were evaluated at d 1 and 45 for meltdown rate and for flavor and body and texture by preference testing. Nonfat and low-fat ice creams that usually had a slower meltdown were produced when processing their mixes by microfluidization instead of by conventional valve homogenization. Sensory scores for the ice cream were significantly higher than sensory scores for the nonfat and low-fat ice creams, but the sensory scores for the conventional valve homogenized controls for the nonfat ice cream and low-fat ice cream were not significantly different from the sensory scores for the nonfat ice cream and low-fat ice cream processed by microfluidization of the mixes, respectively. Microfluidization produced nonfat and low-fat ice creams that usually had a slower meltdown without affecting sensory properties.     

油莎豆油的动态超高压微射流辅助正己烷提取 工艺优化及品质分析

旨在为油莎豆油的高效提取提供参考,以油莎豆为原料,采用动态超高压微射流辅助正己烷提取油莎豆油,通过单因素试验研究了微射流压力、提取温度和提取时间对油莎豆油得率的影响,并采用响应面试验对提取工艺进行优化;对比了动态超高压微射流辅助正己烷提取与单一正己烷提取对油莎豆油得率的影响,并对油莎豆油的品质进行了分析。结果表明：动态超高压微射流辅助正己烷提取油莎豆油的最佳工艺条件为微射流压力110 MPa、提取温度50℃、提取时间7 min,在此条件下油莎豆油得率为22.81%;与单一正己烷提取相比,动态超高压微射流辅助正己烷提取油莎豆油得率更高,提取温度更低,提取时间更短;动态超高压微射流辅助正己烷提取的油莎豆油的理化指标及脂肪酸组成及含量均符合油莎豆油行业标准(LS/T 3259—2018)的要求。综上,动态超高压微射流辅助正己烷提取法是一种高效的油莎豆油提取方法。     

米曲霉产中性蛋白酶条件的优化

以豆瓣酱中分离的米曲霉M1为出发菌株,研究了该米曲霉产蛋白酶的分布及最佳培养温度、时间、pH值等,优化了米曲霉最佳培养基的组成.结果表明,米曲霉产中性蛋白酶的能力最强.产中性蛋白酶适宜的培养条件为:麸皮∶水=1∶1 (w/w),最佳培养温度为30℃,培养时间为72h.培养基的组成为:酵母粉添加量2.0％,蛋白胨添加量0.2％,硝酸钾添加量0.1％,麦芽糖添加量0.1％,葡萄糖添加量0.1％,硫酸铵添加量2.0％.在此条件下培养,最高酶活达到12113.85U/g干基,比优化前提高22.98％.     

液体发酵法制备油桃果醋的工艺优化

研究确定了油桃醋生产过程中酒精发酵的最佳工艺参数,即发酵温度25℃,发酵周期72h,接种量5%。正交试验确定了醋酸发酵的最佳工艺参数,即初始酒精度5%,pH5.5,醋酸菌接种量12%。醋酸发酵液经过滤可直接作为调味品,也可以调配成不同风味的果醋饮料。     

响应面法优化产丙酸杆菌素菌株的培养条件

响应面法已成功运用于发酵过程的优化,可以对发酵培养基及培养条件等诸多因素进行考察和评价,从而有效地确定重要因子的最优水平,取得更好的发酵效果,因此本文主要采用响应面法对丙酸杆菌素产生菌株的发酵培养基进行优化,以提高丙酸杆菌素抑菌能力.首先采用Plackett-Burman(PB)试验设计法筛选出3个主要因素为葡萄糖、Tween80和pH值,然后通过最陡爬坡法和响应面分析方法确定主要因素的最佳质量浓度分别为:葡萄糖2.32g/L,Tween80 0.1 g/L,pH值为7.0.在优化条件下丙酸杆菌素押菌能力增强,形成的抑菌圈直径是24.76 mm,是优化前的1.25倍.     

酶解法制备白藜芦醇的工艺优化

本文对虎杖提取物中白藜芦醇苷酶解制备白藜芦醇的工艺进行研究,以样品中白藜芦醇的含量为指标,对虎杖复合酶、纤维素酶、β-葡萄糖苷酶、虎杖苷专用酶进行了筛选,结果表明,以β-葡萄糖苷酶的转化率最高.采用单因素实验对影响β-葡萄糖苷酶酶解的因素:底物浓度、酶用量、酶解温度、pH和酶解时间进行考察;得出较佳的酶解工艺条件:酶用量3％,pH=5,40℃酶解10h.用该方法制备白藜芦醇的可以得到较高的产率,且苷水解酶可循环使用,重现性较好,适用于工业化大规模生产.     

地衣芽孢杆菌产碱性蛋白酶发酵条件优化

碱性蛋白酶是一类重要的工业用酶,广泛应用于洗涤、制革、酿造等行业,发挥着重要作用。为提高地衣芽孢杆菌的产酶活力,在单因素实验的基础上,采用3因素3水平的响应面分析法,以蛋白酶活力为响应值,对影响地衣芽孢杆菌20203产碱性蛋白酶的因素进行研究分析,得到了最佳发酵条件为:葡萄糖1.5%,豆粕6%,乳糖4%,磷酸铵1.2%,KCl 0.03%,CaCl2 0.07%,MgSO4 0.02%,吐温80 0.05%,初始pH9.0,培养温度37℃,摇瓶转速300r/min,5d后发酵液酶活为2382u/mL。通过非变性聚丙烯酰胺凝胶电泳的方法得到该蛋白酶的分子量为35ku。     

好食脉孢菌固态发酵醋糟产木聚糖酶的工艺优化

以醋糟为主要原料,利用好食脉孢菌固态发酵生产木聚糖酶,以木聚糖酶活力为指标,通过单因素试验和正交试验对培养条件进行优化。结果表明：由5 g醋糟和0.4 g豆渣组成培养基,初始pH 5.5,料水比13 （g/mL）,接种量10⁶个孢子/瓶,28 ℃培养3 d,该条件下的木聚糖酶活力为412.34 U/g,较优化前（114.95 U/g）提高了约3.59倍。     

Degradation of high-methoxyl pectin by dynamic high pressure microfluidization and its mechanism

High-methoxyl pectin was degraded by dynamic high pressure microfluidization (DHPM). It was found that apparent viscosity, average molecular weight and particle size of pectin decreased, whereas the amount of reducing sugars increased with increasing DHPM pressure. At the same time, the surface topography of pectin was changed from large flake-like structure to smaller porous chips. The mechanism of DHPM-induced degradation of pectin was also investigated. Fourier transform infrared spectra showed DHPM had no effect on the primary structure of pectin. On the other hand, reducing sugars content increased linearly with decreasing average molecular weight, suggesting the degradation may derive from the rupture of glycosidic bond. The breakdown of glycosidic bond may not only result from intensive mechanical forces but also from acid hydrolysis, which was evidenced in the reduction of degradation when the concentration of H⁺ was lowered. In addition, neither β-elimination nor demethoxylation occurred with DHPM. Based on these results, a model was proposed to illustrate the degradation of pectin induced by DHPM.     

Activation and conformational changes of mushroom polyphenoloxidase by high pressure microfluidization treatment

Activation and conformational changes of mushroom polyphenoloxidase (PPO) after high pressure microfluidization treatment were observed by means of UV spectrophotometer, far-UV circular dichroism, fluorescence emission spectra, UV absorption spectra and sulphydryl groups detection. The results indicated that, treated under pressures of 90 MPa, 110 MPa, 130 MPa and 150 MPa one pass, and 150 MPa 1, 2 and 3 passes, respectively, mushroom PPO exhibited an increase in activity. The circular dichroism (CD) analysis demonstrated that some of secondary structures such as α-helix were destroyed. There were some indices that the increase of relative activity was accompanied by a decrease in α-helix content. The fluorescence emission spectra analysis indicated that Trp and Tyr residues in mushroom PPO were more or less exposed to solvent, and the result was in good agreement with that of UV absorption spectra analysis. The sulphydryl groups detection showed that the sulphydryl groups content on the surface of mushroom PPO was increased.Industrial relevanceResults of the present study show that high pressure microfluidization can not be used to inactivate mushroom PPO. However, it provides a new way for enzyme preparation, such as enzyme modification, with higher activity. High pressure microfluidization can be easily operated, with shorter treatment time and higher food safety compared with chemical methods.     

动态高压微射流对聚半乳糖醛酸酶的影响

利用动态高压微射流(DHPM)处理聚半乳糖醛酸酶(PG),通过对酶活、圆二色谱、紫外光谱和巯基含量的测定,研究DHPM对PG酶活性和构象的影响.结果显示,经75,125,175 MPa的动态高压微射流处理后,PG酶的相对活性分别为93.2%、95.3%和91.2%;125 MPa分别处理2、3次后,PG酶的相对活性分别为97.4%、88.2%.分子构象分析表明,经不同压力DHPM处理后,PG酶的β-折叠含量有不同程度降低,PG 酶分子结构更为"松散",原来包埋在分子内部的TrP和Tyr残基部分暴露出来,分子表面的二硫键被打断形成巯基,但从分子整体来看,新的二硫键形成的量要多于被打断的量.     

Production of high-oleic palm oil nanoemulsions by high-shear homogenization (microfluidization)

Nanoemulsions present benefits such as an increase in the bioavailability, solubility and targeted delivery of encapsulated substances, and thus, they are a method of incorporating high nutritional value oils, such as high-oleic palm oil (HOPO). In this work, O/W nanoemulsions were obtained by microfluidization using HOPO (1–20% w/w) in the oily phase along with whey (1–20% w/w), Tween 20 (1:1 w/w ratio) and water in the aqueous phase following a surface response design methodology. The response variables were the average drop size (ADS), the polydispersity index (PDI), the zeta potential (ζ), CIELAB color parameters and viscosities of the fresh nanoemulsions (0 days) and nanoemulsions stored at two temperatures (5 and 19 °C) for 4 days. The ADS, PDI and ζ values varied between 163 and 2268 nm, 0.2 and 1, and − 29.7 and − 47.2 mV, respectively. The viscosity was affected by the storage temperature; after 4 days at 19 °C, it increased almost 6-fold compared to the viscosity of the fresh sample. With regards to the color parameters, significant changes were observed based on the concentrations of HOPO and whey. In addition, the prediction equations only presented errors below 7% for the evaluated variables, with R² values above 0.85. Finally, the influence of whey protein denaturation at 60 °C on the stabilities of the two most stable nanoemulsions, according to the optimization process, was observed.Industrial relevanceAmong its many benefits, nanoencapsulation is characterized by increasing the bioavailability of the encapsulated active compound and by the protection that it grants against environmental and processing effects, as micronutrients (for example vitamins) can be susceptible to chemical, enzymatic and/physical instability prior, during and after the processing of food products that contain. One of the techniques studied in recent decades for obtaining nanoemulsions is microfluidization. Microfluidization is a high-energy method that uses high pressure to force the fluid through microchannels that have a specific configuration, emulsifying the fluid by the combined effects of cavitation, shear and impact, thus showing an excellent emulsifying efficiency. However, in food industries the use of microfluidization is not popular and other kind of high shear homogenization are used. In this work, the development of stable emulsions using microfluidization, calls for the use of other types of materials that can provide emulsifying characteristics, such as whey, a compound that is currently one of the main effluents of dairy processes, depending on the type of product.Obtaining nanoemulsions for encapsulation purposes has been studied in many functional products, but to the best of our knowledge, it has not been reported with high-oleic palm oil. This oil contains approximately 50% saturated, 10% di-unsaturated and 40% monounsaturated fatty acids, with oleic acid in sn-2 position in triacylglycerols. This composition makes palm oil as soluble as olive oil. In addition, high-oleic palm oil (HOPO), in particular, has a high stability because it is an oleic acid-rich oil, which has been introduced to replace trans fats and has presented a healthy alternative to such fats in food formulations and the fried food industry.It is also important to highlight that oleic acid has a range of health benefits, such as a decrease in the total cholesterol, an increase in HDL (high-density lipoprotein) and a decrease in LDL (low-density lipoprotein). Oleic acid also retards the development of heart diseases, promotes the formation of antioxidants in the body and reinforces the integrity of the cell wall. In addition, red palm oil (crude) contributes significant nutritional value because it is rich in β-carotenes, α-tocopherol and tocotorienols, supplying vitamins and provitamins that are important for but not produced by the human body.Finally, this work demonstrates that emulsion drop size does not affect the stability of the nanoemulsion if it formulation is designed. Therefore, the goal of this work was to evaluate the most favorable conditions for the microfluidization, formulation and storage of HOPO nanoemulsions using whey powder to produce stable nanoemulsions.     

纳米乳液的制备及稳定性研究进展

本文系统论述了纳米乳液的制备方法以及导致纳米乳化体系不稳定的因素。探讨了纳米乳化技术在食品、医药化工等领域的应用,以及今后的研究动向。     

微射流均质制备乳铁蛋白纳米乳液的研究

以乳液粒度及电位为评价指标,研究了不同均质压力、不同均质次数、不同蛋白含量及温度、pH等因素对乳液稳定性的影响.实验结果表明,当蛋白质浓度为1.5%,均质压力为120MPa,均质次数为2次的条件下,微射流处理能显著减小液滴粒径;室温贮存12h后,温度、pH、防腐剂等条件时乳液粒径没有显著影响;盐离子强度对乳液粒径和Z-电位有很大影响,该实验为乳铁蛋白乳液的研制开发提供依据.     

Physicochemical and rheological properties of modified rice amylose by dynamic high-pressure microfluidization

The effect of dynamic high-pressure microfluidization on physicochemical and rheological properties of rice amylose pastes were examined. The amylose dispersions were pressurized at 60, 100, 140, and 180 MPa. The microfluidization treated rice amylose showed elevated solubility, swelling power, and moisture absorbability. The retrogradability was significantly decreased with the pressure increase. Iodine blue value showed a significant increase at 60~140 MPa, while a slight decrease at 180 MPa. The rheological results indicated that native amylose was a non-Newtonian fluid and displayed pseudoplastic fluids characteristics. The amylose moved toward a Newtonian fluid behavior and its rheopexy decreased with the pressure increased.