Influence of relative humidity on oxidation of the free and encapsulated oil fractions in freeze-dried microencapsulated oils

The objective of this work was to evaluate the effect of relative humidity (RH) on oxidation of the free and encapsulated oil fractions of dried microencapsulated oils (DMOs) during long-term storage at 30 °C. Sunflower and fish oils with different tocopherol content were encapsulated in a milk-based encapsulation matrix. The total non-volatile oxidation products and tocopherol were quantitated. Results showed that 0% and 32% RH were, respectively, the most unfavourable and favourable conditions against lipid oxidation. The 32% RH atmosphere exerted a great protective effect on the free oil as compared to 0% RH, while no or a negligible effect was found in the encapsulated oil. Except for the samples most susceptible to oxidation, the free oil remarkably oxidized more slowly than the encapsulated oil regardless of RH. Therefore, there were factors other than moisture that determined the oxidation rate in the free and encapsulated fractions of the DMOs.     

Effects of the drying method on the oxidative stability of the free and encapsulated fractions of microencapsulated sunflower oil

The influence of the drying method, freeze-drying and spray-drying, on the oxidative stability of microencapsulated sunflower oil depended on the type of encapsulation matrix. For a dairy-type matrix, formed by sodium caseinate and lactose, greater losses of tocopherols were detected during spray-drying, but both the free and encapsulated oil fractions were more stable against lipid oxidation than their freeze-dried counterparts. Results suggested that the free oil was also constituted by droplets that preserved their interfacial membrane and were protected by the matrix. Therefore, the free oil was not necessarily the non-encapsulated fraction. For a matrix constituted by gelatine, maltodextrin and sucrose, the emulsion showed low stability and a great destabilisation during spray-drying. No significant effect of the drying method on the oxidative stability of the encapsulated fraction was found with this matrix, but the free oil of the spray-dried sample oxidised faster, probably due to the emulsion destabilisation observed, which gave rise to a great amount of oil on the particle surface as a consequence of large droplets poorly stabilised.     

Influence of oil droplet size on the oxidative stability of the free and encapsulated fractions of freeze-dried microencapsulated sunflower oil

The effect of oil droplet size (ODS) on the oxidative stability (OS) of dried microencapsulated oils has been scarcely studied, and results are contradictory. A few studies have shown increased OS when the ODS was reduced and this was attributed to a decrease in the surface oil content (SOC). Yet, in such studies, only the total oil fraction was evaluated. In the present work, the free (FO) and encapsulated oil (EO) fractions of freeze-dried microencapsulated sunflower oil were analysed to study the effect of changes in the ODS by using different homogenisation pressure (15 or 70 MPa) in the emulsification step. The OS of both the free and encapsulated fractions increased when the ODS was significantly reduced in two samples with different encapsulation matrix, namely caseinate/lactose and maltodextrin/sucrose/gelatine. A reduction in the SOC would explain the increased stability of the FO, but not that of the EO. An additional protective role of the interfacial film could have been involved. In conclusion, if the encapsulation matrix and the interfacial region are effective as oxygen barriers, a reduction in the ODS of the parent emulsion by an increase in the homogenisation pressure will result in capsules more stable against lipid oxidation.     

几种香辛料对鱼油抗氧化及消臭作用的研究

用乙醇、石油醚分别从辣椒、生姜和香菜中提取抗氧化物质 ,比较了不同溶剂的提取率和不同提取物对鱼油的抗氧化效果。结果表明 ,乙醇对三者均有较高的提取率 ,抗氧化作用以辣椒的乙醇提取物为最强。此外 ,还初步研究了上述几种香辛料提取物对鱼油的消臭效果     

粉末亚麻油的制备研究

以多孔淀粉为载体,玉米醇溶蛋白为壁材,采用旋转锅喷雾包埋法制备粉末亚麻油。结果表明,多孔淀粉吸附亚麻油颗粒与壁材10%玉米醇溶蛋白液的重量比为1.0∶1.5,增塑剂油酸用量3%(以10%玉米醇溶蛋白液为基准),并分次逐渐喷入包埋剂,在70~80℃条件下热风干燥,制得的粉末亚麻油包埋率为95%,产品具有抗氧化、无异味、耐储存、使用方便等优点。     

双歧杆菌微胶囊技术及应用

双歧杆菌对人体有重要的生理和保健功能,但双歧杆菌必须通过胃环境以大量的存活菌到达肠道并能定殖于肠粘膜上才能发挥益生作用,微胶囊技术可以解决这一难题.综述了双歧杆菌微胶囊技术的研究现状,比较了双歧杆菌微胶囊的制备方法,如挤压法、喷雾干燥法、空气悬浮法、相分离凝聚法等,并展望了双歧杆菌微胶囊技术的应用前景.     

Comparative human-sensory evaluation and quantitative comparison of odour-active oxidation markers of encapsulated fish oil products used for supplementation during pregnancy and the breastfeeding period

Three different commercial encapsulated fish oil supplements were evaluated by orthonasal sensory evaluation of the encapsulated oil samples, and were rated according to characteristic odour qualities and hedonic impact. The potent odourants of the fish oil samples were obtained by solvent extraction followed by high vacuum transfer of the volatiles, and were evaluated by means of high resolution gas chromatography–olfactometry (HRGC–O). Comparative aroma extract dilution analysis of the solvent extract samples revealed 40 odourants. Most of these were identified based on their respective retention indices on two capillaries of different polarities, their mass spectral data, as well as their odour characteristics during HRGC–O, in comparison with the respective reference compounds. Thereby (poly)unsaturated fatty acid oxidation products were demonstrated to play a significant role in the volatile fraction of the fish oil supplements. Quantification of selected oxidation marker substances confirmed predominant presence of these compounds in the investigated samples, but also major quantitative differences between samples with regard to specific compounds. These data may be used as the basis for future evaluation of sensory quality of encapsulated fish oil supplements, and might relate to the degree of acceptance or rejection by the mothers being supplemented with the respective products.     

微胶囊化黑芝麻油的制备及性质研究

以乳清蛋白和麦芽糊精为壁材,黑芝麻油为芯材,添加适量乳化剂,通过喷雾干燥的方法制备微胶囊化黑芝麻油.研究了不同乳化剂及不同壁芯质量比对包埋效果的影响,并对微胶囊的流动性和储藏稳定性进行了研究.结果表明,乳清蛋白与麦芽糊精质量比为7∶4,吐温80添加量为1.5%,壁芯质量比为3∶2时微胶囊化产率和包埋效率较为理想,分别为94.62%和88.42%;流动性实验表明,壁芯质量比的变化对其粒度分布和休止角影响不大;储藏稳定性研究表明,经过微胶囊化的黑芝麻油其过氧化值在保藏的过程中低于未被包埋的黑芝麻油.     

The antimicrobial activity of microencapsulated thymol and carvacrol

The aim of the present study was to determine the antimicrobial (AM) properties of plastic flexible films with a coating of microcapsules containing carvacrol and thymol as natural AM agents. Microencapsulation of these agents enables their controlled release and leads to the destruction (or growth inhibition) of a broad spectrum of microorganisms such as, Escherichia coli O157:H7, Staphylococcus aureus, Listeria innocua, Saccharomyces cerevisiae and Aspergillus niger. It was found that the studied AM agents are strong inhibitors to the growth of mycelium, but they were not effective against spore germination of mold. Thymol (T) and carvacrol (C) showed a significant AM activity against the studied microorganisms, with minimal inhibitory concentrations (MIC) of 125-250 ppm and 75-375 ppm for thymol and carvacrol respectively. The synergistic effect of combinations of thymol and carvacrol was also studied and it was found that the highest synergism was achieved at a concentration of 50% T and 50% C. The release of the AM agents was carried out at 4 °C during 28 days. The concentration of the microencapsulated AM agents showed a range of zones of inhibition of 4.3-11.3 mm for the microorganisms at 10% of thymol and 10% of carvacrol. At these concentrations the release of the AM agents (within 48 h) was greater than required for the most resistant microorganism (E .coli O157:H7), as reflected by the relatively large zone of inhibition. The results of the present study confirm the suitability of using microencapsulated thymol and carvacrol incorporated in polymer films for AM food packaging.     

Methyl alpha-D-mannopyranoside-responsive release of microencapsulated glucoamylase

Microcapsules are made of porous membranes through which enzymes or proteins can readily permeate. Glucoamylase was encapsulated into microcapsules in the presence of concanavalin A. Microencapsulated glucoamylase was released from the microcapsules into the bulk phase in the presence of methyl alpha-D-mannopyranoside, while it was not released in the absence of methyl alpha-D-mannopyranoside. The initiation and cessation of glucoamylase release from the microcapsules accurately corresponded to the addition and removal of methyl alpha-D-mannopyranoside, respectively. Methyl alpha-D-mannopyranoside served as a controller for the release of glucoamylase.     

维生素E微胶囊的理化性质表征

采用超声波辅助β-环糊精(β-CD)对维生素E进行包埋,而后再加入乳清浓缩蛋白(WPC)对其进行二次包埋来制备维生素E微胶囊.通过扫描电镜(SEM)发现微胶囊产品与物理混合物的微观形态存在较大差异;在微胶囊产品的差示热扫描(DSC)图谱中出现了一个新的吸热峰;傅里叶变换红外光谱(FT-IR)显示,在微胶囊产品中没有发现维生素E的特征峰并且存在较强的氢键效应;微胶囊产品的X-射线衍射图谱与物理混合物以及β-环糊精的图谱大不相同,在多处变化明显;以上的实验结果证实了维生素E已经被β-环糊精和乳清浓缩蛋白包埋,并且维生素E与β-环糊精之间发生氢键作用形成包合物.     

微胶囊化菠萝粉关键技术研究

以菠萝粉为芯材,阿拉伯胶和麦芽糊精为壁材,菠萝粉中总胡萝卜素的包埋率和Vc保留率为主要考察指标,通过乳化、均质、喷雾干燥等工艺,制备菠萝粉微胶囊,探讨喷雾干燥法制备菠萝粉微胶囊的工艺条件。通过单因素试验和正交试验确定最佳的工艺条件为:进风温度180℃,壁芯比8:50,壁材内部的配比(阿拉伯胶/麦芽糊精)1:12,入料流量15mL/min,所得微胶囊产品的包埋率为89.01%。     

微胶囊蘑菇风味强化调味料研制

双孢蘑菇主要的风味物质１－辛烯－３－醇是以亚油酸为底物在自身酶的作用下生成的，本研究通过在体系中添加富含亚油酸的葵花籽油水解液对其风味进行强化，然后采用乙醇浸渍，复合酶处理提取风味及鲜味物质，再以提取物为心材，以大豆水解蛋白、糊精、阿拉伯胶为壁材，经喷雾干燥制成粉未调味料。     

微胶囊化粉末油脂制品的生产及应用

<正> 粉末油脂是一大类微胶囊化油脂制品的总称。这类产品种类繁多、功能各异、应用广泛。其中有代表性的产品是咖啡伴侣,或称作植脂末(non-dairy creamer),俗称奶精粉。除此之外,粉末油脂制品还可用于食品工业作为加工原料,如冰淇淋、雪糕、饮料工业用油;糖果、巧克力工业用油脂;饼干、蛋糕工业用油;粉末香精、香料和调味料等等。这类产品的优越性在于: 1.油脂含量可根据需要而进行调整,范围从20％～72％; 2.功能性质(如水溶性、乳化性、起泡性)     

茶油微胶囊的性质

以麦芽糊精、大豆分离蛋白(SPI)为壁材,通过喷雾干燥法制备茶油微胶囊,对微胶囊的性质进行了研究。扫描电镜(SEM)观察结果显示:茶油微胶囊表面形态良好,但经40、60℃,30 d贮藏后,茶油微胶囊均出现了干瘪现象,表明微胶囊不能经受长时间的高温贮藏;差示扫描量热仪(DSC)测得微胶囊产品热溶解温度(Tm)为157.2℃,表明产品具有较好的贮藏稳定性及应用范围;TG测得茶油微胶囊280℃开始分解,表明加工温度不宜超过280℃;微胶囊在不同温度和湿度下的释放研究表明,微胶囊应该在低温、低湿度下进行贮藏。     

Antimicrobial and antioxidant activities of carvacrol microencapsulated in hydroxypropyl-beta-cyclodextrin

Carvacrol is a hydrophobic compound that exhibits high antimicrobial and antioxidant activities. Cyclodextrins are used to increase solubility and dissolution through water-insoluble compounds inclusion into their hydrophobic cavities. Hence, this study aimed to characterize carvacrol inclusion complexes with hydroxypropyl-beta-cyclodextrin (HPBCD) by establishing the physico-chemical properties and evaluate their antimicrobial and antioxidant properties. Inclusion complexes were prepared by kneading (KN) and freeze-drying (FD) methods. Entrapment efficiency was 78.09 ± 1.24% for KN, and 83.74 ± 1.15% for FD. Polydispersity index was greater than 0.2 for both methods. Particle size for KN and FD were 0.360 ± 0.003 and 0.377 ± 0.007 μm, respectively. Carvacrol–HPBCD antimicrobial activity was higher (P < 0.05) than for free carvacrol for both bacteria, Escherichia coli K12 and Salmonella enterica serovar Typhimurium LT2, indicating that HPBCD increased water solubility and consequently increased contact between carvacrol and bacteria in medium. Antioxidant activity was lower (P < 0.05) for inclusion complexes indicating HPBCD makes carvacrol less available to react with free radical. The stability study indicated that light did not affect (P > 0.05) degradation, indicating that the microparticles were stable throughout storage. Therefore, carvacrol–HPBCD complexes may have important applications in the food industry as stable antimicrobial systems.     

微胶囊香精在肉制品中的应用

风味是肉制品十分重要的质量指标之一,它与原料、工艺和风味添加物密切相关,因此,要解决肉制品的风味,合理添加肉味香精是必要的。本文从微胶囊香精的制造、作用、特点等方面,探讨了该类香精在肉制品中应用的必要性和可行性。      

耐酸型微胶囊粉末油脂的研制及其性能研究

在对乳化剂品种、用量进行深入研究的基础上,采用喷雾干燥法制备了耐酸型粉末油脂,并对其性能进行了研究。结果表明,用此法可以得到耐酸性很强的微胶囊粉末油脂。复合乳化剂Lc含量下降,制备的产品性能下降,乳化剂Lc对产品的性能影响很大。随着复合乳化剂TH的加入,产品的性能有所回升,复合乳化剂TH对产品性能的改善也会有作用。     

斥水微胶囊DHA在食品中的应用研究

斥水微胶囊技术是应用于DHA等功能油脂的新一代微胶囊技术，斥水微胶囊DHA具有耐水、耐热、抗剪切以及氧化稳定性高等特性，特别适用于加工过程遇水、遇热的食品。在饮料中，斥水微胶囊DHA的氧化稳定性显著高于水溶微胶囊DHA和乳化DHA油；在饼干中，强化斥水微胶囊DHA饼干的DHA保留率很高，为94．70％，而强化水溶微胶囊DHA和直接强化海藻DHA油饼干的DHA保留率分别仅为63．15％和39．62％。