Evaluation of microbial transglutaminase and ribose cross-linked soy protein isolate-based microcapsules containing fish oil

Soy protein isolate (SPI)-based microcapsules containing fish oil were prepared using a modified coacervation method followed by cross-linking treatments. The procedure yielded 95–98% microcapsules containing 0.5–0.6 g fish oil/g capsule with a volume mean diameter ranged from ~ 260 to ~ 280 μm. Four types of microcapsules produced were SPI with sucrose (MC-C/S), SPI with ribose (MC-C/R), SPI with sucrose and microbial transglutaminase (MC-MTG/S) and SPI with ribose and MTGase (MC-MTG/R). Protein cross-linking due to ε-(γ-glutamyl)lysine bonds and “Maillard cross-linking” were evidenced in the SDS-PAGE profiles of MC-C/R, MC-MTG/S and MC-MTG/R. Even though the microcapsules prepared with cross-linking treatments had significantly (P < 0.05) lower protein solubility as compared to that of the control, the results of fish oil release in pepsin solution at 37 °C indicated that the core release of all microcapsules prepared with ribose (MC-C/R and MC-MTG/R) was significantly (P < 0.05) lower than other microcapsules. During storage, microcapsules prepared with ribose had longer shelf life as compared to other microcapsules. This may be due to the release of antioxidative Maillard reaction products during heating and storage and a slower rate of gas permeability through the capsules.

Industrial relevance

The use of protein-based wall materials in the food industry for sensitive ingredients is limited because proteins are generally unstable with heating and damaged by organic solvents and the cross-linking agent is usually harmful. Therefore a novel method of combining two familiar cross-linking agents such as the microbial transglutaminase and ribose can convert SPI microcapsules into a stable form. The application of SPI in industry would be increased.     

不同壁材制备油茶籽油微胶囊的研究

研究以大豆分离蛋白、酪朊酸钠、麦芽糊精、大豆膳食纤维和阿拉伯胶为壁材,通过复配组合,利用喷雾干燥法制备油茶籽油微胶囊产品,同时以乳化稳定性、微胶囊化效率和产率、微胶囊形态的微观表征颗粒完整率和微胶囊感官品质评价为评定指标,比较不同壁材组合得到的微胶囊产品之间的差异。结果表明,以大豆分离蛋白、酪朊酸钠和麦芽糊精为复配壁材的油茶籽油微胶囊产品为乳白色粉末,具有良好冲调性和流动性,微胶囊化效率83.62%和产率63.87%,微胶囊形态的颗粒完整率接近70%,是较好的喷雾干燥制备油茶籽油微胶囊产品的复配壁材之一。     

Characterization of spray-dried microalgal oil encapsulated in cross-linked sodium caseinate matrix induced by microbial transglutaminase

Sodium caseinate (SC) cross-linked by microbial transglutaminase (MTGase) for encapsulating microalgal oil was investigated. Protein cross-linking was evidenced in the SDS-PAGE graph. The emulsifying properties of SC depended on the cross-linked time with MTGase. The emulsifying activity and stability indexes of SC increased with the cross-linking time of 30 to 90 min (P30 to P90), and then declined with longer cross-linked time of 180 to 420 min (P180 to P420). The P30 to P90 as wall material for microencapsulation was superior to P180 to P420 and control sample. The microcapsules prepared with P30 to P90 showed more than 97% of microencapsulation efficiency in contrast to about 90% with the P180 to P420. During storage, the microcapsules prepared with P30 to P90 exhibited higher oxidative stability as compared with other microcapsules. A sustained release of microalgal oil was observed, and core release was time dependent and affected by cross-linking degree. Results showed that the powdered microalgal oil prepared with P30 to P90 demonstrated enhanced physicochemical properties and oxidative stability. Practical Application: The novel method using cross-linked proteins as wall material induced by microbial transglutaminase in food industry for sensitive ingredients could convert microcapsules into a stable form, which would lead to its more widespread utilization as a kind of food additive.     

复凝聚法制备松籽油微胶囊工艺优化及其氧化稳定性分析

以明胶与阿拉伯胶为壁材,采用复凝聚法包埋松籽油制备松籽油微胶囊。考察壁材比(明胶与阿拉伯胶体积比)、芯壁比、壁材质量分数、复凝聚时间对微胶囊包埋率的影响,通过正交试验优化微胶囊制备工艺,并对制备的微胶囊理化特性及氧化稳定性进行分析。结果表明松籽油微胶囊制备的优化工艺条件为壁材比2∶1、芯壁比2∶3、壁材质量分数2%、复凝聚时间50 min,在此条件下微胶囊包埋率达到87.23%。制备的松籽油微胶囊含水率为5.1%,溶解度为98.09%,具有较好的溶解性;通过傅里叶转换红外光谱及扫描电子显微镜分析证明了微胶囊的形成;差示扫描量热分析结果显示,微胶囊热溶解温度较高,在室温下热稳定性良好。包埋后的松籽油经加速贮藏实验表明微胶囊化可以提高松籽油的氧化稳定性,延长松籽油贮藏期。     

Impact of Chitosan-Prunus cerasoides gum exudates on the thermal properties,storage stability and antioxidant activity of anthocyanins from Berberis lycium Royle

For the protection of anthocyanins from berries of Berberis lycium Royle, the freeze dried microencapsulation method was used in five different combinations of chitosan (CH), Prunus cerasoides gum exudate (PG) and galactomannan as wall material with anthocyanin (ANS) as core material. The microencapsulated powders with different proportions of wall material showed encapsulation efficiency in the range of 90.51%–94.60%. Fourier-transform infrared spectroscopy confirmed the cross-linking interactions between ANS and wall materials. Enhanced thermal stability of the ANS with wall materials was indicated by thermogravimetric analysis. The stability of microcapsules and ANS was evaluated by spectrophotometric and liquid chromatographic methods at two conditions (4 °C and room temperature) during 90 days. The results revealed that ANS encapsulated with CH-PG/ANS (4/1) exhibited maximum retention of anthocyanins (72.88% and 60.02%) and enhanced the stability and antioxidant potential of anthocyanins.     

壁材对香草兰精油微胶囊物性与释放特性的影响

本实验分别以β-环糊精（β-cyclodextrin,β-CD）、β-CD＋麦芽糊精（maltodextrin,MD）、辛烯基琥珀酸淀粉钠（octenylsuccinate starch sodium,OSS）、酪蛋白为壁材,以香草兰精油为芯材,采用喷雾干燥制备具有缓释性的微胶囊。以产率、包埋率、溶解性、缓释性、乳化液稳定性等为评定指标,对比分析4?种壁材的包埋效果。结果表明：以OSS为壁材的香草兰精油微胶囊（VO-OSS）产率最高,为84.17%,包埋率为78.04%,溶解度和乳状液稳定性分别为96.31%和97.82%,具有良好的冲调性、溶解性和乳化性。MD与β-CD复配壁材的香草兰精油微胶囊（VO-MD）产率和包埋率最低,分别为71.37%和61.18%。在粒径方面,VO-OSS粒径最小,为190?nm。扫描电子显微镜观察结果显示,VO-OSS表面结构光滑、呈球状。VO-OSS在60?℃贮存10?d后,香兰素的保留率为54.62%,表明缓释性高于其他3?种微胶囊。综合所有指标,对比其他3?种微胶囊产品,OSS是制备香草兰精油微胶囊的最佳壁材。     

A novel process for microencapsulation of fish oil with barley protein

This research represents the first scientific publication reporting barley protein as a wall material to encapsulate fish oil. Solid microcapsules were able to form in aqueous solution by pre-emulsifying barley proteins with a homogenizer followed a microfluidizer system. No organic solvent or cross-linking reagents were used in the preparation process. The wet status microcapsules were converted into free-flowing powder (dry status microcapsules) by a spray-drying process. The optimum microcapsule preparation conditions were 15% protein, oil/protein ratio = 1.0, and an inlet temperature of 150 °C. These microcapsules exhibited high encapsulation efficiency (EE: 92.9–100.2%), loading efficiency (LE: 46.5–50.1%) and low moisture content (0.75–0.90%). The oxidative stability of microencapsulated fish oil was tested at both dry status and in aqueous solutions (pH 7.0 and pH 2.0) in an accelerated storage test (40 °C, 8 weeks). These barley protein microcapsules possessed a strong ability to protect fish oil against oxidation, making them ideally suited for use in liquid/semi-liquid food systems. Food formulation tests confirmed their successful application in milk and yogurt for their respective shelf lives.     

洋葱精油微胶囊制备工艺优化及其品质分析

为得到包埋效果好、品质优良的洋葱精油微胶囊,采用喷雾干燥法,研究壁材种类、芯材-壁材用量比和固形物用量对微胶囊包埋率的影响及在扫描电子显微镜下的形貌、感官性状、包埋度、含水率、溶解度、堆积密度、贮藏稳定性等。结果表明：在复合壁材为阿拉伯胶＋β-环糊精（质量比4∶3）、芯材-壁材用量比1∶4（mL/g）、固形物用量20%的条件下,洋葱精油微胶囊包埋率为92.35%;扫描电子显微镜结果显示微胶囊表面连续,呈光滑的球形;且微胶囊具有良好的感官性状,粉末均匀不黏壁,能够有效掩盖洋葱精油的辛辣刺激性气味,易于被消费者接受;在最佳制备条件下微胶囊的包埋度、含水率、溶解度、堆积密度、玻璃化转变温度分别为21.32%、3.69%、97.56%、0.786?g/cm3、46.35?℃,表明微胶囊易于溶解,含水率低,玻璃化转变温度高于一般贮藏温度。因此,最佳制备条件下微胶囊产品品质较优,具有良好的贮藏稳定性及市场接受度。     

月见草油微胶囊的制备及微观结构分析

采用4 种不同的配方通过喷雾干燥技术制备月见草油微胶囊,并对4 种配方制备的月见草油微胶囊的表面油含量、包埋率、粒径及表面结构进行分析。结果表明：以变性淀粉和麦芽糊精为壁材制备的月见草油微胶囊表面油含量低,包埋率好,粒径小,颗粒圆,微胶囊表面平整光滑。选用以变性淀粉和麦芽糊精为壁材制备的月见草油微胶囊进行脂肪酸组分及含量的测定,发现微胶囊化对月见草油的主要功能性成分亚油酸和γ-亚麻油酸的含量基本没有影响。用N-甲基靛红酸酐标记此配方中的麦芽糊精,通过激光共聚焦扫描显微镜进行断层扫描观察微胶囊的内部结构,发现微胶囊呈球形,单核结构,麦芽糊精在微胶囊壁中均匀分布。     

复凝聚法青鱼内脏鱼油微胶囊的制备及其性能研究

为提高鱼油稳定性,以青鱼内脏鱼油为芯材,大豆分离蛋白(SPI)和壳聚糖(CS)为壁材,制备鱼油微胶囊。采用单因素实验考察了均质速度、pH、壁材总质量分数、SPI/CS比值、芯壁比等因素对鱼油微胶囊制备效果的影响,结合响应面法优化鱼油微胶囊制备工艺,并比较研究了鱼油微胶囊湿囊分别经喷雾干燥和冷冻干燥两种干燥方法所得产品的包埋率、水分含量、贮藏稳定性。结果表明,最佳鱼油微胶囊制备工艺条件为:pH7、壁材总质量分数2%、SPI/CS比值1.3∶1、芯壁比1.3∶1,在此条件下鱼油包埋率为71.98%±0.16%。喷雾干燥法表面含油率为0.73%±0.04%,低于冷冻干燥法3.62%±0.09%,包埋率为71.98%±0.16%,高于冷冻干燥法56.76%±0.37%,说明喷雾干燥法效果优于冷冻干燥法,鱼油微胶囊贮藏期可较未包埋的鱼油延长6 d以上。通过微胶囊化,改善了青鱼内脏鱼油的性能,提高了使用范围和应用价值。     

Co-encapsulation of fish oil with phytosterol esters and limonene by milk proteins

Co-encapsulated microcapsules containing three lipophilic bioactive components (LBCs) including fish oil, phytosterols and limonene were studied and compared with those containing only fish oil. Milk proteins (whey protein isolate and sodium caseinate in a ratio of 4:1) were used as wall materials. Results show that good quality microcapsules can be obtained at inlet temperature of 170 °C and outlet temperature of 70 °C, with the wall to core ratio of 4:1. There was no significant different (p > 0.05) in the microencapsulation efficiency and the oxidation indicators (PV and AV) after the accelerated storage for both types of microcapsules. However, the retention of EPA and DHA in the LBCs-microcapsules was significantly higher (p < 0.05) than the fish oil microcapsules. The phytosterols content was unchanged but loss of limonene occurred after storage. The LBCs-microcapsules had better flavor/odour profile than the fish oil microcapsules after drying and storage.     

油茶籽油中邻苯二甲酸酯污染风险来源分析及防范措施研究

从油茶籽油生产的原料、工艺、设备、产品包装、储存等环节入手,研究了油茶籽油中邻苯二甲酸酯来源及防范措施。结果表明:茶籽原果本身含有极微量的邻苯二甲酸酯,但不是油茶籽油邻苯二甲酸酯污染主要来源;油茶籽油加工环节使用的加工助剂均未检出邻苯二甲酸酯,不是油茶籽油邻苯二甲酸酯的污染来源;油茶籽油中邻苯二甲酸酯主要来源于生产过程中接触的塑料制品,油样温度越高,或油样与含邻苯二甲酸酯的塑料制品接触时间越长,塑料制品中邻苯二甲酸酯向油样的迁移量会增加;对于受到邻苯二甲酸酯污染的油茶籽油可以采用脱臭工艺将其去除,从而有效解决邻苯二甲酸酯污染风险。     

Microencapsulation of Essential Oil for Insect Repellent in Food Packaging System

Microcapsules containing thyme oil were prepared by in situ polymerization, using melamine–formaldehyde prepolymer as a wall material and 3 different emulsifiers (pluronic F‐127, tween 80, and sodium lauryl sulfate [SLS]). The general characteristics and release behavior of microcapsules, and their repellent effect against insects were investigated. The morphology of microcapsules using SLS was spherical shape with smooth surface. Microcapsules began to degrade at 150 °C. The particle size ranged from 1 to 10 μm and the loading efficiency of thyme oil was clearly affected by the emulsifier type. The highest loading efficiency appeared in microcapsules using SLS, which have good thermal resistance and smooth surface. The release rate of thyme oil from microcapsules was not only dependent on the storage temperature but also emulsifier type and microcapsules showed the sustained release properties for a long time. Diets, which were mixed with encapsulated thyme oil, expressed high insect repellent efficacy over 90% for 4 wk. Practical Application : Essential oil has various pest‐control characteristics, including repellent, ovicidal, and antifeedant efficacy. This work showed the sustained release properties and long‐lasting repellency of encapsulated essential oil. The results suggest that the great potential of essential oil microcapsules can be applied in coating or printing of food packaging materials for the insects repelling effects.     

草果精油微胶囊的制备工艺优化及性质研究

草果精油易挥发、不稳定的特点限制其应用范围。为了有效提高草果精油利用率,本文对草果精油微胶囊的制备工艺进行优化并对其性质进行探究。以草果精油、乳化剂为芯材,辛烯基琥珀酸酐淀粉钠（Octenyl Succinic Anhydride Starch,OSA淀粉）、麦芽糊精、胶体为壁材,采用喷雾干燥法制备草果精油微胶囊。通过单因素和正交实验优化其制备工艺,并研究了草果精油微胶囊的物理性质、形貌特征、热稳定性。结果表明:最佳工艺配方为草果精油30%（w/w）、单,双甘油脂肪酸酯1%（w/w）、N-CREAMER 46型号OSA淀粉15%（w/w）、阿拉伯胶0.2%（w/w）,喷雾干燥制备的草果精油微胶囊包埋率81.07%±3.20%,负载率64.43%±5.32%,水分含量3.40%±0.08%,复水后平均粒径（226.37±3.06） nm,微胶囊产品呈干燥粉末状,复水溶解迅速,包埋效果较好。经过同步热重差热分析,包埋后的草果精油的热稳定性得到了明显提高,扫描电镜观察草果精油微胶囊颗粒分布均匀。本研究可为喷雾干燥法制备草果精油微胶囊的工业生产提供一定技术参考。     

木姜子精油微胶囊制备工艺优化及其品质分析

以木姜子精油为主要原料,采用真空冷冻干燥法制备木姜子精油微胶囊,并以包埋率为指标,在单因素实验基础上结合正交试验,进行木姜子精油微胶囊包埋工艺的优化,以确定最佳工艺参数。同时进行木姜子精油微胶囊的质量评定,分析其理化性质、微观结构、及在储藏过程中精油的挥发率及过氧化值。结果表明,木姜子精油微胶囊包埋的最佳工艺参数为:复合壁材比（大豆分离蛋白:β-环糊精）为1:1（g/g）、芯壁材比1:5（g/g）、固形物含量15%、乳化剂含量3%、乳化剂配比1:4（g/g）、乳化温度40 ℃,在此条件下制备出的木姜子精油微胶囊包埋率可达到84.68%,水分含量、溶解度及堆积密度分别为3.05%、91.04%和0.35 g/cm3。扫描电子显微镜结果显示,木姜子精油微胶囊呈不规则块状。随着储藏时间的延长,木姜子精油微胶囊的挥发率和过氧化值均低于木姜子精油,表明木姜子精油通过微胶囊化,能够有效减缓精油的挥发速度,降低精油氧化程度。     

添加玉米低聚肽的紫苏籽油乳状液及其微胶囊的制备

为制备含玉米低聚肽的紫苏籽油微胶囊,选择阿拉伯胶、可溶性大豆多糖、辛烯基琥珀酸淀粉钠（HI-CAP 100）、酪蛋白酸钠和大豆分离蛋白5 种乳化剂,并添加不同质量分数的玉米低聚肽制备紫苏籽油乳状液,筛选出制备紫苏籽油乳状液的最适乳化剂及最佳的玉米低聚肽添加比例;进而采用喷雾干燥法制备高载油量的玉米低聚肽紫苏籽油微胶囊,筛选和评价高载油量玉米低聚肽紫苏籽油微胶囊的壁材。结果显示：HI-CAP 100制备的紫苏籽油乳状液的液滴粒径主要分布在0.1～2 μm之间,并且玉米低聚肽添加量为5%时,乳状液的不稳定性指数为0.275,粒径为（0.76±0.02）μm;以HI-CAP 100为壁材经喷雾干燥制成的目标微胶囊（载油量≥50%）表面油含量为3%,表明HI-CAP 100对紫苏籽油的包埋效果较好,并且微胶囊粒径分布均匀,表面较光滑适合作为高载油量玉米低聚肽紫苏籽油微胶囊的壁材;通过加速贮藏实验证明玉米低聚肽与茶多酚棕榈酸酯复配,能提高紫苏籽油微胶囊的抗氧化性。     

余甘子核仁油微胶囊的制备及其稳定性分析

以阿拉伯胶和麦芽糊精为壁材,对喷雾干燥法制备余甘子核仁油微胶囊的工艺进行研究。通过单因素试验和响应面优化试验考察乳化剂添加量、阿拉伯胶与麦芽糊精质量比、芯壁比及固形物添加量对余甘子核仁油微胶囊包埋率的影响,得到最优微胶囊制备条件为乳化剂添加量1%、阿拉伯胶与麦芽糊精质量比1∶3.4、芯壁比2∶3、固形物添加量14.2%,该工艺条件下得到的余甘子核仁油微胶囊的包埋率达到（90.74±0.51）%,包埋效果好,颗粒形态完整。采用油脂氧化稳定性测定仪（Rancimat法）测定该样品的氧化诱导时间,并对微胶囊在25?℃条件下的货架期进行预测发现,微胶囊的货架期为716?d,未包埋的余甘子核仁油货架期为128?d,由此可见该微胶囊具有良好的贮藏稳定性。     

4种物理方法制备香草兰精油微胶囊的比较分析

本研究采用菠萝蜜种子淀粉作为壁材,利用饱和水溶液法(saturated water solution method,SWSM)、分子包埋法(paste method,PM)、超声波法(ultrasonic method,UM)、喷雾干燥法(spray-drying method,SDM)4种物理方法包埋香草兰精油,通过测定产率、包埋率、载油量、缓释性、贮藏稳定性等指标,对比分析4种物理方法包埋效果。结果表明:香草兰精油微胶囊产率在74.34%~92.06%,对应的包埋率范围为68.90%~74.49%,载油量为21.27%~26.71%。其中SDM的产率和包埋率最大,分别为92.06%和74.49%,PM产率和包埋率最小,分别为74.34%和68.90%。4种方法均能成功包埋香草兰精油,且色泽上无明显差异,微胶囊为均一球状。在粒径方面,SDM制备的香草兰精油微胶囊粒径最大,为600 nm左右,SWSM最小,为200 nm左右。SWSM制备的香草兰精油微胶囊贮存50 d后香兰素保留率为49.11%,贮存15 d后过氧化值为14.24 mmol/kg,说明缓释性、贮藏稳定性较其他3种香草兰精油微胶囊好。综合所有指标,对比其他3种方法,SWSM是香草兰精油微胶囊的最佳制备方法。     

不同制备方式的鱼油微胶囊挥发性成分及贮藏稳定性的比较

本文研究了不同干燥工艺对鱼油和两种微胶囊挥发性成分以及贮藏稳定性的影响。以鱼油作为芯材,魔芋葡甘聚糖和大豆分离蛋白作为壁材,制备成纳米乳液后通过喷雾干燥和真空冷冻干燥工艺制备微胶囊。试验发现,鱼油、喷雾干燥微胶囊和冷冻干燥微胶囊共鉴定出80种挥发性风味物质,其中鱼油42种,喷雾干燥微胶囊41种,冷冻干燥微胶囊20种,共有成分包括十四烷酸乙酯、9-十六碳烯酸乙酯、1-甲基-4-异丙基苯和1-甲基-4-异丙基苯。加速贮藏实验中两种鱼油微胶囊的过氧化值（POV）增长速率均较鱼油低,当贮藏时间达到30 d时,鱼油、喷雾干燥微胶囊和真空冷冻干燥微胶囊POV值分别为15.65 mmol/kg、8.89 mmol/kg和8.14 mmol/kg,喷雾干燥所得鱼油微胶囊包埋率下降速率较冷冻干燥鱼油微胶囊快,包埋率分别为34.29%和40.90%。综合分析,两种鱼油微胶囊制备方法均能够延缓鱼油氧化和掩蔽不良风味,但冷冻干燥制备鱼油微胶囊更佳,对制备鱼油微胶囊具一定的参考意义。     

不同壁材对大豆生物解离乳状液微胶囊品质的影响

为拓宽大豆生物解离乳状液的综合应用,有效解决破乳困难问题,本文采用喷雾干燥法制备大豆生物解离乳状液微胶囊,以乳液的乳化活性、乳化稳定性、粒径分布、流变学性质和喷雾干燥制得的微胶囊包埋率、热稳定性、表面微观结构为指标,研究5种复合壁材对大豆生物解离乳状液微胶囊品质的影响。结果表明,喷雾干燥前,CMC-MD为壁材的混合乳液的黏度最高,为39.18 mPa·s,且乳化性较好,粒径分布向较小粒径方向移动至0.6~2.0 μm。CMC-MD复合壁材制备的微胶囊包埋率最高,达到90.3%,热稳定性最好,结构变化起始温度最高,为98.3℃。扫描电镜图(SEM)显示不同壁材包埋的微胶囊呈现规则的球形或椭球形颗粒,颗粒直径有一定的差异,以CMC-MD为壁材的微胶囊大小均一,结构致密,具有良好的包埋结构,说明CMC-MD能够作为大豆生物解离乳状液微胶囊的壁材,制备出的微胶囊具有良好的包埋率、热稳定性及表面微观结构,对于生物解离乳状液加工应用领域的拓展和产业化的发展具有重大意义。