乳酸菌微胶囊包埋技术与常用壁材的研究进展

从提高乳酸菌在人体胃肠道的生存率出发,概述了微胶囊包埋技术的定义和发展历史,对几种微胶囊包埋技术界面聚合法、相分离法、喷雾干燥法、锐孔法、高压静电喷雾干燥法等的优缺点进行分析;并结合乳酸菌微胶囊的常用壁材和乳酸菌包埋方法进行探讨,指出复配包埋、多层包埋和添加益生元等对乳酸菌的影响。     

Spray Drying for the Production of Nutraceutical Ingredients—A Review

Contributions of spray drying to food processing applications are increasing as compared to other conventional drying methods. Spray drying has not only contributed in drying of fluids but also has played a vital role in encapsulation and microencapsulation of valuable foods and functional–nutraceutical ingredients. Microencapsulation by spray drying is a cost-effective one-step process as compared to other encapsulation methods. Encapsulation using spray drying is mainly used in the food sector to protect bioactive compounds or functional foods from light, temperature, oxidation, etc. This paper reviews the work done in past years in the functional food and nutraceutical sector using spray drying. The paper focuses on the role of spray drying in vitamins, minerals, flavouring substances, antioxidant compounds and fatty acids encapsulation.     

Microencapsulation of flax oil with zein using spray and freeze drying

Microencapsulation of flax oil was investigated using zein as the coating material. Central Composite Design - Face Centered was used to optimize the microencapsulation with respect to zein concentration (x₁) and flax oil concentration (x₂) using spray drying. Also, freeze drying was carried out at two zein:oil ratios. The quality of microcapsules was evaluated by determining encapsulation efficiency, flowing properties (Hausner ratio), and evaluating the morphology with scanning electron microscopy. The response surface model for microencapsulation efficiency showed a high coefficient of determination (R² = 0.992) and a non-significant lack of fit (p = 0.256). The maximum microencapsulation efficiencies were 93.26 ± 0.95 and 59.63 ± 0.36% for spray drying and freeze drying, respectively. However, microcapsules prepared by spray and freeze drying had very poor handling properties based on the Hausner ratio. The bulk density decreased with an increase in zein concentration at the same flax oil concentration. The morphology of the flax oil microcapsules depended on the zein:flax oil ratio and the process used for microencapsulation. Flax oil microcapsules prepared by spray drying appeared to be composed of heterogeneous spheres of various sizes at high zein:flax oil ratios. Microcapsules prepared by freeze drying resulted in agglomerated small spheres. These microcapsules might find a niche as functional food ingredients.     

Effect of Spray Nozzle Design on Fish Oil–Whey Protein Microcapsule Properties

Abstract: Microencapsulation improves oxidative stability and shelf life of fish oil. Spray and freeze drying are widely used to produce microcapsules. Newer spray-nozzles utilize multiple fluid channels allowing for mixing of wall and core materials at the point of atomization. Sonic energy has also been employed as a means of atomization. The objective of this study was to examine the effect of nozzle type and design on fish oil encapsulation efficiency and microcapsule properties. A total of 3 nozzle types, a pressure nozzle with 1 liquid channel, a pressure nozzle with 2 liquid channels, and a sonic atomizer with 2 liquid channels were examined for their suitability to encapsulate fish oil in whey protein isolate. Physical and chemical properties of freeze dried microcapsules were compared to those of microcapsules produced by spray drying. The 2-fluid pressure and ultrasonic nozzles had the highest (91.6%) and the lowest microencapsulation efficiencies (76%), respectively. There was no significant difference in bulk density of microcapsules produced by ultrasonic and 3-fluid pressure nozzles. The ultrasonic nozzle showed a significantly narrower particle size distribution than the other nozzles. This study demonstrated that new nozzle designs that eliminate emulsion preparation prior to spray drying can be beneficial for microencapsulation applications. However, there is still a need for research to improve microencapsulation efficiency of multiple channel spray nozzles. Practical Application: Since this research evaluates new spray nozzle designs for oil microencapsulation, the information presented in this article could be an interest to fish oil producers and food industry.     

复凝聚法鼠李糖乳杆菌微胶囊工艺优化及储藏稳定性

为提高鼠李糖乳杆菌在贮藏过程中的稳定性,以明胶、阿拉伯胶为壁材,采用复凝聚法制备鼠李糖乳杆菌微胶囊。研究以湿态微胶囊的包埋率为指标,考察pH、壁材浓度、转速和菌添加量对复凝聚法微胶囊制备的影响,在单因素试验的基础上进行正交试验,优化最佳工艺。将最优条件下的湿微胶囊进行喷雾干燥和真空冷冻干燥,并在不同水分活度和不同温度条件下研究了喷雾干燥和真空冷冻干燥鼠李糖乳杆菌微胶囊的储藏稳定性。结果表明,pH 3.75、壁材浓度1.5%、转速200 r/min、菌添加量109 CFU,此条件下制备的鼠李糖乳杆菌微胶囊包埋率最高,为93.21%;复凝聚法制备的鼠李糖乳杆菌湿微胶囊干燥后,每克真空冷冻干燥微胶囊的活菌数比喷雾干燥微胶囊高1.9个对数值;储藏时水分活度越低,温度越低,鼠李糖乳杆菌微胶囊的储藏性越好;与喷雾干燥微胶囊相比,储藏时真空冷冻干燥微胶囊在高水分活度下较稳定,且在不同水分活度、不同温度条件下的活性均高于喷雾干燥微胶囊。因此复凝聚法制备的鼠李糖乳杆菌微胶囊真空冷冻干燥后能更好的保护鼠李糖乳杆菌,延长其储藏期。     

Release and antilisterial properties of nisin from zein capsules spray-dried at different temperatures

Nisin is an effective antimicrobial against a broad spectrum of Gram-positive bacteria. It has been proposed that reduced efficacy of nisin in foods can be improved by technologies such as encapsulation to protect it from interferences by food matrix components. The potential of spray drying, a practical technology, was studied in this work for encapsulation of nisin in zein microcapsules at four inlet temperatures between 75 and 120 °C. At 95 °C and above, no apparent loss of nisin activity was observed after spray drying. At pH 6.0, burst release of nisin was impacted by spray drying temperature more than equilibrium release, possibly due to influences on capsule structures. At pH 2.0, complete release of nisin in 30 min was observed, contrasting to limited release over 8 d at pH 8.0. Capsules produced at an inlet temperature of 105 °C showed the most sustained release of nisin at pH 6.0. For these capsules, sustained release of nisin to >80% was observed at pH 6.0 and 8.0 when NaCl was used at 0.5 mol/L. Finally, at 400 IU/mL, the encapsulated nisin demonstrated slightly improved antilisterial properties than free nisin in reduced fat (2g/100g) milk but much work is still needed to enhance the antimicrobial effectiveness.     

Taste Detection Thresholds of Resveratrol

Resveratrol is a polyphenol that is associated with numerous health benefits related to heart disease, cancer, diabetes, and neurological function. The addition of this compound to food products would help to deliver these health benefits to the consumer. However, bitterness associated with resveratrol may impart negative sensory qualities on the food products into which resveratrol is added; thus, decreasing consumer acceptability. This concern may be resolved by encapsulating resveratrol through spray drying, an innovative processing technique. The objectives of this research were to (1) compare taste detection thresholds of unencapsulated resveratrol and encapsulated resveratrol and (2) determine if the inclusion of anhydrous milk fat in the formulation of the encapsulation wall material affects the taste detection threshold of resveratrol within the microcapsules. Resveratrol microcapsules were produced by encapsulating resveratrol in a protein matrix through spray drying. R‐index measure by the rating method was used to determine the average taste detection threshold and the pooled group taste detection threshold. The average and pooled group taste detection thresholds of unencapsulated resveratrol, sodium‐caseinate‐based resveratrol microcapsule without fat (SC), and sodium‐caseinate‐based resveratrol microcapsule with fat (SCAMF) were 90 and 47 mg resveratrol/L (unencapsulated), 313 and 103 mg resveratrol/L (SC), 334 and 108 mg resveratrol/L (SCAMF), respectively. The findings demonstrate that the encapsulation of resveratrol decreased the detection of the compound and provided a means to incorporate resveratrol into food products without imparting negative sensory properties.     

A process for turning pomegranate peels into a valuable food ingredient using ultrasound-assisted extraction and encapsulation

A new method for pomegranate peel application in food industries was developed based on the ultrasound-assisted extraction of phenolic compounds and their subsequent encapsulation by spray drying. The effects of various parameters on extraction yield, on encapsulation efficiency/yield, and on the main physical properties of the microcapsules (moisture content, bulk density, rehydration ability) were studied. Ultrasound was found to increase extraction yield, but mainly to shorten the treatment time by over 20 times. The maximum encapsulation efficiency was 99.80% and the optimum operating conditions were found to be: wall material, maltodextrin/whey protein isolate (50:50); inlet air temperature, 150 °C; drying air flow rate, 17.5 m³/h; ratio of wall to core material, 9/1; feed solid concentration, 30% (w/w). The encapsulated phenolic extract was found efficient in improving the shelf life of hazelnut paste, in spite of the limited solubility of the crude extract in such a high lipid content matrix.Industrial relevancePomegranate peels, a by-product of pomegranate juice and concentrate industries, present a wide range of pharmaceutical and nutraceutical properties. Therefore, the peels could have more beneficial applications in food industries instead of being used as animal feed or in commercial cosmetic products. In this work, a new method for pomegranate peel application was developed based on the ultrasound-assisted extraction of phenolics and their subsequent encapsulation by spray drying.     

New Trends in the Microencapsulation of Functional Fatty Acid‐Rich Oils Using Transglutaminase Catalyzed Crosslinking

Preparing stable protein‐based microcapsules containing functional fatty acids and oils for food applications has been a big challenge. However, recent advances with transglutaminase (TGase) enzyme as an effective protein cross‐linker could provide workable solutions for the encapsulation of omega‐3 and omega‐6 fatty acids without compromising their targeted release and their biological and physicochemical characteristics. The recent and available literature related to the microencapsulation techniques, physical and oxidative properties, and core retention and release mechanisms of TGase‐crosslinked microcapsules entrapping edible oils were reviewed. The effects of factors involved in microencapsulation processes, on the efficiency and quality of the produced innovative microcapsules were also discussed and highlighted. A brief focus has been finally addressed to new insights and additional knowledge on micro‐ and nanoencapsulation of lipophilic food‐grade ingredients by TGase‐induced gelation. Two dominant microencapsulation methods for fish, vegetable, and essential oils by TGase‐crosslinking are complex coacervation and emulsion‐based spray drying. The developed spherical particles (<100 μm) with some wrinkles and smooth surfaces showed an excellent encapsulation efficiency and yield. A negligible release rate and a substantial retention level can result for different lipid‐based cores covered by TGase‐crosslinked proteins during the oral digestion and storage. A significant structural, thermal and oxidative stability for edible oils‐loaded microcapsules in the presence of TGase can be also obtained.     

An integrated process for utilization of pomegranate wastes — Seeds

In this work, a new method for pomegranate seeds application was developed based on the ultrasound-assisted extraction of seed oil and its subsequent encapsulation by spray drying. Extraction temperature, solvent/solid ratio, amplitude level, and pulse duration/pulse interval ratio were the factors investigated with respect to extraction yield. Ultrasound was sound to increase extraction yield, but mainly to shorten the treatment time by over 12 times. Different materials were used as encapsulating agents. Ratio of core to wall material, inlet air temperature, drying air flow rate, and feed solids concentration were the factors investigated with respect to encapsulation efficiency. The resulting microcapsules were evaluated in terms of moisture content, bulk density, and rehydration ability. The optimum operating conditions were found to be: wall material, maltodextrin/Tween 80; ratio of core to wall material, 0.23; inlet air temperature, 150 °C; drying air flow rate, 22.8 m³/h; feed solids concentration, 30% (w/w).Industrial relevancePomegranate seeds, a by-product of pomegranate juice and concentrate industries, present a wide range of pharmaceutical and nutraceutical properties. Therefore, the seeds could have more beneficial applications in food industries instead of being used as animal feed or in commercial cosmetic products. In this work, a new method for pomegranate seeds application was developed based on the ultrasound-assisted extraction of seed oil and its subsequent encapsulation by spray drying.     

沙棘籽油微胶囊的制备及其性质研究

以沙棘籽油为芯材,采用CAS/MD、OSA/MD、WPI/GA/MD 3种壁材配方,通过喷雾干燥制备沙棘籽油微胶囊,并对微胶囊的性质和微观结构进行研究,用气相色谱法测定微胶囊化前后沙棘籽油脂肪酸含量变化。结果表明:3种配方的微胶囊产品均具有较低的含水量和较高的溶解性,其中以CAS/MD为壁材制备的沙棘籽油微胶囊包埋率最高,微胶囊粒径小,表面光滑,热稳定性良好,壁厚度均一,沙棘籽油在胶囊中分布均匀,喷雾干燥制备过程未对沙棘籽油中的功能性成分产生影响。     

Effect of microencapsulation on morphology,physicochemical properties and flavour profiles of solid yoghurt-flavoured bases

Yoghurt-flavoured bases have many applications in food industry, but the poor stability in the volatile compounds limits their applications. In this study, the morphology and physicochemical properties of yoghurt-flavoured base microcapsules were evaluated with four different wall materials including chitosan, β-cyclodextrin, octenyl succinate anhydride and maltodextrin solution by spray drying. The encapsulation efficiencies of these four microcapsule formulations exceeded 93%. Microcapsules produced by chitosan possessed the best physical properties with improved encapsulation efficiency and smooth microstructure, so chitosan was selected as the encapsulating material of yoghurt-flavoured bases. Compared with those without chitosan, the encapsulated yoghurt-flavoured bases with chitosan had smaller particle size, better water solubility and moisture resistance as well as better stability. Furthermore, microencapsulation and spray drying technology can preserve many volatile compounds and the proportion of ketones, aldehydes, alcohols and other compounds increased. Hence, chitosan is a microcapsule material suitable for outputting solid yoghurt-flavoured bases.     

Volatile Retention and Morphological Properties of Microencapsulated Tributyrin Varied by Wall Material and Drying Method

Butyric acid is an important short‐chain fatty acid for intestinal health and has been shown to improve certain intestinal disease states. A triglyceride containing 3 butyric acid esters, tributyrin (TB) can serve as a source of butyric acid; however, the need to target intestinal delivery and mitigate unpleasant sensory qualities has limited its use in food. Microencapsulation, the entrapment of one or more cores within a matrix, may provide a solution to the aforementioned challenge. This research primarily focused on the influence of (1) wall material: whey and soy protein isolate (WPI and SPI, respectively) and gamma‐cyclodextrin (GCD), (2) wall additives: inulin of varying chain length, and (3) processing method: spray or oven drying (SD or OD, respectively) on the morphological properties and volatile retention of TB within microcapsules. SPI‐based microcapsules retained significantly less (P < 0.001) TB compared to WPI‐based microcapsules as measured by gas chromatography. The inclusion of inulin in the SD WPI‐based microcapsules increased (P < 0.001) TB retention over WPI‐based microcapsules without inulin. Inulin inclusion into WPI‐based microcapsules resulted in a smoother, minimally‐dented, circular morphology as compared to noninulin containing WPI‐based microcapsules as shown by scanning electron microscopy. GCD and TB OD microcapsules retained more (P < 0.001) TB (94.5% ± 1.10%) than all other WPI, WPI‐inulin, and GCD TB SD microcapsules. When spray dried, the GCD‐based microcapsules exhibited (P < 0.001) TB retention than all other microcapsules, indicating the GCD may be unsuitable for spray drying. These findings demonstrate that microencapsulated TB in GCD can lead to minimal TB losses during processing that could be utilized in functional food applications for intestinal health.     

Efficacy of pullulan in emulsification of turmeric oleoresin and its subsequent microencapsulation

Numerous advantages of turmeric oleoresins over ground turmeric are offset by their sensitivity to light, heat, oxygen and alkaline conditions. This can be overcome by microencapsulation. The present work evaluates the efficacy of pullulan to achieve a stable emulsion of turmeric oleoresin and its subsequent microencapsulation. Different ratios of gum arabic and maltodextrin (100:0–0:100) were used to evaluate the appropriate wall material for encapsulation of turmeric oleoresin by spray drying. The emulsions were prepared at 10% loading of turmeric oleoresin, and evaluated for emulsion stability index, particle size and viscosity. The microcapsules prepared by spray drying of these emulsions were evaluated for encapsulation efficiency, encapsulation yield, and stability of volatiles, non-volatiles and total curcumin for six weeks. The efficacy of pullulan was seen from emulsion characteristics, encapsulation efficiency and yield, and t_1/2, the time required for a constituent to reduce to 50% of its initial value.     

基于自组装技术的EGCG多层乳液的制备及其微胶囊化

针对表没食子儿茶素没食子酸酯(EGCG,Epigallocatechin gallate)稳定性差、易氧化降解的问题,采用层层自组装技术对其进行包载,建立EGCG稳态体系的制备工艺,并对产品微观形态及离心稳定性进行考察,进而通过喷雾干燥对其微胶囊化包埋,得到了粒径均一、稳定性较好的EGCG微胶囊。结果表明:在辛烯基琥珀酸淀粉钠(SSOS,sodium starch octenyl succinate)添加量70.0 g、水相油相比8:1 (g/g),剪切速率9000 r/min,剪切时间3 min条件下制备EGCG单层乳液,其离心稳定性系数可达0.138;在阿拉伯胶浓度15%,9000 r/min剪切3 min条件下,进一步制备而得的EGCG多层乳液稳定性较高。经喷雾干燥所得微胶囊的粒径在1~10 μm,其包封率达53.5%±0.5%,呈表面有褶皱无裂痕的椭球状,具有较好热力学稳定性。本研究为提高茶多酚稳定性,拓宽茶多酚产品应用领域提供了理论参考。     

Fish oil microencapsulation as influenced by spray dryer operational variables

The effects of spray‐drying air temperature, aspirator rate (drying air mass flow rate), peristaltic pump rate (feed mass flow rate) and spraying air mass flow rate on microencapsulation properties of fish oil including moisture content, particle size, bulk density, encapsulation efficiency and peroxide were investigated. The process was carried out on a mini spray dryer, and skim milk powder was used as the encapsulating wall material. Results indicated that increasing inlet air temperature increased the particle size, encapsulation efficiency and peroxide value but decreased the bulk density and moisture content of product. Increasing aspirator rate resulted in increased particle size and peroxide value but decreased the moisture content and bulk density. Increase in feed mass flow rate increased the moisture content, particle size, bulk density and peroxide value but decreased the encapsulation efficiency of microcapsules. The encapsulation efficiency and bulk density increased with the increasing aspirator rate but moisture content, particle size and peroxide value decreased.     

维生素A微胶囊化工艺的研究

研究了复凝聚法制备凝聚液、喷雾干燥法进行干燥的维生素A微胶囊化的工艺。以微胶囊包埋率为评价指标进行单因素及正交试验,得到最佳工艺条件为:pH值4.2、乳化时间20min、芯壁比3:1、反应温度45℃。     

模糊综合评价优化明胶基微胶囊配方参数的研究

利用明胶和蔗糖为复合壁材,应用喷雾干燥技术制备VA微胶囊,采用旋转中心组合设计,以微胶囊化效率、产率和保留率为评价微胶囊品质的指标,建立模糊综合评价体系,计算出模糊综合评价值,以模糊综合评价值为目标函数,利用SAS8.1统计分析软件对实验数据作回归拟合,并对方程求一阶偏导。确定VA微胶囊最佳配方参数为:壁材中明胶的比例为16.57g/100g,芯材的载量24.51g/100g,固形物含量为29.78g/100g。     

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。     

R‐Index Measure of Microencapsulated Tributyrin in Gamma‐Cyclodextrin Influenced by Drying Method

Microencapsulation is commonly used in the food industry for a variety of purposes including added ingredient functionally and taste‐masking for those ingredients with negative sensory qualities. Tributyrin (TB), a source intestinally‐essential butyric acid, possesses negative aroma (cheesy, fecal) and taste (bitter) qualities. This has significantly limited its use in food applications for the potential improvement of intestinal health. Utilizing spray drying and low‐temperature oven drying, microcapsules containing TB were produced using whey (WPI), WPI and inulin, and gamma‐cyclodextrin (GCD). To determine how microcapsule formulation and drying method affected the perception of TB relative to a control, microencapsulated and free TB were added to an infant formula system and evaluated using the rating method to determine R‐index measures. Pooled R‐index measures (α = 0.01, 2‐tailed, and n = 170) indicated that the only microcapsule not significantly different from the control (R‐index below 57.95%) was the GCD and TB oven dried (GCT OD) microcapsule. All other WPI, WPI–inulin, and GCD and TB spray‐dried (GCT SD) microcapsules were all significantly different from the control. Average individual R‐index results indicated that all microcapsules in infant formula, except for GCT OD, were significantly different (P < 0.01) from the control formula but not from free TB. Spray drying may create microcapsules with surface TB and disturb the GCD–TB complex, allowing free, and surface TB to be perceived by the panelists. The GCT OD microcapsule has the potential to be used for the potential oral treatment of intestinal disorders in functional food applications without the negative sensory qualities of TB.