猪用生长激素(PST)脂质体包封率测定方法的比较

试验对测定包封率的两种方法即凝胶柱分离法和鱼精蛋白凝聚法进行了比较，测得PST脂质体的包封率分别为75．26％、84．58％，PST回收率分别为90．4％和98．22％。因此确定了鱼精蛋白法为试验产品包封率的测定方法。     

Accelerated ripening of cheese using liposome-encapsulated enzyme

Improved efficiency of liposome encapsulation of a cheese-ripening enzyme and increased retention of encapsulated enzyme by cheese curd are reported. The economy of enzyme usage for accelerating the rate of ripening of Cheddar cheese has been improved about 100-fold over previously reported methods. This has made feasible the use of microencapsulated enzymes for large-scale cheese production. Objective measurement of cheese ripening by proteolytic indices, and subjective evaluation of flavour quality and intensity by trained taste panels, indicate that cheeses are ripened by the microencapsulated enzyme in half the normal time. Investigations aimed at further improving the efficiency and commercial feasibility of the process are reported, and the possibility of using this technology for other aspects of food processing are discussed.     

Shelf life and delivery enhancement of vitamin C using chitosan nanoparticles

Chitosan with different molecular masses was reacted with sodium tripolyphosphate (STPP) to prepare different size nanoparticles, in which vitamin C was encapsulated. The effect of molecular weight (Mw) on nanoparticles efficiency, nanoparticles yield, size, and zeta potential was investigated in detail. Low Mw chitosan generated nanoparticles with better size, morphology, and delivery rate. In addition, the shelf life of encapsulated vitamin C increased as compared with its non-encapsulated counterpart. The release of vitamin C from the nanoparticles was pH-dependent. Quick release took place in 0.1 M phosphate buffer solution (PBS, pH 7.4), while the release was slow in 0.1 M HCl. In addition, in vivo release rate in digestive tract of rainbow trout nearly showed the same trend as the in vitro one.     

Encapsulation systems based on ovalbumin fibrils and high methoxyl pectin

In this study we produced microcapsules using layer-by-layer adsorption of food-grade polyelectrolytes. The shell was built with alternating layers of ovalbumin fibrils and high methoxyl pectin. By varying the number of layers, the release of active ingredients can be controlled – increasing the number of layers of the shell from 4 to 8, decreases the release rate by a factor 3. The formation of the capsules involves merely standard operations that can easily be scaled up to industrial production.     

The effect of cholesterol content of phospholipid vesicles on the encapsulation and acid resistance of β-galactosidase from E. coli

β-Galactosidase was encapsulated in lecithin-cholesterol liposomes prepared by dehydration-rehydration (DR) and reverse-phase evaporation (RE). In both methods, the encapsulation efficiency decreased as cholesterol content increased. Enzyme activity was determined to be located both on the surface and in the interior of the vesicle. When the enzyme-loaded vesicles were exposed to acidic buffer solution, the activity on the surface of the vesicle was rapidly lost. The enzyme in the interior of the vesicle was more acid-resistant. The residual activity of enzyme depended on the molar ratio lecithin: cholesterol (L:C ratio). In both methods, the vesicles which showed the greatest acid resistance were those with an L:C molar ratio of 1:3. These vesicles retained their enzymatic activity and acid resistant character after 1 month storage at 5°C under nitrogen.     

Chitosan-coated pectin beads: Characterization and in vitro release of mangiferin

Microspheres of low degree of esterification (DE) pectin with calcium and the same sphere coated with chitosan (PCaC) were prepared. The spheres have diameters in the range 650–680 μm. The layer of chitosan is about of 5–15 μm thick. To obtain firm and stable PCaC beads, chitosan was reacetylated. Two different degrees of acetylation, giving PCaC50 and PCaC80 were adopted. The beads were characterized by FTIR, SEM and swelling measurements. Mangiferin was loaded in PCaC reacetylated in two different ways: by addition in pectin solution (M_p) and by addition in CaCl₂ solution (M_c). The yield in producing the beads, the efficiency in encapsulation and the content of mangiferin in beads were determined. A swelling kinetics study was done in simulated gastric fluid (SGF, pH 1.2) and in simulated intestine fluid (SIF, pH 7.4). The release of mangiferin from the beads was performed in SGF followed by the release in SIF. Based on the yield and efficiency in encapsulation the best bead was found to be PCaC50-M_p. The highest release (7.8 mg of mangiferin/g of bead) was achieved by the PCaC50-M_c. For all beads more bioactive was released in SGF than in SIF.     

Critical review of controlled release packaging to improve food safety and quality

ABSTRACT

Controlled release packaging (CRP) is an innovative technology that uses the package to release active compounds in a controlled manner to improve safety and quality for a wide range of food products during storage. This paper provides a critical review of the uniqueness, design considerations, and research gaps of CRP, with a focus on the kinetics and mechanism of active compounds releasing from the package. Literature data and practical examples are presented to illustrate how CRP controls what active compounds to release, when and how to release, how much and how fast to release, in order to improve food safety and quality.     

Vanillin cross-linked chitosan microspheres for controlled release of resveratrol

In this work, resveratrol (Res) was incorporated into chitosan microspheres for controlled release and stabilisation. The microspheres were prepared by emulsion chemical cross-linking method, and vanillin was used as the novel cross-linker. The microspheres showed a smooth surface with irregular small particles and internal voids with a size distribution between 53 and 311 μm. Interpenetrating network cross-linking mechanisms might account for the Schiff base reaction between chitosan and vanillin. The encapsulation efficiency of Res within microspheres was up to 93.68%. Res contained within microspheres was protected from light and heat compared with the free Res. In addition, release behaviours were governed by two distinct stages and dependent on pH of release media. Diffusion, swelling and erosion mechanisms might coexist for the full controlled release and Higuchi was the most suitable model for the whole release procedure. Thus, controlled release and stabilization of Res were achieved through incorporation of Res into cross-linked chitosan microspheres by vanillin.     

Stability and release properties of double emulsions for food applications

Water-in-oil-in-water (W₁/O/W₂) double emulsions (DEs) containing gelatin and sodium chloride (NaCl) in the inner aqueous phase were developed for controlled release applications. Emulsions were prepared with water and canola oil, as well as with polyglycerol polyricinoleate and polysorbate 80 as emulsifiers for the primary water-in-oil (W₁/O) emulsion and secondary W₁/O/W₂ emulsions, respectively. All DEs containing both NaCl and gelatin were stable against sedimentation for the month-long study whereas control emulsions (with either no NaCl or gelatin) showed visual phase separation. The average oil globule size in freshly-prepared DEs grew from ∼45 to 70 μm with an increase in salt load from 2 to 8% (w/w), and changed little after 1 month. Besides its role in stabilization, NaCl was also used as a marker to evaluate DE release behaviour. The salt diffusion coefficient obtained using Fujita’s model rose from 4.7 to 6.0 × 10⁻¹¹ cm²/s with increasing NaCl concentration in the DEs from 2 to 8% (w/w). All stable DEs showed a high salt retention in the inner aqueous phase (>94%) after 1 month of storage at 4 °C. These results demonstrated the synergistic action of a gelling agent and electrolyte in stabilizing and modulating the release behaviour of NaCl from W₁/O/W₂ DEs.     

Multilayer emulsions as delivery systems for controlled release of volatile compounds using pH and salt triggers

Multilayer oil-in-water (M-O/W) emulsions were compared to primary oil-in-water (P-O/W) emulsions as carriers for volatile organic compounds (VOCs) under various environmental conditions (pH and salt). The M-O/W emulsion consisted of soy oil coated with β-lactoglobulin (βLG) and pectin layers. The release of VOCs with different physiochemical properties from aqueous solutions and emulsion systems was measured using static and dynamic headspace methods. The partition coefficients (K) calculated by the phase ratio variation (PRV) method, showed different volatile release profiles between the emulsion types. An increase in VOC release was found for the unstable P-O/W emulsion at pH 5, whereas M-O/W emulsions were stable at the same pH and retained the hydrophobic VOCs. Hydrophobic interactions and hydrogen bonds with the secondary dense layer of pectin may be responsible for the improved retention. Increasing pH and ionic strength acts as a VOC release trigger to detach the pectin from the interface. The release rates from initial dynamic curves support the results under equilibrium conditions. The results of this study demonstrate the capability of using M-O/W emulsions for controlled release of VOCs, as well as an alternative system to create stable emulsions with similar VOC release profiles.     

甘氨酸螯合铁脂质体制备及其体外释放的研究

为提高甘氨酸螯合铁的稳定性,采用薄膜-超声法制备了甘氨酸螯合铁脂质体。以包封率为指标,考察了胆固醇、芯材、吐温80的量和水相体积对脂质体的影响,得到了最佳的工艺条件为:胆固醇:芯材:吐温80:大豆卵磷脂=0.2:0.1:0.5:1(wt.:wt.:wt.:wt.),水相体积10mL;最大包封率为63.92%。体外释放结果显示,经过5h,脂质体在模拟胃液和模拟肠液中的释放率分别为24.05%和15.35%;因而,脂质体对芯材甘氨酸螯合铁有较好的保护及缓释效果。     

Carboxymethylchitosan-coated proliposomes containing coix seed oil: Characterisation,stability and in vitro release evaluation

In this research, carboxymethylchitosan (CMCS)-coated proliposomes (CM-PL) were prepared in an attempt to deliver coix seed oil (CSO) using conventional ethanol injection followed by surface modification and spray drying. Conventional uncoated liposomes (un-L), CMCS-coated liposomes (CM-L) and uncoated proliposomes (un-PL) were also prepared for comparison. The morphology, encapsulation efficiency (EE), particle size, zeta potential, stability, and CSO release performance were investigated for all samples. The results indicated that CM-PL possessed smoother surface, better heterogeneous size distribution, higher EE and improved stability compared with other samples. Transmission electron microscopy (TEM) showed that rehydrated CM-PL were spherical particles with CMCS layers surrounding the surface of conventional liposomes. The coating mechanism was probably due to H-bonding interactions between CMCS and the interfacial regions of the phosphatidylcholine bilayer. In addition, controlled release of CSO from coated proliposomes was obtained with more sustained release in simulated intestinal fluid (SIF) than in simulated gastric fluid (SGF).     

A novel gelatin crosslinking method retards release of mulberry 1-deoxynojirimycin providing a prolonged hypoglycaemic effect

Mulberry 1-deoxynojirimycin (DNJ), a potent α-glycosidase inhibitor, has therapeutic potency in the suppression of postprandial blood glucose levels thereby possibly preventing diabetes mellitus. However, DNJ has a relatively short half-life in vivo (about 2 h). Therefore, several doses of mulberry DNJ are required to achieve optimal therapeutic results. This study aimed to delay the release of mulberry DNJ with biodegradable matrices to maintain the intestinal DNJ concentration and prolong the hypoglycaemic effect in vivo. A novel, simple, and commercially viable method was adopted to develop DNJ-entrapped microspheres (DNJ-MSs). A higher extent of crosslinking and the larger sized DNJ-MS decreased the rate of mulberry DNJ release in vitro. Consequently, an in vivo study was performed in Wistar rats over a 6 h period. The area under curve (AUC) of rats with DNJ-MS was significantly increased, compared to animals dosed with mulberry powder (control). DNJ-MS suppressed postprandial glucose from sucrose administration at the initial and 3 h time points indicating a prolonged hypoglycaemic effect.     

柠檬烯脂质体的乙醇注入法制备及其体外释放

为提高柠檬烯稳定性,增加其水溶性,采用乙醇注入法制备了柠檬烯脂质体。以包封率为指标,考察了影响脂质体制备的一些重要的工艺参数,优化了制备柠檬烯脂质体的工艺条件,得到了最佳的工艺条件为:芯材:胆固醇:吐温80:大豆卵磷脂=0.2:0.1:1:10(质量比),醇水体积比1:10,最大包封率为86.6%。体外释放结果显示,经过25h,脂质体在模拟胃液和模拟肠液中的释放率分别为12%和18%;因而,脂质体改善了柠檬烯的水溶性,增加了其稳定性,对柠檬烯有较好的保护及缓释效果,这有利于提高其生物利用率。     

Preparation of iron-loaded alginate gel beads and their release characteristics under simulated gastrointestinal conditions

The formulation and processing variables affecting the preparation of iron-loaded alginate beads for potential use as controlled release carriers were studied. The effect of alginates with different mannuronic/guluronic acid ratios, calcium concentration, loading of iron (II) and iron (III) compounds, variable iron loading times and incorporation of iron at different stages in the preparation were considered. Two successful strategies for the incorporation of iron into alginate beads involved using a mixed iron/calcium cross-linking bath or taking preformed calcium cross-linked beads and subsequently loading them with iron. Beads with 50–80 mg iron/g dried bead could be made with ferrous gluconate, high guluronic acid alginate and the mixed cross-linking bath method. Beads with higher loading, up to 180 mg iron/g dried bead, could be made by loading ammonium ferric citrate. Under simulated gastrointestinal conditions the beads progressively released iron in nutritionally relevant amounts.     

Development of antioxidant food packaging materials with controlled release properties

In this study, cellulose acetate (CA) films with different morphological features were prepared in order to control the release rates of low molecular weight natural antioxidants, L-ascorbic acid and L-tyrosine. Increasing CA content in the casting solution decreased the average pore size and porosity of the films, thus, reduced the diffusion rates of both antioxidants through the films. Although both antioxidants have similar molecular weights, L-tyrosine released into water much more slowly than L-ascorbic acid. The highest antioxidant activity in release test solutions was observed with highly porous L-tyrosine containing films. However, when the porosity of the films reduced, the antioxidant activity of L-ascorbic acid released into solution was found to be higher due to trapping of significant amount of L-tyrosine in dense films. The use of different antioxidants caused different changes in morphological and mechanical properties of the CA films. Varying the structural features of the films with the preparation conditions or using different surfaces of the films allowed the controlled release of each antioxidant.     

Continuous dual feed homogenization for the production of starch inclusion complexes for controlled release of nutrients

The use of food grade biopolymers, such as starch, has been suggested as a technological solution for the controlled delivery of health promoting ingredients. This staple food carbohydrate may form molecular inclusion complexes, termed V-amylose, with numerous ligands. This study aimed to develop and assess a continuous production process for the formation of such complexes using three starches varying in the amylose:amylopectin ratio. The heart of the technique is the use of dual feed homogenizer for in situ complexation in accord with homogenization, to form micron and sub micron particles. Results show that pre-dissolving high amylose corn starch or corn starch in a hot alkali solution leads to the formation of a bi-modal population of 0.04–20 μm or a mixed population of 0.04–3 μm V-type particles, respectively. These stearic acid-loaded particles exhibit V-type X-ray diffraction and release the stearic acid mainly upon pancreatic amylases treatment. This technology could prospectively be used in numerous applications including as a delivery system for the controlled delivery of bioactives.

Industrial relevance

Introduction of nutraceuticals and bioactive nutrients into foods is a major technological challenge since many of these compounds have low chemical stability during product processing, storage and consumption. One of the industrial approaches to overcome this drawback is the use of encapsulation technologies, mainly with cheap, common and safe food ingredients. This study describes a unique continuous process to exploit starches’ natural and spontaneous tendency to form single helical molecular inclusion complexes, termed V-amylose, as a possible platform for nano and micro-encapsulation. This process involves coupling pH titration, which induces complexation, to a pressurized homogenization which induces rapid complexation and particle size reduction. Thus, it is suggested to help overcome the main drawbacks of current batch processing, i.e. large particle size, particle aggregation and prolonged duration of production. Additionally, the continuity of the process offers the technological possibility of incorporating the process in existing industrial settings of continuous manufacturing. These molecular inclusion complexes could prospectively be used in a wide variety of applications in the food, pharmaceutical and biotechnology industries including as a delivery system for the controlled and targeted delivery of nutrients, nutraceuticals and/or drugs to the lower gastrointestinal tract.     

Encapsulation of Probiotic Bacteria in Biopolymeric System

Encapsulation of probiotic bacteria is generally used to enhance the viability during processing, and also for the target delivery in gastrointestinal tract. Probiotics are used with the fermented dairy products, pharmaceutical products, and health supplements. They play a great role in maintaining human health. The survival of these bacteria in the human gastrointestinal system is questionable. In order to protect the viability of the probiotic bacteria, several types of biopolymers such as alginate, chitosan, gelatin, whey protein isolate, cellulose derivatives are used for encapsulation and several methods of encapsulation such as spray drying, extrusion, emulsion have been reported. This review focuses on the method of encapsulation and the use of different biopolymeric system for encapsulation of probiotics.     

食品添加剂的控制释放技术

介绍了一种食品工业中新近应用到的技术控制释放技术,主要综述了其控制释放的方式与机理以及在食品添加剂控制释放方面的应用.