Background Bioactive compounds possess plenty of health benefits, but they are chemically unstable and susceptible to oxidative degradation. The application of pure bioactive compounds is also very limited in food and drug formulations due to their fast release, low solubility, and poor bioavailability. Encapsulation can preserve the bioactive compounds from environmental stresses, improve physicochemical functionalities, and enhance their health-promoting and anti-disease activities. Scope and approach Micro and nano-encapsulation based techniques and systems have great importance in food and pharmaceutical industries. This review highlights the recent advances in micro and nano-encapsulation of bioactive compounds. We comprehensively discussed the importance of encapsulation, the application of biopolymer-based carrier agents and lipid-based transporters with their functionalities, suitability of encapsulation techniques in micro and nano-encapsulation, as well as different forms of improved and novel micro and nano-encapsulate systems. Key findings and conclusions Both micro and nano-encapsulation have an extensive application, but nano-encapsulation can be a promising approach for encapsulation purposes. Maltodextrin in combination with gums or other polysaccharides or proteins can offer an advantageous formulation for the encapsulation of bioactive compounds by using encapsulation techniques. Electro-spinning and electro-spraying are promising technologies in micro and nano-encapsulation, while solid lipid nanoparticles and nanostructure lipid carriers are exposing themselves as the promising and new generation of lipid nano-carriers for bioactive compounds. Moreover, phytosome, nano-hydrogel, and nano-fiber are also efficient and novel nano-vehicles for bioactive compounds. Further studies are required for the improvement of existing encapsulate systems and exploring their application in food and gastrointestinal systems for industrial application.

Advances in micro and nano-encapsulation of bioactive compounds using biopolymer and lipid-based transporters

Background Encapsulation of flavor and aroma in an appropriate form is an important concern for a long time. Encapsulation is the most successful way not only to preserve or mask flavor and aroma compounds but also to enhance their thermal and oxidative stability, overcome the limitations of high volatility, to control the fast release and improve the poor bioavailability, as well as to increase their application in food systems. Scope and approach This review focuses on the recent advances in micro and nano-encapsulation of flavor and aroma compounds. We comprehensively highlight the suitability of micro and nano-encapsulation approaches for the retention of flavor and aroma including emerging techniques, new formulations and novel encapsulate systems, to illustrate the flavor release mechanisms, and depict the industrial applications of encapsulated flavor and aroma compounds. Key findings and conclusions Nano-encapsulation has attracted more attention compared to microencapsulation; showing better encapsulation efficiency, enhanced stability of capsule, and more control on flavor release. Recently, spray chilling and spray freeze drying as an alternative to spray drying, can overcome the thermal loss of flavor, promising for the microencapsulation of heat sensitive compounds. In contrast, electro-spraying and electro-spinning in combination with the emulsion or coaxial approach are novel and promising for the nano-encapsulation of flavor and aroma compounds. The combination of carrier materials, e.g. polysaccharide with protein can improve the encapsulation efficiency and capsule functionality. However, application of micro and nano-encapsulates into different food and gastrointestinal systems needs to be explored in order to expose their release mechanisms and application efficiency.

Micro and nano encapsulation, retention and controlled release of flavor and aroma compounds: A critical review

In this study, the feasibility of developing Alyssum homolocarpum seed gum (AHSG) nanocapsules containing d-limonene by electrospraying has been investigated. d-limonene emulsions with constant AHSG (0.5% w/w) and various flavor concentrations (10-30% based on gum weight) with 0.1% Tween 20 were electrosprayed at 20kV and 0.1ml/h of flow rate. The effects of key parameters of emulsions (rheological properties, droplet size, surface tension and electrical conductivity) on the morphology of structures have been studied. The morphology of nanocapsules had strong dependency on solution properties. The aggregated irregular shaped nanoparticles were obtained from electrospraying of AHSG solution. After incorporation of 10 and 20% d-limonene, spherical nanocapsules were yielded. However, morphology of nanocapsules changed to nanofibers by increasing the flavor content to 30%. The encapsulation efficiency for 10 and 20% d-limonene loaded nanocapsules was around 87-93%. Attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) were also employed to study the physicochemical characteristics of nanocapsules. These experiments provided evidences that electrosprayed AHSG nanoparticles introduce a novel and efficient carrier for encapsulation of bioactive ingredients.

Development and characterization of electrosprayed Alyssum homolocarpum seed gum nanoparticles for encapsulation of d-limonene

Water loss of fresh fruit: Influencing pre-harvest, harvest and postharvest factors

Acacia gum polysaccharide based hydrogel wound dressings: Synthesis, characterization, drug delivery and biomedical properties.

Effect of microencapsulation by spray drying on cocoa aroma compounds and physicochemical characterisation of microencapsulates

Summary
A mathematical model was developed from experimental measurements to describe the evolution of the O2, CO2 and ethylene in a modified atmosphere packaging system for Cavendish bananas. The respiration and ethylene production in the fruits were experimentally obtained from a closed system method and then represented by Michaelis–Menten equations of enzyme kinetics. The gas transfer through the packaging was described by a Fick's diffusion equation, and the temperature dependence was represented based on the Arrhenius law. The model was validated by packaging the fruit in perforated bags of polypropylene and low density polyethylene at 12 °C for a period of 8 days. With the developed model it was possible to satisfactorily describe the experimental evolution of the gas content in the headspace of the packages, obtaining coefficients of determination (R2) of 0.93 for the O2 levels, 0.90–0.91 for the CO2 levels, and 0.89–0.93 for the ethylene levels.

Aníbal O. Herrera

Papers

Effect of microencapsulation by spray drying on cocoa aroma compounds and physicochemical characterisation of microencapsulates

Ethylene production, respiration and gas exchange modelling in modified atmosphere packaging for banana fruits

Modelling the evolution of O2 and CO2 concentrations in MAP of a fresh product: Application to tomato

Morphologic and stability cassava starch matrices for encapsulating limonene by spray drying

Modelling water vapour transport, transpiration and weight loss in a perforated modified atmosphere packaging for feijoa fruits