Improving the thermal stability of natural bioactive ingredients via encapsulation technology.

Bioactive compounds (bioactives) such as phenolic acids, coumarins, flavonoids, lignans and carotenoids have a marked improvement effect on human health by acting on body tissues or cells. Nowadays, with increasing levels of knowledge, consumers prefer foods that can provide bioactives beside the necessary nutrients (e.g., vitamins, essential fatty acids and minerals). However, an important barrier for incorporating bioactives into foods is their low thermal stability. Nevertheless, thermal processing is widely used by the food industries to achieve food safety and desired texture. The aim of this work is to give an overview of encapsulation technology to improve thermal stability of bioactives incorporated into different food products. Almost all thermal analysis and non-thermal methods in the literature suggest that incorporation of bioactives into different walls can effectively improve the thermal stability of bioactives. The level of such thermal enhancement depends on the strength of the bioactive interaction and wall molecules. Furthermore, contradictory results have been reported in relation to the effect of encapsulation technique using the same wall on thermal stability of bioactives. To date, the potential to increase the thermal resistance of various bioactives by gums, carbohydrates, and proteins have been extensively studied. However, further studies on the comparison of walls and encapsulation methods to form thermally stable carriers seem to be needed. In this regard, the same nature of bioactives and the specific protocol in the report of study results should be considered to compare the data and select the optimum conditions of encapsulation to achieve maximum thermal stability.

Recent progresses in the delivery of ß-carotene: From nano/microencapsulation to bioaccessibility.

Beta-carotene (BC) as an efficient pro-vitamin is effective in improving vision, immune system and cognitive function as well as preventing coronary diseases and cancer. However, besides its poor chemical stability, the high lipophilic nature of BC reduces its dispersibility and consequently bioavailability which limits its application into food, pharmaceutical and nutraceuticals. Different carriers with vesicular or particulate structures have been studied and utilized for promoting BC solubility, dispersibility, and protection against diverse operational or environmental stresses and also controlling BC release and subsequent bioaccessibility. The current study, therefore reviews different micro/nanocarriers reported on BC encapsulation with special focusing on its bioavailability. Liposomal structures have been successfully used for enhancing BC stability and bioavailability. Besides, emulsion-based carriers including Pickering emulsions, nanoemulsions and microemulsions have been widely evaluated for BC encapsulation and protection. In addition, lipid-based nanoparticles and nanostructural carriers have also been applied successfully for this context. Moreover, gel structures including emulgels, hydrogels and oleogels are studied in some researches. Most of these delivery systems led to higher hydro-solubility and dispersibility of BC which consequently increased its bioavailability; thereupon could promote its application into food, cosmetic and nutraceutical products. However, for remarkable incorporation of BC and other bioactive compounds into edible products, the safety and toxicological aspects of these delivery system especially those designed in nano scale should be addressed in the further researches.

Microemulsions as nano-reactors for the solubilization, separation, purification and encapsulation of bioactive compounds.

Bioactive components possess various functionalities and are most interested for different food, nutraceutical and pharmaceutical formulations. The current review will discuss the preparation methods and fabrication techniques to design microemulsions (MEs) for the solubilization, separation, encapsulation and purification of various agro-food bioactive compounds. ME systems have shown suitable potential in enhancing oil recovery, protein extraction, and isolation of bioactive compounds. Moreover, the capability of ME based systems as drug and nutraceutical delivery cargos, and synthesis of various organic and inorganic nanoparticles, especially using biopolymers, will be investigated. ME liquid membranes are also developed as nano-extractor/nano-reactor vehicles, capable of simultaneous extraction, encapsulation or even synthesis of hydrophilic and lipophilic bioactive compounds for food, nutraceutical and drug applications.

Microemulsion as nanoreactor for lutein extraction: Optimization for ultrasound pretreatment.

In the present study, the capability of microemulsion technique, as a novel technique for synchronous extraction and solubilization of lipophilic compounds, on lutein extraction from marigold petals was investigated. Under the optimized sonication (amplitude 100%, 120 s, 25°C), the extraction efficiency increased (85%) using SDS:ethanol (1:2)-based ME. Moreover, sonication led to smaller droplets (12-163 nm) with favorable thermodynamic stability. In addition, the developed MEs showed higher thermal and especially UV stability in comparison to organic solvent extracts which were fainted with first-order kinetics. It was also found that co-surfactant could be eliminated from formulation on the expense of the optimized sonication, was valuable output form industrial point of view. These findings revealed the high potential of ultrasound technique on the extraction and solubilization of lutein by ME technique which can be directly utilized in lutein-enriched functional foods and beverages. PRACTICAL APPLICATIONS: From applicability point of view, the solvent extracted compounds cannot be easily dissolved in food or pharmaceutical systems that are mostly hydrophilic. Therefore, microemulsions (MEs), as green and environmentally friendly food-grade systems, due to their potential capability for simultaneous extraction and solubilization of carotenoids are of great interest. Therefore, the present study confirmed the practical ability of MEs in lutein extraction and protection. All in all, the developed lutein MEs with high lutein extraction capacity and superior lutein chemical stability against thermal treatment and especially UV radiation is an original finding which allows design of new functional foods and could be potentially useful for enriching foods, pharmaceuticals, nutraceuticals, and supplement formulation.

Nano based lutein extraction from marigold petals: optimization using different surfactants and co-surfactants.

Nanotechnology has high potential in processing of industrial crops and by-products in order to extract valuable biological active compounds. The present study endeavored to take advantage of nanotech approach (i.e microemulsion, ME), as a novel green technique, for lutein extraction from marigold (Tagetes erecta) as an industrial crop. The pseudo-ternary phase diagrams confirmed the effect of surfactant type on the formation of mono-phasic lutein MEs. The combination of sucrose monopalmitate:1-poropanol (1:5) showed the highest efficiency in the presence of marigold petal powder (MPP, 18%) and water (42%). In addition, the efficiency of primitive MEs (without co-surfactants) was outstandingly increased as MPP was moistened by co-surfactants. Furthermore, different MEs resulted in various droplet size (14-250nm), PDI (0.05-0.32) and zeta potential (-1.96 to -38.50 mV). These findings revealed the outstanding importance of the surfactants and co-surfactants and their ratio on the extraction capability of MEs. These findings also proved the capability of microemulsion technique (MET) as a potential alternative to conventional solvent with possible applicability for extraction of lutein and other industrial plant based bio-compounds.