MICROENCAPSULATION BY SPRAY DRYING

Abstract

Spray drying technique has been widely used for drying heat-sensitive foods, pharmaceuticals, and other substances, because of the solvent rapid evaporation from the droplets, Although most often considered a dehydration process, spray drying can also be used as an encapsulation method when it entraps ‘active’ material within a protective matrix, which is essentially inert to the material being encapsulated. Compared to the other conventional microencapsulation techniques, it offers the attractive advantage of producing microcapsules in a relatively simple continuous processing operation. This chapter will present a brief overview of the main considerations involved in the application of spray drying for microencapsulation, with a special emphasis given to microencapsulation of volatile materials. The potential use of spray drying microencapsulation for pharmaceutical applications, particularly the preparation of microparticulate drug delivery systems, will also be discussed     

Spray-Drying Microencapsulation of Anthocyanins by Natural Biopolymers: A Review

There has been an increased interest in the development of food colorants from natural sources as alternatives to synthetic dyes because of both legislative actions and consumer concerns. Anthocyanins are of great interest for the food industry since they give a wide range of colors as well as nutraceutical activities. Nevertheless, due to their low stability to environmental conditions during processing and storage, introducing those compounds into foods is challenging. Microencapsulation may be an efficient way to introduce such compounds into those products. An important step in developing microcapsules is the selection of a biopolymer (wall material) which meets the required criteria. Hence, this review will focus on microencapsulation of anthocyanins with different biopolymers through spray drying to develop natural colorant pigments which possess high stability, solubility, and dispersibility. Our goal is to give updated information regarding microencapsulation of anthocyanins by spray drying, as well as its effectiveness, developments, and optimized conditions which will be discussed.     

Microencapsulation of extra‐virgin olive oil by spray‐drying: Influence of wall material and olive quality

Encapsulation is a process by which small particles of core products are packaged within a wall material to form microcapsules. One common technique to produce encapsulated products is spray‐drying which involves the conversion of liquid oils in the form of an emulsion into dry powders. Emulsification conditions, wall components, and spray‐drying parameters have been optimized for the microencapsulation of different extra‐virgin olive oils. To achieve this goal, the influences of emulsion conditions have been evaluated for different wall components such as proteins (sodium caseinate and gelatin), hydrocolloids (Arabic gum), and hydrolyzed starches (starch, lactose, and maltodextrin). In addition, for each of the tested conditions the ratio of wall solid‐to‐oil and spray‐drying parameters were as well optimized. The microencapsulation effectiveness was determined based on process yield and the ratio between free and encapsulated oil (microencapsulation efficiency). Highest encapsulation yields were achieved when gelatin, Arabic gum and maltodextrin and sodium caseinate and maltodextrin were used as encapsulation agents and the ratio of wall solid‐to‐oil was 1:4 and 1:2, respectively. Under these conditions, 53% of oil was encapsulated. The influence of olive oil quality in the microencapsulation process was evaluated in terms of fatty acids profile alteration after the microencapsulation process.     

Encapsulation Efficiency of Food Flavours and Oils during Spray Drying

Microencapsulation is a rapidly expanding technology which is a unique way to package materials in the form of micro- and nano-particles, and has been well developed and accepted within the pharmaceutical, chemical, food and many other industries. Spray drying is the most commonly used encapsulation technique for food products. A successful spray drying encapsulation relies on achieving high retention of the core materials especially volatiles and minimum amounts of the surface oil on the powder particles for both volatiles and non-volatiles during the process and storage. The properties of wall and core materials and the prepared emulsion along with the drying process conditions will influence the efficiency and retention of core compounds. This review highlights the new developments in spray drying microencapsulation of food oils and flavours with an emphasis on the encapsulation efficiency during the process and different factors which can affect the efficiency of spray drying encapsulation.     

Microencapsulation of tea tree oil by spray‐drying with methyl cellulose as the emulsifier and wall material together with chitosan/alginate

Amphiphilic methyl cellulose (MC) was used as the emulsifier and the internal wall material to increase the microencapsulation efficiency (ME) of tea tree oil (TTO) and the stability of the emulsion for spray‐drying. The results of microscopy images, zeta potential, and microencapsulation efficiency indicated that the wall material components affected the morphology, stability, and ME of the microcapsules. The microcapsules with the wall materials of MC/chitosan (CTS)/alginate (ALG) were spherical and had higher ME than those with monocomponent or bicomponents of MC, CTS, or ALG, or triple components of MC/ALG/CTS. Spray drying conditions were optimized to find the optimum microencapsulation conditions. The highest ME 89.4% and the highest oil embedding rate (ER) 90.4% were obtained through spray‐dying the emulsion of 0.8 mL TTO embraced by 0.4 g MC, 0.6 g CTS, and 3 g ALG at the drying conditions of inlet air temperature 210 °C, needling frequency 2 s, and pump flow rate 55 r/min. Microencapsulation obviously decreased the release of TTO. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44662.     

Solvent evaporation and spray drying technique for micro- and nanospheres/particles preparation: A review

This article presents a comprehensive review of research relating to the preparation of biodegradable and biocompatible controlled/sustained release of micro and nanoparticles. It covers recent developments in the area of technology through solvent evaporation followed by lyophilization and spray drying. The last decade seen a shift from empirical formulation efforts to a technological approach based on better understanding of micro and nanoparticle formation in the solvent evaporation and spray drying technique. This review provides concepts and a theoretical framework for the preparation of micro and nanoparticle formation. Encapsulation of pharmaceutical materials has received much attention due to enhanced effectiveness, bioavailability, and the dissolution rates that can be achieved. Polymeric micro and nanoparticles can be used to transport drug in a rate-controlled and sometimes targeted manner. Initially, laboratory-scale experiments are performed, but for industrial scale-up, experiments are required using sophisticated technologies. The objective of this review article is to summarize the solvent evaporation and spray drying techniques for the preparation of biodegradable and biocompatible controlled/sustained release of micro and nanospheres/particles with focus on the steps involved in its preparation, materials used, and the technique of microencapsulation. The review also summarizes recent research on solvent evaporation and spray drying.     

Product Design and Process Engineering using the Example of Flavors

Recently, formulation processes have become increasingly important in the product design of flavors. Traditionally, the focus of flavorists and the chemists that support them has mostly been on the chemical composition of the flavors, which are generally in liquid form, although product characteristics that can be influenced by process engineering, e.g., shelf life and controlled release, are currently been seen to be just as important. An exact knowledge of the physico‐chemical properties of the flavor and carrier materials is important if process engineering measures are to be used to influence product properties. This review article discusses recent progress in microencapsulation of flavors and presents a detailed discussion of the topic using the processes of spray drying, spray granulation, extrusion and multi‐material nozzles as examples.     

医药微胶囊技术

综述了医药微胶囊的结构、制备和应用。介绍了喷雾干燥法、喷雾冻疑法、空气悬浮法、相分离法、粉末床法、界面聚合法的制备原理和方法。     

A New Technique for Spray-Dried Encapsulation of Lycopene

A new technique for lycopene microencapsulation by spray drying using dehumidified air as the drying medium was developed and the optimum operating conditions for encapsulation efficiency were determined. A pilot-scale spray dryer was employed for the spray-drying process. The modification made to the original design consisted of connecting the dryer inlet air intake to an absorption air dryer. The dextrose equivalent (DE) of maltodextrin, ratio of core to wall material, feed temperature, inlet air temperature, drying air flow rate, and compressed air flow rate were the factors investigated with respect to encapsulation efficiency. The resulting microcapsules were evaluated in terms of moisture content, bulk density, rehydration ability, lycopene isomerization, and storage stability. The optimum operating conditions were found to be as follows: ratio of core to wall material, 1:3.3; feed temperature, 52°C; inlet air temperature, 147°C. Under these conditions, the maximum encapsulation efficiency was about 93%. The use of dehumidified air was proven to be an effective way of increasing lycopene encapsulation efficiency.     

Sensory Assessment of Microencapsulated Fish Oil Powder

The aim of the study was to investigate the influence of microencapsulation by spray drying on fish oil sensory quality. Evaluated fish oil powders were coated with modified cellulose, skim milk powder and a mixture of fish gelatin and cornstarch. Samples were stored in the presence of air and under vacuum and then sensory evaluated. It was shown that fish oil powders were very susceptible to oxidation resulting in off-flavor formation. Odor profiles of samples stored in the presence of air were unstable and showed increases in undesirable odor attributes, which were significantly correlated with peroxide value, especially in the case of samples formed by spray drying. Elimination of air from the packaging improved stability of all samples during storage in both odor profile and peroxide value. The main conclusion of this study is that microencapsulation, especially by spray drying, provokes strong changes in fish oil sensory quality. Microencapsulated fish oil powder is not stable and rapidly oxidizes in the presence of air. However, its stability may be improved when stored under vacuum.