Encapsulation and Controlled Release Technologies in Food Systems (eBook)

Jamileh M. Lakkis (Herausgeber)

eBook Download: EPUB

2016 | 2. Auflage
John Wiley & Sons (Verlag)
978-1-118-94687-9 (ISBN)

Infos

The emergence of the discipline of encapsulation and controlled release has had a great impact on the food and dietary supplements sectors; principally around fortifying food systems with nutrients and health-promoting ingredients. The successful incorporation of these actives in food formulations depends on preserving their stability and bioavailability as well as masking undesirable flavors throughout processing, shelf life and consumption.

This second edition of Encapsulation and Controlled Release Technologies in Food Systems serves as an improvement and a complement companion to the first. However, it differentiates itself in two main aspects. Firstly, it introduces the reader to novel encapsulation and controlled release technologies which have not yet been addressed by any existing book on this matter, and secondly, it offers an in-depth discussion on the impact of encapsulation and controlled release technologies on the bioavailability of health ingredients and other actives. In common with the first edition the book includes chapters written by distinguished authors and researchers in their respective areas of specialization.

This book is designed as a reference for scientists and formulators in the food, nutraceuticals and consumer products industries who are looking to formulate new or existing products using microencapsulated ingredients. It is also a post-graduate text designed to provide students with an introduction to encapsulation and controlled release along with detailed coverage of various encapsulation technologies and their adaptability to specific applications.

Dr Jamileh M. Lakkis has more than 20 years' experience in the food, dietary supplements and consumer products industries. She has been very active in promoting and implementing microencapsulation and controlled release technologies in these industries.

Textauszug

Chapter 1
Introduction

Jamileh M. Lakkis

Encapsulation and controlled-release systems are designed to protect actives from undergoing undesirable interactions while enhancing their functionality and bioavailability. Other objectives include masking the taste of bitter components, ensuring adequate administration of heat- or oxidation-labile health actives, and ensuring their delivery at a predetermined rate to a target site. In foods and nutraceuticals, encapsulation and controlled release have found applications in many categories such as confections, bakery, breakfast cereals, dairy products, beverages, packaging, among others. Markets and Markets Research estimated the value of food-related encapsulation market to reach $39.5 billion by 2020 (http://www.marketsandmarkets.com).

European Directive 3AQ19a defined controlled release as a “modification of the rate or place at which an active substance is released.” Such modification can be made using materials with specific barrier properties for manipulating the release of the active and to provide unique sensory and/or functional benefits.

The addition of small amounts of nutrients to a food system may not affect its appearance and taste significantly; however, incorporating high levels of nutrients to meet certain requirements or treat an ailment will most often result in unstable and unpalatable foods. Examples of such nutrients include fortification with calcium, vitamins, or polyunsaturated fatty acids, which often results in undesirable sensory changes such as grittiness, medicinal or oxidized taste, and others. Different types of encapsulation and controlled-release systems are currently available to help overcome these challenges and to provide a wide range of release requirements.

A wide variety of cores (encapsulants), wall-forming materials (encapsulating agents), and technologies are commercially available for manufacturing microcapsules and microparticles of different sizes, shapes, morphological properties, and costs, as well as controlling the release of the encapsulated actives.

Wall-forming materials

Materials used in microencapsulation as film coating or matrix-forming components include several categories:

1. Lipids and waxes: beeswax, candelilla and carnauba waxes, wax microemulsions and macroemulsions, glycerol distearate, and natural and modified fats
2. Proteins: gelatins, whey proteins, zein, soy proteins, caseins and caseinates, gluten, etc. All these proteins are available in both native and modified forms.
3. Carbohydrates: starches, maltodextrins, chitosan, sucrose, glucose, ethylcellulose, cellulose acetate, alginates, carrageenans, chitosan, etc.
4. Food-grade polymers: polypropylene, polyvinylacetate, polystyrene, polybutadiene, etc.

Core materials

These materials include flavors, antimicrobial agents, vitamins, minerals, antioxidants, probiotics, colors, acidulants, alkalis, buffers, sweeteners, enzymes, cross-linking agents, yeasts and chemical leavening agents, omega-3 fatty acids, and other nutrients.

Release triggers

Encapsulation and controlled-release systems can be designed to respond to one or a combination of triggers that can activate the release of the entrapped substance and to meet a desired release target or rate. Triggers can be one or a combination of the following:

1. Temperature: ideally for release of actives from fat/wax matrices, gelatin, and other meltable polymers
2. Moisture: essential for releasing actives entrapped in hydrophilic matrices
3. pH: can release actives from enteric-coated particulates or emulsions (coalescence)
4. Enzymes: can release actives from enteric-coated particulates due to disintegration of the wall material with amylases, proteases, lipases, etc.
5. Shear: chewing, physical fracture, and grinding represent physical means for release of actives during actual consumption
6. Lower critical solution temperature: release takes place at a critical temperature below which the components of a mixture are miscible for all compositions (often encountered in phase diagrams).

Payload

Payload is a term used to estimate the amount of active (core) entrapped in a given matrix or wall material (shell) and is expressed as:

Current approaches to encapsulation and controlled release

Entrapment in carbohydrate matrices

Encapsulation into a carbohydrate matrix generally involves melting a crystalline polymer using heat and/or shear to transform the molecular structure into an amorphous phase. The encapsulant is then incorporated into the meta-stable amorphous phase followed by cooling to solidify the structure and form glass, thus restricting molecular movements.

Carbohydrates are excellent candidates for this type of encapsulation due to several attributes; they (1) form an integral part of many food systems, (2) are cost-effective, (3) occur in a wide range of polymer sizes, and (4) have desirable physicochemical properties such as solubility, melting, phase change, etc.

Sucrose, maltodextrins, native and modified starches, polysaccharides, and gums have been used for encapsulating flavors, minerals, vitamins, probiotic bacteria, as well as pharmaceutical actives. The unique helical structure of the amylose molecule, for example, makes starch a very efficient vehicle for encapsulating lipids and flavors (Conde-Petit et al., 2006). Some carbohydrates such as inulin and trehalose can provide additional benefits for encapsulation applications; inulin is a prebiotic that can enhance the survival of probiotic bacteria, while trehalose serves as support nutrient for yeasts.

Two main technologies–spray-drying and extrusion–are commonly used in large-scale encapsulation applications into amorphous matrices, although different mechanisms are used. In spray-drying, the active is entrapped within the porous membranes of hollow spheres, while in extrusion, the goal is to entrap the active in a dense, impermeable glass.

Encapsulating actives via spray-drying requires emulsifying the substrate into the encapsulating agent. This is especially important for flavor applications, considering the fact that most flavors are made of components of various chemistries (e.g., polarity, hydrophobic-to-hydrophilic ratios), thus limiting their stability when dispersed or suspended in different solvents. Hydrophobicity is one of the most critical attributes that can play a significant role in determining flavors payload as well as their release in food systems.

The basic principle of spray-drying can be found in an excellent book by Masters (1979). Briefly, the process comprises atomizing a micronized (1- to 10-µm droplet size) emulsion or suspension of an active and an encapsulating substance(s) and further spraying into a chamber. Drying takes place at relatively high temperatures (210 oC inlet and 90 oC outlet), although the active's exposure to these temperatures lasts only few seconds. The process results in free flowing, low bulk density powders of 10 to 100 µm. Optimal payloads of 20% can be expected for flavors encapsulated in starch matrices. Maltodextrins and lower molecular weight sugars, due to their low viscosities and inadequate emulsifying activities, often lead to lower flavor payloads.

Several factors can impact the efficiency of encapsulation via spray-drying, –mainly, those related to the emulsion or dispersion (e.g., solid content, molecular weight, emulsion droplet size, viscosity) and to the process (e.g., feed flow rate, inlet/outlet temperatures, gas velocity). Release of flavors from spray-dried matrices takes place on reconstitution of the dried emulsion in the release medium (water or saliva). Reasonable prediction of the release behavior should take into consideration the complex chemistry of flavors and prevailing partition and phase transport mechanisms between aqueous and nonaqueous phases (Larbouss et al., 1992; Shimada et al, 1991).

Encapsulation into an amorphous matrix via extrusion has gained wide popularity in the past two decades with applications ranging from entrapping flavors for their controlled release to masking the grittiness of minerals and vitamins. Hot melt extrusion is a process with many unique advantages for encapsulation applications, namely:

1. Extruders are multifunctional systems (many unit operations) that can be manipulated to provide desired processing temperature and shear rate profiles by varying screw design, barrel heating, mixing speed, feed rate, moisture content, plasticizers, etc.
2. There is the possibility of incorporating actives and other ingredients at different points of the extrusion process. Heat-labile actives, for example, can be incorporated via temperature-controlled inlets toward the end of the barrel, and their residence time in the extruder can be minimized to avoid degradation of the active and preserve its integrity.
3. Extruders are also formers; encapsulated products can be recovered in practically any desired shape or size (pellets, rods, ropes, etc.).
4. Only a very limited amount of water is needed to transform carbohydrates from native crystalline to amorphous glassy matrices in an extruder, thus limiting the need for expensive downstream drying.
5. High payload can exceed 30% when encapsulating solid actives in extruded pellets.
6. Favorable economics due to the high throughput, continuous mode, and limited need for drying make extrusion a very attractive process for manufacturing encapsulated...

Produkt-Details

• Erscheint lt. Verlag: 9.3.2016
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Biologie
• Themenwelt: Technik ► Lebensmitteltechnologie
• Themenwelt: Weitere Fachgebiete ► Land- / Forstwirtschaft / Fischerei
• Schlagworte: Active packaging • Chemie • Chemistry • Controlled Release • Delayed release • Delivery systems • encapsulation • extended release • food engineering • Food Science & Technology • Foods, Nutrients Bioavailability • Functional Food • Functional Food, Nutraceuticals • Functional Foods & Nutraceuticals • Lebensmittelforschung u. -technologie • Lebensmitteltechnik • microcapsules • Pharmaceutical & Medicinal Chemistry • Pharmazeutische u. Medizinische Chemie • sustained release
• ISBN-10: 1-118-94687-1 / 1118946871
• ISBN-13: 978-1-118-94687-9 / 9781118946879