Journal of the Science of Food and Agriculture
J Sci Food Agric 86:2038–2045 (2006)
Review Recent trends in the lipid-based nanoencapsulation of antioxidants and their role in foods M Reza Mozafari,1∗ John Flanagan,1 Lara Matia-Merino,2 Ajay Awati,1 Abdelwahab Omri,3 Zacharias E Suntres4 and Harjinder Singh1 1 Riddet
Centre, Private Bag 11-222, Massey University, Palmerston North, New Zealand of Food, Nutrition and Human Health, Massey University, Private Bag 11-222, Palmerston North, New Zealand 3 The Novel Drug and Vaccine Delivery Systems Facility, Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada 4 Medical Sciences Division, Northern Ontario School of Medicine, Lakehead University, Thunder Bay, Ontario, P7B 5E1, Canada 2 Institute
Abstract: Antioxidants may be utilised for two main purposes, to protect the sensory and nutritive quality of the food and/or to protect the body against chronic and age-related diseases. Generally, antioxidants are subject to process degradation and, when given to the body in their free form, cannot pass cell membranes and are rapidly cleared from the general circulation. Because of their unique properties, lipid-based nanoencapsulation systems enhance the performance of antioxidants by improving their solubility and bioavailability, in vitro and in vivo stability, and preventing their unwanted interactions with other food components. This paper reviews nanoliposomes, archaeosomes and nanocochleates with respect to their potential applications as antioxidant carriers in foods. 2006 Society of Chemical Industry
Keywords: antioxidants; archaeosome; nanocochleate; nanoencapsulation; nanoliposome
INTRODUCTION Oxidation reactions are the main deterioration processes of fats, oils and lipid-based foods which result in decreased nutritional value and sensory quality.1 It has also been suggested that the oxidation of biomolecules is involved in several chronic and age-related disorders, including cancer, cardiovascular disease, cataract, diabetes mellitus and rheumatoid arthritis.2 – 6 A method of protection against oxidation is employment of compounds that possess antioxidant properties. Antioxidants such as vitamin E (tocopherols), vitamin C (ascorbic acid), carotenoids and phenolic compounds are introduced into the human body in the form of food components. Moreover, they are often added to food products to protect the sensory and nutritive quality of the food itself.1 Antioxidants may be separated into different classes based on their mechanisms of action, and examples of some of the naturally occurring antioxidants in foods are depicted in Table 1. Before being accepted for incorporation into food products, antioxidants must satisfy several requirements. They should maintain their activity and protect the finished product even on long-term
storage; they should not impart a foreign colour, odour or flavour to the food; they should be stable to heat processing; they should be easy to incorporate and be effective at low concentrations.1 On the other hand, most antioxidants intended to protect the body from oxidative stress are effective in vitro when applied at relatively high concentrations, while they provide only modest benefit to animals and humans. This has been attributed mostly to the inability of antioxidants to cross cell membranes and/or to their rapid clearance from cells. In addition, exposure of animals to antioxidant enzymes (e.g. superoxide dismutase and catalase) has resulted in immunogenicity and antigenicity problems. It must be noted that recent research has shown that the links between antioxidant activities of bioactives in vitro and their effects in vivo are extremely complex owing to unresolved issues of absorption, bioavailability and metabolite formation in blood and other tissues.7,8 For example, it has recently been shown that 15 different anthocyanin glycosides from berry fruits are absorbed and excreted unmetabolised by both humans and rats.9 Consequently, it is necessary to employ strategies to enhance the delivery and retention of antioxidants in cells and tissues. A possible approach to meet
∗ Correspondence to: M Reza Mozafari, Riddet Centre, Private Bag 11-222, Massey University, Palmerston North, New Zealand E-mail:
[email protected] (Received 3 August 2005; revised version received 6 December 2005; accepted 8 May 2006) Published online 24 July 2006; DOI: 10.1002/jsfa.2576
2006 Society of Chemical Industry. J Sci Food Agric 0022–5142/2006/$30.00
Lipid-based nanoencapsulation of antioxidants Table 1. Mechanisms of antioxidant activity (adapted from Ref. 1 with permission)
Antioxidant class
Mechanism of antioxidant activity
Examples of antioxidants
Proper antioxidants Hydroperoxide stabilisers
Inactivating lipid free radicals Preventing decomposition of hydroperoxides into free radicals Promoting activity of proper antioxidants Binding heavy metals into inactive compounds Transforming singlet oxygen into triplet oxygen Reducing hydroperoxides in a non-radical way
Phenolic compounds Phenolic compounds
Synergists Metal chelators Singlet oxygen quenchers Substances reducing hydroperoxides
all these criteria is the application of encapsulation technologies.10 While previous encapsulation methods employed to protect antioxidants in foods have proven successful, the encapsulation of antioxidants for delivery to the human body to help to combat disease is in the early stages of development. As with the delivery of drugs, the delivery of any bioactive to various sites within the body is directly affected by particle size,11,12 and thus nanoencapsulation has the potential to enhance bioavailability, improve controlled release and enable precision targeting of the bioactive compounds to a greater extent than microencapsulation-type delivery systems. In accordance with this, the focus of the present review will be exclusively on nanoencapsulation systems. Nanoencapsulation involves the incorporation of bioactive materials, including food ingredients, vitamins, antioxidants, enzymes and slimming agents, in small capsules with submicron diameters. One possible nanoencapsulation approach is the utilisation of lipid-based formulations. Studies have shown that the encapsulation of antioxidants and other bioactive agents in lipid-based carrier systems improves their therapeutic potential by facilitating intracellular delivery and prolonging their retention time inside the cell.13 – 17 Lipid-based nanostructures that have been developed for drug delivery applications include lipid nanotubes,18 lipid nanospheres,19 – 22 lipid nanoparticles23,24 and lipid emulsions25 – 27 (for a review see Ref. 12). Their exploitation in food technology is yet to be explored. This paper provides an overview of food and biological oxidation, current antioxidant strategies and potential applications of the most promising lipidbased carriers, namely nanoliposomes, nanocochleates and archaeosomes, in antioxidant encapsulation.
FOOD OXIDATION Oxidative degradation is most damaging in lipid-based foods, especially those containing polyunsaturated fats. Lipid oxidation leads to the development of rancidity, off-flavour compounds, polymerisation, reversion and other reactions causing reduction of shelf life, nutritive value and sensory quality of the food product. This oxidation process is a major cause J Sci Food Agric 86:2038–2045 (2006) DOI: 10.1002/jsfa
Citric acid, ascorbic acid Phosphoric acid, Maillard compounds, citric acid Carotenes Proteins, amino acids
of deterioration of fats and edible oils,28 legumes and cereal grain-based products,29 beef, lamb and poultry meats,30 numerous food emulsions such as mayonnaise,31 butter and dairy spreads,32 as well as fresh and spray-dried eggs.33 Fats, oils and lipidbased foods deteriorate through several degradation reactions both on heating34 and on long-term storage.35 Triglycerides are the components that are of most significance as potential sources of oxidative off-flavours in these foods. The phospholipids present in plant or animal tissues used as foods may also be an important substrate for oxidative deterioration. The spontaneous reaction of atmospheric oxygen with lipids is known as autoxidation. Lipid autoxidation is one of the major concerns in food technology. It occurs autocatalytically through free radical intermediates and is generally initiated by trace metals and peroxides present as ubiquitous impurities in food systems. Several factors such as UV or ionising radiation are known to bring about initiation. When light and a sensitiser such as chlorophyll are present, activation of oxygen to singlet oxygen may play a role in the initiation of oxidative deterioration. Alternatively, metals such as iron or copper, or the enzyme lipoxygenase, may play a role in the process by which oxidative deterioration is initiated. Lipoxygenase is present in plant tissues, including those of tomato, pea and soybean. The enzyme may cause oxidative deterioration of lipids during isolation of oils from oilseeds, but it also plays a role in the formation of positive flavours in vegetables during mastication.36,37 Retardation of these oxidation processes is important for the food producer and for all involved in the entire food chain from factory to consumer. Oxidation may be inhibited during processing and storage by prevention of contact with oxygen, use of lower temperatures and use of appropriate packaging.38 Another method of protection against oxidation is to use specific additives which inhibit oxidation. These were referred to as oxidation inhibitors, but nowadays are mostly called antioxidants. While lipid oxidation in foods has been of major concern to food scientists from an early stage, it is now becoming increasingly apparent that antioxidants present in foods may also play a role in the control of several chronic and age-related disorders.5,6 2039
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Thus consideration of the biological mechanisms of oxidation in the human body should be of paramount importance if we wish to control levels of oxidation in vivo and, in turn, reduce the risk of lipid oxidationinduced diseases.
BIOLOGICAL ASPECTS OF OXIDATION PROCESSES Free radicals are atoms or molecules that have one or more unpaired electron(s). They are unstable and try to fill their electron vacancies. The oxygen-centred radicals generated under normal aerobic metabolism are called reactive oxygen species (ROS) and are mainly produced by leucocytes and by the respiratory mitochondrial chain. Enzymatic processes such as the electron transport chain in the mitochondria, xanthine oxidase in ischaemia reperfusion and cytochrome P450-dependent activation of xenobiotics are known to play an important role in the generation of ROS.4,39 ROS are essential for certain biological processes such as cell signalling and bacterial defence. Release of ROS has been demonstrated in the respiratory burst of neutrophils and macrophages.40,41 Under normal conditions, each day around 1% of ROS escape the control of the endogenous antioxidant defences, damage the surrounding tissues and thereby contribute to aging.6 If the antioxidant defence mechanisms of the body fail, ROS can attack any biochemical component of the cell, including vital proteins, carbohydrates, lipids and DNA. Recently, it is becoming clear that ROS are involved in the pathways that convey both extracellular and intracellular signals to the nucleus under a variety of pathophysiological conditions.4,40,41 Moreover, various anticancer drugs and xenobiotics are known to exert their therapeutic and/or toxic effects via the generation of ROS.42 – 46 An elevation in the steady state concentration of ROS, including hydrogen peroxide, hydroxyl radical and superoxide anion, has been found to be responsible for oxidative stress.39,47 There is increasing evidence connecting oxidative stress with a variety of pathological disorders such as chronic inflammatory disease, post-ischaemic organ injury, diabetes mellitus, rheumatoid arthritis as well as neoplastic and cardiovascular diseases.2 – 6 ROS have also been implicated in triggering apoptosis or programmed cell death.4,40,48 Apoptotic cell death is characterised by controlled autodigestion of the cell, with the end result being the breakdown of the cell into membrane-bound fragments or apoptotic bodies, in most tissues being phagocytosed by adjacent cells. Activated neutrophils responding to inflammatory stimulation produce ROS that attack neighbouring cells, triggering apoptosis. Changes in cellular redox potentials, depletion of reduced glutathione and decreases in reducing equivalents such as NADH and NADPH in the mitochondria by oxidants are also known to cause programmed cell death.49 – 51 2040
ANTIOXIDANTS Antioxidants can be defined as substances which significantly inhibit or delay oxidation of a substrate while present in minute amounts.52,53 Endogenous antioxidant defences are both non-enzymatic and enzymatic. The main non-enzymatic antioxidants are uric acid, glutathione, bilirubin, thiols, albumin and nutritional factors, including vitamins and phenols. The major enzymatic antioxidants include catalase, superoxide dismutase and glutathione peroxidase. Under normal circumstances the endogenous antioxidant defences balance the ROS production, except for the aforementioned 1% daily leak.6 The trace elements Cu, Se, Mn and Zn are essential components of the endogenous enzymatic antioxidant defences. Nutritional antioxidants act through different mechanisms and in different compartments but are mainly free radical scavengers:6 (i) they directly neutralise free radicals; (ii) they reduce peroxide concentrations and repair oxidised membranes; (iii) they quench iron to decrease ROS production; (iv) via lipid metabolism, short-chain free fatty acids and cholesteryl esters neutralise ROS.54 While the body has its own antioxidant defence mechanisms, antioxidants added to foods also have the potential to augment these natural mechanisms. Antioxidants added to food may be defined as any substance capable of delaying, retarding or preventing the development of rancidity or other flavour deterioration due to oxidation.37 The most widely used synthetic and natural antioxidants in food have often been reviewed and compared.55 – 57 Food antioxidants are generally divided into two groups: (i) acids (and their salts and esters) such as citric and ascorbic acid used to prevent oxidative discolouration in fruit, meat and other foods; (ii) phenolic compounds (synthetic and natural) such as butylated hydroxyanisole (BHA) and tocopherols employed to prevent oxidation of fats and lipids of foods. Antioxidants can inhibit or retard oxidation either by scavenging free radicals, in which case the compound is described as a primary antioxidant, or by a mechanism that does not involve direct scavenging of free radicals, in which case the compound is a secondary antioxidant. Primary antioxidants include phenolic compounds such as vitamin E (αtocopherol). Secondary antioxidants operate by a variety of mechanisms, including binding metal ions, scavenging oxygen, converting hydroperoxides to nonradical species, absorbing UV radiation or deactivating singlet oxygen. Normally, secondary antioxidants only show antioxidant activity when a second minor component is present. This can be seen in the case of sequestering agents such as citric acid, which are effective only in the presence of metal ions, and reducing agents such as ascorbic acid, which are effective in the presence of tocopherols or other primary antioxidants.37 J Sci Food Agric 86:2038–2045 (2006) DOI: 10.1002/jsfa
Lipid-based nanoencapsulation of antioxidants
LIPID-BASED NANOENCAPSULATION STRATEGIES The protection of micronutrients from oxidative degradation has been studied extensively with regard to microencapsulation systems.58 However, to give targeted controlled release is a key functionality that can be provided much more efficiently by employing nanoencapsulation technologies. As a consequence of improved stability and targeting, the amount of material required to exert a specific effect when encapsulated is much less than the amount required when unencapsulated. This is particularly useful when dealing with expensive bioactive agents. A timely and targeted release improves the effectiveness of micronutrients, broadens the application range of food ingredients and ensures optimal dosage, thereby improving cost-effectiveness of the product. Reactive or sensitive micronutrients such as antioxidants can be turned into stable ingredients through encapsulation by nanocarrier systems. Lipid-based nanoencapsulation systems are among the most promising encapsulation technologies employed in the rapidly developing field of nanotechnology. Compared with other encapsulation strategies such as chitosan- and alginate-based carriers,59 – 61 lipid-based nanoencapsulation systems have unparalleled advantages, including the ability to entrap material with different solubilities, the possibility of being produced using natural ingredients on an industrial scale, and targetability.62 – 65 Lipid-based carriers can shield an ingredient from free radicals, metal ions, pH and enzymes that might otherwise result in degradation of the food ingredient. They impart stability to water-soluble material, particularly in highwater-activity applications.58 They can accommodate not only water-soluble material but also lipid-soluble agents, if required, simultaneously, providing a synergistic effect.66 Another unique property of lipid-based nanocarriers is the targeted delivery of their content to specific areas within the food matrix. In addition, lipidbased nanocarriers may be targeted to the required site inside the body via active (e.g. by incorporation of antibodies) and passive (e.g. targeting based on particle size) mechanisms.65 The main lipid-based nanoencapsulation systems that can be used for the protection and delivery of foods and nutraceuticals in general and antioxidants in particular are explained below. Nanoliposomes The word liposome derives from two Greek words, lipos (fat) and soma (body or structure), meaning a structure in which a fatty envelope encapsulates aqueous core(s) or compartment(s). A recent definition, proposed at a conference in the field of liposomology, describes liposomes as ‘closed, continuous bilayered structures made mainly of lipid and/or phospholipid molecules’.67 They are under intensive investigation and development by the pharmaceutical, cosmetic and food industries as micro- and nanocarrier systems J Sci Food Agric 86:2038–2045 (2006) DOI: 10.1002/jsfa
for the protection and delivery of bioactive agents. Recent studies suggest that liposomes are even naturally present in the very first food we take, breast milk.68,69 Liposomes are composed of one or more lipid and/or phospholipid bilayers and can contain other molecules such as proteins or polymers in their structure. A liposome composed of a number of concentric bilayers is known as a multilamellar vesicle (MLV), while one composed of many small non-concentric vesicles encapsulated within a single lipid bilayer is known as a multivesicular vesicle (MVV). Another type of liposome is known as a unilamellar vesicle (ULV), which contains a single lipidic bilayer (Fig. 1). Owing to the possession of both lipid and aqueous phases, liposomes can be utilised in the entrapment, delivery and release of both water-soluble and lipid-soluble material. The term nanoliposome has recently been introduced to exclusively refer to nanoscale lipid vesicles,65 since liposome is a general word encompassing many classes of lipid vesicles whose diameter range from tens of nanometres to several micrometres. Nanoliposomes possess the same physical, structural and thermodynamic properties as the liposomes described previously. Manufacture of both liposomes and nanoliposomes requires input of energy to a dispersion of lipid/phospholipid molecules in an aqueous medium.65,70 The underlying mechanism for the formation of liposomes and nanoliposomes is basically the hydrophilic–hydrophobic interaction between phospholipids and water molecules. Owing to the fact that liposomes are dynamic entities that tend to aggregate and/or fuse and as a result increase in size, vesicles prepared in nanometric size ranges may end up becoming micrometric particles upon storage. Nevertheless, nanoliposomes should have adequate stability to retain their sizes and could be defined as ‘bilayer lipid vesicles possessing and maintaining nanometric size ranges during storage and application’.65 The unique properties of liposomes have triggered numerous applications in different fields of science and technology, from basic studies of membrane structure/function to bioactive agent delivery. In
Figure 1. Schematic representation of a multilamellar vesicle (MLV), a multivesicular vesicle (MVV) and a unilamellar vesicle (ULV). The shaded areas are the lipidic phases of the liposomes, while the enclosed white areas are their aqueous phases. Compared with ULVs, MLVs and MVVs have higher lipid phase/aqueous phase ratios. Therefore, for entrapment of lipid-soluble material, MLVs and MVVs are more suitable, while ULVs have more capacity for encapsulation of water-soluble material.
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agriculture they can be used to improve the efficacy of different biocides and to deliver some essential nutrients.71,72 An example of liposome application in food is the entrapment of proteolytic enzymes in cheese production.73 – 75 Application of liposomal enzymes can produce a cheese with good texture and flavour in half the normal time, with the overall enzyme requirement reduced 100-fold.10,76,77 With respect to treating oxidant-induced tissue injuries, it has been demonstrated that liposome encapsulation of antioxidants promotes their therapeutic potential, probably by facilitating intracellular uptake and extending the half-lives of the encapsulated antioxidants.78 – 80 Liposomes and nanoliposomes have been employed for encapsulation and delivery of the antioxidant glutathione (GSH) in vivo, since these carriers offer a method of protecting GSH and prolonging its levels in the body.45,81 A significant advantage of liposomes and nanoliposomes is that they can incorporate and release two materials with different solubilities simultaneously. Lipid vesicles containing two bioactive agents are known as bifunctional liposomes.66 One example is the incorporation of two antioxidant agents, namely α-tocopherol (a lipid-soluble molecule) and glutathione (a water-soluble molecule), in the same lipid vesicle.66,82 Another bifunctional liposome antioxidant system containing ascorbic acid and α-tocopherol has been reported.10 α-Tocopherol reacts with peroxy radicals in the continuous phase of the food to form α-tocopheroxyl radicals, which are less effective than peroxy radicals in oxidation chain reaction initiation.83 The α-tocopheroxyl radical can be reduced to α-tocopherol by ascorbic acid, hence extending the antioxidant effect of the α-tocopherol. However, α-tocopherol is hydrophobic and therefore cannot interact with the water-soluble ascorbic acid. It is possible to use lipid-soluble derivatives of ascorbic acid, but effective dispersion requires high temperatures, increasing the likelihood of oxidation problems in the food system. Lipid-based nanoencapsulation systems can incorporate and deliver both vitamin E and ascorbic acid to a site of oxidation, hence providing a synergistic effect. It has been reported that liposome-entrapped α-tocopherol is more effective at preventing oxidation in oil-in-water emulsions than when it is in the free form and dissolved in the oil.84 Since oxidation occurs first at the water/oil interface, if the liposome is situated at this interface, the α-tocopherol in the membrane could reduce the peroxy radicals before the radicals initiate oxidation. Ascorbic acid entrapped in the aqueous regions of the liposome could regenerate the α-tocopherol. Liposome entrapment of the ascorbic acid would minimise the degradation of the ascorbic acid by other food components and ensure maximum α-tocopherol regeneration.10 In addition to antioxidant delivery, liposomes have also been used extensively as artificial membrane systems to examine and compare the antioxidant 2042
properties of several agents.85 – 87 The use of liposomal membranes for the examination of antioxidant properties of several compounds against an oxidant insult appears to be advantageous over the use of endogenous membrane systems such as microsomes and mitochondria. Endogenous biological membranes contain antioxidants that may influence the outcome of the experiment. For example, the presence of αtocopherol in microsomal membranes enhances the antioxidant effect of certain antioxidants such as ascorbic acid or GSH because of the ability of these antioxidants to regenerate the oxidised α-tocopherol.88 Also, microsomes contain metabolising enzymes that may modulate the antioxidant actions of compounds by either activating or detoxifying them. The composition of liposomal membranes can be fully controlled and may be used to simulate the lipid composition of individual cellular membranes that often exhibit distinct lipid composition. For instance, the neuronal membranes are rich in sphingomyelin, while the liver mitochondrial membranes contain phosphatidylcholine, lysophosphatidylcholine, diacylglycerol and phosphatidylethanolamine.89,90 Liposomes have been used to evaluate the antioxidative activities of vegetable extracts,91 to assess the total antioxidant activity of fruits and vegetables arising from both lipid-soluble and water-soluble agents92 and to comparatively study some commonly used antioxidants (BHA, BHT, TBHQ, α-tocopherol and caffeic acid).57 The results of such studies add to our knowledge of the structure–activity relationships of antioxidants and may have a practical outcome regarding the optimal levels of use of the examined compounds. Archaeosomes Archaeosomes are liposomes made from one or more of the polar ether lipids extracted from the domain Archaea (Archaeobacteria). Many Archaea live in environments including high salt concentrations, low pH values or high temperatures. Hence their membrane lipids are unique and enable them to survive in such hostile conditions. Compared with liposomes (which are made from ester phospholipids), archaeosomes are relatively more thermostable and more resistant to oxidation and chemical and enzymatic hydrolysis. They are also more resistant to low pH and bile salts that would be encountered in the gastrointestinal tract.93 Archaeosomes prepared from the total polar lipid extract or from individual purified polar lipids show great promise as an oral delivery system for bioactive agents. Considering that some liposome formulations have been found to retain their structural integrity with high encapsulation efficiency after treatments at sterilisation temperatures,65,70,94 the fact that archaeosomes are even more thermostable makes them ideal candidates to protect antioxidants during food processing. J Sci Food Agric 86:2038–2045 (2006) DOI: 10.1002/jsfa
Lipid-based nanoencapsulation of antioxidants
As is the case with liposomes, it is possible to incorporate ligands such as polymers into archaeosomes to increase the blood circulation time of these lipid-based carriers. It has been shown that incorporation of poly(ethylene glycol) and coenzyme Q10 into archaeosomes can alter the tissue distribution profiles of intravenously administered vesicles.95 Omri et al.96 have recently reported that intravenous and oral delivery of nanometric-sized archaeosomes to an animal model was well tolerated with no apparent toxicity. The results of these studies are very promising for the utilisation of archaeosomes in the encapsulation and delivery of antioxidants. Nanocochleates Nanocochleates are well-defined, small-sized, stable lipid-based carriers comprising mainly a negatively charged lipid (e.g. phosphatidylserine) and a divalent cation (e.g. calcium).97,98 They have a cigar-shaped multilayered structure consisting of a continuous, solid, lipid bilayer sheet rolled up in a spiral fashion with little or no internal aqueous space. Hydrophobic, amphiphilic, negatively or positively charged molecules can be delivered by nanocochleates. Cochleates and nanocochleates have been used to deliver proteins, peptides and DNA for vaccine and gene therapy applications.99,100 Owing to their stability and nanometric size, nanocochleates have revealed great potential to deliver bioactive agents both orally and parenterally. In addition, they are resistant to degradation in the gastrointestinal tract.97 – 100 Nanocochleates containing AmB are now in development to enter Phase I clinical trials for both the oral and parenteral treatment of fungal infections.98 The unique structure and properties of nanocochleates make them ideal candidates for oral and systemic delivery of antioxidants and other sensitive moieties. An important parameter in the utilisation of the above-mentioned lipid-based carriers in the area of food in general is their preparation procedure. The manufacturing methods of these carriers generally involve utilisation of non-food-grade solvents and detergents for solubilisation or dissolution of the lipid ingredients. These chemicals not only affect the structure and stability of the entrapped substance but will also remain in the final encapsulation formulation, thus contributing to toxicity and influencing the stability of the carrier system. Another issue in lipidbased encapsulation for the food industry is the scaling up of the preparation method at acceptable levels and costs. These problems can be addressed by employing a new preparation method developed in our laboratory, known as the heating method, a detailed description of which is given elsewhere.65,101,102
CONCLUDING REMARKS The control of lipid oxidation of foods, primarily for extending shelf life, has been extensively studied J Sci Food Agric 86:2038–2045 (2006) DOI: 10.1002/jsfa
over many years. Many of these studies involved encapsulation to protect the antioxidants from degradation throughout the processing and storage stages. It is now becoming increasingly apparent that antioxidants present in foods may also play a role in the control of several chronic and age-related disorders. Thus the design of encapsulation systems that can not only protect foods from oxidation but also play a role in the control of disease is required. Nanoencapsulation systems such as nanoliposomes, archaeosomes and nanocochleates are especially relevant for oral delivery of antioxidants owing to their stability in the gastrointestinal tract. The potential of these lipidbased nanoencapsulation systems is yet to be explored in the utilisation of the protective effect of antioxidants both in food products and in the body.
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