![]() Gelled DEs would allow widening the application of betalains as antioxidants and natural food colorants in food matrices where solid-like properties are desirable. However, the encapsulation of betalains in DEs, mostly from reed beet, is scarce and, to the best of our knowledge, gelled DEs have not been evaluated as encapsulation strategy. ![]() Among the different encapsulation technologies used for betalains encapsulation, spray-drying is one of the most commonly used. Encapsulation technology could be a useful strategy to prevent betalains degradation in food matrices (Khan, 2016). The stability of betalains is an important aspect to consider for using these bioactive compounds in foods, since they are affected by pH, concentration of buffer, water activity, light, oxygen, temperature and enzymatic activities. Furthermore, betalains have been associated with several beneficial effects on human health, such as protection against oxidative stress-related and cardiovascular diseases. In this context, the purple cactus pear (Opuntia ficus-indica) is an interesting alternative as a source of betalains, where betanin is the main colourant compound, and indicaxanthin and isobetanin have been detected at a low level. However, red beet has an earth-like flavour attributed to geosmin and 3- sec-butyl-2 methoxypyrazine, and besides it has high nitrate levels. Although several betalains sources have been described (amaranth, djulis, some cactaceas such as cactus pear, pitayas, pitahayas, red beet ( Beta vulgaris L.) is the main source of commercial betalains, which is classified as additive E-162 (EU) and 73.40 (FDA, USA). īetalains are natural water-soluble pigments composed of two structural groups: betacyanins (reddish-purple) and betaxanthins (orange–yellow). Transglutaminase covalently binds different protein residues, leading to the formation of relatively thermostable gels. In this context, the incorporation of microbial transglutaminase and gelatin into W 2 led to the formation of thermostable cold-set double emulsion gels. Cold-set gelation is an attractive alternative for gelling DEs when heat-labile bioactive compounds are encapsulated. Different compounds such as pectin, alginate, gellan gum, glycyrrhizic acid nanofibrils have been incorporated into the external aqueous phase of DE to form double emulsion gels. However, the gelation of the external aqueous phase, embedding the emulsion droplets in a continuous hydrogel matrix, is the most promising strategy to also provide a fat analog with solid-like properties. Gelling of the internal or external aqueous phase, together with the structuring of the oil phase are among the different strategies attempted for stabilizing DEs. However, DEs do not provide solid-like texture unless oil droplets are closely packed. Furthermore, plastic properties are desirable for DEs when they are used for replacing animal fat in food products, which is highly saturated and solid at room temperature, to mimic adipose tissue in its physical properties. ![]() ![]() Īlthough DEs offer several advantages over simple oil-in-water emulsions, mainly the encapsulation, protection and release of both water-soluble and lipid-soluble compounds, as well as the reduction of the overall fat content of oil-in-water emulsions by loading the oil phase with water droplets, they also show higher instability. Furthermore, DEs have been proposed as a strategy for masking unpleasant flavors, developing reduced-fat and/or salt products and, by suitable formulation of the oil phase, improving the lipid profile. In recent years, there has been a growing interest in the incorporation of DEs in food applications, since they can be used as encapsulation and delivery systems for both hydrophilic and hydrophobic bioactive compounds due to their multi-compartmentalized structure. Water-in-oil-in-water (W 1/O/W 2) double emulsions (DEs) are multi-compartmentalized systems in which droplets of a water-in-oil (W 1/O) emulsion are dispersed within an outer continuous aqueous phase (W 2).
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