Design of high solids emulsions for dehydration and carotenoids stabilisation

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Lim, Aaron Soon Liang
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University College Cork
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The application of layered interface in emulsion can improve microencapsulation, protection, and delivery of oil-soluble bioactives in food materials. The present study investigated (i) flocculation in high total solids layer-by-layer (LBL) emulsion and deflocculation at various pH conditions, and whey protein isolate (WPI) concentration and total solids content effects on LBL emulsions stability; (ii) stability and loss kinetics of carotenoids in freeze-dried single-layer (SL) and LBL emulsions with trehalose as wall material; (iii) spray drying of high total solids SL and LBL emulsions with trehalose-low DE maltodextrin (9-12), carbohydrate (trehalose) and non-carbohydrate (WPI), or trehalose-high DE maltodextrin (23-27) as wall materials; and (iv) ability of the SL and LBL spray dried structures to protect encapsulated lutein and all-trans-β-carotene upon storage in the vicinity of the glass transition temperature (Tg). LBL interfacial formation was confirmed by charge reversal in ζ-potential. Depletion flocculation occurred in LBL systems but deflocculation was possible in systems with sufficient primary layer. Coalescence was observed in systems with insufficient primary layer. Systems with higher amount of primary layer and total solids contents exhibited the highest stability against creaming. High total solids (45-50%) SL and LBL emulsions were successfully spray dried to give free flowing powders with differences in critical powder characteristics. Carotenoids degradation followed first order kinetics and increased with storage temperature but was less rapid in dehydrated LBL emulsions. Two-step degradation kinetics displaying rapid initial decrease followed by a second slower degradation was observed in spray dried systems. There was non-Arrhenian increase in carotenoids degradation with increasing storage temperature during the rapid initial degradation in spray dried emulsions and in freeze-dried emulsions. Carotenoids retention was higher in LBL systems upon long term storage. LBL interfacial structuring is applicable in formulated materials to control the stability of oil-soluble bioactives in the food and pharmaceutical industries.
Lutein , β-carotene , Spray drying , Freeze-drying , Layer-by-layer , O/W emulsion , High solids
Lim, A. S. L. 2017. Design of high solids emulsions for dehydration and carotenoids stabilisation. PhD Thesis, University College Cork.
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