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Margarine‐Like Emulsions Prepared with Coconut and Palm Oils: Analysis of Microstructure and Freeze–Thaw Stability by Differential Scanning Calorimetry
Author(s) -
Bertoia Luz,
Wagner Jorge R.,
Márquez Andrés L.
Publication year - 2020
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1002/aocs.12399
Subject(s) - differential scanning calorimetry , emulsion , exothermic reaction , materials science , aqueous solution , microstructure , aqueous two phase system , crystallization , chemical engineering , phase (matter) , enthalpy , palm oil , chromatography , chemistry , composite material , organic chemistry , food science , thermodynamics , physics , engineering
Abstract The objective was to study the microstructure and freeze–thaw stability of margarine‐like emulsions formulated with vegetable fats using differential scanning calorimetry. Emulsions were prepared with 20% w/w dispersed aqueous phase and a continuous lipid phase composed by coconut oil (CO) and/or palm oil (PO) plus polyglycerol polyricinoleate (PGPR) as emulsifier. Mean temperature ( T M ) and crystallization enthalpy (Δ H c ) were obtained from the exothermic peaks corresponding to freezing of aqueous phase. Successive cooling–heating–cooling cycles were applied to analyze changes in the exothermic peak. The emulsion prepared with CO (without PO) and 1% w/w PGPR in lipid phase showed higher water droplets size ( T M = −44.8 ± 0.1 °C) and lower quantity of stabilized aqueous phase (Δ H c = 28.9 ± 1.2 J g −1 ) prior to application of temperature cycles, while coalescence and (presumably) water transfer processes occurred during the treatment. The use of 2% w/w PGPR was sufficient to accomplish full stabilization of aqueous phase ( T M = −45.9 ± 0.1 °C; Δ H c = 42.6 ± 0.3 J g −1 ) before and after the freeze–thaw treatment. The total or partial (50%) substitution of CO by PO in emulsions with 1% w/w PGPR also improved the stability of the system, exhibiting slight microstructural changes. This enhanced stability would be linked to reduced water droplets size because of more rapid crystallization of lipid phase and immobilization of aqueous phase after emulsion preparation. In conclusion, it is possible to obtain margarine‐like emulsions prepared with CO and/or PO using relatively low emulsifier concentration and maintaining a desired microstructure after freeze‐thawing if the percentage ratio of both fats is controlled.