FCT/MCTES for financial support to CIMO (UIDB/00690/2020). National funding by FCTFoundation
for Science and Technology, through the institutional scientific employment programcontract
of A. Fernandes, I. Fernandes, and L. Barros. Valor Natural project (Project Norte-01-0247-
FEDER-024479).
The use of natural colorants is needed to overcome consumer concerns regarding synthetic
food colorants0 safety. However, natural pigments have, in general, poor stability against environmental
stresses such as temperature, ionic strength, moisture, light, and pH, among others. In this
work, water-in-oil-in-water (W1/O/W2) emulsions were used as protective carriers to improve color
stability of a hydrophilic Sambucus nigra L. extract against pH changes. The chemical system comprised
water and corn oil as the aqueous and oil phases, respectively, and polyglycerol polyricinoleate
(PGPR), Tween 80, and gum Arabic as stabilizers. The primary emulsion was prepared using aW1/O
ratio of 40/60 (v/v). For the secondary emulsion,W1/O/W2, different (W1/O)/W2 ratios were tested
with the 50/50 (v/v) formulation presenting the best stability, being selected as the coloring system
to test in food matrices of different pH: natural yogurt (pH 4.65), rice drink (pH 6.01), cow milk
(pH 6.47), and soy drink (pH 7.92). Compared to the direct use of the extract, the double emulsion
solution gave rise to higher color stability with pH change and storage time, as corroborated by visual
and statistical analysis.
