PROTECTION OF CAROTENOIDS BY OIL-IN-WATER EMULSION: EVALUATION OF WHEY PROTEIN ISOLATE EMULSIFIER PROPERTY

Vol1,2018 - 93749
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Abstract

Carotenoids are used as food colorant and some of them can act as precursors of vitamin A, in the prevention of cancer, heart disease and have anti-inflammatory properties. However, carotenoids are lipophilic, which hinders their dispersion/ application in hydrophilic matrices and products. Moreover, they easily oxidize, causing loss of color in foods, difficulting their storage and application in food products. An alternative to minimize these problems is the microencapsulation of oil rich in this bioactive compound. For this reason, the objective of this work was the coencapsulation of pequi and buriti oils (rich in carotenoids) by oil-in-water emulsion, followed by freeze-drying. Oil-in-water emulsions were prepared using a mixture of pequi and buriti oils (mixture containing 10%-w/w buriti oil) as oil phase and whey protein isolate solution (WPI) (4% w/v) as emulsifier and aqueous phase, in proportion of oil phase: aqueous phase (in total solids) of 1:3. The WPI was used in two ways in order to analyze its emulsifier property: with and without heat treatment, resulting in treatments HPB and PB, respectively. The emulsion HPB was done with aqueous WPI solution heated at 50 °C for 45 minutes under constant magnetic stirring. The solution was then cooled to room temperature, the pH adjusted to 5.9 and heated again at 82 °C for 45 minutes under constant magnetic stirring. The emulsions were frozen in a freezer (-18 °C) and freeze-dried (Terroni, São Carlos, Brazil). The emulsions were characterized by optical microscopy, particle size measurement and rheology. The dry particles were analyzed for accelerated oxidation by Rancimat and carotenoid retention (determined spectrophotometrically) during storage for 30 days at 37 °C. There was no morphological difference between the formulations, that is, the use of WPI with different treatments did not affect the formation of droplets. The average particle sizes were 0.88 ± 0.03 and 1.09 ± 0.09 um for HPB and PB, respectively. Regarding the rheology study, it was observed that modified WPI can be used without effect on the viscosity of the system. The particles, after freeze-drying, presented oxidative stability index (OSI) (measured in hours) of 46.10 ± 3.54 and 51.20 ± 4.38 h for HPB and PB, respectively. The mixture of non-encapsulated oils presented an OSI of 20.53 ± 0.10 h, showing that both types of emulsions protected the oils against oxidation, increasing their oxidative stability twice when compared to the non-encapsulated oils. The results obtained for carotenoid retention showed that formulation HPB promoted better protection to the carotenoids, with retention values of 31.75 ± 2.51, 50.43 ± 1.25 and 48.30 ± 1.48 % for the non-encapsulated mixture of buriti and pequi oils, HPB and PB, respectively, after 30 days of storage. So, particles of buriti and pequi oil were successfully produced by oil-in-water emulsion followed by freeze-drying and WPI can be used as carrier and emulsifier, promoting better protection to encapsulated compound when submitted to heat treatment.

Institutions
  • 1 Faculdade de Zootecnia e Engenharia de Alimentos - USP/FZEA / Universidade de São Paulo; Faculdade de Engenharia de Alimentos - FEA/ Unicamp
  • 2 Faculdade de Zootecnia e Engenharia de Alimentos (FZEA/USP)
  • 3 FZEA - USP
Keywords
Stability
Pequi
Buriti