Enhanced Oxidative Stability and Bioaccessibility of Sour Cherry Kernel Byproducts Encapsulated by Complex Coacervates with Different Wall Matrixes by Spray- and Freeze-Drying

Abstract

Sour cherry (Prunus cerasus L.) seeds are obtained as byproducts of the processing of sour cherries into processed foods. Sour cherry kernel oil (SCKO) contains n-3 PUFAs, which may provide an alternative to marine food products. In this study, SCKO was encapsulated by complex coacervates, and the characterization and in vitro bioaccessibility of encapsulated SCKO were investigated. Complex coacervates were prepared by whey protein concentrate (WPC) in combination with two different wall materials, maltodextrin (MD) and trehalose (TH). Gum Arabic (GA) was added to the final coacervate formulations to maintain droplet stability in the liquid phase. The oxidative stability of encapsulated SCKO was improved by drying on complex coacervate dispersions via freeze-drying and spray-drying. The optimum encapsulation efficiency (EE) was obtained for the sample 1% SCKO encapsulated with 3:1 MD/WPC ratio, followed by the 3:1 TH/WPC mixture containing 2% oil, while the sample with 4:1 TH/WPC containing 2% oil had the lowest EE. In comparison with freeze-dried coacervates containing 1% SCKO, spray-dried ones demonstrated higher EE and improved oxidative stability. It was also shown that TH could be a good alternative to MD when preparing complex coacervates with polysaccharide/protein networks.

Figure 1

Schematic representation of the experimental section. Components of coacervates (a, b); Encapsulated bioactive compound, SCKO (b); Blank and SCKO loaded coacervates (d), Drying of coacervate dispersion with SCKO by using spray-drying and freeze-drying (e); In vitro bioaccessibility of SCKO in spray-dried and freeze-dried coacervate dispersions.

Figure 2

Effect of the wall material concentration and the amount of SCKO in encapsulation formulation on the EE (%) of coacervates.

Figure 3

Effect of the drying method (freeze-drying vs spay drying) on oxidative stability of SCKO in different coacervate formulation during at 15 days storage period. A, B changes on the peroxide value, (A) freeze-dried coacervate dispersions; (B) spray-dried coacervate dispersions. C, D changes on the TBRAS value, (C) freeze-dried coacervate dispersions, (D) spray-dried coacervate dispersions. *The formulation of each sample is given in Table 1.

Figure 4

In vitro bioaccessibility (%) of SCKO in coacervates with different wall material composition and different ratios during at 2 h in vitro biodegradation. (A, B) Freeze-dried coacervate dispersions with different SCKO concentrations where MD and TH were used as a wall material, respectively; (C, D) spray-dried coacervate dispersions with different SCKO concentrations where MD and TH were used as a wall material, respectively.

Figure 5

SEM images of dried coacervate dispersions. A, B spray-dried coacervate dispersions, (a) the wall material of coacervates is MD; (b) the wall material of coacervates is TH. C, D freeze-dried coacervate dispersions, (c) wall material of coacervates is MD; and (d) wall material of coacervates is TH.