Optimization of the Emulsifying Properties of Food Protein Hydrolysates for the Production of Fish Oil-in-Water Emulsions

Abstract

The incorporation of lipid ingredients into food matrices presents a main drawback—their susceptibility to oxidation—which is associated with the loss of nutritional properties and the generation of undesirable flavors and odors. Oil-in-water emulsions are able to stabilize and protect lipid compounds from oxidation. Driven by consumers’ demand, the search for natural emulsifiers, such as proteins, is gaining much interest in food industries. This paper evaluates the in vitro emulsifying properties of protein hydrolysates from animal (whey protein concentrate) and vegetal origin (a soy protein isolate). By means of statistical modelling and bi-objective optimization, the experimental variables, namely, the protein source, enzyme (i.e., subtilisin, trypsin), degree of hydrolysis (2–14%) and emulsion pH (2–8), were optimized to obtain their maximal in vitro emulsifying properties. This procedure concluded that the emulsion prepared from the soy protein hydrolysate (degree of hydrolysis (DH) 6.5%, trypsin) at pH 8 presented an optimal combination of emulsifying properties (i.e., the emulsifying activity index and emulsifying stability index). For validation purposes, a fish oil-in-water emulsion was prepared under optimal conditions, evaluating its physical and oxidative stability for ten days of storage. This study confirmed that the use of soy protein hydrolysate as an emulsifier stabilized the droplet size distribution and retarded lipid oxidation within the storage period, compared to the use of a non-hydrolyzed soy protein isolate.

Biofunctionality of Enzymatically Derived Peptides from Codfish (Gadus morhua) Frame: Bulk in vitro Properties, Quantitative Proteomics, and Bioinformatic Prediction

“…The observed levels for EAI and ESI are in good agreement with previous studies of FPHs, where EAI is generally reported to be in the range 25-270 m2/g and ESI in the range 22-48 min [8]. In comparison, hydrolysates from soy and whey protein have been reported to possess EAI in the range 2-12 m2/g and ESI in the range 10-40 min [47]. Consequently, FPHs possess much higher emulsifying activity without any cost in emulsion stability.…”

“…This covers inclusion of aromatic AAs such as Tyr, Trp and Phe [47,68,69], hydrophobic AAs including Val, Leu and Ala [47,[68][69][70][71] sulphur-containing AAs, i.e. Met and Cys [47,68,69], acidic AAs, i.e. Glu and Asp [70,72], alkaline AAs, i.e.…”

“…Glu and Asp [70,72], alkaline AAs, i.e. His, Lys and Arg [47,69,73,74], as well as Pro [8], which all may dramatically influence the antioxidative activity of peptides. Furthermore, high content of N-terminal Leu, Ala and Val has also been reported to positively affect antioxidant activity [8,75].…”

Novel Pickering High Internal Phase Emulsion Stabilized by Food Waste-Hen Egg Chalaza

“…New strategies have also been employed to generate novel Pickering emulsions. Okara dietary fiber particulate obtained via Maillard reaction and protein Hydrolysates showed great efficiency in building the split-new emulsion systems [35,36]. Moreover, the HIPEs stabilized by these particles have also been declared to be a promising template for the constructing of biocompatible scaffold for 3D cell culture.…”

Introduction to the Special Issue: “Advance in Recovery and Application of Bioactive Compounds from Seafood”

“…This approach requires emulsifiers with good emulsifying properties for preparing emulsions with high physical and oxidative stability. Padial-Dominguez and co-workers optimized the enzymatic hydrolysis conditions used for the preparation of hydrolysates of whey protein and soy protein with optimal emulsifying properties [ 3 ]. They also investigated the physical and oxidative stability of fish oil-in-water emulsions prepared with soy protein hydrolysates.…”