Evaluation of the Physical and Oxidative Stabilities of Fish Oil-in-Water-in-Olive Oil Double Emulsions (O1/W/O2) Stabilized with Whey Protein Hydrolysate

This work studied the physical and oxidative stabilities of fish oil-in-water-in-olive oil double emulsions (O1/W/O2), where whey protein hydrolysate was used as a hydrophilic emulsifier. A 20 wt.% fish oil-in-water emulsion, stabilized with whey protein hydrolysate (oil: protein ratio of 5:2 w/w) and with a zeta potential of ~�����40 mV, only slightly increased its D4,3 value during storage at 8 C for seven days (from 0.725 to 0.897 m), although it showed severe physical destabilization when stored at 25 C for seven days (D4,3 value increased from 0.706 to 9.035 m). The oxidative stability of the 20 wt.% fish oil-in-water emulsion decreased when the storage temperature increased (25 vs. 8 C) as indicated by peroxide and p-anisidine values, both in the presence or not of prooxidants (Fe2+). Confocal microscopy images confirmed the formation of 20 wt.% fish oil-in-water-in-olive oil (ratio 25:75 w/w) using Polyglycerol polyricinoleate (PGPR, 4 wt.%). Double emulsions were fairly physically stable for 7 days (both at 25 and 8 C) (Turbiscan stability index, TSI < 4). Moreover, double emulsions had low peroxide (<7 meq O2/kg oil) and p-anisidine (<7) values that did not increase during storage independently of the storage temperature (8 or 25 C) and the presence or not of prooxidants (Fe2+), which denotes oxidative stability.the I+D+i projects CTQ2017-87076-R and PID2020-114137RBI00 funded by MCIN/AEI/10.13039/50110001103

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

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.Spanish Government CTQ2017-87076-

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

The incorporation of lipid ingredients into food matrices presents a main drawback&mdash;their susceptibility to oxidation&mdash;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&rsquo; 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&ndash;14%) and emulsion pH (2&ndash;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

Diseño y estabilización de lípidos funcionales

El objetivo de esta tesis doctoral es desarrollar procesos de estabilización de ácidos grasos Omega-3 mediante técnicas de emulsionado y microencapsulado, empleando para ello agentes emulsificantes-antioxidantes de naturaleza peptídica, procedentes de la hidrólisis enzimática de proteínas alimentarias tales como lactosuero, soja y bacaladilla. Para ello, esta investigación cuenta con los siguientes objetivos específicos que dividen este trabajo en tres secciones diferenciadas: 1. Obtención de hidrolizados de proteínas alimentarias con actividad emulsificante y antioxidante. 2. Estudio de la estabilidad física y oxidativa de emulsiones de aceites ricos en ácidos grasos Omega-3 estabilizadas con hidrolizados de proteínas alimentarias. 3. Microencapsulación de emulsiones de aceites ricos en ácidos grasos Omega-3 estabilizadas con hidrolizados de proteínas alimentarias mediante secado por atomización.Tesis Univ. Granada