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.

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Ice creams produced with unsaturated fats rich in oleic (OO, 70.7% of oleic) and linoleic (LO, 49.0% of linoleic) fatty acids, were compared to ice cream based on saturated coconut oil (CO, 50% of lauric acid). The globule size distribution of OO mix during aging (72 h at 4°C) followed a similar trend to CO mix, being stable after 48 h; whereas LO mix destabilized after 24 h. CO mix showed higher destabilization during ice cream production, but no significant differences among fats were observed in the particle size of the ice cream produced. The overrun was also lower for OO and LO ice creams (34.19 and 27.12%, respectively) compared to CO based ice cream (45.06%). However, an improved melting behavior, which gradually decreased from 88.69% for CO to 66.09% for LO ice cream, was observed. Practical applications: This work evaluates the use of high unsaturated fats in the production of ice cream as alternative to highly saturated coconut oil. Common unsaturated fats normally lead to ice cream with low quality in terms of overrun and melting points. Nevertheless, the results obtained in this study indicated that the two fats assayed, rich in oleic and linoleic acids, are adequate for the production of ice cream. Therefore, these highly unsaturated fats are a promising alternative for the development of healthier ice creams. Unsaturated fats are introduced in ice cream and compared to saturated coconut oil. Similar fat globule size and viscosity are found, while melting behavior is improved.

This work aims at studying the impact that the degree of unsaturation of fatty acids (FA) with the same chain length exerts on the esterification yield and the regiodistribution of FA in the glycerol backbone. To that end, triacylglycerols (TAG) are produced by esterifying several mixtures (stearic, oleic, and alpha-linolenic acids) employing Novozyme 435 and Lipozyme RM IM. All esterifications achieve a high content of TAG (>69 mol%) with Lipozyme RM IM being more active. Both lipases initially esterify stearic acid, while linolenic acid is preferably esterified in the last step of the esterification. Additionally, the higher the degree of unsaturation, the higher the concentration at the position sn-2. This trend is more marked for Novozyme 435. The structure of the FA causes steric hindrance resulting in competitive-like behavior among the FA. Hence, the selectivity of lipases might be affected by the composition of the substrate. Practical Applications: Omega-3 FA have a high nutritional value and are industrially employed to produce concentrates and structured or functional lipids. The regiodistribution of FA in the glycerol determines its bioavailability; those linked to the central position are more efficiently metabolized while those in the sn-1 and sn-3 positions are merely stored or excreted. Structured lipids are produced employing lipases, hence the regioselectivity of the lipases is a key point for the production. The results show that, for the same chain length, the regioselectivity of lipases can be affected by the composition of the substrate and that polyunsaturated FA tend to be esterified in the central position when employing Novozyme 435 and Lipozyme RM IM.

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 µm), although it showed severe physical destabilization when stored at 25 °C for seven days (D4,3 value increased from 0.706 to 9.035 µm). 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.