Physical and Oxidative Stability of Low-Fat Fish Oil-in-Water Emulsions Stabilized with Black Soldier Fly (Hermetia illucens) Larvae Protein Concentrate.

Lucas Sales Queiroz,Flemming Jessen,Fatemeh Ajalloueian,Mohammad Amin Mohammadifar,Charlotte Jacobsen,Betül Yesiltas,Aberham Hailu Feyissa,Federico Casanova,Italo Tuler Perrone,Antonio Fernandes De Carvalho

doi:10.3390/foods10122977

Abstract

The physical and oxidative stability of fish oil-in-water (O/W) emulsions were investigated using black soldier fly larvae (BSFL) (Hermetia illucens) protein concentrate as an emulsifier. To improve the protein extraction and the techno-functionality, defatted BSFL powder was treated with ohmic heating (BSFL-OH) and a combination of ohmic heating and ultrasound (BSFL-UOH). Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were performed in order to characterize the secondary structure and thermal stability of all protein concentrate samples. The interfacial properties were evaluated by the pendant drop technique. The lowest interfacial tension (12.95 mN/m) after 30 min was observed for BSFL-OH. Dynamic light scattering, ζ-potential and turbiscan stability index (TSI) were used to evaluate the physical stability of emulsions. BSFL-OH showed the smallest droplet size (0.68 μm) and the best emulsion stability (TSI = 8.89). The formation of primary and secondary volatile oxidation products and consumption of tocopherols were evaluated for all emulsions, revealing that OH and ultrasound treatment did not improve oxidative stability compared to the emulsion with untreated BSFL. The results revealed the promising application of BSFL proteins as emulsifiers and the ability of ohmic heating to improve the emulsifying properties of BSFL proteins.

Highlights

Long-chain (LC) fatty acids such as docosahexaenoic acid (DHA), 22:6 (n-3) and eicosapentaenoic acid (EPA), 20:5 (n-3) can be found in fatty fish such as mackerel, tuna, cod fish and salmon, and they are collectively referred to as marine omega-3 (n-3) fatty acids [1]
Using ohmic heating as a pre-treatment on the insect flour (BSFL-Ohmic heating (OH)), the yield of protein extraction reached 66.7 ± 0.1%, and using the combination of ohmic heating and ultrasound (BSFL-UOH), the protein content was equal to 66.2 ± 0.1%
Emulsions stabilized with black soldier fly larvae (BSFL)-OH showed the most promising physical stability, which was confirmed by turbiscan stability index (TSI) value and the hydrodynamic diameter

Summary

Introduction

Long-chain (LC) fatty acids such as docosahexaenoic acid (DHA), 22:6 (n-3) and eicosapentaenoic acid (EPA), 20:5 (n-3) can be found in fatty fish such as mackerel, tuna, cod fish and salmon, and they are collectively referred to as marine omega-3 (n-3) fatty acids [1]. Notwithstanding, n-3 PUFA-enriched foods have shown important benefits for human health, and they come with the challenge of negatively affecting oxidative stability, since n-3 PUFAs are very susceptible to oxidation. Fish oil-in-water (O/W) emulsions have been used as an advantageous system for LC n-3 PUFA delivery in order to reduce lipid oxidation [2]. Emulsions might protect n-3 PUFAs against oxidation, they are thermodynamically unstable [2]. Oxidation in emulsions is initiated at the oil– water interface and factors such as the thickness and charge of the interface can affect the oxidative stability of the emulsion [3]. Comprehending the structure, properties and inner dynamics of the emulsion interface is essential to improve physico-chemical stability and potentially reduce oxidative effects on food emulsions

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