INTRODUCTION
Krill Oil (KO) has garnered significant attention owing to its potential health benefits, stemming from its abundant reservoir of omega-3 polyunsaturated fatty acids (PUFAs) and the potent antioxidant astaxanthin. Nevertheless, the seamless integration of KO into diverse food products is beset with challenges, primarily stemming from its limited water solubility. This inherent challenge arises from KO’s composition, rich in hydrophobic PUFAs such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are essential for human health but poorly soluble in water (Zhao et al., 2020). The hydrophobic nature of these components gives rise to hurdles in achieving a uniform dispersion of KO within aqueous matrices, ultimately leading to issues related to phase separation and the emergence of undesirable sensory attributes in the final product. Furthermore, KO remains highly susceptible to oxidative degradation, especially when exposed to oxygen during food processing and storage. The inherent oxidative instability of PUFAs can culminate in the development of off-flavors and a decline in the nutritional quality of food products containing KO (Zhou et al., 2020). Consequently, the resolution of both solubility and oxidative stability issues assumes paramount importance in fully realizing the potential of KO within the food industry.
To tackle the challenges associated with incorporating KO into food products, extensive research efforts have been dedicated to developing effective delivery systems capable of encapsulating and safeguarding KO. Among these systems, oil-in-water (O/W) emulsions have risen as a prominent and promising choice. These emulsions are composed of minuscule oil droplets dispersed within an aqueous phase, and their characteristics are intricately linked to the size and distribution of these droplets (Uluata et al., 2016). Traditionally, researchers have addressed KO’s limited solubility and vulnerability to oxidation by introducing antioxidants or surfactants into the emulsion system. Antioxidants play a crucial role in mitigating lipid oxidation, while surfactants enhance emulsification and stabilize the resulting emulsion (Wang et al., 2020). While these additives have proven effective in extending the shelf life of KO- infused products, they have also attracted significant attention and scrutiny from consumers. The modern consumer landscape increasingly favors clean label products characterized by straightforward and transparent ingredient lists. This trend aligns with food regulations that impose restrictions on the use of specific emulsifying agents or surfactants in many formulated food items. Consequently, there has been a growing preference for physical processing methods to create emulsion systems (Zhou et al., 2022), particularly those enriched with polyunsaturated fatty acids like KO. This evolving scenario has revitalized interest in physical processing techniques for crafting emulsions, particularly those offering a clean label appeal.
In the realm of emulsion preparation, physical processing methods exert a crucial influence by providing substantial energy input to the system, ultimately shaping the properties of the resulting emulsions. Two primary techniques, high-pressure homogenization (HPH) and microfluidization (MF), have garnered attention for their capacity to produce emulsions with minute droplets. These methods assume paramount importance in overcoming the challenges associated with encapsulating KO. HPH stands as a conventional technique widely employed for emulsion production (Kaya et al., 2021). In this process, the emulsion undergoes exposure to high pressures, inducing mechanical shear forces. These forces disrupt and reduce the oil droplets, leading to a reduction in their size. However, HPH exhibits a limitation in its potential to yield inconsistent droplet distributions, which can impact the overall emulsion stability. MF has emerged as an alternative and advanced method for emulsion preparation. It offers precise control over droplet size distribution, effectively addressing the non-uniformity issue observed in HPH. In the microfluidization process, the emulsion is compelled through a microchannel under high pressure, generating intense shear forces, turbulence, and cavitation (Zhao et al., 2021). These factors contribute significantly to a substantial reduction in droplet size. The precise control over these parameters in microfluidization allows for the production of emulsions characterized by remarkably consistent and small droplet sizes. During emulsion preparation, various factors come into play, exerting a significant impact on the stability, texture, and functional properties of the final product. These factors encompass the composition of the oil and water phases, the emulsifying properties of the aqueous phase, and the fatty acid composition of the oil phase. The choice of processing method, whether HPH or MF, can introduce variations in these factors, thereby influencing the overall performance of the emulsion. While prior studies have delved into the effects of different processing methods on emulsion properties, such as droplet size and distribution, these investigations have often been conducted using diverse oil-water compositions and emulsion systems. Consequently, a systematic comparison between HPH and MF in terms of their impact on the oxidative stability and digestive behavior of emulsions has been lacking. This knowledge gap underscores the significance of the present study, as it seeks to illuminate the potential advantages of homogenization in crafting KO emulsions suitable for a wide array of food applications.
This study aims to elucidate the impact of two homogenization methods, namely microfluidization (MF) and high-pressure homogenization (HPH), on the properties of KO emulsions. Its objective is to provide comprehensive insights by systematically evaluating various factors, including particle size, distribution, oxidative stability, controlled release, and bioaccessibility. The investigation addresses pressing challenges encountered by the food industry when incorporating krill oil into a diverse range of food products. By harnessing the advantages of emulsions, which enhance solubility and protect against oxidation, and by exploring innovative homogenization techniques like microfluidization, this study endeavors to offer valuable insights. These insights are expected to facilitate the development of krill oil-based food-grade emulsions characterized by superior stability and bioavailability. This, in turn, lays the foundation for the seamless integration of this beneficial marine oil into a wide array of culinary and dietary offerings. Ultimately, this research contributes to the sustainable and efficient utilization of marine functional lipids within the food industry.