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.