# Marine Bioactives and Their Application in the Food Industry: A Review
## 3 Marine Bioactive Compounds and the Food Industry
### Bioactive Marine Polyunsaturated Fatty Acids  
Enhancing food products with omega-3 PUFA notification has been recognized as an effective approach to increasing their dietary intake (Figure 3). Figure 3: Common omega-3 fatty acids enriched foods available in the world market. Fortification and microencapsulation are the most popular methods in this enrichment process. The inclusion of fish oil in food products such as bakery, dairy, and pasta by using modern technologies is a growing industry, and recent advances in this sector have resulted in a recognizable change in the functional food sector. For example, novel microencapsulated oil, which is known as MEG 3 (produced by Ocean Nutrition Canada; now DSM), has the ability to remain unaffected until it reaches the GI tract. However, preventing lipid oxidation and related fishy off-flavors associated with lipid degradation after incorporation of fish oil and, in the meantime, protecting the sensory attributes of food products are some of the major technical hurdles to overcome during the application [147; 148]. The formation of both primary and secondary oxidation products in polyunsaturated fatty acids (PUFAs) over extended periods of storage significantly contributes to the degradation of quality in fish oil and food products that contain fish oil. Nevertheless, the extent to which fish oil can be fortified in products like bakery goods, dairy items, and other frozen foods has been limited primarily because fish oil is highly prone to oxidation over time. Recent studies have indicated that fatty acids present in fish oil might undergo oxidative deterioration [9]. As a consequence of this degradation of the original PUFAs, the possibility of forming reactive lipid radicals and ultimately unhealthy volatile off-flavor molecules is high. Generally, the oxidation of fatty acids (EPA and DHA) results in the production of different volatile aldehydes and ketones. Depending on the substrate and environmental compositions, these volatiles can vary. Moreover, they belong to several groups such as short-chain aldehydes (acetaldehyde, 2-proposal, propanal, and 2-butanal), long-chain aldehydes (hexanal, 2,4-heptadienal, nonal, and nonadienal), diunsaturated aldehydes (nonadienals and 2,4-heptadien isomers), saturated aldehydes (hexanal, pentanal, and nonanal), ketones (1-penten-3-one), alcohols (1-penten-3-ol), hydrocarbons (pentane, 1-pentene, 2-methyl-1-buttene, 1,3-pentadiene, and 1-heptene) and acids (formic acid, propanoic acid, hexanoic acid, and butanoic acid) [147]. However, introducing or incorporating fish oil into foods is a challenging and difficult task as omega-3 PUFAs are extremely liable to oxidation. Moreover, executing preventive measures is not enough for industrial-scale usages of fish oil and fish oil-incorporated products. Hence, the use of antioxidants has gained attention in order to enhance the shelf life of oil-related food products by retarding the oxidation process. Particularly, synthetic antioxidants, such as butylated hydroxyapatite, butylated hydroxytlouene, t-butyl-hydroxyquinone, and propyl gallate, and natural antioxidants, such as tocoperbols, ascorbic acid, gallic acid, and lactoferrin, among others, have been studied for preventing oxidation of bulk fish oil, fish oil emulsions, and other marine oils [149; 150]. Nevertheless, crude fish oils often contain impurities and oxidation products. Due to their compositional characteristics, these oils are often considered a good source for tanning, margarine oil (hydrogenated), supplement, and aquaculture industries [151]. Therefore, refining and purification procedures should be practiced, especially before their incorporation into food products. Recent studies on the sensory evaluation of foods enriched with fish oil have also revealed that the addition of fish oil can negatively affect the sensory properties of fortified foods [128]. Nevertheless, there are numerous instances of omega-3 fatty acid-enriched foods that are available in the market worldwide, while maintaining sensory attributes.