Nutritional, Microbiological and Functional Properties of Unrefined Omega-3 Oils and Natural Essential Oils as Preservatives

This study evaluates the oxidative stability, microbiological parameters, color characteristics, and fatty acid profiles of unrefined omega-3-rich oils (flaxseed, hemp seed, grape seed, chia, algae, fish, and cod liver oils). Volatile compounds from essential oils of coriander, bay leaf, and dill—used as natural antioxidants—were analysed, along with their antimicrobial activity. All oils demonstrated acceptable oxidative stability and typical color values. Coriander oil showed the highest chlorophyll A (32.98 ppm) and carotenoids (61.14 ppm). Infrared spectroscopy indicated the highest omega-3 content in flaxseed, hemp, and chia oils. Fish, cod liver, and algae oils showed unique ester profiles due to their vitamin and phospholipid content. Microbial analysis revealed values below 10 cfu/g for the presence of pathogenic bacteria, moulds, yeasts, and total viable count (TVC), with essential oils—particularly coriander— exhibiting strong antimicrobial effects. Chia oil was richest in omega-3s, followed by flaxseed, algae, fish, and cod liver oil. Grape seed oil had high α- and γ-tocotrienol content, enhancing its antioxidant potential. Phytosterols and triterpenoids were present in all plant oils, with squalene in chia oil and cycloartenol in flaxseed oil. Chia, algae, and cod liver oils show promise for functional dairy applications due to their stability and favourable sensory properties.