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

¹ Department of Technology of Milk and dairy Products, University of Food Technologies, 26 Maritza Blvd., 4002, Plovdiv, Bulgaria
² Department of Microbiology, University of Food Technologies, 26 Maritza Blvd., 4002, Plovdiv, Bulgaria
³ Department of Physics and Biophysics, Medical University-Varna, 55 Marin Drinov Str., 9000, Varna, Bulgaria
⁴ Department of Food Sciences and Technology, University of Natural resources and Applied Life Sciences, 33 Gregor-Mendel Strasse Str., A-1190, Vienna, Austria
⁵ Department of Technology of Tobacco, sugar, vegetable and essential oils, University of Food Technologies, 26 Maritza Blvd., 4002, Plovdiv, Bulgaria

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

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.