91��ý

Every year, the global wine industry generates 8–9 million tonnes of grape pomace. Traditionally, this byproduct is fed to livestock and largely forgotten. Yet up to 70% of phenolic compounds remain concentrated in this waste — making it a potentially rich source of high-value bioactive materials.

This observation is the starting point for a new Kazakhstani research project. "Study of the Stability of Black Seed Oil and Grape Seed Oil through the Synergistic Effect Observed during Joint Supercritical CO₂ Extraction" is funded under the priority direction "Energy, Advanced Materials and Transport" for 2025–2027. The team brings together expertise in biochemistry, organic chemistry, food chemistry, physical chemistry, and chemical engineering.

Grape seed oil (GSO) and black seed oil (BSO) are individually valuable and compositionally complementary. GSO is rich in linoleic acid, tocopherols, and polyphenols that provide antioxidant protection. Partial replacement of animal fat with GSO improves the physicochemical properties of meat emulsions; incorporation into gelatin-pectin films preserves chicken breast quality for 12 days; its use in frying reduces the formation of toxic glycation products.

BSO exhibits anti-inflammatory, antioxidant, antimicrobial, and anticancer properties. It reduces knee pain by 16%, improves sleep quality, lowers cortisol levels, and shows litholytic activity. Its composition — polyunsaturated fatty acids, tocopherols, tocotrienols, phytosterols, phenolic compounds, carotenoids, and thymoquinone — makes it a pharmacologically potent material.

The shared weakness of both oils is limited oxidative stability. As they oxidise over time, they generate toxic compounds — peroxides, aldehydes — that reduce shelf life and biological value. This is where the central scientific idea of the project takes shape: when the two oils are extracted together, a synergistic interaction may occur that increases oxidative stability beyond what either oil achieves alone. The nature of this synergy and the chemical compounds responsible for it have never been systematically studied.

Conventional extraction methods each carry limitations. Cold pressing produces low yields: SC-CO₂ extraction of GSO was shown to recover 17% more oil than cold pressing. Microwave-assisted extraction promotes oxidation of volatile compounds. Organic solvents are toxic and require removal. Soxhlet extraction is slow and uses large solvent volumes.

Supercritical CO₂ (SC-CO₂) extraction resolves these issues simultaneously. CO₂ is cheap, non-toxic, non-explosive, and reaches supercritical conditions at just 31.1°C and 72.9 bar. The method is single-stage, fast, selective, and leaves no solvent residue. It has been used industrially for decades in Europe, the USA, Japan, China, and South Korea. The research team itself has a proven record with this technology, having previously completed successful projects on extracting carotenoids from plant material, nicotinic acid from tobacco waste, and rare earth metals from phosphogypsum using SC-CO₂.

The project's primary goal is the development of a zero-waste technology producing two new products: a functional oil (FO) from GSO and BSO, and activated carbons (AC) from the post-extraction pomace, modified with urea and thiourea.

Direction one: the synergistic effect. The project addresses a set of unanswered scientific questions. Do antioxidant properties intensify when GSO and BSO are co-extracted by SC-CO₂? Which chemical compounds are responsible for the synergy? At what extraction conditions is oxidative stability maximised?

Three extraction modes are studied — static, dynamic, and combined. The effect of pressure and temperature in both the extractor and separator on the qualitative and quantitative composition of FO is systematically characterised. The optimal grape seed to black seed ratio is determined. Analysis includes anisidine, iodine, and peroxide values, free fatty acid content, saponification number, K270 values, and total oxidation index. Antioxidant activity is measured by DPPH assay, total phenol content by Folin-Ciocalteu reagent, and fatty acid composition by gas chromatography-mass spectrometry.

Direction two: safety and quality characterisation. At the accredited laboratory of Nutritest LLP, the FO is tested for benzo(a)pyrene, erucic acid, pesticide residues, and beta-carotene content — the core safety parameters required for application in food, pharmaceutical, and cosmetic industries.

Direction three: activated carbons from pomace. The post-extraction pomace is not discarded. Thermal carbonisation at 200–800°C in an inert atmosphere (argon) produces a carbonisate. Modification with urea/thiourea then develops sulphur- and nitrogen-containing functional groups on the carbon framework, substantially enhancing sorption activity. The resulting ACs are characterised by their sorption capacity for methylene blue, copper ions, and lead ions — contaminants of direct relevance for water treatment. Earlier work by the same team already demonstrated that grape seed-based AC exhibits CO₂/N₂ adsorption selectivity of 64.7 with a specific surface area of 700 m²/g, providing a strong foundation for this work.

The project is backed by real, operational equipment. The laboratory unit comprises a 500 ml extractor, two separators — one with heating (up to 100°C) and one with cooling — and two pumps: one for CO₂ flow (0–100 g/min) and one for co-solvent (25 ml/min). The pilot-scale unit has a 5-litre extractor and 2-litre separator, enabling preliminary calculations for industrial scale-up. Both units are already in use, providing the team with direct experimental capability from day one.

The project delivers two genuinely new products. The first is a functional oil with a balanced fatty acid profile, enriched with bioactive compounds, and exhibiting elevated oxidative stability through synergistic interaction. Its applications span food production — frying, salad dressings, flavour enhancement — cosmetics — moisturising, anti-ageing, and protective creams — and pharmaceuticals — slowing oxidative ageing, suppressing free radical activity, supporting cardiovascular and nervous system function. The second product is modified AC with high sorption capacity for heavy metals and organic dyes, with direct application in water purification.

For Kazakhstan, the project aligns with a measurable economic trend: domestic vegetable oil production has grown by 13.1% while imports have fallen by 22.7%. A domestically produced functional oil with verified health benefits and superior shelf life is positioned exactly where this market is heading.

All results will be published in international peer-reviewed journals indexed in Scopus and Web of Science, contributing to both the scientific literature on supercritical extraction and the emerging field of synergistic functional oil production.