A method for producing edible oil and edible oil

Abstract

A method for producing an edible oil comprises the steps of: (1) contacting an edible oil with a corresponding oilseed press cake under conditions that allow extraction of bioactive compounds into the oil to obtain an oil–cake slurry; (2) warm extraction step; (3) adding pellets of seed to the slurry; (4) re-pressing the obtained substrate; (5) filtering the oil from the repressed substrate. The edible oil obtained has an increased content of natural bioactive compounds, e.g. polyphenol, compared to the non-optimzed oil of the same source.

Description

[0001] Title

[0002] A method for producing edible oil and edible oil

[0003] Technical Field

[0004] The present application relates to the field of edible oils and, in particular, to methods for enhancing the stability, frying performance, and shelflife of cold-pressed edible oils.

[0005] Background of the Invention

[0006] Cold-pressed edible oils are widely recognized for their nutritional quality and bioactive constituents, including polyphenols, phytosterols, and tocopherols. However, despite their health benefits, cold-pressed oils suffer from limited oxidative stability and poor frying performance due to their high content of unsaturated fatty acids and the presence of pro-oxidant compounds. As a result, their industrial application and use in professional kitchens is restricted.

[0007] High-oleic (HO) oil varieties, such as high-oleic sunflower or rapeseed oil, were developed to improve the oxidative stability of oils through altered fatty acid composition. While such modifications reduce the degree of unsaturation, they do not sufficiently increase frying stability or shelflife under practical conditions. Thus, HO oils still face challenges when subjected to prolonged heating or deep-frying, where total polar compounds (TPC) rapidly accumulate beyond the acceptable regulatory threshold of 24% (Codex Alimentarius).

[0008] Existing methods to improve the quality of cold-pressed oils include centrifugation, filtration, and refining processes. Centrifugation can remove particulate matter and certain pro-oxidants, but it requires specialized equipment, is energy-intensive, and may reduce the concentration of beneficial minor compounds. Refining processes improve stability but simultaneously strip oils of natural antioxidants, leading to nutritionally inferior products compared to their cold-pressed counterparts. Documents EP1221286A1 “Oil having increased polyphenol content” discloses a method including contacting oil with olive fruit material in the presence of an acidic solution (e.g., citric or hydrochloric acid) and stirring during the contact time to enhance transfer of polyphenols into the oil.

[0009] Documents WO2022058566A1 / EP3970505A1 “Sunflower processing with double / repeated pressing” disclose a method involving multiple pressing steps, where the press cake is re-pressed after the first pressing with the aim to extract remaining oil content.

[0010] Documents CA2661397C “Aqueous processing of oilseed press cake” discloses a method that uses press cake from single or double pressing as starting material for aqueous extraction, with the press cake re-pressed after a second heating step with the aim to recover additional oil without using solvents. However, there remains a need for a simple, efficient, and cost-effective method that enhances the oxidative stability and frying performance of edible oils while retaining or even enriching their natural polyphenol content. Such a method should improve both the technological and sensory properties of the oil, reduce waste generation in frying applications, and offer advantages in sustainability and economics for professional and domestic use.

[0011] Object of the Invention

[0012] It is an object of the present invention to provide a method for producing edible oil and edible oil having improved technological and sensory properties, which reduce waste generation in frying applications, and offer advantages in sustainability and economics for professional and domestic use.

[0013] Summary of the Invention

[0014] This pobject is attained by providing a method according to claim 1 and edible oil according to claim 18. Preferred emboiments are described by the features of the dependent claims.

[0015] The present invention provides a method for producing edible oils with enhanced oxidative stability, prolonged frying usability, and increased bioactive content, without relying on costly and energyintense processing such as centrifugation and raflfination. Furthermore, the present invention relates to edible oils having improved properties for frying. The method is suitable for a wide range of plant oils, including but not limited to high-oleic rapeseed oil (HORO), high-oleic sunflower oil (HOSO), and black cumin oil (Nigella sativa).

[0016] Starting from a base workflow which comprises step 1 : mixing oil and unground press cake to obtain an oil-cake slurry; step 2: warm extraction; step 3: adding pellets step 4: re-press process; step 5: filtering, one or more of the following steps (A-D) could be included in the process before the mixing step 1, between mixing step 1 and repressing step 4, or after pressing step 4, but before final filtration step 5 as indicated. Each step A-D is designed to increase transfer of target small- to mid-sized polyphenols (phenolic acids, certain flavonols like herbacetin, and lignans) into the oil phase and to reduce co-extraction or retention of unwanted astringent high-molecular weight phenolics. Analytical control step E (LC-MS (Liquid Chromatography - Mass Spectrometry) or Folin + LC-MS marker panel) is explicitly used to decide whether to proceed or repeat cycles.

[0017] Step A — Controlled Moisture Activation (matrix swelling)

[0018] Adjust the moisture content of the press cake to a defined low, non-aqueous level prior to oil contact to swell cell walls and mobilize bound polyphenol conjugates. Do not fully wet — target low moisture that does not create free water phase.

[0019] Parameters

[0020] Target cake moisture: 3-8% w / w (preferably 4-6%). • Method: spray or tumble with food-grade water vapor or a fine mist at ambient to 40 °C for 5- 20 minutes until equilibrium moisture reached.

[0021] • Hold 10-30 min for equilibration.

[0022] Mechanistic rationale

[0023] Slight rehydration swells cell walls and loosens cell-matrix binding (hydrogen bonds), increasing diffusivity of polyphenolic aglycones and small phenolic acids into the oil phase during subsequent oil contact. Because moisture is low, hydrolysis reactions are limited (avoids high free fatty acid formation) while accessibility of bound phenolic esters is enhanced.

[0024] Selectivity

[0025] Low moisture preferentially mobilizes low-molecular-weight phenolic acids and medium-sized flavonoids which are adsorbed or superficially bound, but does not solubilize large condensed tannins that require higher aqueous solubility or harsh hydrolysis to detach — so astringent, high-molecular weight phenolics are less transferred.

[0026] Analytical control

[0027] Measure one marker (e.g., p-coumaric acid) in a small pilot slurry sample after 10-15 min of oil contact; if below target, proceed to step B or repeat moisture activation.

[0028] Step B — Transient COz-Pressurization (pH modulation I acidification by dissolved COz) Briefly expose the oil-cake slurry to pressurized COz (or sparge COz at slight overpressure) to transiently lower local pH in the water films and promote release of carboxylated phenolic acids from salt / metal complexes or ion-pairs; then relieve pressure and continue extraction.

[0029] Parameters

[0030] • COz partial pressure: 0.5-3 bar (gauge) for 1-10 minutes; typical preferred: 1-2 bar for 2-5 minutes.

[0031] • Temperature: 40-50 °C (same as mixing temperature).

[0032] • After pressurization, slowly release to ambient and continue mixing 5-30 min.

[0033] Mechanistic rationale

[0034] Dissolved COz forms carbonic acid in residual water films (microaqueous domains) causing mild, reversible acidification. Many phenolic acids (with carboxyl functions) shift equilibrium and become more extractable into the oil microphase or oil-bound microemulsions. The acidification also can help dissociate phenol-metal complexes that otherwise keep phenolic acids in the solid matrix.

[0035] Selectivity

[0036] This step particularly enhances extraction of carboxylated phenolic acids (chlorogenic acid, p-coumaric acid, caffeic acid) compared with non-carboxylated, astringent polyphenols, because protonation and complex dissociation favor the small acid molecules’ mobility.

[0037] Safety / food-grade

[0038] COz is food-grade and leaves no residue. Analytical control

[0039] measure chlorogenic acid and p-coumaric acid after depressurization; proceed if increases > predefined % (e.g., +10-15% from baseline) — otherwise continue gas cycles up to 3 times.

[0040] Step C — Alternating Vacuum I Pressure Pulsing (hydraulic impregnation I mass transfer enhancement)

[0041] Subject the oil-cake mixture (slurry) to alternating low-pressure (vacuum) and moderate positivepressure cycles prior to pressing, to drive oil deeply into cake pores and extract bound phenolics via convective mass transfer rather than pure diffusion.

[0042] Parameters

[0043] • Vacuum level: -0.6 to -0.85 bar (absolute ~ 0.15-0.4 bar) for 30-180 s.

[0044] • Positive pressure: 0.2-1.5 bar (gauge) for 30-180 s.

[0045] • Number of cycles: 2-8 cycles, typical 3-5 cycles.

[0046] • Temperature: 40-50 °C.

[0047] Mechanistic rationale

[0048] Vacuum removes trapped air and expands gas-filled pores; positive pressure forces oil into pore network; repeated cycling creates rapid convective exchange and extracts polyphenols that are physically trapped. This finishes faster than passive mixing and reduces required extraction time. Selectivity

[0049] Improves recovery of both small and some medium-sized polyphenols by mechanical displacement. Because cycles are brief and conducted at mild temperature and low moisture, excessively hydrophilic large tannins remain largely in the solid phase.

[0050] Analytical control

[0051] sample oil after last pressure cycle and determine LC-MS markers; if target profile reached, continue to repressing; if not, one additional cycle allowed.

[0052] Step D — Controlled Micro-Emulsion I Shear Pulse (short high-shear pulses to form transient oil microdomains)

[0053] Apply short (10-120 s) high-shear pulses (e.g., rotor-stator) to create transient oil-in-solid microemulsions that improve mass transfer of mid-polarity polyphenols into the oil; pulses are short to avoid stable emulsification which would complicate separation.

[0054] Parameters:

[0055] • Shear rate: 100-5,000 s ' for 10-120 s.

[0056] • Temperature: 40-50 °C.

[0057] • Immediately follow with pellet addition and repressing.

[0058] Mechanistic rationale High-shear pulses create transient microdomains and increase interfacial area, accelerating transfer of moderately lipophilic polyphenols (e.g., herbacetin) that prefer oil microdomains. Because pulses are brief, coalescence and stable emulsions are avoided; pressing easily separates phases.

[0059] Selectivity

[0060] The step favors mid-polarity molecules rather than large hydrophilic tannins.

[0061] A device suitable for performing step D may be a rotor-stator homogenizer, e.g. IKA Ultra-Turrax® (e.g. UTL 2000 series) suitable for up to 125,000 L samples, with adjustible shear rate.

[0062] Step E — Analytics-Driven Process Control (mandatory for inventive character)

[0063] Integrate real-time or near real-time analytics (rapid LC-MS method or validated surrogate assays) into production to drive decision points: e.g. whether to proceed to pressing or to perform additional pressure cycles.

[0064] Parameters & endpoints examples

[0065] • Primary markers: chlorogenic acid, p-coumaric acid, herbacetin, 3,4-dimethoxycinnamic acid, selected lignans.

[0066] • Acceptance thresholds (examples to use in claims):

[0067] o OHOSO: total LC-MS polyphenol sum > 120 pmol / kg, and chlorogenic acid > 25% increase over baseline; detection of gallic acid.

[0068] o 0H0R0: total LC-MS sum > 30 pmol / kg, p-coumaric acid > 80% increase.

[0069] • If thresholds are not met after repressing, perform up to n repeat extraction cycles (n < 2-3). Mechanistic rationale

[0070] A process that is controlled by measurements yields a reproducible, industrially robust product and the analytical result determines manufacturing decisions.

[0071] Example integrated protocol (preferred embodiment — combines steps 1-5 and steps A, C) a) (step A) Collect press cake (unground), determine initial moisture. Adjust moisture to 5% by light misting and equilibrate 15 min (A).

[0072] b) (steps 1 and 2) Mix oil and cake at 1:2.5 w / w at 45 °C for 30 min under gentle agitation. c) (step C) Apply 3 vacuum / pressure cycles (-0.7 bar to +1.0 bar; 90 s each) to the slurry (C). d) (step 3) Add 20% press-cake pellets (w / w), homogenize for 2-5 min.

[0073] e) (step 4) Re-press (screw press) at <50 °C to separate oil.

[0074] f) (step 5) Filter (filter press) and

[0075] g) (step E) Perform rapid LC-MS assay. If OHOSO target markers not met (e.g. chlorogenic acid or p-coumaric thresholds), repeat steps 1-5 once more. Stop when analytical targets met.

[0076] The combinbation of method steps mentioned above e.g.: low-moisture unground cake, pellet addition, transient CO2 acidification, alternating vacuum / pressure cycles, brief high-shear pulses, is configured to selectively enrich specific marker polyphenols. The method is controlled by an analytic decision loop. The method includes a control-by-analytics element (process decisions depend on measured polyphenol markers).

[0077] In a preferred embodiment, the press cake may not be milled but adjusted to a moisture content of 3-8% and equilibrated. The oil and cake may be mixed at 40-50 °C (preferably 45 °C) for 20-60 minutes. The slurry may be subjected to alternating vacuum / pressure cycles (vacuum ~ 0.15-0.4 bar absolute and positive pressure ~ 0.2-1.5 bar gauge) for 2-8 cycles to enhance convective mass transfer of matrix-bound phenolics into the oil phase. Prior to repressing, 10-25% w / w press-cake pellets may be added to the slurry to increase porosity and mechanical grip during pressing. Optionally, a brief CO2 pressurization (0.5-3 bar, 1-10 minutes) may be applied to induce mild, reversible acidification of microaqueous domains and promote extraction of carboxylated phenolic acids. Following pressing, the resulting oil may be analyzed (e.g. LC-MS / MS) and the measured polyphenol fingerprint (e.g., increased chlorogenic acid, p-coumaric acid, herbacetin; detection of gallic acid; specified total polyphenol thresholds) may be used as a process control parameter: if targets are not met, the extraction cycle is repeated.

[0078] Generally, the object of the invention is achieved by a method for producing an edible oil, comprising the steps of:

[0079] (1) contacting an edible oil with a corresponding oilseed press cake under conditions that allow extraction of bioactive compounds into the oil to obtain an oil-cake slurry;

[0080] (2) warm extraction step;

[0081] (3) adding pellets of seed to the slurry;

[0082] (4) re-pressing the obtained substrate;

[0083] (5) filtering the oil from the repressed substrate.

[0084] The oil and the press cake may originate from the same plant species.

[0085] It is preferred that the edible oil is a cold-pressed oil.

[0086] The oil may be selected from the group consisting of sunflower oil, rapeseed oil, flaxseed oil, black cumin oil, soybean oil, com oil, peanut oil, olive oil, or mixtures thereof.

[0087] The oil may be a high-oleic variety.

[0088] In a preferred embodiment step 1 comprises mixing the press cake and the oil in a weight ratio of 1 : 1 to 1:5 (press cake: oil).

[0089] The weight ratio of press cake:oil may be 1:1.5 to 1:3, more preferably 1: 1.75 to 1:2.25.

[0090] In a preferred embodiment mixing may be carried out under agitation at 100-500 rpm for 5-120 minutes.

[0091] The separating step may be performed by press filtering.

[0092] Pressing may be repeated one or more times using fresh oil.

[0093] The filtering step may be performed by press filtering. It is preferred that the oil obtained has a phenol acid content which is at least 40% higher than the one from the corresponding non-optimized cold pressed oil, preferably at least 45%, more preferably at least 50%.

[0094] It is preferred that the oil obtained exhibits a total polar compound (TPC) content of less than 30% of the corresponding non-optimized cold pressed oil after three days of deep-frying at typical conditions such as 150 °C.

[0095] In a preferred embodiment the oil may exhibit improved antioxidant capacity in radical scavenging assays compared to the corresponding non-optimized oil.

[0096] In a preferred embodiment of the method, the method avoids centrifugation and chemical refining. It is preferred that the process valorizes oilseed press cake as a source of bioactive compounds.

[0097] The method may include another method step A of controlled moisture activation of the press cake before or after step 1 with a preferred target cake moisture of 3-8% w / w, preferably 4-6% w / w. The method may include another method step B of transient CCE-pressurization, particularly in an atmosphere having a partial pressure of 0.5-3 bar (gauge) for 1-10 minutes.

[0098] The method may include another method step C prior to step (5) of exposing the substrate to alternating vacuum and / or pressure pulsing (hydraulic impregnation / mass transfer enhancement). The method may include another method step D of exposing the substrate to short high-shear pulses to form transient oil microdomains, with a preferred shear rate of 100-5,000 s ' for 10-120 s.

[0099] The method may include another method step E performed after step (4) or after step (5) of analytics-driven process control by controlling parameters of the pressed oil, determining one or more threshold values for one or more parameters, and repeating one or more of the steps (l)-(4) and A-D.

[0100] The object of the invention is achieved by providing an edible oil obtained by the method described above, characterized by an increased polyphenol content and improved frying stability compared to the corresponding non-optimized oil.

[0101] The object of the invention is also achieved by providing an edible oil characterized by an increased content of natural bioactive compounds compared to the non-optimzed oil of the same source.

[0102] The bioactive compounds may comprise polyphenols, tocopherols, carotenoids, or combinations thereof.

[0103] It is preferred that the phenolic acid content is at least 40% higher than in non-optimized cold pressed oils of the same source, preferably at least 45%, more preferably at least 50%.

[0104] It is preferred that the the oil exhibits improved antioxidant capacity in radical scavenging assays by 40%, preferably at least 50% compared to non-optimized cold pressed oil of the same source.

[0105] It is preferred that the the oil exhibits a total polar compound (TPC) level of less than 30% of the corresponding non-optimized cold pressed oil after three days of deep-frying at 150 °C or similar deep-frying temperature, e.g. 150°C-180°C, wherein the boundary conditions were as follows:

[0106] The deep-frying experiment was designed according to established frying protocols and adapted from relevant literature and industrial guidelines (DGF, 2023; Petersen et al., 2013; Romano et al., 2021). The oils tested included refined sunflower oil (RAFSO), high-oleic sunflower oil (HOSO), optimized high-oleic sunflower oil (OHO SO).

[0107] Each frying system consisted of a domestic fryer (Bestron Nederland BV, model AF370CO) filled with 2 L of oil and heated to 150 °C under a closed lid (according to DGF, 2023). Before the first frying cycle, oils were thermally equilibrated for 2 h at 150 °C to simulate industrial pre-heating. French fries (Billa Backrohr Pommes, 750 g package, Billa GmbH, Austria) were used as the standardized frying substrate.

[0108] Thirty minutes before frying, 150 g of frozen fries were removed from storage at -20 °C (DGF, 2023). Each batch was fried for 4 min, drained for a few seconds, and the fryer lid was closed again to minimize oxidation between cycles. Frying was repeated four times per day, with 2 h intervals between cycles (Petersen et al., 2013), resulting in a total of 8 h per day of thermal load (Romano et al., 2021).

[0109] At the end of each day, oils were filtered through Whatman filter paper (11 pm pore size) to remove particulate residues. A 50 mb sample was collected for LC-MS analysis and stored at -80 °C until measurement. The filtered oil was refilled into the cleaned fryer and replenished with fresh oil to maintain a constant volume of 2 L. Overnight, the temperature was maintained at 130 °C (DGF, 2023) to simulate industrial holding conditions. The entire frying process was conducted over three consecutive days with continuous thermal exposure above 130 °C.

[0110] Further boundary conditions and experimental results are described with reference to Fig. 4.

[0111] The oil may be selected from the group consisting of sunflower oil, rapeseed oil, flaxseed oil, black cumin oil, soybean oil, com oil, peanut oil, olive oil, or any other edible oils or mixtures thereof. The oil may be a high-oleic variety.

[0112] It is preferred that the edible oil is obtained by a process comprising contacting edible oil with press cake, pressing, and filtering.

[0113] Brief description of the drawings

[0114] Further features and advantages of the invention will become apparent from the following description with reference to the figures. They show:

[0115] Fig. 1 illustrates the effect of roasting (R) and green extraction (30 and 90 min) on oxidative stability parameters of black cumin seed oil obtained from Austrian (AT) and Egyptian (E) origin. Parameters shown are: (A) free fatty acids (FFA, % oleic acid), (B) oxidation induction time (OIT, hours), and (C) peroxide value (PV, meq 02 / kg oil).

[0116] Fig. 2 illustrates the effect of green extraction for 30 and 90 minutes on carotenoid and chlorophyll content in black cumin seed oil from Austria (AT) and Egypt (E).

[0117] Fig. 3 shows the antioxidant capacity of refined, high-oleic (HO), and optimized high-oleic sunflower and rapeseed oils, determined by three independent photometric assays. Data are presented as mean ± standard deviation (n = 3). (A) ABTS assay: statistical analysis by one-way ANOVA followed by Tukey’s post hoc test. (B) DPPH assay: statistical analysis by one-way ANOVA followed by Tukey’s post hoc test. (C) FRAP assay: for rapeseed oils, ANOVA with Tukey’s post hoc test; for sunflower oils, Brown-Forsythe and Welch ANOVA with Dunnett’s T3 post hoc test.

[0118] Fig. 4 shows a heat map of polyphenols detected in non-fried (TO) and deep-fried (day 1-3, T1-T3) refined, high-oleic (HO), and optimized high-oleic sunflower oils determined by LC-MS analysis. “X” indicates not detectable.

[0119] Fig. 5 shows polyphenol classes detected in non-fried (TO) and deep-fried (day 3, T3) refined, high-oleic (HO), and optimized high-oleic sunflower oils, determined by LC-MS analysis.

[0120] Fig. 6 illustrates a heat map of polyphenols measured in non-fried (TO) and deep-fried (day 1-3; TITS) refined, high-oleic (HO), and optimized high-oleic rapeseed oils, determined by LC-MS analysis. “X” indicates that the respective compound was not detectable.

[0121] Fig. 7 shows polyphenol classes of the measured polyphenols in non-fried (TO) and deep-fried (day 3; T3) refined, high-oleic (HO), and optimized high-oleic rapeseed oils, determined by LC-MS analysis.

[0122] Fig. 8 shows Total Polar Compounds (TPC) of refined, high-oleic (HO), and optimized high-oleic sunflower oils, determined by column chromatography. The legally accepted threshold for used frying oils in Austria is 27% TPC.

[0123] Fig. 9 shows Total Polar Compounds (TPC) of refined, high-oleic (HO), and optimized high-oleic rapeseed oils, determined by column chromatography. The legally accepted threshold for used frying oils in Austria is 27% TPC.

[0124] Fig. 10 illustrates the acid value of refined, high-oleic (HO), and optimized high-oleic (HO) sunflower oils before and after deep-frying for up to three days. Dots represent the threshold for cold-pressed oils, while the dashed line indicates the threshold for refined oils.

[0125] Fig. 11 shows The tocopherol content in refined, high-oleic (HO), and optimized high-oleic (OH) rapeseed oil, determined by HPLC-UV analysis.

[0126] Fig. 12 is a comparison of the number of fried portions in refined rapeseed oil and optimized cold-pressed rapeseed oil before the oil had to be discarded, as evaluated by chefs from six different restaurants. Data are presented as mean ± standard deviation, and significant differences are indicated by different letters (two-sample t-test for dependent samples, p < 0.05).

[0127] Description of preferred embodiments of the invention

[0128] The following embodiments refer to exemplary methods for producing edible oil according to the invention and edible oil according to the invention and their properties.

[0129] Fig. 1 shows the effect of roasting (R) and green extraction (30 and 90 min) on oxidative stability parameters of black cumin seed oil obtained from Austrian (AT) and Egyptian (E) origin. Parameters shown are: (A) free faty acids (FFA, % oleic acid), (B) oxidation induction time (OIT, hours), and (C) peroxide value (PV, meq 02 / kg oil).

[0130] Method: Oils were produced by cold pressing of raw and roasted black cumin seeds. The roasted variants were subjected to mild dry roasting at 180 °C for 8 min. The resulting oil was subsequently optimized using the green extraction process described above, where the oil was mixed with its corresponding press cake at a ratio of 1:2 (w / w) and stirred for 30 or 90 min prior to re-pressing and filtration. Free fatty acids were determined according to AOCS Cd 3d-63, peroxide values according to AOCS Cd 8b-90, and oxidation induction time using Ranzimat apparatus under an oxygen flow (100 °C, 20 L O2 / h).

[0131] Results:

[0132] • The roasting pretreatment significantly reduced free faty acid content in both origins, indicating lower enzymatic hydrolysis activity after thermal treatment.

[0133] • The green extraction process (especially 90 min) increased OIT values by up to 12% compared to the unoptimized Austrian control oil.

[0134] • Peroxide values were reduced by up to 69% after roasting and optimization, indicating a delayed onset of primary oxidation.

[0135] Conclusion:

[0136] Roasting prior to oil pressing and subsequent green extraction markedly enhanced oxidative stability by enriching natural antioxidants and reducing hydroperoxide formation. The data demonstrate that the process can be tuned (via extraction duration) to maximize the stability of black cumin seed oil, independent of geographical origin.

[0137] Fig. 2 shows the effect of green extraction for 30 and 90 minutes on carotenoid and chlorophyll content in black cumin seed oil from Austria (AT) and Egypt (E).

[0138] Method: Black cumin seed oils were produced by cold pressing, followed by optimization via the green extraction process as described above. Briefly, oil and its corresponding press cake were mixed at a weight ratio of 1 :2 (w / w) and stirred at 200 rpm for 30 or 90 minutes at room temperature prior to re-pressing and filtration. The resulting oils were analyzed spectrophotometrically for total carotenoid and chlorophyll content. Carotenoids were quantified at 470 nm and chlorophyll at 670 nm according to ISO 29841:2012, expressed as mg / kg oil.

[0139] Results:

[0140] • The optimized Austrian oil (AT) exhibited a 33% increase in total carotenoid content after 90 minutes of green extraction compared to the non-optimized control oil.

[0141] • Chlorophyll concentration in the same oil increased by approximately 58% under the same conditions. • In contrast, the Egyptian oil (E) showed minor or no significant changes in pigment concentrations after green extraction, indicating potential varietal or environmental differences in pigment distribution within the press cake matrix.

[0142] Conclusion:

[0143] The green extraction process effectively enhanced pigment retention and transfer from the press cake into the oil phase, particularly in the Austrian black cumin seed oil. The pronounced increase in carotenoids and chlorophylls not only contributes to a richer color profile but also provides additional antioxidant protection, synergistically improving oxidative stability. These findings further substantiate the functionality of the optimized extraction process described in the patent claims.

[0144] Fig. 3 shows the antioxidant capacity of refined, high-oleic (HO), and optimized high-oleic sunflower and rapeseed oils, determined by three independent photometric assays. Data are presented as mean ± standard deviation (n = 3). (A) ABTS assay: statistical analysis by one-way ANOVA followed by Tukey’s post hoc test. (B) DPPH assay: statistical analysis by one-way ANOVA followed by Tukey’s post hoc test. (C) FRAP assay: for rapeseed oils, ANOVA with Tukey’s post hoc test; for sunflower oils, Brown-Forsythe and Welch ANOVA with Dunnett’s T3 post hoc test.

[0145] Method:

[0146] The antioxidant capacity of six different edible oils was evaluated using established spectrophotometric assays. The oils tested included:

[0147] • RAFSO: refined sunflower oil,

[0148] • RAFRO: refined rapeseed oil,

[0149] • HOSO: non-optimized high-oleic sunflower oil,

[0150] • HORO: non-optimized high-oleic rapeseed oil,

[0151] • OHOSO: optimized high-oleic sunflower oil, and

[0152] • 0H0R0: optimized high-oleic rapeseed oil.

[0153] Three complementary assays were used to assess the oils’ antioxidant potential:

[0154] 1. ABTS assay (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)): Measures the ability of antioxidants to scavenge ABTS * radicals, reflecting both hydrophilic and lipophilic antioxidant activity.

[0155] 2. DPPH assay (2,2-diphenyl-l-picrylhydrazyl): Determines the hydrogen-donating ability of antioxidants toward stable DPPH radicals, mainly capturing lipophilic antioxidant activity. 3. FRAP assay (Ferric Reducing Antioxidant Power) : Quantifies the reduction of Fe3+to Fe2+under acidic conditions, indicating the overall electron-donating capacity of antioxidants. Results:

[0156] Except for the ABTS assay, all optimized oils (OHOSO and 0H0R0) showed the highest antioxidant capacity among all tested oils, significantly exceeding that of both refined and non-optimized high-oleic oils. • In the ABTS assay, optimized high-oleic sunflower oil (OHOSO) demonstrated the strongest radical scavenging activity among all samples. Optimized high-oleic rapeseed oil (0H0R0) exhibited slightly lower ABTS values than non-optimized high-oleic rapeseed oil (HORO), but still significantly higher activity compared to refined sunflower oil (RAFSO).

[0157] • In the DPPH and FRAP assays, both optimized oils (OHOSO and 0H0R0) displayed the highest antioxidant capacities, confirming their superior radical scavenging and reducing potential.

[0158] Conclusion:

[0159] The green extraction-based optimization process markedly enhanced the antioxidant potential of both high-oleic sunflower and rapeseed oils. The combined increase in phenolic compounds and pigments, together with improved oxidative stability, indicates that the optimized oils possess a significantly higher intrinsic resistance to oxidation. The consistent superiority of OHOSO and 0H0R0 across multiple antioxidant assays underlines the technological relevance of the patented method for producing edible oils with extended frying stability and shelflife.

[0160] Fig. 4 refers to the heat map of polyphenols detected in non-fried (TO) and deep-fried (day 1-3, TITS) refined, high-oleic (HO), and optimized high-oleic sunflower oils determined by LC-MS analysis. “X” indicates not detectable.

[0161] Method:

[0162] The deep-frying experiment was designed according to established frying protocols and adapted from relevant literature and industrial guidelines (DGF, 2023; Petersen et al., 2013; Romano et al., 2021). The oils tested included refined sunflower oil (RAFSO), high-oleic sunflower oil (HOSO), optimized high-oleic sunflower oil (OHOSO).

[0163] Each frying system consisted of a domestic fryer (Bestron Nederland BV, model AF370CO) filled with 2 L of oil and heated to 150 °C under a closed lid (according to DGF, 2023). Before the first frying cycle, oils were thermally equilibrated for 2 h at 150 °C to simulate industrial pre-heating. French fries (Billa Backrohr Pommes, 750 g package, Billa GmbH, Austria) were used as the standardized frying substrate.

[0164] Thirty minutes before frying, 150 g of frozen fries were removed from storage at -20 °C (DGF, 2023). Each batch was fried for 4 min, drained for a few seconds, and the fryer lid was closed again to minimize oxidation between cycles. Frying was repeated four times per day, with 2 h intervals between cycles (Petersen et al., 2013), resulting in a total of 8 h per day of thermal load (Romano et al., 2021).

[0165] At the end of each day, oils were filtered through Whatman filter paper (11 pm pore size) to remove particulate residues. A 50 mb sample was collected for LC-MS analysis and stored at -80 °C until measurement. The filtered oil was refilled into the cleaned fryer and replenished with fresh oil to maintain a constant volume of 2 L. Overnight, the temperature was maintained at 130 °C (DGF, 2023) to simulate industrial holding conditions. The entire frying process was conducted over three consecutive days with continuous thermal exposure above 130 °C.

[0166] Analytical Method:

[0167] Polyphenols were quantified by liquid chromatography-mass spectrometry (LC-MS) using electrospray ionization (ESI) in negative mode. Quantification was performed against external standards for key phenolic acids and flavonoids (chlorogenic acid, p-coumaric acid, gallic acid, 3,4-dimethoxycinnamic acid, herbacetin, and lignans such as matairesinol and lariciresinol). The results were visualized as a heat map representing relative intensity and detectability (T0-T3). “X” indicates that the compound was below the detection limit.

[0168] Results:

[0169] At the initial time point (TO), the optimized oil (OHOSO) exhibited higher baseline levels of phenolic acids (notably gallic acid and p-coumaric acid) and flavonoids (such as herbacetin) compared to their non-optimized counterparts. During deep-frying (T1-T3), refined oil (RAFSO) rapidly lost detectable p-coumaric acid, being undetectable after the first frying day.

[0170] In contrast, the optimized oil retained measurable amounts of p-coumaric acid and herbacetin over the entire 3 -day frying period.

[0171] Conclusion:

[0172] The LC-MS heat map confirms that the green extraction-based optimization process significantly improves both the initial concentration and thermal retention of characteristic polyphenols during deep-frying. The presence and persistence of specific phenolic markers — particularly p-coumaric acid and herbacetin — are key indicators distinguishing optimized oils from conventional or refined oils. This data supports the technical effect of the patented process: an increased resistance to oxidative degradation through selective enrichment of thermally stable antioxidant polyphenols.

[0173] Fig. 5 shows polyphenol classes detected in non-fried (TO) and deep-fried (day 3, T3) refined, high-oleic (HO), and optimized high-oleic sunflower oils, determined by LC-MS analysis.

[0174] Method:

[0175] Polyphenols were quantified and classified using liquid chromatography-mass spectrometry (LC-MS) in negative electrospray ionization mode. Quantification was performed using external calibration with authentic standards representing the major phenolic classes in sunflower oil: phenolic acids, flavonoids, and lignans. For each sample, total polyphenol content (sum of all detected compounds) and the relative distribution across classes were calculated. Measurements were performed before frying (TO) and after three consecutive frying days (T3).

[0176] Results:

[0177] At the initial time point (TO), refined sunflower oil (RAFSO) contained only trace amounts of phenolic acids (~5 pmol / kg), and no flavonoids or lignans were detectable. After the third day of deep-frying (T3), all polyphenols in RAFSO were below the detection limit, indicating complete oxidative degradation.

[0178] The non-optimized high-oleic sunflower oil (HOSO) initially contained approximately 80 pmol / kg total polyphenols, mainly composed of phenolic acids with some contributions from flavonoids. After three days of frying (T3), the total polyphenol content was reduced by approximately 50%, reaching about 40 pmol / kg. Especially phenolic acids decreased substantially, indicating limited thermal stability of native antioxidants in non-optimized oil.

[0179] In contrast, the optimized high-oleic sunflower oil (OHOSO) exhibited a markedly higher initial total polyphenol content of approximately 135 pmol / kg at TO. This enrichment was characterized by both a higher concentration of phenolic acids and a distinct presence of flavonoids. Although a reduction in total polyphenols was observed after three frying days, OHOSO retained comparable polyphenol levels to HOSO at T3 — despite starting from a significantly higher baseline, suggesting a protective effect of polyphenols in the OHOSO.

[0180] Conclusion:

[0181] The data demonstrate that the optimized oil (OHOSO) not only contains a higher initial concentration of polyphenols but also a broader and more balanced composition across phenolic classes. While total polyphenol levels decrease under prolonged frying, the optimized oil maintains an advantageous antioxidant profile compared to refined and non-optimized oils. This selective enrichment and retention of both phenolic acids and flavonoids directly result from the green extraction process described in the invention and underpin the oil’s superior oxidative stability and shelflife.

[0182] Fig. 6 is a heat map of polyphenols measured in non-fried (TO) and deep-fried (day 1-3; T1-T3) refined, high-oleic (HO), and optimized high-oleic rapeseed oils, determined by LC-MS analysis. “X” indicates that the respective compound was not detectable.

[0183] Method:

[0184] Polyphenol profiling was performed using liquid chromatography-mass spectrometry (LC-MS) under the same analytical conditions as described for sunflower oils. The analysis covered key phenolic acids, flavonoids, and lignans known to occur in rapeseed oil, including p-coumaric acid, herbacetin, 3, 4-dimethoxy cinnamic acid, lariciresinol, and matairesinol. Samples of refined rapeseed oil (RAFRO), high-oleic rapeseed oil (HORO), and optimized high-oleic rapeseed oil (0H0R0) were collected before frying (TO) and after one, two, and three consecutive days of deep-frying (T1-T3) under standardized conditions (150 °C, 8 h per day).

[0185] Results:

[0186] At the initial time point (TO), 0H0R0 exhibited a markedly richer polyphenol profile compared to both HORO and RAFRO. In particular, 0H0R0 contained substantially higher concentrations of p-coumaric acid, herbacetin, and 3,4-dimethoxycinnamic acid, as well as elevated levels of the lignans lariciresinol and matairesinol. These compounds were either absent or detectable only in lower amounts in HORO and RAFRO.

[0187] During frying, the overall polyphenol content decreased across all oil types; however, the decline was notably slower in 0H0R0. Specifically, p-coumaric acid remained clearly detectable up to T2 in 0H0R0, whereas it had already dropped below the detection limit in RAFRO after Tl. By T3, no phenolic compounds were detectable in any of the tested oils, indicating complete oxidative depletion after extended thermal exposure.

[0188] Conclusion:

[0189] The optimized high-oleic rapeseed oil (0H0R0) demonstrates a distinct and enriched polyphenol fingerprint, characterized by higher levels of phenolic acids (notably p-coumaric acid and 3,4-dimethoxycinnamic acid), flavonoids (herbacetin), and lignans (lariciresinol, matairesinol). The prolonged persistence of p-coumaric acid and related compounds up to day 2 of frying confirms the enhanced thermal stability and antioxidant resilience achieved through the optimized extraction process. These findings substantiate the unique composition and functional advantage of 0H0R0 compared to refined and conventionally cold-pressed rapeseed oils.

[0190] Fig. 7 shows polyphenol classes of the measured polyphenols in non-fried (TO) and deep-fried (day 3; T3) refined, high-oleic (HO), and optimized high-oleic rapeseed oils, determined by LC-MS analysis.

[0191] Method:

[0192] Polyphenols were quantified and classified according to their chemical groups — phenolic acids, flavonoids, and lignans — using liquid chromatography-mass spectrometry (LC-MS). Samples of refined rapeseed oil (RAFRO), high-oleic rapeseed oil (HORO), and optimized high-oleic rapeseed oil (0H0R0) were analyzed before frying (TO) and after three days of deep-frying (T3) under standardized thermal conditions (150 °C, 8 h per day).

[0193] Results:

[0194] At TO, RAFRO contained the lowest total amount of polyphenols (approximately 16 pmol / kg), consisting exclusively of phenolic acids and flavonoids. After three days of frying (T3), no phenolic compounds were detectable in RAFRO, and lignans were absent at both TO and T3.

[0195] In HORO, the total polyphenol content was higher at TO (over 20 pmol / kg) compared to RAFRO. In addition to phenolic acids, HORO also contained detectable amounts of lignans. However, after frying (T3), all polyphenolic compounds had degraded below the detection limit.

[0196] The optimized high-oleic rapeseed oil (0H0R0) showed the highest total polyphenol concentration at TO — nearly 40 pmol / kg. The polyphenolic profile of 0H0R0 included flavonoids, phenolic acids, and lignans, indicating a broader antioxidant composition than in HORO and RAFRO. After three days of frying, however, no polyphenols could be detected in 0H0R0 either, reflecting complete thermal degradation of these compounds under prolonged heat exposure. Conclusion:

[0197] Among the analyzed oils, 0H0R0 exhibited the most abundant polyphenol composition prior to frying, with notable contributions from phenolic acids, flavonoids, and lignans. Despite the total loss of detectable polyphenols after three days of deep-frying, the initially higher concentration in 0H0R0 suggests enhanced oxidative protection and improved thermal resistance during the early stages of frying, supporting the functional superiority of the optimized extraction process compared to refined and conventional HO rapeseed oils.

[0198] Fig. 8 shows Total Polar Compounds (TPC) of refined, high-oleic (HO), and optimized high-oleic sunflower oils, determined by column chromatography. The legally accepted threshold for used frying oils in Austria is 27% TPC.

[0199] Method:

[0200] The total polar and nonpolar fractions of the frying oils were determined according to the standard IUPAC method 2.507 (IUPAC, 1987). The separation was carried out using column chromatography, and the quality of fractionation was verified by thin-layer chromatography (TLC).

[0201] A mini glass column (15 mm x 200 mm) was packed with 5 g of silica gel suspended in a solvent mixture of n-hexane / diethyl ether (87: 13, v / v). A 0.5 g oil sample was dissolved in 4 mb of the same solvent mixture and applied gently to the column. The nonpolar fraction was eluted with 60 mb n-hexane / diethyl ether (87: 13, v / v), followed by elution of the polar fraction with 60 mb diethyl ether. Both eluates were collected in pre-weighed round-bottom flasks and evaporated using a rotary evaporator: the nonpolar fraction at 400 mbar and 40 °C for 35 min, and the polar fraction at 600 mbar and 40 °C for 25 min. Residual solvent was removed under nitrogen flow, and the flasks were reweighed. The difference in weight before and after solvent removal, divided by the sample weight, yielded the percentage of the polar and nonpolar fractions.

[0202] For TLC verification, 2 mb of the solvent mixture n-hexane / diethyl ether / acetic acid (70:30:2, v / v / v) were used to redissolve both fractions and applied to a silica-aluminum plate. After developing the plate in a saturated chamber until the solvent front reached the upper edge, it was air-dried, sprayed with phosphomolybdic acid, and heated at 120 °C for 10 min. The spots were visualized and compared to confirm complete separation.

[0203] Results:

[0204] The measured total polar compound (TPC) contents of the fried sunflower oils are shown in Figure 8. At day 0 (TO), refined sunflower oil (RAFSO), high-oleic sunflower oil (HOSO), and optimized high-oleic sunflower oil (OHOSO) showed no significant differences (p > 0.05), with mean values of 3.15 ± 0.38%, 2.08 ± 0.23%, and 2.42 ± 0.12%, respectively.

[0205] From day 1 onward, the TPC in OHOSO was significantly lower than in both RAFSO (p < 0.0001) and HOSO (p < 0.01). By day 3, all oils differed significantly (p < 0.0001) in their TPC levels. Curve fitting indicated that the rate of TPC formation was much steeper in RAFSO and HOSO compared to OHOSO, which had been produced using the green extraction process described in the patent.

[0206] Conclusion:

[0207] OHOSO demonstrated a significantly slower accumulation of polar compounds during frying, indicating improved oxidative and thermal stability compared to refined and conventional high-oleic sunflower oils. The TPC values in OHOSO remained well below the Austrian threshold of 27%, confirming the superior frying performance and stability of the optimized oil produced through the patented green extraction method.

[0208] Fig. 9 shows Total Polar Compounds (TPC) of refined, high-oleic (HO), and optimized high-oleic rapeseed oils, determined by column chromatography. The legally accepted threshold for used frying oils in Austria is 27% TPC.

[0209] Method:

[0210] The total polar and nonpolar fractions of the fried rapeseed oils were determined using the standard IUPAC method 2.507 (IUPAC, 1987) as described in Figure 8. Briefly, the separation was achieved by column chromatography on silica gel with subsequent TLC verification to confirm the quality of separation. Elution solvents, sample preparation, and analytical parameters were identical to those used for the sunflower oils.

[0211] Results:

[0212] Figure 9 shows the evolution of total polar compounds in refined and high-oleic rapeseed oils during the frying process. Similar to the sunflower oils, there were no significant differences (p > 0.05) in TPC at day 0 (TO) between refined rapeseed oil (RAFRO: 3.08 ± 0.16%), high-oleic rapeseed oil (HORO: 2.34 ± 0.30%), and optimized high-oleic rapeseed oil (0H0R0: 3.06 ± 0.87%).

[0213] From day 1 onward, both RAFRO (p < 0.01) and HORO (p < 0.05) showed significantly higher TPC values compared to OHORO. At day 2 and day 3, significant differences (p < 0.0001, except RAFRO vs. HORO at day 2: p < 0.001) were observed between all oils. The trend lines clearly indicate that OHORO, produced via the patented green extraction process, accumulated polar compounds at a substantially slower rate than the conventional oils, suggesting enhanced thermal stability and extended usability during deep frying.

[0214] The obtained values are consistent with literature reports, which cite polar compound contents between 0.1% and 6% for HO rapeseed oils (Xu et al., 2020; Zhou et al., 2024), and approximately 3.95 ± 0.08% for refined rapeseed oil (Chen et al., 2022). All measurements in this study fall within this established range.

[0215] Since potentially toxic polar compounds accumulate during repeated frying, most European countries have established regulatory thresholds between 24% and 27% TPC (Senanayake, 2024), with Austria specifying a maximum limit of 27% (Federal Ministry of Social Affairs, Health, Care and Consumer Protection, 2019). Based on these data, the usable frying durations were calculated as follows:

[0216] • RAFSO: 2.83 days

[0217] • HOSO: 3.26 days

[0218] • OHOSO: 3.94 days

[0219] corresponding to a 21% increase in usability through green extraction.

[0220] For the rapeseed oils:

[0221] • RAFRO: 3.30 days

[0222] . HORO: 2.91 days

[0223] . 0H0R0: 4.45 days

[0224] corresponding to a 53% increase in frying lifetime due to the optimized extraction process.

[0225] Conclusion:

[0226] The green extraction process significantly improved the oxidative stability and usability of rapeseed oil during frying, leading to over 50% longer safe use compared to refined and conventional HO oils.

[0227] 0H0R0 thus represents a technologically superior and more sustainable alternative for high-temperature food applications, maintaining polar compound levels well below the Austrian limit of 27% TPC for used frying oils.

[0228] Fig. 10 illustrates the acid value of refined, high-oleic (HO), and optimized high-oleic (HO) sunflower oils before and after deep-frying for up to three days. Dots represent the threshold for cold-pressed oils, while the dashed line indicates the threshold for refined oils.

[0229] Method:

[0230] The acid value (AV) was determined in accordance with the AOCS Official Method Cd 3d-63 (AOCS, 2024). The acid value expresses the amount of free fatty acids (FFA) in the oil and is defined as the milligrams of potassium hydroxide (KOH) required to neutralize the free fatty acids in 1 g of oil sample.

[0231] Briefly, 3 g of oil were dissolved in 100 mb of a 1:1 mixture of ethanol (C2H6O) and diethyl ether ((C^HsEO) in a 250-mL Erlenmeyer flask. After equilibration in a 40 °C water bath for 45 seconds, seven drops of phenolphthalein were added as an indicator. The flask was placed on a magnetic stirrer, and the solution was titrated dropwise using 0.05 N KOH in ethanol from a burette until a persistent pink color appeared for at least 2 minutes. The KOH consumption was recorded, and the acid value was calculated according to Equation (9):

[0232] Acid Value [(mg KOH) / g] = (V x c x M) I m

[0233] where:

[0234] • V = volume of titration solution (mL)

[0235] • c = concentration of KOH (0.05 mol / L)

[0236] • M = molar mass of KOH (56.1 g / mol)

[0237] • m = mass of the oil sample (g) Results:

[0238] The acid values of the fried sunflower oils are shown in Figure 10. At day 0 (TO), the refined sunflower oil (RAFSO) showed the lowest acid value (0.60 ± 0.05 mg KOH / g; p < 0.0001). The high-oleic sunflower oil (HOSO) and the optimized high-oleic sunflower oil (OHOSO) differed significantly at TO, with values of 2.10 ± 0.06 mg KOH / g and 1.90 ± 0.12 mg KOH / g, respectively (p < 0.01).

[0239] During frying, the acid value of RAFSO increased gradually over the three days, reaching 1.70 ± 0.06 mg KOH / g at day 3. In contrast, HOSO showed a continuous and pronounced rise, reaching 4.23 ± 0.09 mg KOH / g at day 3. OHOSO, on the other hand, initially decreased slightly after day 0 and then increased modestly to 1.86 ± 0.02 mg KOH / g by day 3, showing no significant difference from its initial value.

[0240] At day 3, RAFSO and OHOSO differed significantly (p < 0.05). while OHOSO maintained acid values well below the thresholds for cold-pressed and refined oils. These results clearly indicate that the green extraction process effectively reduced the formation of free fatty acids during thermal stress, stabilizing the oil against hydrolytic degradation.

[0241] Conclusion:

[0242] The optimized high-oleic sunflower oil (OHOSO) exhibited the lowest increase in acid value during deep frying, confirming the beneficial impact of the green extraction process on oil quality and resistance to hydrolysis. The data demonstrate that the process yields oils with greater oxidative and hydrolytic stability, thereby prolonging usability while maintaining compliance with regulatory acid value limits for edible and frying oils.

[0243] Fig. 11 shows The tocopherol content in refined, high-oleic (HO), and optimized high-oleic (OH) rapeseed oil, determined by HPLC-UV analysis.

[0244] Method: Tocopherols were extracted from oil samples with 2-propanol, using rac-tocol as an internal standard, and analyzed by HPLC-UV with a Shim-pack VP-ODS column and photodiode array detection at 295 nm. Quantification was based on external calibration curves for a-, y-, and 5-tocopherol.

[0245] Results: The figure shows the total tocopherol content and the distribution of individual tocopherols (a-, y-, and 5-tocopherol) in refined rapeseed oil (RAFRO), high-oleic rapeseed oil (HORO), and optimized high-oleic rapeseed oil (0H0R0). OHORO exhibited a significantly higher total tocopherol content (67.0 ± 3.2 mg / 100 g) compared to RAFRO (60.6 ± 0.7 mg / 100 g) and HORO (60.4 ± 1.3 mg / 100 g). a-Tocopherol was significantly enriched in OHORO compared to HORO, while y-tocopherol was higher in OHORO compared to RAFRO. 5-Tocopherol was not detected in any of the oils.

[0246] Conclusion: The optimized high-oleic rapeseed oil (OHORO), produced via the green extraction process described herein, contains higher levels of tocopherols compared to non-optimized oils, demonstrating enhanced transfer of antioxidants from the press cake into the oil and improved functional properties, including oxidative stability.

[0247] Fig. 12 is a comparison of the number of fried portions in refined rapeseed oil and optimized cold-pressed rapeseed oil before the oil had to be discarded, as evaluated by chefs from six different restaurants. Data are presented as mean ± standard deviation, and significant differences are indicated by different letters (two-sample t-test for dependent samples, p < 0.05).

[0248] Method: A paired two-sample t-test was applied to compare the dependent samples. In addition to usage duration, the number of portions fried before oil disposal was recorded for each oil type.

[0249] Results: The figure illustrates the difference in frying performance between conventional refined rapeseed oil (RAFRO) and optimized cold-pressed rapeseed oil (0H0R0) as assessed in a real-world restaurant setting. Chefs reported that they used conventional rapeseed oil for an average of 3.08 ± 1.74 days, whereas the optimized rapeseed oil could be used for 4.83 ± 3.17 days on average.

[0250] Conclusion: The optimized rapeseed oil (0H0R0) exhibited a significantly longer usage period compared to conventional refined oil (p < 0.05), corresponding to a 56.8 % improvement in heat stability. Furthermore, the optimized oil allowed the preparation of significantly more portions (70.33 ± 45.61) compared to the conventional oil (49.17 ± 38.13), representing a 43 % increase. These results demonstrate the enhanced functional performance and practical benefits of the optimized oil for frying applications.

[0251] Other embodiments of the invention are described as follows:

[0252] Embodiment 1 - General Method

[0253] 1. Mixing Step

[0254] The oil, which is obtained after seed pressing, is mixed with the corresponding press cake, which is collected and grounded after seed pressing, in a predetermined weight ratio. Typical ratios range from 1: 1 to 1:5 (press cake:oil), with preferred ranges of 1: 1.5-1:3, particularly 1:1.75-1:2.5, more particularly 1:1.75-1:2.25, and most particularly 1:2. The mixture is stirred at a speed of 200-250 rpm for a period between 15 and 90 minutes, preferably 25-45 minutes. The oil serves as a green solvent for extracting bioactive substances, including polyphenols, tocopherols, and carotenoids, from the press cake.

[0255] 2. Re-Pressing Step

[0256] After mixing, the oil-press cake mixture is subjected to pressing to separate the oil phase from the solid matter. This step improves oil purity and enables higher extraction efficiency of antioxidants compared to simple centrifugation. Re-pressing can be repeated multiple times using the fresh oil to achieve the desired and selective polyphenol profile and content.

[0257] 3. Filtration Step

[0258] The pressed oil is filtered using a filter press to remove residual particulate matter. Filtration ensures oil clarity and contributes to reduced formation of total polar compounds (TPC) during subsequent frying operations.

[0259] Determination of Polyphenol Profile and Content

[0260] The polyphenol content of the resulting oil can be determined using advanced methods such as LCMS / MS. A target polyphenol content for e.g. sunflower oil may be at least 120 pmol / kg, preferably 130 pmol / kg, more preferably 135 pmol / kg. The extraction cycle may be repeated only until the predetermined polyphenol profde and concentration is achieved. Targeted re-pressing / press fdter extraction (“green extraction”) enabled specific polyphenol compounds in the oil to be increased in a reproducible manner, which were shown to be responsible for the beneficial effect, such as prolonged heat stability during deep-frying. For sunflower oil (OHOSO), chlorogenic acid, p-coumaric acid, and herbacetin were detected in increased concentrations (increases of approximately 26%, 67%, and 42%, respectively, compared to the non-optimized base cold pressed sunflower oil). Furthermore, gallic acid was detectable in OHOSO, while it was not detectable (or only in trace amounts) in the comparison oils. For rapeseed oil (0H0R0), there was a significant enrichment of p-coumaric acid and herbacetin, as well as the first occurrence / increased occurrence of 3, 4-dimethoxy cinnamic acid; in addition, lignans (e.g., lariciresinol, matairesinol) were increasingly detectable. These specific compounds and the associated classes (phenolic acids, flavonoids, and lignans) form a characteristic profile of optimized oils and are suitable as markers for distinguishing them from conventional refined or cold-pressed oils, especially when measured immediately after completion of the manufacturing process.

[0261] Use of a profile panel for identifying an optimized sunflower oil produced according to claim 1 compared to a respective non-optimized, cold pressed sunflower oil, wherein the panel comprises at least three of the following findings: (i) chlorogenic acid increased by >25% compared to the respective non-optimized, cold pressed oil; (ii) p-coumaric acid increased by >60%; (iii) detection of gallic acid; (iv) total polyphenol content (LC-MS sum) > 120 pmol / kg and / or (v) increase in phenolic acids by at least 50%.

[0262] Use of a profile panel for identifying an optimized rapeseed oil produced according to claim 1, wherein the panel comprises at least three of the following findings: (i) p-coumaric acid increased by >80% compared to the non-optimized rapeseed oil; (ii) increased herbacetin by a minimum of 25%; (iii) increase of 3, 4-dimethoxy cinnamic acid by at least 50%; (iv) total polyphenol content (UC-MS sum) > approx. 30 pmol / kg and / or (v) increase in phenolic acids by at least 40%.

[0263] Optional Repeat Cycle

[0264] Steps 1 to 3 may be repeated n times (n = 0, 1, 2 ...) using fresh oil. The process is terminated when the desired bioactive content and oil purity are reached, and the purified oil is collected for storage or further use. Embodiment 2 - Application to High-Oleic Sunflower Oil (OHOSO)

[0265] • The green extraction increased total polyphenol content by approximately 50%, while tocopherol levels remained largely unchanged.

[0266] • The resulting oil demonstrated improved antioxidant capacity in ABTS and DPPH assays by at least 60%, as well as higher oxidative stability in Rancimat tests by 50% compared to nonoptimized HOSO.

[0267] • After a three-day deep-frying simulation at 150°C, OHOSO exhibited 33% fewer total polar compounds, and 50% lower acid value, compared to non-optimized cold pressed sunflower oil, demonstrating enhanced frying stability.

[0268] Embodiment 3 - Application to High-Oleic Rapeseed Oil (OHORO)

[0269] • The green extraction increased polyphenol content by 60% and tocopherols by 10%.

[0270] • OHORO (optimized cold pressed high-oleic rapeseed oil) exhibited 40% higher antioxidant capacity according to the FRAP assay than HORO (non-optimized cold pressed high-oleic rapeseed oil)

[0271] • After a three-day deep-frying simulation at 150°C, OHORO formed 50% fewer polar compounds than HORO.

[0272] Embodiment 4 - Application to Black Cumin Oil

[0273] • Applying the green extraction to Nigella sativa seeds enabled enrichment of carotenoids (increase of 33%) and chlorophyll (58%) in Austrian black cumin oil, improving nutritional quality.

[0274] • Acid and peroxide values were substantially reduced by 82% and 57%, respectively, through combined roasting and green extraction, achieving levels compliant with Codex Alimentarius standards.

[0275] • Also the oxidation induction time at 100°C (shelflife) was increased by 115% through combined roasting and green extraction.

[0276] Embodiment 5 - Frying Performance

[0277] • The method reduces TPC formation during deep-frying. After three days of deep-frying at 150°C, TPC values in the optimized oils were approximately 15%, well below regulatory limits (25-30% depending on national jurisdiction).

[0278] • Improved oil stability translates into prolonged usability in professional kitchens, reduced oil waste, and cost savings.

[0279] • The optimized rapeseed oil enabled 43% more portions to be prepared, as evaluated by chefs (n=7) in real restaurants, which led to a reduction of the total cooking oil waste by 36%. Embodiment 6 - Sustainability and Green Chemistry

[0280] • The method utilizes press cake as a natural source of bioactive compounds, allowing valorization of by-products and compliance with green chemistry principles.

[0281] • The process avoids extensive centrifugation or chemical refining, reducing energy consumption by a factor of 5 and preserving the nutritional and functional properties of the oil. Refined rapeseed oil production requires multiple energy-intensive steps:

[0282] Extraction (heat & solvents): ~2.5 MJ / L

[0283] Refining (degumming, neutralization, bleaching, deodorization): -7-10 MJ / L

[0284] Total Energy Consumption: -9.5-12.5 MJ / L

[0285] Optimized cold-pressed rapeseed oil requires minimal energy:

[0286] Pressing & Filtration: -1.5-2.5 MJ / L

[0287] — ► 4-6 times lower energy consumption than refined oil production.

[0288] Embodiment 7 - Summary

[0289] The invention provides a versatile, environmentally friendly, and economically advantageous method for producing edible oils with enhanced shelflife, improved frying performance, and higher levels of natural bioactive compounds. The method is applicable to a variety of plant oils, including high-oleic sunflower, rapeseed, and black cumin oils. Optional repetition of extraction cycles allows precise control over polyphenol profile and enrichment, while filtration ensures high oil purity.

Claims

Claims1. A method for producing an edible oil, comprising the steps of:(1) contacting an edible oil with a corresponding oilseed press cake under conditions that allow extraction of bioactive compounds into the oil to obtain an oil-cake slurry;(2) warm extraction step;(3) adding pellets of seed to the slurry;(4) re-pressing the obtained substrate;(5) filtering the oil from the repressed substrate.

2. The method of claim 1, wherein the oil and the press cake originate from the same plant species.

3. The method of claim 1 or 2, wherein the edible oil is a cold-pressed oil.

4. The method of any of the preceding claims, wherein the oil is selected from the group consisting of sunflower oil, rapeseed oil, flaxseed oil, black cumin oil, soybean oil, com oil, peanut oil, olive oil, or mixtures thereof.

5. The method of any of the preceding claims, wherein the oil is a high-oleic variety.

6. The method of any of the preceding claims, wherein step 1 comprises mixing the press cake and the oil in a weight ratio of 1 : 1 to 1:5 (press cake mil).

7. The method of claim 5, wherein the weight ratio of press cake:oil is 1:1.5 to 1:3, more preferably 1:1.75 to 1:2.25.

8. The method of any of the preceding claims 5 or 6, wherein mixing is carried out under agitation at 100-500 rpm for 5-120 minutes.

9. The method of any of the preceding claims, wherein the separating step is performed by press filtering.

10. The method of claim 8, wherein pressing is repeated one or more times using fresh oil.

11. The method of any of the preceding claims, wherein the filtering step is performed by filter press.

12. The method of any of the preceding claims, wherein the oil obtained has a phenol acid content which is at least 40% higher than the one from the corresponding non-optimized cold pressed oil, preferably at least 45%, more preferably at least 50%.

13. The method of any of the preceding claims, wherein the oil obtained exhibits a total polar compound (TPC) content of less than 30% of the corresponding non-optimized cold pressed oil after three days of deep-frying at 150 °C.

14. The method of any of the preceding claims, wherein the oil exhibits improved antioxidant capacity in radical scavenging assays compared to the corresponding non-optimized oil.

15. The method of any of the preceding claims, wherein the process avoids centrifugation and chemical refining.

16. The method of any of the preceding claims, wherein the process valorizes oilseed press cake as a source of bioactive compounds.

17. The method of any of the preceding claims, wherein the method includes a step A of controlled moisture activation of the press cake before or after step 1 with a preferred target cake moisture of 3-8% w / w, preferably 4-6% w / w.

18. The method of any of the preceding claims, wherein the method includes a step B of transient CCE-pressurization, particularly in an atmosphere having a partial pressure of 0.5-3 bar (gauge) for 1-10 minutes.

19. The method of any of the preceding claims, wherein the method includes a step C prior to step (5) of exposing the substrate to alternating vacuum and / or pressure pulsing (hydraulic impregnation / mass transfer enhancement).

20. The method of any of the preceding claims, wherein the method includes a step D of exposing the substrate to short high-shear pulses to form transient oil microdomains, with a preferred shear rate of 100-5,000 s ' for 10-120 s.

21. The method of any of the preceding claims, wherein the method includes a step E performed after step (4) or after step (5) of analytics-driven process control by controlling parameters of the pressed oil, determining one or more threshold values for one or more parameters, and repeating one or more of the steps (l)-(4) and A-D.

22. An edible oil obtainable by the method of any of the preceding claims, characterized by an increased polyphenol content and improved frying stability compared to the corresponding non-optimized oil.

23. An edible oil characterized by an increased content of natural bioactive compounds compared to the non-optimzed oil of the same source.

24. The edible oil of claim 22 or 23, wherein the bioactive compounds comprise polyphenols, tocopherols, carotenoids, or combinations thereof.

25. The edible oil of any of claims 22 to 24, wherein the phenolic acid content is at least 40% higher than in non-optimized cold pressed oils of the same source, preferably at least 45%, more preferably at least 50%.

26. The edible oil of any of claims 22 to 25, wherein the oil exhibits improved antioxidant capacity in radical scavenging assays by 40%, preferably at least 50% compared to nonoptimized cold pressed oil of the same source.

27. The edible oil of any of claims 22 to 26, wherein the oil exhibits a total polar compound (TPC) level of less than 30% of the corresponding non-optimized cold pressed oil after three days of deep-frying at 150 °C.

28. The edible oil of any of claims 22 to 27, wherein the oil is selected from the group consisting of sunflower oil, rapeseed oil, flaxseed oil, black cumin oil, soybean oil, com oil, peanut oil, olive oil, or any other edible oils or mixtures thereof.

29. The edible oil of claim 28, wherein the oil is a high-oleic variety.

30. The edible oil of any of claims 22 to 29, obtainable by a process comprising contacting edible oil with press cake, pressing, and filtering.

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