How to make rosemary leaf extract?

The extraction of "rosemary leaf extract" is not simply boiling a pot of herbal tea, but rather a process that must be carried out under conditions that "preserve activity, remove impurities, stabilize color, and comply with regulations." The following analyzes the four main process flows for extraction:

 

Steam Distillation Method:
The oldest and most equipment-efficient method – steam distillation.
① Raw material pretreatment: Fresh leaves → air-drying to reduce water content to ≤10% → cutting into 0.5 cm segments. This step determines the subsequent "oil extraction" speed;
② Distillation parameters: Material-to-liquid ratio 1:5, heated to 98℃ and maintained for 90 minutes, condensate pH 6.5-7.0, yielding 1.0-1.2% of colorless to light yellow essential oil;
③ Component spectrum: α-pinene, 1,8-cineole, camphor, borneol, but does not contain strong antioxidants such as rosmarinic acid and carnosic acid;
④ Registration difficulties: In China, it can only be considered "rosemary essential oil," and for use as a food additive, it must go through the "flavoring" channel, and for cosmetic registration, it can only be used as a "fragrance."

 

Solvent Extraction Method:

The most commonly used method in industry is the "food-grade ethanol-water" system, but why does the same ethanol yield 23% carnosic acid in small-scale tests, but drop to 14% when scaled up to a 3-ton tank?
The key lies in "three controls and one filtration":
Water control: When the water content of the leaves is >12%, the effective concentration of ethanol is diluted, and the carnosic acid precipitation rate decreases by 6-8%;
Temperature control: Hot reflux extraction at 55℃ for 3 times, 40 minutes each time; above 60℃, carnosic acid begins to decarboxylate;
pH control: The extract is adjusted to pH 3.5-4.0 with citric acid, where rosmarinic acid has the highest stability;
Ceramic membrane filtration: 50 nm pore size, removing polysaccharides and chlorophyll particles in one step, otherwise the pressure for subsequent resin purification will double. After completing these four steps, including pressure reduction and concentration followed by spray drying, a brownish-green powder containing 20%-25% salvianolic acid and 4%-6% rosmarinic acid is obtained. The water solubility turbidity is <0.5 NTU, directly meeting the US FDA's "GRAS" self-assessment requirements.

 

Supercritical CO₂ Extraction:

When the brand owner requires that the product can be added to "transparent aqueous solutions," the factory will use supercritical extraction.
Process window: Pressure 30 MPa, temperature 45 ℃, CO₂ flow rate 25 kg/h, with 3% food-grade ethanol added as an entrainer;
Yield: 6-7 kg of oily resin is obtained from every 100 kg of dried rosemary leaves, with a salvianolic acid content as high as 35%, but rosmarinic acid is almost zero (CO₂ cannot carry highly polar molecules);
Decolorization: Using 1% activated carbon at 35 ℃ for 30 minutes, the color difference ΔE can be reduced from 18 to <3, making it suitable for transparent serums;
Cost: Material-reagent-energy consumption total ≈ 180 yuan/kg, 2.6 times more expensive than the ethanol method, but the selling price can be quadrupled, specifically for high-end skincare products.

 

Enzymatic Hydrolysis-Fermentation Combined Process:
A pilot test conducted by Xi'an Sost biotech Laboratory in 2023: First, cellulase + pectinase (1:1, 0.3%) were used for enzymatic hydrolysis at 40 ℃ for 1 hour to break down the leaf mesophyll cell walls, then a mixed Lactobacillus culture (L. plantarum + L. rhamnosus) was added for 12 hours of fermentation, and the pH naturally dropped to 4.0.
Results:
Salvianolic acid yield increased by 12%, and rosmarinic acid by 8%;
Natural lactic acid is produced during fermentation, and the powder has its own pH buffer, eliminating the need for additional acid adjustment when formulating masks;
Microorganisms degrade chlorophyll into demetallated chlorophyll, reducing the powder's color value by 30%, and the customer accepts the product as "not green."

 

Key Components of Rosemary Leaf Extract

Carnosic acid: Oil-soluble, ROS scavenging rate ≈ 3.2 times that of vitamin E, extending the induction period by 4 times in accelerated oxidation experiments at 60°C in oils;
Rosmarinic acid: Water-soluble, inhibits hyaluronidase activity, anti-"blue light-induced photoaging" cell experiment IC50 = 18 μg/mL;
Ursolic acid: Triterpenoid, activates the Nrf2/ARE pathway, a newly popular ingredient in anti-aging skincare;
Volatile oil monoterpenes: 1,8-cineole, α-pinene, mainly providing olfactory and immediate cooling sensations, contributing <5% to antioxidant effects.

 

Applications of Rosemary Leaf Extract Core Formula

 

Edible oil: Adding 200 ppm carnosic acid (20% specification) to sunflower oil, after 14 days in a 60°C oven, the POV value was only 1/4 of the control group, allowing for the claim "TBHQ-free" on the label;
Plant-based meat: Spraying 0.15% powder before high-temperature extrusion solves the problem of easy rancidity of Omega-3 algal oil, extending shelf life by 90 days;

Water-based essence: 3% rosmarinic acid + 1% ectoine, in a blue light repair experiment, keratinocyte survival rate increased by 28% after 8 hours of HEV irradiation, generating the topic "savior for computer users" on redbook (a Chinese social media platform);
Pet treats: Adding 0.05% rosemary leaf extract to cat treats replaces potassium sorbate, resulting in a 30% premium for the "0 chemical preservatives" claim among cat owners;

Gummies: Gelatin gummies at pH 3.2, with 0.8% rosmarinic acid + 0.02% natural strawberry flavor, showed no oily or fishy taste after 3 months of accelerated testing at 38°C, successfully entering the Japanese functional food market.

 

With so many rosemary extract suppliers, why choose Xi'an Sost Biotech?

 

Raw Material Source: 3200 acres of GAP-certified rosemary cooperative base in southern Shaanxi, ensuring fresh leaves are processed within ≤6 hours from harvest to extraction, guaranteeing zero loss of enzyme activity;
Process Technology: Ethanol method + supercritical fluid extraction dual production lines, with an annual capacity of 260 tons, providing stable supply of rosmarinic acid in all specifications from 5% to 35% and rosemary leaf extract carnosic acid from 3% to 20%;
Regulatory Compliance: Complete with six certifications: domestic SC, ISO22000, ISO9001, Kosher, and Halal;
Customization: Provides complete documentation and testing, supporting customers in customizing differentiated specifications;
Logistics: Safety stock is maintained in our California warehouse, with FOB delivery available from the Port of Los Angeles within 72 hours.

 

How to obtain free samples and detailed specifications? - Contact Xi'an Sost Biotech directly via email
Email: info@sostherbusa.com
Website: www.sosterb.com

 

References
[1] Almela L, et al. Rosmarinic acid content in rosemary leaf extracts: kinetic model of hot-water extraction. Innovative Food Science & Emerging Technologies, 2021.
[2] Zhang Y, et al. Supercritical CO₂ extraction of carnosic acid from rosemary leaves: optimization and scale-up. Journal of Supercritical Fluids, 2022.
[3] National Health Commission of the People's Republic of China. GB 2760-2024 Standard for the Use of Food Additives.
[4] Sost Biotech Internal Technical Report. Pilot plant data of enzymatic hydrolysis-fermentation combined process, 2023.