Rosemary is an aromatic herb that is commonly used to flavor foods like roast meats, soups, and sauces. The distinctive pine-like flavor of rosemary comes from chemical compounds called volatile oils. These oils can be extracted from the rosemary leaves to create concentrated rosemary flavor that can be used in cooking and food manufacturing.
Quick Answers
Here are quick answers to common questions about extracting rosemary flavor:
- What part of the rosemary plant contains the flavor oils? The leaves and small stems contain the highest concentration of flavor oils.
- What methods can be used to extract the oils? Distillation, solvent extraction, supercritical CO2 extraction, or cold pressing.
- What is the main flavor compound in rosemary? Alpha-pinene, a terpene that gives rosemary its pine-like aroma.
- How is rosemary oil used? As a food flavoring or ingredient in products like seasonings, marinades, sauces, and aromatherapy oils.
- Is extracted rosemary oil edible? Yes, food-grade rosemary oil can be safely consumed.
Active Compounds in Rosemary
The characteristic flavor and aroma of rosemary come from phytochemicals called volatile oils or essential oils. The main volatile oils in rosemary include:
- Alpha-pinene – A monoterpene that gives rosemary its piney, herbaceous smell. It has anti-inflammatory effects.
- 1,8-cineole – Also called eucalyptol, this is a monoterpene with a camphor-like scent. It has antioxidant and antimicrobial activities.
- Camphor – A terpene with a strong camphoraceous aroma. It has antibacterial and anti-fungal effects.
- Borneol – A bicyclic terpene alcohol with a piney-camphor scent. It has anesthetic and antioxidant effects.
- Beta-caryophyllene – A sesquiterpene with a woody, spicy aroma. It has anti-inflammatory and pain-relieving properties.
These volatile plant oils are responsible for rosemary’s use as a food flavoring and in aromatherapy. They can make up 1-2.5% of the weight of fresh rosemary leaves. The exact oil composition depends on the rosemary variety, geographical origin, and growing conditions.
Extraction Methods
There are several ways the flavorful phytochemicals can be extracted from rosemary leaves:
Distillation
Steam distillation is the most common method. Rosemary leaves are placed in a still with water. The mixture is heated to boil the water. The steam captures the volatile oils from the rosemary and condenses it back to a liquid essential oil.
Water distillation is slower but gentler than steam distillation. The rosemary soaks in hot water, which takes longer to extract the oils.
Solvent Extraction
A solvent like hexane or ethanol is used to extract the oils from rosemary. The leaves are soaked in the solvent, which dissolves the volatile compounds. The solvent is then evaporated off, leaving concentrated rosemary oil.
Supercritical CO2 Extraction
Carbon dioxide is put under high pressure and temperature to reach a “supercritical” state. This allows it to take on solvent-like properties. The supercritical CO2 is passed through chopped rosemary to extract the oils.
Cold Pressing
Rosemary leaves are crushed to release the oils, then pressed slowly at a low temperature. This is a gentler approach than distillation.
Solvent extraction and supercritical CO2 extraction require expensive equipment. For home DIY extraction, distillation or cold pressing are the most accessible methods.
Using Extracted Rosemary Oil
The concentrated rosemary flavor extracted into the essential oil has many culinary uses:
- It can be added to soup stocks, marinades, sauces, baked goods, and other foods as a flavoring.
- Drops of oil can be stirred into olive oil and vinegar to infuse salad dressings.
- The oil can be blended with seasonings to make homemade rubs for meat.
- It is an ingredient in some liqueurs like Benedictine.
- It can flavor aromatherapy oil blends for diffusers.
- Rosemary oil can be added to cosmetics like shampoos and skin creams.
The appropriate amount of rosemary oil to use depends on the specific recipe and strength of the oil. Start with small amounts like 1/4 teaspoon per pound of meat or 1-2 drops per tablespoon of sauce and adjust to taste.
Making Homemade Rosemary Oil
It’s possible to extract rosemary oil at home with simple kitchen equipment. Here is an overview of DIY methods:
Infusing Oil
Fresh rosemary can be infused into a carrier oil like olive or grapeseed oil. This involves:
- Rinse rosemary sprigs and dry well.
- Pack rosemary loosely into a small glass jar.
- Pour oil over rosemary until it’s completely covered.
- Cover jar tightly and place in a sunny spot. Let steep for 2 weeks.
- Strain oil through cheesecloth into an airtight container.
The infused oil will keep for several months stored in a cool, dark place. It can be used for sautéing, salad dressings, marinades, etc.
Distilling
A basic stove-top distillation setup can extract rosemary oil using steam:
- Pack freshly chopped rosemary into a distiller pot.
- Add enough water to just cover the rosemary.
- Bring to a boil, then lower to a simmer.
- As steam rises, it cools and condenses back into liquid in the connected condenser.
- Collect the distilled liquid in a container. Separate the oil from water.
More complex distillation equipment like a still with fractionating column will increase efficiency and yield more pure rosemary oil.
Cold Pressing
While less efficient than distillation, rosemary oil can also be released by cold pressing:
- Harvest rosemary leaves and chop finely.
- Wrap chopped rosemary in a towel and crush with a mallet or rolling pin.
- Place bundle in a press and slowly apply pressure to squeeze out oil.
- Collect expressed oil in a jar.
Cold pressing is time and labor intensive, but avoids exposing the oil to heat damage.
| Extraction Method | Equipment Needed | Yield | Advantages | Disadvantages |
|---|---|---|---|---|
| Infusing Oil | Glass jar | Low |
|
|
| Distilling |
|
High |
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| Cold Pressing |
|
Low-Medium |
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|
Purchasing Rosemary Oil
For convenience, it’s often easier to buy pre-made rosemary essential oil. When purchasing rosemary oil, look for:
- Pure oil – It should contain 100% rosemary oil without additives or adulterants.
- Food-grade – If using the oil for cooking, it must be food-safe and FDA approved.
- Reputable brand – High quality oil from brands known for purity like DoTerra, Plant Therapy, or Edens Garden.
- Dark glass – It should come in an opaque bottle to protect from light damage.
- Refrigerate after opening – For maximum shelf life, store opened bottles in the fridge.
Avoid rosemary oil labeled “fragrance oil,” “perfume oil,” or “flavored oil” as these are synthetic and don’t provide the same benefits.
Storage and Shelf Life
Extracted rosemary oil should be stored properly to maximize its shelf life. General storage guidelines include:
- Keep in air-tight containers in a cool, dark place.
- Refrigeration can extend the lifespan, especially for culinary oils.
- Shelf life depends on the oil quality, but can range from 1-3 years.
- Watch for signs of spoilage like odor changes, cloudiness, or rancidity.
- Oxygen, light exposure, and heat damage can cause oils to degrade faster.
Infused oils have a shorter shelf life around 2-3 months due to their water content. Refrigeration is especially important for homemade infusions.
Properly stored rosemary oil can retain its flavor, aroma, and health benefits for future use in your cooking recipes or aromatherapy blends.
Health Benefits
In addition to providing flavor, compounds in rosemary oil offer a variety of potential health benefits:
Antioxidant Activity
Rosemary oil contains antioxidant compounds like rosmarinic acid, carnosic acid, and carnosol. These can help stabilize free radicals and protect cells from oxidative damage.
Anti-Inflammatory Effects
The terpenes in rosemary oil like alpha-pinene and beta-caryophyllene have demonstrated anti-inflammatory actions. This can help reduce inflammation involved in arthritis, injuries, digestive issues, and heart disease.
Improved Memory and Focus
Inhaling rosemary oil appears to increase alertness and enhance cognitive functions like memory recall, focus, and information processing speed.
Antimicrobial Properties
Studies reveal rosemary oil can inhibit the growth of bacteria like E. coli, Salmonella, Staphylococcus aureus and Candida albicans. This suggests it has antimicrobial effects against common pathogens and may help preserve foods.
However, most research has used concentrations much higher than typical culinary levels. Further studies are needed on its antimicrobial efficacy in foods.
Possible Side Effects and Safety
Rosemary oil is likely safe for most people in the small amounts used for cooking and aromatherapy. However, potential side effects can include:
- Skin irritation – Large amounts of rosemary oil applied directly to the skin may cause irritation, redness or allergic reactions in some individuals.
- Gynecological issues – Women who are pregnant, breastfeeding or have endometriosis may want to avoid large or medicinal amounts of rosemary due to possible hormone-like effects.
- Seizures – There are isolated reports of rosemary oil triggering seizures in people prone to epilepsy. It may interact with anticonvulsant medications.
- High blood pressure – Rosemary may raise blood pressure in people with hypertension.
Overall, normal food consumption is widely considered safe. But consult your doctor before ingesting any essential oils or using them medicinally.
Conclusion
Rosemary is an extremely versatile herb. Its pine-like fragrance comes from healthy phytochemicals that can be extracted as a flavorful essential oil.
Distillation produces the highest quality rosemary oil, but it can also be extracted through solvents, CO2, or by simply infusing the leaves in a carrier oil.
Incorporating just a small amount of rosemary oil allows you to add concentrated flavor to soups, meats, sauces, and more. And the active compounds offer additional antioxidant, antimicrobial and health benefits.
So experiment with this robust Mediterranean herb to add a savory depth and slight floral aroma to many dishes.
