How to preserve mint leaves

In this brief guide, we will answer the question “How to preserve mint leaves” and discuss the different methods used to preserve mint leaves.

How to preserve mint leaves

In 1995, the global market for medicinal herbs was approximately USD 17 billion, but a recent market analysis suggests that by 2023 this will increase to approximately USD 111 billion (compound annual growth rate of 7% to 8%) (1).

Mint leaves can be preserved by refrigerating, freezing, dehydrating and making mint sugar. Mint leaves are added as a flavor to many dishes and are also used in cocktails.

How to preserve mint leaves by refrigerating

Fresh mint leaves can be preserved by refrigeration. A study showed that the color of mint leaves and stems did not change significantly after 21 days of storage at 0°C, but there was a decrease in the phenolic compounds and the flavonoid content was 45% below the starting value (2).

To refrigerate mint leaves in a plastic bag or container:

  • Clean and wash the leaves.
  • Place them in a bag with a damp towel or wrap the leaves with a damp towel. The damp towel will retain the moisture and prevent the leaves from wilting.
  • Next, place in a plastic bag or a container and cover loosely. Do not seal the bag as the build-up of too much moisture could cause mold growth.

To refrigerate mint leaves in water:

  • Place clean mint leaves with the ends trimmed in a glass.
  •  Pour about 1 inch of water into the glass.
  • Cover the glass loosely with a bag or paper towel and place it in the refrigerator.
  •  If the water in the glass turns cloudy, drain it off and replace it with new water.

A study showed that  leafy parsley stored under cold storage conditions keep more ascorbic acid when stored using the traditional method of tufts immersed in water (3).

How to preserve mint leaves by freezing

Preservation of foods usually involves technologies that prevent microbial growth as well as retard quality degradation reactions. Among such processes, freezing is a proven and efficient method. For vegetables, freezing is widely recognised as the most satisfactory method for long-term preservation, and it is an important segment of the frozen food market (4).

Freezing preserves both the flavor and texture of mint leaves. There are several methods to freeze mint leaves. Mint leaves can be frozen either whole or chopped.

To freeze whole mint leaves without water (5):

  • Wash and dry the mint leaves.
  • Place the mint leaves in a ziplock bag and squeeze out all the air. A vacuum sealer can be used to freeze mint leaves if available.
  • Seal, label and place the bag in the freezer.

Mint leaves can also be frozen in ice cube trays with water. Whole mint leaves frozen in water can be easily added to drinks such as lemonade and cocktails.

To freeze whole mint leaves in water :

  • Wash the mint leaves.
  • Add one or two mint leaves into each cubicle of an ice cube tray.
  • Top-off with clean water. Lemon juice can be used instead of water.
  • Place the tray in the freezer.

To freeze chopped mint leaves in water:

  • Wash and dry the mint leaves using a paper towel.
  • Trim the stems and chop the mint leaves.
  • Transfer 1 to 2 teaspoons of mint leaves into each cubicle of an ice cube tray.
  • Top-off with clean water. Lemon juice can be used instead of water.
  • Place the tray in the freezer.

After freezing, the ice cubes with the mint leaves can be transferred into a ziplock bag, sealed and returned to the freezer.

Frozen mint leaves will retain their flavor for about 3 months.

How to preserve mint leaves by dehydration

Drying is one of the oldest methods of food preservation and represents a very important aspect of food processing. Drying of food products is aimed at longer storage periods, lower packaging requirements and shipping weights (6).

There are several methods to dehydrate mint leaves. After dehydration, the leaves must be stored in an airtight container in a cool, dry place. Mint leaves can also be crushed using a food grinder and then stored in an airtight container.

Dehydrated mint leaves last for 1 to 3 years when stored properly. Dried foods should be stored in cool, dry, dark areas. Recommended storage times for dried foods range from 4 months to 1 year. Because food quality is affected by heat, the storage temperature helps determine the length of storage; the higher the temperature, the shorter the storage time. Most dried fruits can be stored for 1 year at 60ºF, 6 months at 80ºF. Vegetables have about half the shelf-life of fruits (7).

Mint leaves can be dehydrated by:

  • Air drying 
  • Oven drying
  • Microwave drying
  • Using a food dehydrator

To dehydrate mint leave by air drying:

  • Wash and dry a bunch of mint leaves, do not remove the cut or trim the leaves.
  • Cover a bunch of mint leaves with a paper bag.
  • Hang the paper bag upside down in a well-ventilated, dark and dry area.

Dehydrating mint leaves by air drying takes a long time and it will take at least 1 to 2 weeks to completely dehydrate the leaves. 

To dehydrate mint leaves by oven drying:

  • Wash, drain and blot the mint leaves using a paper towel.
  • Set the oven to the lowest temperature setting.
  • Place the leaves in an oven tray lined with parchment paper or on a cookie sheet.
  • Place in the oven for 2 to 4 hours.
  • Make sure to check on the leaves every 30 minutes or so and slightly toss the leaves to prevent them from burning.

To dehydrate mint leaves by microwaving:

  • Wash, drain and blot the mint leaves using a paper towel.
  • Place the leaves in a paper towel.
  • Microwave for 1 to 2 minutes. If the leaves are not done in 2 minutes, keep microwaving by increasing time for 10-second intervals.

To dehydrate mint leaves by using a food-dehydrator:

  • Wash, drain and blot the mint leaves using a paper towel.
  • Place the leaves on the dehydrator tray and follow the instructions of the dehydrator manual.

How to preserve mint leaves by making mint sugar

Chopped mint leaves can be mixed with sugar and stored for about a month. More about making mint sugar and mint preservation can be found here.

Conclusion

In the brief guide, we answered the question “how to preserve mint leaves” and discussed the different methods of preserving mint leaves. 

If you have any questions or comments, please let us know.

References 

  1. Ałtyn I, Twarużek M. Mycotoxin Contamination Concerns of Herbs and Medicinal Plants. Toxins. 2020, 12, 182.  
  2. Curutchet, Ana, et al. Nutritional and sensory quality during refrigerated storage of fresh-cut mints (Mentha× piperita and M. spicata). Food chem, 2014, 143, 231-238.  
  3. Sitarek-Andrzejczyk, Monika, Jarosław Przybył, and Marek Gajewski. The effect of post-harvest treatment and storage conditions on vitamin C content in two leafy parsley cultivars. International scientific conference RURAL DEVELOP, 2017
  4. Evans, Judith A., ed. Frozen food science and technology. John Wiley & Sons, 2009.
  5. Preserving herbs. 2022. South Dakota State University.
  6. Dattatreya, M. Kadam, and Kumar Gupta Manoj. Thin layer convective drying of mint leaves. J Med Plants Res, 2011, 5, 164-170.
  7. Drying Packaging and Storing Dried Foods. National Center for Home Food Preservation.