What is Happening in the Herb Garden and Kitchens This Week?

By Barbara F. Smith

Research for this week’s column has taken an interesting turn. Many readily available reference books on herbs provide information dating back centuries, occasionally millennia, including wonderful historical and folklore information, in addition to describing the customary cultivation and uses of countless herbs. Granted, many of those sources are usually European or North American-focused. To my surprise, not many of those “regulars” include information on this week’s herb – stevia. Which is to say, much of what follows has more to do with modern times.

Stevia rebaudiana is a herb native to Paraguay and Brazil, where the Guarani Indians used the ‘Ka’a He’ê” leaves as a sweetener in traditional bitter drinks for hundreds, perhaps thousands, of years. Occasionally, stevia is referred to as “sugar grass” or “yerba dulce” (sweet leaf). The Latin genus “Stevia” derives from a Spanish botanist named Pedro Jaime Esteve. The species “rebaudiana” honors Paraguayan chemist Ovidio Rebaudi. The ‘discovery’ of the sweet herb was revealed in 1899 by Moises Bertoni, a Swiss-born scientist who emigrated to Paraguay and lived there for 44 years, during which time he classified more than 7000 plants. In 1905, he gave the name to the herb that it bears today.

Stevia is a tender perennial (in zone 9 and higher) within the large Asteraceae/Compositae/sunflower family of plants, containing such other familiar plants as arnica, calendula and santolina. An unassuming plant to look at, stevia grows up to 30 inches tall, with clusters of tiny white flowers (see photo above). In the garden, stevia likes heat and humid conditions. Leaves should be harvested late in the season for the most sweetness, dried on a screen or in a low-temperature oven, then crumbled or crushed as needed. In our climate, the plant can be overwintered indoors as a houseplant.

The compounds in stevia leaves, known as steviol glycosides, provide sweetness anywhere from 40 to 300 times greater than sugar, depending on where the plant is grown. In small amounts, the leaves taste sweet, but in larger amounts, the flavor turns bitter. Some describe stevia’s flavor as delicate, reminiscent of mild licorice, or possibly menthol. Stevia has no calories and a glycemic index of zero, so it is a good choice for people who want to avoid sugar in their diet. Much of the information on stevia focuses on the use of sweetness in food and beverages. Following its approval by the FDA — more on that later — stevia is now available as a powder or a clear liquid extract. It comes in tabletop packets, liquid drops, dissolvable tablets, and spoonable products, as well as in baking blends.

However, products containing stevia were not generally available in the first half of the 1900s. A 1928 Washington Post article described stevia as a “wonder plant,” but the attention declined. During World War II, stevia began to be consumed in the United Kingdom due to sugar shortages and rationing of sugar consumption. In the 1960s, Japanese farmers took an interest in stevia, when they began to grow it commercially. Now, China, Paraguay, Brazil, and India produce the bulk of stevia grown worldwide. Stevia may be found in such varied products as soft drinks, candy and snack foods, pickles, meat pastes, soy sauce, and ice cream.  

Here in the United States, following the introduction of the synthetic sweetener aspartame in 1983, the Food and Drug Administration (FDA) moved to ban stevia as a food additive, a decision which was seen by some as an effort to protect the aspartame product NutraSweet. In 1995, the FDA approved the use of stevia as a dietary supplement, but not as a sweetener.vLater, in 2008, after a vigorous food safety study, the FDA reclassified high-purity extracts of stevia as “GRAS” – Generally Regarded As Safe.vToday, purified stevia extracts are allowed and commonly used in products sold in the United States.

Beyond use in food products, stevia’s properties have been studied for more than a century; that research confirms the efficacy of stevia leaf preparations for use in treating certain health conditions. Such research has determined that the biological properties of stevia extract are anti-hypertensive, anti-obesity, anti-diabetic (by stimulating insulin production), antioxidant, anti-inflammatory, and antimicrobial; they also have been shown to support improvement of kidney function and to have protective effects on the digestive system. Stevia helps stop the growth of microorganisms that cause tooth decay.

Turning to more modest kitchen/culinary uses for stevia, it is a natural sugar substitute – using stevia to sweeten lemonade or tea seems reasonable. However, before you cook with it, check the stevia package for details on the sugar-to-stevia ratio. Baking results will vary because of the different chemical makeup compared with sugar. For example, stevia won’t caramelize, form a meringue or harden into candy.  

The next time you visit the BBG Herb Display Garden, look for the stevia plant.  Who would suspect by looking at it how much research has been done, and funding has been spent, on this particular herb!

WHAT’S HAPPENING IN THE BBG KITCHEN?

Apple mint, chocolate mint and lemon mint (see photo) were all harvested, and the indoor Herb Associates crew set the plant material to dry. The lovely red leaves of opal basil and shiso/perilla (see photo) were infused in separate vinegars, to be ready either to bottle “as is” or to incorporate in a salad dressing or marinade yet to be assembled. Still more opal basil was made into jelly (serving suggestion in last week’s column). Labels were added to a large batch of ever-popular Herb Mustard and taken to the Gift Shop. This season, the Kitchen Crew has added several new products – Herb Finishing Salts for that extra crunch and flavor explosion added just before serving, and Herb Infused Sugars, which enhance many recipes from baked goods to cocktails. 

For lemon lovers out there, the Kitchen Crew aimed to please with products in several categories. Try Lemon Balm and Lemon Verbena Jelly, Dill Lemon Vinaigrette, Sage and Lemon Balm Finishing Salt, and Lemon Balm and Lemon Zest Infused Sugar – Yum! The Kitchen Crew also prepared a batch of Strawberry Mint Shrub and Lovage Finishing Salt.  

Looking for that perfect hostess gift, birthday present or treat for yourself?  Try one or more of these delicious handmade products, found in the BBG Visitors’ Center Gift Shop.  Proceeds benefit the Garden.

Particular Resources:  reports by the National Library of Medicine, National Center for Biotechnology Information, National Institute of Health (September 2021) [pmc.ncbi.nlm.nih.gov] “Natural sweetener Stevia rebaudiana: functionalities, health benefits and potential risks;” “FDA Regulatory Approach to Steviol Glycosides” (2018); “The Global Origins of a Paraguayan Sweetener” Journal of World History (June 2016); The New American Herbal by Stephen Orr, Clarkson Potter Publishers (2014); The Culinary Herbal by Susan Belsinger & Arthur O. Tucker, Timber Press (2016)

The Berkshire Botanical Garden’s Herb Associates began in 1957 and has been making and selling products for the benefit of BBG ever since. At BBG, the Herb Associates oversee a display garden and production garden, both located near the Center House. Members/volunteers meet every Tuesday morning during the late spring through mid-autumn each year, coinciding when the gardens themselves are open to the public. Members plant, weed and tend the gardens, as well as harvest and process the variety of herbs.