1. History

2. Form

3. Growing

4. Nutritional analysis

5. Microgreens sprout comparison

6. Storage and commercial transport

7. References

Edible young greens and grains are produced from various kinds of vegetables, herbs or other plants. They range in size from {{convert|1|to|3|in|cm}}, including the stem and leaves. A microgreen has a single central stem which has been cut just above the soil line during harvesting. It has fully developed cotyledon leaves and usually has one pair of very small, partially developed true leaves. The average crop-time for most microgreens is 10–14 days from seeding to harvest.^[1][2]

History

Microgreens began showing up on chefs' menus as early as the 1980s, in San Francisco, California.^[1]

In Southern California, microgreens have been grown since about the mid{{nbhyph}}1990s. There were initially very few varieties offered. Those available were such as arugula, basil, beets, kale, cilantro and a mixture called Rainbow Mix. Having spread eastward from California, they are now being grown in most areas of the United States with an increasing number of varieties being produced.^[6] Today, the U.S. microgreens industry consists of a variety of seed companies and growers.^[1]

Form

Microgreens have three basic parts: a central stem, cotyledon leaf or leaves, and typically the first pair of very young true leaves. They vary in size depending upon the specific variety grown, with the typical size being {{convert|1|to|1.5|in|mm|abbr=on|0}} in total length. When the green grows beyond this size, it should no longer be considered a microgreen. Larger sizes have been called petite greens.^[3] Microgreens are typically 2–4 weeks old from germination to harvest.^[4] Both baby greens and microgreens lack any legal definition. The terms "baby greens" and "microgreens" are marketing terms used to describe their respective categories. Sprouts are germinated seeds and are typically consumed as an entire plant (root, seed, and shoot), depending on the species. For example, sprouts from almond, pumpkin, and peanut reportedly have a preferred flavor when harvested prior to root development. Sprouts are legally defined, and have additional regulations concerning their production and marketing due to their relatively high risk of microbial contamination compared to other greens. Growers interested in producing sprouts for sale need to be aware of the risks and precautions summarized in the FDA publication Guidance for Industry: Reducing Microbial Food Safety Hazards for Sprouted Seeds (FDA 1999).^[5]

Growing

Growing microgreens is relatively easy. Many small "backyard" growers have sprung up selling their greens at farmers markets or to restaurants. A shallow plastic container with drainage holes, such as a nursery flat or prepackaged-salad box, will facilitate sprouting and grow out on a small scale.^[6] Growing and marketing high-quality microgreens commercially is much more difficult.^[5] Artificial lighting is not necessarily needed for growing microgreens. This is because microgreens can grow under various lighting conditions, including under indirect natural light and grow lights, or even in complete darkness.^[7] Different lighting conditions can change the flavors of the microgreens being grown. For instance, corn microgreens are sweet when grown in the dark, but become bitter when exposed to light due to photosynthesis processes taking place in the sprouting plants.^[7]

Nutritional analysis

Researchers at the USDA Agricultural Research Service have published, as of early 2014, several studies that identify the nutritional make-up and the shelf life of microgreens. Twenty-five varieties were tested, key nutrients measured were ascorbic acid (vitamin C), tocopherols (vitamin E), phylloquinone (vitamin K), and beta-carotene (a vitamin A precursor), plus other related carotenoids in the cotyledons.

Among the 25 microgreens tested, red cabbage, cilantro, garnet amaranth, and green daikon radish had the highest concentrations of vitamin C, carotenoids, vitamin K, and vitamin E, respectively. In general, microgreens contained considerably higher levels of vitamins and carotenoids—about five times greater—than their mature plant counterparts, an indication that microgreens may be worth the trouble of delivering them fresh during their short lives.^[9]

Results of the microgreens research project conducted by the University of Maryland and the USDA has garnered attention from several national media outlets including National Public Radio (NPR) and The Huffington Post.^[13]

Microgreens sprout comparison

Sprouts are germinated or partially germinated seeds. A sprout consists of the seed, root, stem, while microgreens are harvested without the roots.{{Citation needed|date=January 2014}}

Microgreens have stronger flavors compared to sprouts, and come in a wide selection of leaf shapes, textures and colors.

Microgreens are grown in soil or soil-like materials such as peat moss. Microgreens require high light levels, preferably natural sunlight with low humidity and good air circulation. Microgreens are planted with very low seed density compared to sprout processing. Crop times are generally one to two weeks for most varieties, though some can take four to six weeks. Microgreens are ready to harvest when the leaves are fully expanded. Harvesting is usually with scissors cutting just above the soil surface, excluding any roots. Some growers sell them while still growing, rooted in the growing trays so that they can be cut later. Once removed from their growing environment, these trays of microgreens must be used quickly or they will rapidly begin to elongate and lose color and flavor.

Sprout seeds are soaked in water for usually eight hours and then drained. A high density of seed is placed inside of sprouting equipment or enclosed containers. The seed germinates rapidly due to the high moisture and humidity levels maintained in the enclosures. Seeds can also be sprouted in cloth bags that are repeatedly soaked in water. The sprouting process occurs in dark or very low light conditions. These dark, wet, crowded conditions are ideal for the rapid proliferation of dangerous pathogenic bacteria.{{Citation needed|date=January 2014}} After a few days of soaking and repeated rinsing in water (several times a day to minimize spoilage), the processing is complete and the sprouts are ready to consume.

The conditions that are ideal for properly grown microgreens do not encourage the growth of dangerous pathogens. These growing methods would not work for the production of sprouts.

However, the potential for food safety issues with microgreens may be increasing due to the number of indoor microgreen growing operations in which excessive seed density, low light intensity, low air circulation or most commonly, a lack of GAP (good agricultural practices) and GMP (good manufacturing practices) based food safety procedures. Certain provisions of the Guidance for Industry: Reducing Microbial Food Safety Hazards For Sprouted Seeds ^[14] may be beneficial and prudent for growers of microgreens to follow. Also, not all plants can be grown as microgreens due to toxicity concerns. For instance, nightshade plants (eggplants, tomatoes, potatoes, etc.) should not be grown as microgreen sprouts, since nightshade sprouts are toxic.^[7][8]

Storage and commercial transport

Microgreens have a short shelf life and better methods of storing and transporting microgreens are currently being studied, which at this time are mainly focusing on buckwheat.^[15] Commercial microgreens are most often stored in plastic clamshell containers, which do not provide the right balance of oxygen and carbon dioxide for any live greens to breathe.{{citation needed|date=May 2015}} Among package materials called films, differences in permeability, (see Permeation), are referred to as the oxygen transmission rate.

The ARS researchers found that buckwheat microgreens packaged in films with an oxygen transmission rate of 225 cubic centimeters per square inch per day had a fresher appearance and better cell membrane integrity than those packaged in other films tested. Following these steps, the team maintained acceptable buckwheat microgreen quality for more than 14 days—a significant extension, according to authors. This study was published in LWT-Food Science and Technology in 2013.^[9]

References

• Silo
• Siloam Cemetery
• Siloam, North Carolina
• Siloam Springs, Howell County, Missouri
• Siloam Springs State Park
• Siloam Township, Surry County, North Carolina
• Siloam tunnel
• Silo Asturias
• SILO (boot loader)
• Siloboura
• Siloca
• Silo cleaning
• Silodor Open Pairs
• Silodosin
• Silo (electronics)
• Silo High School
• Silo high school
• Silohuette
• Si Loin de Vous
• Si loin de vous (Hey oh... par la radio)
• Silo (library)
• Silo mentality
• Silom Line
• Si Lom Road
• Silone