Trehalose is a naturally occurring disaccharide, a type of sugar composed of two glucose molecules. What sets it apart from common sugars like sucrose or glucose is its ability to stabilize biological materials. This unique sugar is found widely in various organisms.
What is Trehalose and Its Natural Occurrence
Trehalose consists of two α-D-glucose units joined by an α,α-1,1-glycosidic bond, which gives it high stability against acid hydrolysis and heat. This specific linkage also makes it a non-reducing sugar, meaning its aldehyde or ketone end-groups do not readily react with proteins, a process known as glycation.
This disaccharide is prevalent in many forms of life, excluding mammals. It is found in plants such as resurrection plants, sunflower seeds, and various algae, where it contributes to their resilience in harsh environments. Fungi, including mushrooms like shiitake and maitake, along with yeasts used in brewing and baking, also contain trehalose.
In the insect world, trehalose serves as a primary blood sugar and an energy reserve. Honeybees, silkworms, grasshoppers, and butterflies all utilize trehalose for energy, particularly for activities like flight. Microorganisms, including various bacteria and yeasts, synthesize and store trehalose, sometimes in substantial amounts, accounting for up to 10% to 20% of their dry weight. Organisms produce trehalose primarily for protection against environmental stresses, a role that extends beyond simple energy storage.
The Unique Properties of Trehalose and Its Diverse Applications
Trehalose exhibits remarkable protective properties that enable organisms to endure extreme conditions. One such property is desiccation tolerance. Trehalose forms a “glass” or amorphous solid when water is removed, effectively immobilizing and protecting cellular structures from drying out.
The sugar also excels at protein stabilization, preventing proteins from denaturing or aggregating when exposed to stressors like heat, cold, or drying. It is believed to replace water molecules around proteins and membranes, maintaining their three-dimensional structure. Furthermore, trehalose contributes to membrane protection, helping to preserve the integrity of cell membranes under low temperatures.
These unique properties translate into diverse applications. In the food industry, trehalose acts as a stabilizer, texture enhancer, and cryoprotectant. It helps retain moisture in baked goods, maintaining freshness, and improves the texture and freeze-thaw stability of frozen foods by inhibiting ice crystal formation. It can also adjust sweetness in candies and beverages, and prevent discoloration in fruits and vegetables.
In pharmaceuticals and biotechnology, trehalose is used to stabilize sensitive biological materials such as vaccines, proteins, and enzymes. Its cryoprotective abilities are also leveraged in the preservation of cells and organs for transplantation. Cosmetic products incorporate trehalose for its moisture-retention capabilities.
Beyond these uses, trehalose finds application in agriculture as a stress protectant for crops. It helps plants withstand abiotic stresses like drought, high salinity, and extreme temperatures by acting as an osmoprotectant, stabilizing cellular components, and promoting antioxidant activity. Genetic engineering and exogenous application of trehalose are being explored to enhance crop yields and improve stress tolerance in plants.
Trehalose and Human Health
When consumed, trehalose is metabolized in the human body by the enzyme trehalase, found in the small intestine. This enzyme breaks down trehalose into two glucose molecules, which are then absorbed into the bloodstream.
While most healthy individuals can digest trehalose without issues, some people have a deficiency in the trehalase enzyme, which can lead to digestive discomfort such as bloating or diarrhea if undigested trehalose reaches the large intestine. Trehalose has a lower glycemic index compared to glucose, causing a less rapid increase in blood sugar levels. Its sweetness is about 40-45% that of sucrose.
Ongoing research explores trehalose’s potential roles in various health conditions, including neurodegenerative diseases like Alzheimer’s and Parkinson’s, and metabolic disorders. Studies suggest trehalose might offer neuroprotective effects by enhancing autophagy, reducing protein aggregation, and mitigating oxidative stress. However, these are areas of active investigation, and trehalose is not an established treatment for these conditions. Trehalose is recognized as safe (GRAS) by regulatory bodies, including the U.S. Food and Drug Administration (FDA) and the Joint WHO/FAO Expert Committee on Food Additives (JECFA), for use as a food additive.