Trehalose is a naturally occurring sugar found in various organisms, from plants and fungi to insects and marine life. It is widely used in the food industry, and its presence in both natural and processed foods has led to questions about its properties and effects on human health. This article explores trehalose, its roles in food, and its safety for consumption.
Understanding Trehalose
Trehalose is a disaccharide, a sugar composed of two alpha-glucose molecules joined by a unique α,α-1,1-glycosidic bond. This chemical linkage makes trehalose highly resistant to acid hydrolysis, allowing it to remain stable under high temperatures and acidic conditions often encountered in food processing. Unlike some other sugars, trehalose is a non-reducing sugar, meaning it does not participate in browning reactions with amino acids and proteins, known as the Maillard reaction. This stability contributes to its utility.
Presence in Food
Trehalose is found in many natural sources and is also added to a wide range of processed foods. Naturally, it occurs in significant amounts in certain mushrooms, such as shiitake, oyster, and king oyster varieties, sometimes referred to as “mushroom sugar.” It is also synthesized by yeast, including baker’s yeast, and is present in certain insects, like grasshoppers, locusts, and bees, where it serves as a primary circulatory sugar. As a food additive, trehalose is identified as E957 in Europe and is generally recognized as safe (GRAS) in the United States. In processed foods, it is often manufactured through enzymatic conversion from starch, such as cornstarch or tapioca starch.
Functional Roles in Food Production
Trehalose serves several functions in food production, making it a versatile ingredient. It retains moisture, preventing dehydration and maintaining texture in products like baked goods, dried fruits, and processed meats. It achieves this by forming a stable, glass-like structure that encapsulates water molecules, extending shelf life and preventing staling.
Trehalose also acts as a stabilizer, protecting proteins and cells from damage during extreme conditions like freezing, thawing, and heat processing. It is particularly useful in frozen desserts, such as ice cream, where it can reduce the formation of ice crystals, resulting in a smoother texture. In seafood, trehalose helps maintain the integrity, hardness, and gel strength of proteins, especially at low temperatures.
In terms of sweetness, trehalose provides a mild taste, typically about 45% to 50% as sweet as sucrose (table sugar). This lower sweetness allows food manufacturers to reduce the overall sugar content in products while still maintaining texture and body. Trehalose can also enhance certain flavors and mask undesirable off-notes, such as bitterness from proteins or high-intensity sweeteners, and can even amplify salty and citrus flavors.
Human Health and Dietary Trehalose
When consumed, trehalose is digested by an enzyme called trehalase, primarily found in the brush border of the small intestine. This enzyme breaks down trehalose into two glucose molecules, which are then absorbed into the bloodstream. Trehalase activity can vary among individuals, with some having lower levels or a deficiency, which may lead to digestive discomfort similar to lactose intolerance if large amounts are consumed.
The glycemic response to trehalose is lower and more gradual compared to other common sugars like sucrose. While it contributes approximately 4 calories per gram, its slower digestion prevents a rapid spike in blood sugar levels. This characteristic has led to research exploring its potential benefits for glucose metabolism and insulin sensitivity, with some studies suggesting it may help improve glucose tolerance.
Trehalose is considered safe for the general population as a food ingredient. It has received “generally recognized as safe” (GRAS) status from the U.S. Food and Drug Administration (FDA) and an “acceptable daily intake not specified” by the Joint WHO/FAO Expert Committee on Food Additives (JECFA). However, some research has explored its interaction with gut microbiota. Studies in mice have suggested a link between trehalose consumption and the proliferation of specific strains of Clostridioides difficile (C. diff), a bacterium that can cause severe intestinal infections. Other research indicates that trehalose supplementation may prevent simulated C. diff infection by promoting the growth of beneficial bacteria that compete with C. diff. This remains an area of ongoing scientific investigation, and current evidence does not definitively establish a negative impact for the general public from dietary trehalose.