Satiety can be difficult to pronounce much less understand, yet this term is likely to become part of the baking industry’s jargon as more focus is placed on health and wellness. Understanding consumers’ eating behavior has always been an important factor for manufacturers of baked products. Meeting consumers’ expectations for healthier products that deliver great taste that bakers must develop products that perhaps offer more volume with fewer calories without sacrificing flavor.
While hunger and appetite represent the physiological and psychological need and desire to eat, respectively, satiety describes the opposite end of the hunger/appetite spectrum–representing both the physiological and psychological feeling of fullness. What researchers have discovered is that it isn’t only the quantity of food that promotes satiety, but its macronutrient (i.e., protein, carbohydrate, fat) and ingredient composition, such as fiber and whole grains. As such, bakers are taking more of an interest in ingredient selection as they strive to satisfy weight conscious consumers’ hunger and appetite with smaller portions and reduced calorie offerings.
Satiety’s mechanism
One of the reasons behind the somewhat nebulous definition of satiety is the subjectivity of its measurement. For instance, what triggers the psychological sensation of fullness? And, do these factors not vary by individual? According to the article entitled “Satiety enhancers in food,” European Food Scientist magazine (Nov. 19, 2007; www.scientistlive.com), “satiety results from eating food that makes people
stop eating.”
Not to complicate matters, but the terms satiety and satiation have different meanings. Satiation refers to the point at which a meal, or that which is eaten at one sitting, satisfies hunger. In other words, a person is satiated when that particular meal ends. Satiety describes the effects of a meal after it has ended. The mechanisms involved range from those involved with digestion, such as gastric distention and emptying, to more complex hormonal effects.
“Soluble and insoluble fiber have a slightly different mechanism in how they affect satiety,” explains Rajen Mehta, Ph.D., senior manager, fiber applications and technical service, SunOpta Inc., Bedford, Mass. “Soluble fiber tends to build up viscosity, which affects gastric distention and how long it stays in the small intestine. Soluble fiber tends to maintain a viscosity, so consequently there’s a delay in feeling hungry for a long time. Insoluble fiber’s satiation effect is more the case of load. It’s a bulking effect without the calories. Insoluble fiber gives a very fast effect on satiation and then fullness continues for a long time as long as the fiber stays in the digestive system.”
Nutrient absorption is another factor that affects satiety. It’s not just the rate, but the amount that’s absorbed, notes Mehta. For instance, simple sugars are absorbed more rapidly than complex carbohydrates, such as starch, causing a person to feel hungry sooner. Material that is digested more slowly provides a
prolonged feeling of fullness.
Peggy Dantuma, manager, bakery applications group, Kerry Ingredients, Hoffman Estates, Ill., explains how satiety might be measured: “Probably the most preliminary method is to have people eat food of the same caloric value, say a serving that has 240 calories, and ask them questions at different intervals about how full they are.”
“Researchers can also measure body temperature,” adds Dantuma. “Typically, body temperature is going to increase when food is being digested, and that in turn is going to cause a hormone release. You can measure both of these things, the body temperature increase and the release of this hormone.”
Formulating for satiety
Fats, proteins and non-fiber carbohydrates contribute caloric value to foods. Although researchers have in the past suggested that fat promotes satiety because of its delayed stomach emptying, it may actually not be effective at increasing satiety because its sensory enhancing properties stimulate overeating, notes Mehta. On the other hand, studies do indicate that protein, monosodium glutamate, nucleotides and certain types of carbohydrates promote fullness.
Dairy Management Inc. (DMI), Rosemont, Ill., recently completed a thorough review of scientific literature on the effects of protein, dairy protein and whey on satiety, notes Sharon Gerdes, DMI technical support consultant, Richlandtown, Pa. According to this paper entitled “Protein, Dairy Protein and Whey: Effects on Satiety and Food Intake Regulation,” (© 2007, National Dairy Council), “Data directly comparing dairy proteins to other protein sources in humans suggest that whey has a greater effect on satiety versus casein, egg albumen and carbohydrate.”
Kerry Ingredients developed some proprietary ingredients that promote satiety. “In one particular ingredient–Micellnor protein–we filter casein micelles from fresh nonfat milk using proprietary membrane technology,” Dantuma explains. “We have these casein micelles, which are basically the building blocks of milk. They’re still intact, which gives them a great water holding capacity. They also release slowly in the bloodstream. One of the other unique things about them is, since the micelles are intact when you eat them, it’s similar to the way cheese is produced in that when they get to the acid content of the stomach, they basically coagulate, which makes them slower to digest and takes longer to release in the body. This prolonged gastric emptying helps with satiety.
Water also is a key factor in building satiation, particularly when it is incorporated into the food’s matrix. Fiber brings a lot of water into a formulation because of its water-binding properties, notes Dantuma. Fiber also is beneficial because it is digested slowly, or not at all. Still, all fibers are not created equal, adds Mehta. Viscosity is key when using soluble fiber. For example, hydrolyzed guar gum likely does not have the same effect on satiety as non-hydrolyzed guar, simply because of the differences in viscosity.
Using the right insoluble fiber also is important. “There are 14 different insoluble oat fibers that we sell, and each one has a slightly different effect on texture and water-binding properties,” explains Mehta. “How do you choose the right soluble/insoluble fiber and resistant starch recognizing that a lot of the time resistant starch won’t give you much of a satiation effect, but it incrementally gives you a good taste? Balancing some of these things out are some of the challenges that food scientists face.”
Mehta usually recommends a 75:25 ratio of insoluble to soluble fiber, especially when formulating for very high fiber levels. The soluble fiber portion may be comprised of inulin and gums, if formulation and functional characteristics permit. The addition of fiber, such as resistant starch, gives a texture associated with starch, and bran gives the formuation a boost of
whole grain.
Polydextrose and satiety
Historically, polydextrose, a polysaccharide derived from glucose, sorbitol and citric acid, was known as an effective bulking agent. A specialty carbohydrate that only contributes one Kcal per gram also is now considered a prebiotic fiber that is partially fermented in the colon and has digestive health benefits, notes Donna Brooks, regional director, sweetener and pectin, Danisco USA Inc., Elmsford, N.Y.
Reduced calorie baked products made with polydextrose can impart an increased feeling of fullness or satiety, allowing consumers to delay a feeling of hunger longer, Brooks adds. In addition, a major portion of the sugar and fat can be replaced in a standard muffin when polydextrose is used in combination with lactitol, a disaccharide polyol. This effectively reduces the caloric density of the muffin by 25 percent.
Bakers will turn to many of these satiety-promoting ingredients as they strive to develop products that have fewer calories, and yet deliver on taste and fullness. These products should not only provide a feeling of fullness, but help delay the feeling of hunger.
“We know through market research that satiety is a compelling benefit to consumers because it is a simple, easy-to-understand aid to weight management and weight loss, that is, you feel full, so you snack less,” Gerdes says. “It’s no wonder that companies are interested in it."