Technical Talk: March 2007

New Ways to Satisfy Appetites.  Innovation in satiety means eating less and feeling full…

This column is written by Dr. John Michaelides of the Guelph Food Technology Centre 519-821-1246, www.gftc.ca

Question: What is satiety, and how can low-caloric food products be developed to help achieve it?

Answer:  Satiety is not a term that consumers tend to be familiar with. The term describes the state of feeling full or being gratified beyond satisfaction. It is the opposite of feeling hungry or having the appetite to eat more. Modern western society in developed countries has evolved around the notion of overeating. For example, the practice of offering appetizers prior to a meal stimulates overeating. We are now facing the epidemic of obesity, and the various chronic diseases that are associated with it.  So, if we can help people feel full (achieve satiety) with foods that do not contribute to gaining body weight (lower energy intake), this will be a valuable tool in combating obesity.

The feeling of being full is not simply a function of the amount of food we eat, but also of the composition of food. Components such as water, fibre, protein and other nutrients contribute to satiety. Some will physically fill the gut, and will not be digested, while other components may affect gut hormones that influence appetite. Specifically, the hormone ghrelin, is a hormone produced in the stomach and stimulates appetite. Australian researchers have developed the satiety index, which is based on evaluating foods in terms of how satisfied they make people feel, and how long the satiety lasts.  They used white bread as a baseline, with a score of 100. They evaluated 38 different foods, and scored them according to whether they satisfied the individual, and how long the individual was individual satisfied. Foods that scored less than a 100 were found to be less satisfying, and therefore, people who eat them will become hungry much sooner, and will tend to eat more in the course of a day.  On the other hand, foods that score higher than a 100 were deemed more satisfying, and will keep hunger down for a longer period of time.  Based on this index, baked goods such as cakes, croissants and doughnuts were rated with a satiety index ranging from 47 to 68, while whole grain breads, whole meal breads and brown pasta ranged from 154 to 188.  Both the glycaemic index (a test that evaluates foods according to their ability to raise the blood glucose level) and satiety index are an expensive way of evaluating foods, given the complex formulations of today’s food products in the market, because each and every formulation has to be evaluated for its physiological or sensory parameters, using groups of people to obtain the necessary data.

Several scientific studies have concluded that eating whole, unrefined grains can increase satiety, and, therefore, may contribute to weight loss, and may reduce the risk of certain diseases. The majority of the grain food products we consume today are wheat-based. This is probably due to the association with the functionality of gluten that enables bakers to produce bread and other baked goods with the appearance that consumers are accustomed to.  However, other grains can be of more importance with regard to achieving satiety, and contributing to health and nutrition. For example, oats, barley and rye not only contain high amounts of dietary fibre, but also other micronutrients, such as magnesium, potassium, selenium, copper and iron, as well as vitamins such as thiamin, niacin, folate, vitamin B6 and riboflavin. The dietary fibre in these grains has a high proportion of soluble component, which is more likely to contribute to satiety. Soluble dietary fibres such as beta glugan from oats, as well as psyllium, become viscous when mixed with water and the acidic environment of the stomach. The increase in viscosity slows the movement within the intestinal track, resulting in the feeling of being full for a longer period of time. This action also facilitates a more efficient absorption of nutrients. Unfortunately, the use of these grains in product formulations is very low, despite the excellent opportunity they present to develop products with high satiety properties, and lower energy intake. More recently, Lupin, a legume cultivated in Western Australia (800,000 tones annually), has been researched for its potential to increase satiety. The Lupin seed contains about 30 per cent protein (slightly less than soybeans, at 45 per cent), and substantial amounts of both insoluble and soluble dietary fibre. In addition, researchers have shown that individuals fed bread containing Lupin flour produced only half the amount of the gut hormone responsible for increased appetite, compared to those eating regular white bread. Lupin flour, due to its higher protein content and other components, can reduce the energy intake substantially, and at the same time, increase satiety. Other legume flours, such as those from common beans, may have similar effect, but have not yet been evaluated.  Other ingredients that can be used to increase the satiety properties of baked goods can include alginates and other gums, as well as inulin, a fructooligossaccharide, which also possesses prebiotic properties.

Many consider satiety the “Holy Grail of Nutrition,” and believe it is a key element in the battle against obesity, and its associated health issues. The combined market for weight management products in Europe and North America is estimated to be $4.9 billion US. Some of the major food manufacturers are now looking at developing food products with properties that increase satiety and reduce energy intake.

Although research is increasingly proving that various foods have the ability to influence satiety, more investigations are needed, and a cautious approach should to be taken in the development and marketing of food products with such properties. It is obvious, due to the complex formulations of such products, that their effectiveness needs to be evaluated. Such a proposition may be an expensive one. We also have to remember that in developing new products, we have to keep in mind the element of good taste, which, above all, is an absolute necessity for the success of food products in the market.

For more information, or fee for service help with product or process development needs please contact the GFTC at 519-821-1246, by fax at 519- 836-1281, by e-mail at gftc@gftc.ca.