Jerusalem Artichoke Association of Canada
An ancient crop for future clean sugar
Unlike other tubers, the main storage carbohydrate in the Jerusalem artichoke tubers is sugar inulin instead of starch. The lack of starch and the presence of inulin have resulted in the recommendation that the Jerusalem artichoke tuber is a suitable food for diabetics, that may be consumed in moderate amounts without an important increase in glucose. Moreover, since the human body cannot digest inulin, the tubers can promote satiety while reducing the caloric intake. Thus, Jerusalem artichokes may also be of value as a low calorie food. In addition to being marketed as a health food product, the Jerusalem artichoke is also the natural raw material for the derivation of "clean sugar".
Jerusalem artichoke tubers contain high amounts of medium length chains of inulin that can be extracted in the similar process as the extraction of sugar from sugarcane. Commercial pure inulin exists as a white powder and is neutral in taste. It is a linear polysaccharide made of fructose monomers connected by β (2,1) glycosidic linkages, and terminated with one d-glucose molecule linked to the fructose chain by an α (2,1) bond. The degree of polymerization of inulin generally ranges from 2 to 60. It is a well-known prebiotic fiber – “a selectively fermented ingredient that allows specific changes, both in composition and/or the activity of the gastrointestinal microflora and in beneficial to the host’s well-being and health”. The consumption of prebiotics has been linked to an improved immune system, increased mineral absorption, and reduced risk of colon cancer, metabolic syndrome and obesity.
Inulin is mainly extracted from chicory roots. This isolated form can be used as an ingredient in large range of foods either to improve the texture and/or taste or to increase the dietary fiber intake. Inulin has a low calorie and is regarded as safe and well tolerated up to a level of 20 g per day. Currently, inulin is mostly used as a low-calorie fat/sugar replacer and texturizer in spreads, dressing, dairy, baked foods and ice-cream.
There are commercial possibilities to use dry Jerusalem artichoke as a functional nutrient to develop food products with low glycemic index. Due to its prebiotic properties, the use of inulin from Jerusalem artichoke can be an innovative way to add value to food products in terms of functionality and in profitability for the food industry. Because of its desirable textural and nutritional properties, inulin from Jerusalem artichokes can be used as prebiotics, a source of low glycemic food, a fat/sugar replacer and a texture modifier.
Inulin can be completely hydrolysed to fructose which is widely utilized as a sweetener instead of sucrose or glucose especially in beverages, functional foods and pharmaceuticals. Fructose is more soluble than sucrose making it a desirable syrup. Moreover, fructose is about 1.5 times sweeter than sucrose. Because a smaller amount of fructose is required to achieve the same level of sweetness as sucrose, the use of fructose contributes to a smaller calorific contribution. A lower sugar intake helps reduce the microbial degradation and accumulation thus lowering the chance of tooth decay. In addition, fructose has a lower glycemic index compared to glucose or sucrose, making it the most favorable sweetener for diabetics. The glycemic index represents the relative ranking of carbohydrates according to how they affect the glucose level in the blood. The glycemic index of glucose, sucrose and fructose are 100, 65 and 23 respectively. Carbohydrates with low glycemic index are more slowly absorbed and metabolized and cause a lower and slower rise in blood glucose. Thus, the Jerusalem artichoke is an attractive source of fructose. In the United States, fructose is mainly produced from corn. Conventionally, starch from corn is hydrolyzed in a three steps procedure that results in 45% fructose and 55% glucose. Inulin from Jerusalem artichoke is a more advantageous source of fructose since inulin is hydrolyzed to fructose in only one step with a fructose yield of 95%. The economic viability of this hydrolysis process is highly dependent on the activity of enzymes, the operating mode and the bioreactor configuration.
Fructooligosaccharides or oligofructose are other functional ingredients that can be derived from the partial hydrolysis of inulin. Oligofructose is a short chain polysaccharide that contains 2-10 fructose units. It has very similar functional and nutritional characteristics as inulin.