Maltodextrins, particularly low DE products serve as fat and oil replacers. Maltodextrin substituted directly into a food product provides 4 kcal of energy per gram of solid material (Altschul, 1989). However, when maltodextrins are being used as oil or fat replacers they are generally utilized in a 1:3 maltodextrin:water ratio thus giving a solution or gel (depending on DE) which provides only 1 kcal g-1. Several commercial products are already being marketed as fat replacers and many more are in development. Some of the existing fat replacers will now be described in order to provide the reader with some idea of the variety and potential of maltodextrins in this area, and to give an idea of the suitability of these products for the task at hand.
A potato starch, enzymatically derived, maltodextrin known as Paselli SA2 has been developed (Anon, 1988). This fully digestible product has been successfully used to replace in excess of 50% fat in a variety of products (Kaper and Gruppen, 1987; Anon, 1990a). It has a DE of approximately 3 (therefore it is technically not a true maltodextrin) and a slightly acidic pH. Under the correct conditions and concentrations, it forms a smooth gel with a fat-like texture and little or no taste. The calorific content of this gel is ca. 1 kcal g-l and its only major drawback is it hygroscopicity which means that it does not store well for more than approximately 12 months.
Another commercially available maltodextrin is Amalean I which is a modified high amylose food starch which has been used to replace 100% of fat in some cases, resulting in a calorific reduction of some 96%! (LaBell and Duxbury, 1990). It has been used as a dry material or as a precooked paste. A suitable gel for fat replacement can be achieved by heating a paste or slurry of suitable proportions (8% mal to dextrin is often sufficient) to ca. 900 e for 3 min.
Stellar™ is a recent but important addition to the field and is a fat-mimicking microparticulate cornstarch gel that restructures and immobilizes water (Pszczola, 1991). This tightly held water is unable to migrate in, for example, bakery products and this is thought to be responsible for its slowing of the staling process (Anon, 1991). Using the product, a low fat (2.2%) Danish pasty can be made to stay soft for up to 35 days.