M. G. LINDLEY, Lintech, Reading University Innovation Center, Reading, G.B. INTRODUCTION Sucrose is a particularly versatile functional ingredient used as a vital component in a broad range of foods and beverages. Sucrose functions as a texturiser, stabiliser, preservative and bulking agent in products, all features which are delivered along with excellent sweetness and taste qualities. Despite these excellent functional and taste benefits of sucrose, the ingredient would probably find wider application in foods if its sweetness could be controlled. In some food products, further functional benefits might result from the use of higher concentrations of sucrose, but the use of sucrose to maximum functional advantage is limited by the sweetness which inevitably comes along with the ingredient. If sucrose was not sweet, it could be used to function effectively as a replacer of fat in some systems, for example in biscuit creams and fillings. Foods or systems designed to be used at freezer temperatures use high concentrations of low molecular weight carbohydrates, including sucrose, but would be of improved sensory quality with lower sweetness levels. Inclusion of sucrose in recipes is also limited to sweet foods. These and other examples illustrate a market need to be able to control the degree of sweetness delivered by sucrose. 1. SWEETNESS INHIBITORS The existence of compounds which have the capacity to inhibit sweet taste perception has been known for many years. Extracts of the Gymnema sylvestra plant (gymnemic acids) have long been known to inhibit sweetness on a non-selective basis. Other plant materials, notably extracts from Ziziphus jujuba (ziziphins), also have the capacity to inhibit sweet taste perception. Sweetness is also inhibited by various degradative agents, that is, materials which act to disrupt the taste cell membrane, including the surfactant sodium lauryl sulphate (SLS) and proteolytic enzyme preparations such as Pronase E. In all these examples, inhibition appears to be non-selective in that the sweetness elicited by all sweeteners is reduced by essentially equivalent amounts. None of these inhibitors is appropriate from practical, food technological, standpoints since their effects all last for some extended periods. Gymnemic acids inhibit sweetness for an hour or more, and those inhibitors which disrupt cell membranes also exert their effects over some hours. Thus, the temporal features of their effects clearly will act contrary to what is acceptable in foods. It is clearly going to be unacceptable to inhibit sweetness for prolonged times, irrespective of the possible benefits which could result in any particular product containing one of these inhibitors. Nonetheless, extracts of Gymnema available commercially in the Far-East where there is various nutritional effects which are attributed to the material, some of which are of dubious veracity. Many sweet taste inhibitors are now known which are structural analogues of sweeteners. The first to be described was the chlorinated galactose derivative which is an analogue of a potently sweet derivative of sucrose. Since then, many other examples have been described, and one sweetness inhibitor has been commercialised successfully in the USA. This compound, 2-(4-methoxyphenoxy) propanoate, is a potent inhibitor of the sweetness of sucrose and other sweeteners. It appears to function as an inhibitor of the sweetness elicited by all sweeteners, and to be a competitive inhibitor. Crucially, it exerts its effects immediately, sweetener and inhibitor must be mixed for the effects to be observed, and the inhibition effect is rapidly and completely reversible. Thus, its potential to be used in food systems is not hindered by any unusual temporal characteristics. Although it functions against sweetness derived from all sweeteners, it is obviously its ability to inhibit the sweetness of sucrose and other small molecular weight carbohydrates which is of commercial interest. 2. INHIBITION OF SWEETNESS IN FOOD APPLICATIONS As is well understood, the functionalities of sucrose are extremely valuable in many food applications. In fact, it has frequently been stated that « even if sucrose did not taste sweet it would continue to be a valuable ingredient for use in many food applications » In addition to being used for its sweetening functionality, sucrose lowers Aw values, hense functioning as a preservative, it can be used to replace fat, it can be used to enhance palatability, and, in a non-sweet form, it allows development of savoury versions of what today are exclusively sweet foods, thus extending dietary choice. Applications in bakery products Clearly, the potential to use sucrose for its texture developing features, only applied to savoury versions, is of substantial interest. For example, the typical textures of biscuits are developed most easily by varying the sugar: fat ratios. Preparation of, for example, savoury versions of digestive biscuits for consumption with cheese is of interest to that industry and by controlling the sweetness of sucrose, it becomes possible to prepare such a product. Many cake products are viewed as being excessively sweet. In the UK in particular, where the « craft » bakery tradition has suffered serious decline, the mass market is dominated by a small number of major suppliers. Distribution chains are quite extended, requiring that shelf-lives of 21-28 days can be achieved. To do this, many bakery products must contain very high levels of sucrose for its preserving capability. This can have a detrimental impact on flavour delivery, which is able to be restored by controlling sweetness levels. Sucrose is able to function as an adequate alternative to fat in some bakery applications. For example, bakery fillings can be prepared using sucrose as an effective alternative, but to do so will require very high levels being incorporated. Again, controlling the sweetness of the sucrose added for this purpose permits preparation of quality fat-reduced bakery fillings. Savoury snacks Sucrose, along with other small molecular weight carbohydrates, can influence texture quite dramatically in extruded products, contributing a crispness and melt which is frequently beneficial. In addition, there is some potential for starch breakdown through the extrusion process, leading to the generation of sweetness which may distort flavours. Frozen products Sucrose, of course, influences freezing points in frozen products. In fruited frozen goods, particularly sorbets, flavour delivery and « sharpness » can be improved through control of sweetness. In addition, manufacturers have long expressed a desire to be able to prepare savoury versions of some of their products, for example, to be consumed at the beginning of a meal, rather than at the end. CONCLUSIONS These examples merely serve to illustrate the potential to broaden the applicability of sucrose in foods with control of the sweetness it delivers. Other possible applications in toppings, frostings and fillings also exist, particularly for enhancing flavour delivery and reducing fat contents. With simple to achieve control of sweetness intensity, full use can be made of the versatile functionality of sucrose.

Auteur : M. G. LINDLEY