Hidrokolloidlerin sinerjik etkilerinin dolgu ve dolgulu bisküvi kalitesi üzerine etkisi

In recent years, food contents has become more important for consumers of food industry. Preservatives, artificial ingredients or additives are replaced by more natural ones in those days and the consumes prefer more natural foods. Food industry uses hydrocolloids very commonly for different purposes so that research in this area is still in concern and widespread. Hydrocolloids improve the stability of food by means of different properties; thickening, suspending, gelling and emulsifying. Often gums are preferred as hydrocolloids. In food legislations there is no limitation for gums. Hydrocolloids are also used for; extending shelf-life, as a fat substitute, for reducing fat migration, reducing the expensive input consumption, providing structural integrity of extruded product or utilizing calorie-reduced diet products without resulting in loss of flavor. Considering the variety of products in the market, each food has its own different characteristics: Liquid products, juices, spoonable ice creams, garnished cookies, jam on the state deposit, jellies, etc. Hydrocolloids are major ingredients that give different structure and fun experience to food. Food hydrocolloids when replaced with the use of multiple hydrocolloids can result in totally different structures. For example, some polymers has not gelling property but, if these polymers react with another hydrocolloid, they can show gelling property while mixing. This effect is known as "synergism". Synergism can take place by formation of covalent bonds between the two polymers. Hydrocolloids have contribution to the texture, stability, color, taste etc. These colloids are added to provide at least one or two of these effects. The desired structure must be well defined and the hydrocolloid that is to be used must be selected properly. Generally, combinations of hydrocolloids are preferred although it is hard to understand the effect of each hydrocolloid in the food system. There are several reasons to use combination of hydrocolloids in food recipes. Most of hydrocolloids have synergistic effect with each other. They give more strong texture and viscosity to the product which it is added. The gum combinations creates more effective three-dimensional network for water structure. The purpose of this study is to analyse, evaluate and determine the synergistic effect of different hydrocolloids on filled biscuit quality. Different ratios of starch and xanthan gum, carrageenan and locust bean gum mixtures are analyzed on biscuit quality periodically. In the first step of this study, starch that is to be used was decided. Four different types of starches were added to base filling recipe; wheat, corn, tapioca and rice. starch was at 5% level and filling is prepared and then deposited on biscuit. Moisture value, water activity and pH was measured for the first day, after one week and two weeks later. Corn starch was selected because of its water retention quality. After selecting starch type, two different base type fillings were prepared. Starch- xanthan gum, carrageenan -locust bean gum combinations were applied. For the first combination; 5% corn starch, 0,2% and 0,8% xantan gum were prepared. As the second combination; 0,5% carragenan, 0,1% and 0,2% locust bean gum fillings were deposited on biscuits. In the fillings at 1., 15., 30., 45., 60., 75. ve 90. days of storage; moisture, water activity (aw), pH values were measured, and the whole products were analyzed for their hardness and brittles parameters. In addition, DSC was used for determining the gelling behaviour of them. Xanthan and locust bean gum was found to increase water retention properties besides hardness and brittleness of biscuits. While evaluating DSC parameters samples were prepared at 25% concentrations. At the first day and 14th day of storage samples were analyzed. According to results; addition of xanthan gum decreased starch gelatinization temperature and retrogradation values. Locust bean gum also decreased gelling point of carrageenan. Both of the combinations increased dehydradation temperature of samples. In this study, evaluation of starch-xanthan and carrageenan-locust bean gum combinations according to water retention capacity and their effects on filling structures and filled biscuit quality was performed. Starches are used in fillings for their thickening or gelling property. But, by the addition of xanthan gum to the filling it effects water retention capability of the filling. Especially this property is important in filled biscuits as problems arise by the migration of moisture from filling to the biscuit. At the end of shelf life, results showed that water activity of fillings were decreased by the addition of xanthan gum. Starch and xanthan gum combination together give strength and viscosity to the filling. Hardness and brittleness results for biscuits changed by migration of water, after 30 days hardness decreased and then biscuit started to get firmer. The same situation is applicable to carrageenan based filling. Carrageenan and locust bean gum forms a gel in the filling and is more effective than xanthan gum-starch combination according to water activity retaining. Carrageenan and locust bean gum has water retention capability either in combination or alone. As a result of this study, synergism of hydrocolloids provides advantages to filling such as cost, shelf life extention and desired texture. Carrageenan and locust bean gum combination is found to increase water retention more than the starch and xanthan gum combination. Besides, starch-xanthan gum combination have softer texture for the biscuits they are filled. Thus, this study showed that for both biscuit fillings and other food products hydrocolloid combinations can solve the problems or improve the quality. As there are many hydrocolloids available, new studies are necessary to study their two or even more combinations to understand their synergistic effects.