تولید دونات فاقد شکر با جایگزینی توسط شیرین‌کننده‌های رژیمی استویا، اریتریتول و مالتودکسترین

دونات به‌واسطه ویژگی‌های ارگانولپتیک مناسب از پر‌مصرف‌ترین محصولات غذایی در سراسر جهان محسوب می‌شود. امروزه با گسترش دیابت و تغییر سبک زندگی، مصرف‌کنندگان توجه زیادی به استفاده از مواد غذایی فاقد شکر و محصولات رژیمی نشان می‌دهند. بنابراین، در این پژوهش امکان‌سنجی تولید دونات فاقد شکر به‌عنوان یک محصول رژیمی با استفاده از جایگزین‌کننده‌های استویا، اریتریتول و مالتودکسترین مطالعه شد. برای این منظور، ابتدا مخلوط شیرین‌کننده فاقد کالری (استویا، اریتریتول و مالتودکسترین) طراحی شد. این مخلوط به جای شکر با نسبت صفر (شاهد)، 50 (کم شکر) و 100 درصد (فاقد شکر) در فرمولاسیون دونات و آیسینگ افزوده شد. بررسی خصوصیات کیفی شامل محتوی رطوبت، جذب روغن، دانسیته، رنگ و نسبت تخلخل و ارزیابی حسی برای دونات‌ها انجام گرفت. همچنین، خصوصیات کیفی ماندگاری دونات شامل ارزیابی نرمی بافت، عدم جذب آیسینگ و عدم رشد کپک طی 14 روز بررسی گردید. تجزیه و تحلیل‌های آماری در قالب طرح کاملاً تصادفی انجام شد (05/0>p). نتایج نشان داد که، جایگزینی 100 درصد شکر در دونات از نظر حفظ خصوصیات کیفی موفقیت‌آمیز بود. خواص کیفی دونات با 50 درصد جایگزینی (محصول کم شکر) مطلوب نبود. دونات فاقد شکر خواص کیفی (دانسیته، تخلخل، رنگ و ماندگاری) مناسبی در مقایسه با شاهد داشت. جذب روغن دونات فاقد شکر با نمونه شاهد اختلاف معنی‌دار نداشت و ارزیابی حسی آن نیز بسیار مطلوب بود. بنابراین از مخلوط شیرین‌کننده‌های فاقد کالری و کم کالری در این پژوهش می‌توان در تهیه دونات فاقد شکر بهره گرفت.

Production of sugar-free doughnut by replacing sugar with dietary sweeteners of stevia, erythritol and maltodextrin

Introduction: Doughnut is one of the most widely consumed food products in the world due to its suitable organoleptic properties. Today, with the spread of diabetes and lifestyle changes, consumers are paying more attention to the use of sugarfree foods and dietary products. In the bakery products, sweeteners play an important role in providing moisture, sweetening, texture formation and increasing the shelf life of the final product. Sweeteners intended to replace sucrose should be watersoluble, with enough flavor, and costeffective. Also, these compounds must also comply with national and international law. Stevia, which is composed of steviol and glycosides, is resistant to heat and pH and is not fermentable. Therefore, its amount should be chosen in such a way that it has no effect on cooking. In contrast, sweeteners containing dextrose and maltodextrin are also heatresistant and can affect cooking and maintain the quality properties of fermentation. In order to use stevia in products as a substitute for sugar to maintain the formulation ratios, the fillers including lowcalorie sweeteners such as erythritol and maltodextrin should be used. Therefore, in this study, the feasibility of producing sugarfree doughnuts as a dietary product was studied using stevia, erythritol and maltodextrin as sugar substitutes.   Materials and Methods: The low calorie sweetener blend (stevia, erythritol and maltodextrin) was designed in the first step. It was found that if 46.175 g of stevia and 1997.82 g of erythritol were mixed and homogenized, a mixture would be obtained with sweetness four times higher than sucrose. So, the &sweetener blend& was used for onefourth of the sugar removal mass and the rest was compensated with filler as maltodextrin. Instead of sugar, this mixture was added with zero ratio (control), 50 (low sugar) and 100% (no sugar) in the formulation of doughnuts and icing. Evaluation of qualitative characteristic including moisture content, oil absorption, density, color and porosity ratio and sensory analysis for doughnuts were performedThe properties of shelf life, including soft tissue assessment, nonabsorption of icing and nongrowth of mold were also investigated within 14 days. Statistical analysis was performed in a completely randomized design (p < 0.05).   Results discussion: The results showed that replacing 100% sugar in doughnuts was successful in terms of maintaining quality characteristics. The quality properties of doughnuts with 50% replacement (low sugar product) were not desirable. Sugarfree doughnuts had good quality properties (density, porosity, color and shelllife) compared to the control. Replacing the type of sweetener from sucrose to alcohol sugar can increase the moisture level of the product. As the amount of erythritol increased (no sugar sample), the texture became more moist and soft. The oil uptake of sugarfree doughnut did not show significant difference from the control sample and its sensory evaluation was so favorable. Maltodextrin could act as a bulking agent, stabilizer, and thickener agent in a sugar free formulation. Sugar free doughnuts had more brightness (L*) and less redness (a*), and its yellowness (b*) did not show significant difference with the control sample. It can be said that because more air has penetrated in sugar free doughnut the brightness parameter (L*) increased. The use of polyols (erythritol) results in a brighter color in the product, which is due to the lack of participation of polyols in the Millard reaction because they lack a reactive aldehyde group. The early development of the Millard reaction led to changes in hardness. Therefore, replacing reducing sugars with nonreducing compounds such as alcohol sugars in the formulation decreased tissue changes in the direction of hardening. Because of Millard reaction will reduce the sugars available as a plasticizer in the formulation. Sugar free doughnut showed suitable soft tissue during 14 days and indicated that sweetener has an effect on texture because it controls hydration and tends to disperse starch and protein molecules, thus preventing the formation of a continuous mass. No sugar doughnuts showed suitable sensory evaluation about color, taste, smell, texture, and overall acceptance.Therefore, a mixture of nocalorie and lowcalorie sweeteners in this study can be used in the preparation of dietary doughnuts.