Kek kalitesi üzerine bazı emülgatörlerin etkilerinin araştırılması /
Yazar: NURGÜL MERCAN
Danışman: DOÇ. DR. HİKMET BOYACIOĞLU
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Geomatik Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 1998
Konu: Gıda Mühendisliği = Food Engineering
Dizin: Buğday = Wheat ; Emülgatörler = Emulgators ; Kek = Cake ; Kek kalitesi = Cake quality

Özet:
Bu çalışmada yağ, su ve hava fazlarının homojen olarak karışmasını sağlayan ve kek iç yapısının oluşmasında önemli rolü olan bazı emülgatörlerin kek kalitesine etkileri araştırılmıştır. Bu amaçla kek üretimi için kullanılan Triticum compactum türü yumuşak buğdaylardan elde edilmiş, üç farklı kalitede un ve pişirme endüstrisinde yaygın olarak kullanılan lesitin, sodyum stearol-2-laktilat (SSL), mono ve digliseritler ve mono ve digliserit türevi emülgatörler kullanılmıştır. Çalışmada Amerikan Hububat Kimyacıları Birliği AACC'nin 10-90 "Kek Ununun Pişme Kalitesi " metodundaki kek formülü modifıye edilerek kullanılmıştır. Karıştırmayı takiben, hamur 190 °C'de 20 dakika pişirilmiştir. Yüksek şekerli, beyaz kekler 30 dakika tavada ve 30 dakika tavadan çıkarıldıktan sonra toplam 1 saat, 18°C'de %50 nisbi rutubetli ortamda soğutulmuştur. Soğutma işleminden sonra keklerin hacim, simetri ve tekdüzelik indeksleri AACC'nin method 10-91'e göre ölçülmüştür. Daha sonra keklerin gözenek yapısı (tekdüzelik, büyüklük, duvar kalınlığı), kumluluk, doku (nemlilik, gevreklik, yumuşaklık), iç yapı rengi ve kokudan oluşan iç yapısal özellikleri beş eğitimli panelist tarafından duyusal olarak değerlendirmiştir. Duyusal değerlendirme sırasında farklılık testlerinden Puanlama Testi kullanılmıştır. Yapılan pişirme denemeleri sonunda elde edilen keklerin, hacim, simetri ve tekdüzelik indeksleri arasındaki farklar ve iç yapısal özellikleri arasındaki duyusal farklar istatistiksel olarak değerlendirilmiştir. Sonuç olarak, lesitin, SSL, mono ve digliserit ve mono ve digliserit türevi emülgatörlerin kek hacmi, simetri ve tekdüzelik indeksi üzerine etkisi istatistiksel olarak önemsiz bulunmuştur. Üç farklı kalitede yumuşak buğday unu ile yukarıda belirtilen dört farklı emülgatör kullanılarak yapılan kek denemelerinden mono ve digliserit kullanılarak yapılan kekler, diğerlerinden farklı iç yapısal özellikler göstermiş ve duyusal değerlendirmede en yüksek puanı (100 üzerinden 84) almıştır. Mono ve digliserit türevi, lesitin kullanılarak yapılan kekler ile kontrol (emülgatörsüz) keklerinin benzer iç yapısal özellikler gösterdiği ve duyusal değerlendirmede sırasıyla 77, 75 ve 73 puanlarını aldığı tespit edilmiştir. SSL ile yapılan kekler ise diğer tüm keklerden farklı iç yapısal özellikler göstermiş ve duyusal değerlendirmede en düşük puanı (66) almıştır.

Abstract:
Cakes are important products in the baking industry that are available in a great variety. Today, there is no specific standart prepared by the Turkish Standart Institute in our country which has a 143 10 tons of marketing potential annually. It is difficult to give a precise definition of cake production due to their different types and broad variation in their formulations. In general, it can be defined as a baked batter made from flour, sugar, salt, leavening, shortening, milk, eggs and flavourings. The major ingredients of cake are considered to be as flour, sugar, shortenings and eggs. The minor ingredients are accepted as emülsifiers, egg products, milk (milk products), salt, chemical leavenings, certain flavour, spice and coloring materials. A proper combination of the ingredients can give a high quality of product with desirable texture and flavour. Cakes, generally, have been classified according to the type of ingredients taking place in the formulation. Cakes are classified as shown in Tablel. Cake production consists of five steps: a) storage of raw material, b) mixing, c) transfer to baking area, d) baking, e) cooling. The most important two steps of cake making are mixing and baking operations. There are several methods for mixing operation. The purpose of batter mixing is: to disperse all the ingredients as efficiently as possible and to incorporate air into the mix. A high quality cake is expected to show a multitude of evenly distributed minute cells without any large holes, to have good colour and sheen, eat moist, a good flavour and attractive appearance with a good eye appeal. The quality of cakes is governed by three major parameters, namely, the special suitability of the ingredients for the type of cake being made, an appropriate and properly balanced formula, and the adherence to optimal mixing and baking procedures. To produce high quality products with traditional appearance and taste, it is necessary to use new ingredients and additives. A group of additives widely used for their functional properties in the baking industry is emülsifiers.Table 1. Cakes classification a) Ordinary cake all cake made with regular hydrogenated shortening b) High absorbtion cake all cake made with emulsified shortening regular hydogenated shortening emulsified shortening 4) The ratio of flour, sugar and total liquid a) High ratio cake b) High liquid cake c) High ratio/High liquid cake * All cake made according to properties The presence of emülsifıer from batter to cake guarantees a reliable process in terms of required baking stability. The finely dispersed batter structure is retained throughout the entire baking process to create a cake with a fine uniform crumb structure. The emulsifiers use in some food systems is often made attractive by just one of their singular properties. This helds true even more so in the case of cakes in which all of the properties of a emülsifıer, or of some combination of several of them, are utilized to the fullest extent. In cakes, they provide such quality improvements as larger volume, fine grain and texture, a more tender crumb, improved eating quality, a higher degree of symmetry and extention of the keeping quality. IXIn this study, it was aimed to research effects of some emülsifiers which provide properly mixing of oil phase with water phase and which have an important role in forming of crumb structure on cake quality. For this purpose, three soft wheat flour in three different qualities in which given Table 2 and Table 3 and lecithin, sodium stearoyl-2-lactylate, mono and diglyceride and mono and diglyceride derivative were used. During research, the cake formula in method 10-90 "Baking Quality of Cake Flour" of Approved Methods of American Association of Cereal Chemists (AACC)'1983 was modified. Firstly, the ingredients which in the formula were mixed to give cake batters. Then, specific gravity of cake batters were determined (Table 4). After baking pans were greased with commercial pan grease, cake batters were scaled 212.5 gr in to pans and were baked at 190 °C, 20 minutes. Baked high ratio, white cakes were cooled in pans for about 30 minutes, removed from pans, and continued cooling about 30 minutes more. Table 2. Chemical properties of flour samples1 1 Values are means of four determinations 2 In dry matter 3N*5.7 Table 3. Rheological properties of flour samples1 Values are means of four determinationsTable 4. Specific gravity of cake batters1 Emulsifiers Flour sample Control Lecithin SSL2 MDG3 MDG3 Derivative Means 0.95 0.92 0.92 0.94 0.94 1 Values are means of two determinations 2 Sodium stearoyl-2-lactylate Mono and digliyceride After cooling; volume, symmetry and uniformity indexes of cakes were measured according to method 10-91 of AACC 1983 (Table 5). From the measurement of the cake diameters, it was obvious that the volume index was not a true measure of cake volume. But, It was shown that there was a linear relationship between volume and volume index. In cake industry, volume index value has been used to refer to index value of control cake. The term "symmetry" has traditionally been used in cake industry to indicate contour. With another words; symmetry index is a measurement of the peaking of the cake surface: the higher the values, the greater the peaking. Uniformity index measures the symmetry of the cake. Values approaching zero indicate symmetry and are desirable. Table 5. Volume, symmetry and uniformity indexes of cakes1 Emulsifiers Values are means of two determinations Sodyum stearol-2-lactlylate Mono and diglyceride XIFinally, internal sensorial factors of cakes were evaluated with sensory evaluation five trained panelists using a scoring method. Specific gravities, volume, symmetry and uniformity indexes and sensory evaluation results were statistically analyzed using competely randomized block design. When the value of F probability was greater than p < 0.05 probability, means of treatments were compared with each other using Duncan's New Multiply Range Test. As a result, between the differences volume, symmetry and uniformity indexes of the cakes which were prepared with three soft flour in different quality and with several emülsifiers were found to be unimportant at p < 0.05. According to sensory evaluation results, cakes which were prepared with mono and digliseride showed different internal factors from others and scored the highest point. Cakes which prepared with mono and digliseride derivative, lecithin and control cakes (no emülsifiers) showed similar internal factors and scored in order of 77, 75 and 73. Although cakes which were prepared with sodium stearoyl-2-lactylate showed different internal factors in all cakes and scored the lowest point 66 during sensory evaluation (Table 6). Table 6. Sensory evaluation results of cakes1 Emülsifiers Means with the same letter are not significantly different ( P< 0.05). 2 Sodium stearoyl-2-lactlylate 3 Mono and diglyceride