Kakaolu fındık kremasında yağsız süt tozu ikamesi olarak kullanılan nohut, kestane ve kinoa unlarının reolojik, tekstürel ve duyusal etkilerinin incelenmesi
Investigation of the rheological, textural and sensory effects of chickpea, chestnut and quinoa flours used as a milk powder substitute in cocoa hazelnut cream
Yazar: IŞILAY IŞIK
Danışman: DOÇ. DR. ASLI CAN KARAÇA
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Gıda Mühendisliği Ana Bilim Dalı / Gıda Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2024
Konu: Gıda Mühendisliği = Food Engineering

Özet:
Kakaolu kremalar, yağ içeriğine sahip, süt tozu, kakao tozu, fındık püresi, lesitin içeren ve farklı aromalarla çeşitlendirilerek istenilen reolojik, tekstürel ve duyusal özellikler elde edilerek pastacılık sektöründe yaygın olarak kullanılan gıda ürünleridir. Son yıllarda ön plana çıkan tüketici trendleri incelendiğinde vegan ürünlerin pazar payının her geçen gün arttığı görülmektedir. Bitkisel proteinlerin hayvansal proteinlere ikame olarak kullanımı güncel tarihli yeni ürün geliştirme çalışmalarında araştırma konusu olmaktadır. 
Bu çalışmada, yağsız süt tozu yerine farklı un çeşitleri kullanılarak vegan beslenmeye uygun kakaolu fındık kreması geliştirilmesi amaçlanmıştır. Bu amaçla kestane unu, kinoa unu ve ön pişirme işlemi uygulanmış nohut unu temin edilmiştir. İlk olarak krema formülasyonu oluşturulmuştur. Krema formülasyonunda şeker, fındık püresi, natürel kakao tozu, alkalize kakao tozu, bitkisel yağ (palm), ayçiçek yağı, maltitol, lesitin, tarçın, tuz kullanılmıştır. Krema formülasyonundaki hammaddelerin kullanım oranları endüstriyel krema örnekleri referans alınarak belirlenmiştir. Krema numuneleri laboratuvar ortamında bilyalı değirmende hazırlanmıştır. Kakaolu fındık kreması formülasyonunda kestane unu, kinoa unu ve nohut unu %5 ve %10 oranlarında çalışılarak son ürünler reolojik, tekstür profili, renk, pH ve duyusal özellikler açısından karakterize edilerek sonuçlar karşılaştırılmıştır.
Yapılan fiziksel analiz sonuçları incelendiğinde renk ve pH değerlerinde istatiksel açıdan önemli bir fark bulunmamıştır. Örneklerin pH değerleri 5,57 ila 6,05 arasında değişmiştir. Örneklerin L değerleri 20,91 ila 24,12 arasında değişkenlik göstermiştir. En düşük parlaklık %10 kestane unu içeriğine sahip krema örneğinde elde edilmiştir. Diğer taraftan en yüksek parlaklık kontrol örneğinde gözlemlenmiştir. 
Yapılan tekstür analizi sonuçları değerlendirildiğinde sertlik ve yapışkanlık değerlerinde istatiksel açıdan anlamlı bir fark bulunmamıştır. Krema örneklerinin sertlik değerleri 1075,20 g ila 1894,30 g arasında değişmiştir. Krema örneklerinin sertlik değerleri incelendiğinde, kontrol örneği en düşük sertlik değerine sahip olduğu görülmüştür. Diğer taraftan %10 yağsız süt tozu içeriğine sahip krema örneği en yüksek sertlik değerini göstermiştir. Öte yandan krema örneklerinin yapışkanlık değerleri 871,00 g.s ila 1720,60 g.s arasında değişmiştir. Yapışkanlık değeri kremanın dişlere yapışma derecesini göstermekte olup sertlik değeri ile doğru orantılıdır. Buna göre en yüksek sertlik değerine sahip olan %10 nohut unu örneği ve %10 yağsız süt tozu örneği en yüksek yapışkanlık değerine sahiptir. Öte yandan %5 kinoa unu içeriğine sahip krema örneği ile kontrol örneği en düşük sertlik ve yapışkanlık değerleri göstermiştir.  
Ürünlerin reolojik özellikleri incelendiğinde viskozite ve akma gerilimi değerlerinde istatiksel açıdan anlamlı bir fark bulunmamıştır. Krema örneklerinin viskozite değerleri 1042,50 mPa.s ila 1895,70 mPa.s arasında değişmiştir. Diğer taraftan akma gerilimi değerleri 2,64 Pa ila 6,85 Pa arasında değişmiştir. İncelenen ürünlerin viskozite değerlerinin formülasyondaki bitkisel protein oranının artışı ile artış göstermiştir. Akma gerilimi değerlerinin ise formülasyondaki bitkisel protein oranının artışı ile azalma gösterdiği görülmüştür. Buna karşılık nohut unu ile yapılan çalışma sonuçlarında tam tersi eğilim gözlemlenmiştir. Bu çalışma sonucu farklı oranlarda kullanılan çeşitli unların son ürünün duyusal özellikler üzerine önemli etkisi olduğunu göstermiştir. Çalışma kapsamında kakaolu fındık kremasında yağsız süt tozu ikamesi olarak üç farklı un kaynağı değerlendirilmiş; reolojik, tekstürel ve duyusal parametrelere istatiksel anlamda önemli etkileri olduğu görülmüştür. Diğer taraftan renk ve pH parametrelerine istatiksel anlamda önemli etkisi olmadığı görülmüştür. Çalışma kapsamında incelenen tüm parametreler topluca değerlendirildiğinde; kakaolu fındık kremasında yağsız süt tozu yerine bitkisel kaynaklı bir ikame olarak kestane ununun değerlendirilebileceği sonucuna varılmıştır.

Abstract:
Cocoa creams are food products that are widely used in the pastry industry, having fat content, containing milk powder, cocoa powder, hazelnut puree, lecithin and diversified with different flavors to obtain the desired rheological, textural and sensory properties. It is seen that food products containing vegetable protein are preferred instead of industrial food products containing animal protein in the world and in our country. It is becoming increasingly common for changing consumption trends to be reflected in frequently consumed products such as spreadable chocolate with different formulations and finding a place on market. The functional properties of spreadable chocolate products, which are widely preferred and consumed, are improved with the addition of bioactive components. When the consumer trends that have come to the fore in recent years are examined, it is seen that the market share of vegan products is increasing day by day. The use of plant proteins as a substitute for animal proteins is a subject of research in current new product development studies.
The milk content in chocolate gives it a creamier and smoother texture (Beckett, 2000). The milk powder content gives cocoa hazelnut creams a creamy spreadable texture. Various milk powder substitutes have been tried in order to reduce production costs in chocolate and chocolate spreads, as well as to develop a cream formulation that does not contain animal protein.
The variety of vegan products has increased due to the increasing and widespread prevalence of food allergies in our society. In the literature, the number of studies conducted in the field of vegan nutrition is increasing day by day. There are many studies in the literature on different product groups such as ice cream, chocolate, yoghurt and pastry cream. Vegetable proteins can be used directly as a substitute for milk powder or as an ingredient in product formulations.
Dry beans; It is considered a beneficial food source with its high amounts of protein, carbohydrate and dietary fiber components. As an alternative to grain flour, legume flour is used in many different products. On the other hand, legume flours contain some vitamins and minerals (Ruiz-Ruiz et al., 2008) and essential amino acids (Vasconcelos et al., 2010). Dried legumes have a remarkable place in the diet with their protein content two to three times higher than grains (~18 – 32%). Evaluation of legume flours and proteins in product formulations; While it improves properties such as texture, viscosity, emulsion and foam formation, it also increases the nutritional value of the products (Dirim et al., 2014).
Chickpea contains 19-23% protein, 55-60% total carbohydrate, 30-53% starch, 10-20% dietary fiber, 4-7% fat, 2-4% mineral substances, some vitamins, functional components and antinutritional substances (Boukid et al., 2019). The starch content of chickpeas is between 30-53%, and the amylose content of chickpeas is approximately 20-46%. Chickpea is a legume rich in mineral content.
Chestnut flour contains 4-7% protein, 20-32% sugar, 50-60% starch, 4-10% dietary fiber and a low amount of 2-4% fat. In addition, it has a rich content in terms of E and B group vitamins, potassium, phosphorus and magnesium (İnkaya, 2008). Chestnut flour is frequently used in gluten-free product development studies. The use of chestnut flour in the production of gluten-free products developed for celiac patients is thought to be advantageous due to its rich nutritional value.
Quinoa has a protein content between 13.8-16.5%; This ratio may vary depending on the climatic conditions in which it is grown. Quinoa has a starch content of 58-65%. Quinoa seeds have a richer content in terms of oil compared to grains. Quinoa seeds have an oil content of 4.5-8.75%; This oil content is rich in oleic acid (24%) and linoleic acid (52%). 
In recent years, it has become a new food ingredient that is highly preferred in the diets of vegans and vegetarians, as well as individuals with allergic risks caused by grains (Paśko et al., 2009). Quinoa seeds were ground into flour and used in the production of grain products such as pasta, cakes, biscuits, cookies, baby supplements, breakfast cereals and bread (Schumacher et al., 2010).
In this study, it was aimed to develop cocoa hazelnut cream suitable for vegan nutrition by using different types of flour instead of skim milk powder. For this purpose, chestnut flour, quinoa flour and pre-cooked chickpea flour were provided. First, the cream formulation was created. Sugar, hazelnut puree, natural cocoa powder, alkalized cocoa powder, vegetable oil (palm), sunflower oil, maltitol, lecithin, cinnamon and salt were used in the cream formulation. The usage rates of raw materials in the cream formulation were determined with reference to industrial cream samples. Cream samples were prepared in a ball mill in a laboratory environment. In the formulation of cocoa hazelnut cream, chestnut flour, quinoa flour and chickpea flour were used at 5% and 10% ratios and the final products were characterized in terms of rheology, texture profile, color, pH and sensory properties and the results were compared.
When the physical analysis results were examined, no statistically significant difference was found in color and pH values. The pH values of the samples ranged from 5.57 to 6.05. L values of the samples varied between 20.91 and 24.12. The lowest gloss was obtained in the cream sample with 10% chestnut flour content. On the other hand, the highest brightness was observed in the control sample.
When the results of the texture analysis were evaluated, no statistically significant difference was found in the hardness and stickiness values. The hardness values of the cream samples varied between 1075.20 g and 1894.30 g. When the hardness values of the cream samples were examined, it was seen that the control sample had the lowest hardness value. On the other hand, the cream sample with 10% skim milk powder content showed the highest hardness value. On the other hand, the stickiness values of the cream samples varied between 871.00 g.s and 1720.60 g.s. The stickiness value shows the degree of adhesion of the cream to the teeth and is directly proportional to the hardness value. Accordingly, the 10% chickpea flour sample with the highest hardness value and the 10% skimmed milk powder sample have the highest stickiness value. On the other hand, the cream sample with 5% quinoa flour content and the control sample showed the lowest hardness and stickiness values.	
When the rheological properties of the products were examined, no statistically significant difference was found in the viscosity and pour point values. The viscosity values of the cream samples ranged from 1042.50 mPa.s to 1895.70 mPa.s. On the other hand, yield point values varied between 2.64 Pa and 6.85 Pa. The viscosity values of the examined products increased with the increase in the proportion of vegetable protein in the formulation. It was observed that the yield stress values decreased with the increase in the amount of vegetable protein in the formulation. On the other hand, the opposite trend was observed in the results of the study conducted with chickpea flour. The result of this study showed that various flours used in different proportions have a significant effect on the sensory properties of the final product. Within the scope of the study, three different flour sources were evaluated as a substitute for skimmed milk powder in cocoa hazelnut cream; It was observed that it had statistically significant effects on rheological, textural and sensory parameters. On the other hand, it was observed that it had no statistically significant effect on color and pH parameters. When all parameters examined within the scope of the study are evaluated collectively; It was concluded that chestnut flour can be evaluated as a plant-based substitute for skimmed milk powder in cocoa hazelnut cream.
As a result, flour types with high nutritional value such as quinoa flour, chickpea flour and chestnut flour have techno-functional properties that are important for end product applications; Therefore, they stand out as suitable raw materials for developing cream that does not contain skimmed milk powder. New food choices due to health issues such as intolerance or allergy to animal products have led to more work towards the development of new food formulations. In this context, characterization studies were carried out by developing an optimum recipe formulation using three different flours, which were used as a substitute for skimmed milk powder in cocoa hazelnut cream. In the future, there is a need for studies to increase consumer acceptance and improve the textural properties of products.