Ticari aquafabanın fonksiyonel özelliklerinin incelenmesi ve glütensiz kek uygulaması
Evaluation of functional properties of commercial aquafaba and gluten-free cake application
Yazar: GÖĞEM SANEM DAĞLI
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:
Yumurtanın alerjen özellikleri, tüketici talepleri doğrultusunda vegan beslenme tercihi ve sürdürülebilirlik çalışmaları gibi birçok nedenden dolayı hayvansal gıda olan yumurtanın yerine alternatif bitki bazlı protein arayışı devam etmektedir. Aquafaba, çeşitli baklagillerin, özellikle de üretiminde en çok kullanılan baklagil olan nohutun pişirme suyundan elde edilen bir yan ürün olarak tanımlanmaktadır. Aquafabanın fonksiyonel özellikleri; unlu mamuller, soslar, beze ve vegan gıda formülasyonları gibi çeşitli gıda ürünlerinde yumurta ve yumurta akının yerini alabilmektedir. 
Ayrıca çölyak hastalarının veya glüten duyarlılığı olan tüketicilerin glütensiz beslenme seçeneklerini artırmak için çeşitli gıda formülasyonlarına ihtiyaç duyulmaktadır. Glütensiz kekler, buğday glüteni içermeyen alternatif unlar içerdiği için, geleneksel keklere kıyasla farklı yapısal özelliklere ve lezzet profiline sahip olabilmektedir. Bu bağlamda, aquafaba gibi bitkisel bazlı bir bileşenin glütensiz keklerde kullanılması, ürün kalitesini etkilemesi açısından bir potansiyele sahip olabilmektedir. 
Bu çalışmanın amacı ticari aquafaba tozunun fonksiyonel özelliklerini değerlendirmek ve glütensiz kek formülasyonu geliştirmektir. İlk olarak ticari aquafaba örneklerinin pH ayarlaması sitrik asit ve sodyum bikarbonat kullanılarak gerçekleştirilmiş ve çeşitli konsantrasyonlarda aquafaba çözeltileri hazırlanmıştır. Aquafaba örneklerinin köpürme kapasitesi ve stabilite özellikleri, emülsiyon özellikleri, en düşük jelleşme konsantrasyonu, su ve yağ tutma kapasiteleri gibi fonksiyonel özellikleri; pH değişimi (5-6,5), konsantrasyon ve kuru madde miktarı (%5-30) ve çırpma süresi (3-10 dk.) gibi faktörler dikkate alınarak değerlendirilmiştir. Daha sonra ticari aquafaba kullanılarak glütensiz kek formülasyonları oluşturulmuştur. Kek hamuruna ait pişirme kaybı, nem kaybı, hacim indeksi, renk parametreleri ve doku profili gibi fiziksel parametreleri analiz edilmiştir. Araştırmanın ilk aşamasında, farklı konsantrasyonlardaki ticari toz aquafaba örneklerinin çeşitli fonksiyonel özellikler incelenmiştir.  Çalışmanın ikinci aşamasında ise aquafaba bazlı glütensiz kek formülasyonları geliştirilmiş ve standart glütensiz kek formülasyonları ile karşılaştırılmıştır. 
Sonuçlar kek formülasyonlarında aquafaba kullanımının fiziksel ve kimyasal özelliklere etkisini değerlendirmek için önemli bilgiler sağlamaktadır. Aquafabanın fonksiyonel özellikleri kuru madde içeriğine ve aquafaba çözeltisi içerisindeki aquafaba tozu konsantrasyonlarına bağlı olarak değişmektedir. İstenilen fonksiyonel özelliklerin elde edilmesi için farklı konsantrasyon ve pH değerlerinin kullanılabileceği tespit edilmiştir. Aquafaba'nın köpürme kapasitesi ve köpük stabilitesi, uygulanan çırpma işlemi süresine bağlı olarak artmıştır. Köpürme özellikleri için en ideal koşullar, pH değerinin 5.2 ve aquafaba konsantrasyon değerinin %10 olduğu koşul olarak belirlenmiştir. Emülsiyon özellikleri incelendiğinde konsantrasyon arttıkça emülsiyon kapasitesi arttığı görülmüştür. En düşük jelleşme konsantrasyonu en düşük pH değeri için %13-14, en yüksek pH değeri için ise %7-8 olarak belirlenmiştir. 
Glütensiz kek uygulaması için i-kontrol, ii-vegan, iii-glütensiz ve iv-hem vegan hem glütensiz olmak üzere 4 farklı kek formülasyonu geliştirilmiştir. Pirinç unu, buğday unu ve aquafaba kullanılarak uygulaması gerçekleştirilen kek örnekleri ve kek hamurları için kalite özellikleri değerlendirilmiştir. Formülasyonunda yumurta ikamesi olarak aquafaba kullanılan keklerin hacimsel olarak daha küçük boyutlarda ve daha koyu renge sahip oldukları gözlemlenmiştir. Nem içeriği en yüksek örnekler yine aquafaba içeren örnekler olmuştur. Tekstür analiz sonuçlarına göre, kek örnekleri arasında sertlik, yapışkanlık ve lastiksi yapı özellikleri arasında anlamlı bir fark elde edilememiştir. Yaylanma ve çiğnenebilirlik değerleri incelendiğinde ise en düşük değere sahip örnekler pirinç unu ve aquafabadan oluşturulan formülasyona aittir.  Kek hamurları incelendiğinde ise aquafaba içeren örnekler daha düşük pH değerine sahip olduğu görülmüştür. Son olarak glütensiz kek uygulaması belirlenen şartlar doğrultusunda gerçekleştirilerek tüketici beğenileri değerlendirilmesi amacıyla duyusal analiz sonuçları elde edilmiştir. Elde edilen sonuçlara göre en çok tercih edilen ve tüketicilerin beğenisini kazanan örneğin aquafaba ve buğday unundan elde edilen formülasyona ait olduğu tespit edilmiştir. Tüketici alışkanlıklarına bağlı olarak pirinç ununun tercih edilmeyebileceği göz önünde bulundurulmalıdır. Çalışma sonucunda tüketicilerin fırıncılık ürünlerinde aquafaba kullanımına yönelik yaklaşımları olumlu bulunmuştur. 
Literatürde bu alanda sınırlı sayıda çalışma bulunması ve ticari toz aquafabanın kek formülasyonlarında kullanımı için fonksiyonel özelliklerini bir arada değerlendiren bir çalışmaya rastlanmaması nedeniyle, bu çalışma ticari toz aquafabanın fırıncılık ve kek endüstrisinde kullanım potansiyelini ortaya koymaktadır.

Abstract:
The search for alternative plant-based proteins instead of eggs, which is animal-based food, continues due to various reasons such as the allergenic effect of eggs, consumer preferences towards vegan diet and sustainability activities. Aquafaba is defined as a by-product obtained from the cooking water of various legumes, especially chickpeas, which are the most commonly used legumes in production. The functional properties of aquafaba can replace eggs and egg white in various food products such as bakery goods, sauces, meringues, and vegan food formulations. Additionally, aquafaba presents an environmentally sustainable option in food production. By utilizing a by-product that would otherwise be discarded, the food industry can reduce waste and environmental impact. This aligns with growing consumer awareness and demand for eco-friendly practices in food manufacturing. As research and innovation continue to explore the potential of aquafaba and other plant-based alternatives, the future holds promising opportunities for sustainable and ethical food choices that cater to diverse dietary needs and preferences worldwide.
Furthermore, there is a need for various food formulations to increase gluten-free diet options for celiac patients or consumers with glüten sensitivity. The demand for gluten-free options encompass a wide range of bakery products and processed foods. Manufacturers are increasingly exploring ingredients such as aquafaba to enhance the texture and mouthfeel of gluten-free products while maintaining their nutritional integrity. By leveraging aquafaba's foaming, emulsifying and binding properties, gluten-free formulations can achieve the desired consistency and structure, providing consumers with enjoyable alternatives that meet their dietary restrictions without compromising on taste or quality. As advancements continue in both ingredient innovation and consumer education, the accessibility and variety of gluten-free choices are expected to expand, catering to a growing population of individuals seeking healthier and allergen-conscious food options. Gluten-free cakes, containing alternative flours that do not include wheat gluten, can have different structural properties and flavor profiles compared to traditional cakes. In this context, the use of plant-based components like aquafaba in gluten-free cakes has the potential to affect the quality of the cakes. 
The aim of this study is to evaluate the functional properties of commercial aquafaba powder and to develop a gluten-free cake formulation. Initially, the pH adjustment of commercial aquafaba samples was performed using citric acid and sodium bicarbonate, and samples were prepared at various aquafaba solution concentrations. Functional properties of aquafaba samples such as foaming capacity and stability, emulsion properties, least gelation concentration, water, and oil absorption capacities were evaluated considering factors like pH change (5-6.5), concentration, dry matter content (5-30%), and whipping time (3-10 min). Subsequently, gluten-free cake formulations were created using commercial aquafaba. Physical parameters such as baking loss, moisture loss, volume index, color parameters, and texture profile of cake and cake batter samples were analyzed. . In the first stage of the study, various functional properties were examined on commercial aquafaba powder samples at different concentrations. In the second stage of the study, aquafaba-based & gluten-free cake formulations were developed and compared with standard traditional cake formulations
The results provide important information to evaluate the effect of using aquafaba in cake formulations on physical and chemical properties. The functional properties of aquafaba vary depending on the dry matter content and the concentrations of aquafaba powder in the aquafaba solution. It has been determined that different concentrations and pH values can be used to obtain the desired and ideal functional properties. The foaming capacity and foam stability of Aquafaba increased with whipping time. The most ideal conditions for foaming properties have been determined as a pH value of 5.2 and an aquafaba concentration of 10%. When examining foam stability, the first 15 minutes were found to be crucial for aquafaba solutions with concentrations of 10% and 15%. This is because after the initial 15 minutes, the stabilization of the foams begins to deteriorate. However, it has been observed that the foam stability of aquafaba solutions with a concentration of 20% is higher. A nearly stable foam formation was observed during the first 60 minutes, after which the foam stability started to change. It can be said that the most stable foam formation occurs at a concentration of 20%.  When examining changes in foaming properties depending on whipping time, it was observed that foaming capacity generally increased as expected with longer whipping times. The whipping time at which the highest foaming capacity was observed was determined to be 7 minutes. Similarly, values for foaming stability increased with longer whipping times. Instances with longer whipping times exhibited more stable foam formations. Although not statistically significant, a slight decrease in foaming capacity was noted after 7 minutes when whipping was continued for 10 minutes. This suggests that foaming capacity may be negatively affected after a certain whipping duration.
When the emulsion properties were examined, the emulsion capacity increased as the concentration increased. Aquafaba solutions have generally exhibited positive characteristics in terms of emulsion capacity and stability. It has been concluded that aquafaba samples possess good emulsion capabilities.  An increase in the pH value of aquafaba solutions has positively affected their emulsion properties. The concentration of aquafaba solution with the lowest emulsion capacity was found to be 5%. No significant difference was obtained among the samples in terms of emulsion stability comparison. The lowest gelation concentration was determined as 13-14% for the lowest pH value and 7-8% for the highest pH value. This also indicates that as the pH value increases, the lowest gelation concentration decreases, whereas as the pH value decreases, the lowest gelation concentration increases. Increasing the pH value in aquafaba solutions enhances gelation ability, whereas decreasing the pH value may reduce gelation ability. Water and oil holding capacities are important for maintaining the moisture and fat content of products and for forming emulsions. In this study, the water holding capacity of aquafaba was found to be 1.59 g/g water, while the oil holding capacity was found to be 4.82 g/g oil. Compared to literature, it can be said that commercial aquafaba exhibits good water and oil holding capabilities.
For gluten-free cake application, 4 different cake formulations have been developed: i-control, ii-vegan, iii-gluten-free, and iv-both vegan and gluten-free. Quality characteristics were evaluated for cake samples and cake doughs made using rice flour, wheat flour and aquafaba. It was observed that the cakes using aquafaba as an egg replacer in their formulation were smaller in volume and darker in color. 
The samples with the highest moisture content were again the samples containing aquafaba. However, when the values of moisture loss and baking loss for cake samples were calculated, no statistically significant difference was found. This situation may indicate that the combinations of ingredients alone did not affect these parameters, and it can be interpreted that aquafaba could play a balancing role when used with various flours. When examining color parameters, differences were observed both among samples and within individual samples. Generally, it was determined that both top and bottom crust colors differed across all samples. Aquafaba samples exhibited similar color properties among themselves, while samples with added eggs also showed similar color properties among themselves. Significant differences were found between cake samples with added aquafaba and those with added eggs. This finding is important evidence for the potential impact of aquafaba on color profiles. When compared, it was determined that the gluten-free cake sample was closest in color to the control sample. Although rice flour contributed to color changes, this result demonstrates that the addition of aquafaba is the most significant factor influencing color differences. According to the texture analysis results, no significant difference was observed when comparing the the hardness, gumminess and adhesiveness values of the cake samples. However, significant differences were found among cake samples in terms of properties such as springiness, chewability and cohesiveness. When the springiness and chewability values are examined, the samples with the lowest values belong to the formulation created from rice flour and aquafaba. Increased springiness indicates a more aerated cake batter structure and stronger gluten formation. Therefore, in gluten-free cake samples, springiness values were found to be lower. Chewiness, on the other hand, represents the ease of chewing. According to the findings, the easiest to chew cake samples belong to the control group. Adhesiveness represents the adherence of two different surfaces, such as the feeling of sticking to the mouth, while cohesiveness represents the ability to keep the components together. Thus, cohesion represents the ability of a cake to be cut into slices. Cake samples with the highest cohesiveness property are those with added eggs, while the lowest cohesiveness property is observed in samples with added aquafaba. When cake doughs are examined, samples containing aquafaba have a lower pH value. This could be interpreted as aquafaba providing a slight acidic effect on the cake samples. Dough density can be associated with the air bubbles present in the dough. If there are more dough bubbles, the dough volume is higher, resulting in cakes having a larger volume. A high dough density indicates a decrease in cake volume. When comparing cake batters, the highest density values were found in samples with added aquafaba. This confirms the thesis that cakes with added aquafaba will have a lower volume.
Finally, the gluten-free cake application was carried out in accordance with the specified conditions and sensory analysis results were obtained in order to evaluate consumer tastes. According to the panelists, when comparing cake samples with added aquafaba and cake samples with added eggs, the most noticeable difference was determined to be in volume. Cake samples with added aquafaba were found to have lower volume compared to cake samples with added eggs. Additionally, participants mentioned that the cakes with aquafaba had more vibrant colors. When panelist evaluations of parameters such as moisture and stickiness were examined, it was determined that cake samples with added aquafaba received higher scores compared to samples with added eggs. Similar results were obtained for smell, taste, and flavor across all cake samples. Participants noted that they did not experience a bitter aftertaste in their mouths after sampling. According to the results obtained, it was determined that the most preferred and appreciated by consumers was the formulation obtained from aquafaba and wheat flour. It should be taken into consideration that rice flour may not be preferred depending on consumer habits. As a result of the study, consumers' attitudes towards the use of aquafaba in bakery products were found positive.
Since there are a limited number of studies in this field in the literature and there is no study that evaluates the functional properties of commercial powdered aquafaban for use in cake formulations, this study reveals the potential of commercial powdered aquafaban for use in the bakery and cake industry. Moreover, exploring the application of aquafaban in gluten-free and vegan products could pave the way for innovative formulations that cater to a growing market of health-conscious consumers. By understanding its emulsifying, foaming, and binding properties, manufacturers can optimize recipes to achieve desired textures and structures in various baked goods. This research underscores aquafaban's versatility and its potential to contribute to the development of sustainable and inclusive food products that meet diverse dietary needs. In conclusion, the exploration of commercial powdered aquafaba in this study underscores its promising role in the bakery and cake industry. By demonstrating its functional properties and potential applications in cake formulations, this research opens avenues for innovative, plant-based, and gluten-free products. As consumer preferences shift towards sustainable and health-conscious choices, aquafaba offers a versatile solution that enhances product quality while meeting diverse dietary needs. Continued research and development in this field will further unlock aquafaba's capabilities, paving the way for more inclusive and environmentally friendly food options in the market.