Solubility and emulsifying properties of red pepper seed flour and protein

Protein, yağ ve lif içeriği oldukça zengin olan kırmızı biber tohumlarının, gıda sanayiinde kullanılarak değerlendirilmesi oldukça önem kazanmaktadır. Kırmızı biber tohum unu ve proteininin çözünürlük ve emülsiyon özellikleri, ticari ürün olan soya protein konsantresi ile karşılaştırılarak incelenmiştir. Bu amaçla yağı alınmış kırmızı biber tohum unu hazırlanmış ve bu undan ekstraksiyon ve izolasyon metodu ile protein elde edilmiştir. Kırmızı biber tohum proteini için en düşük çözünürlük değeri pH 4’de elde edilmiş ve bu değerin altındaki ve üstündeki pH değerlerinde çözünürlük artmıştır. Kırmızı biber tohum proteini, alkali koşullarda kırmızı biber tohum unu ve soya protein konsantresinden daha yüksek çözünürlüğe sahiptir. Genel olarak tüm örneklerde tuz konsantrasyonu arttıkça çözünürlük de artmaktadır. Kırmızı biber tohum proteininde tuz konsantrasyonun çözünürlüğe olan etkisi kırmızı biber tohum ununa göre daha fazladır. Kırmızı biber tohum unu ve proteinin emülsiyon aktivitesi değerleri sırasıyla %49.3-54.7 ve %48.8-70.4; emülsiyon stabilitesi ise %52.9-54.33 ve %47.19-64.9 aralığında değişmektedir. Kırmızı biber tohum proteinin, emülsiyon özellikleri proteinlerin çözünürlük eğrileri ile paralellik göstermektedir. Kırmızı biber tohum proteini, bazik pH koşullarında kırmızı biber tohum ununa ve soya protein konsantresine göre daha yüksek emülsiyon özelliklerine sahiptir. Kırmızı biber tohum proteini ile oluşturulan emülsiyonun stabilitesi kırmızı biber tohum unu ile oluşturulana göre daha yüksektir. Kırmızı biber tohum proteinin emülsiyon özellikleri tuz ilavesi ile azalırken, kırmızı biber tohum unu ve soya protein konsantresinin emülsiyon özellikleri değişmemektedir. Anahtar Kelimeler: Kırmızı biber, emülsiyon, çözünürlük, protein.Recently more attention has been focused on the utilization of food processing by-products and wastes. Obviously, such utilization would result in the production of various new products for food and contribute these products into foods. Only a small portion of plant material is utilized directly for human consumption. The remaining portion of this material or part of it may be converted into nutrients for either food or feed or into fertilizer. Peppers belong to the genus Capsicum, where C. annuum L. is the most widely cultivated species. They are grown mainly for its fruit although the seeds could also be used as spice after drying and grinding. They are processed into dehydrated products, pickled peppers, and sliced or diced frozen peppers or into products such as sauce, paste, puree and powder for flavoring or coloring purposes and many more. Red pepper seeds are excellent sources of protein, oil and fiber and they are rich in total essential amino acids, lysine, threonine, total aromatic amino acids, and tryptophan. Among the pepper producing countries, Turkey ranks the third after China and Mexico with 1,745,000 tons of produce per year. Utilization or the disposal of solid wastes remaining after canned/frozen pepper products processing that consist of stems, leaves and seeds are the most challenging tasks for the industry. Proteins, as isolates or concentrates, are necessary ingredients in many food processes where they perform specific functions. Functional properties of proteins can be defined as physicochemical properties which affects the behaviour of proteins and contribute to the food quality and sensory properties during food preparation, processing, storage and consuming. Proteins change the physical properties of food by interacting with solvent, ions, other proteins, polysaccharides, lipids inside the surrounding environment. Properties such as solubility, water holding capacity, lipid binding property, foam capacity and stability, emulsion capacity and stability and gel formation of protein are the functional properties that affect the food quality. Emulsifying properties are important functionality traits related to the protein used in food products. Emulsifying capacity and emulsion stability are usually used to investigate the emulsifying properties of proteins in food emulsion systems. Various factors and conditions affect emulsifying properties of proteins including source of protein, protein concentration, pH, solubility, temperature, equipment and the method used to produce the emulsion. Solubility plays a role in emulsifying properties of proteins. Highly in soluble proteins display very poor emulsifying properties. In this study, emulsifying properties of red pepper seed flour and protein were monitored in relation to influence of pH and concentration. It is hoped that the data will provide information on utilizing red pepper seed flour in various food applications. The red pepper seed consists of 9.30% moisture, 19.32% fat, 23.64% protein, 3.55% ash, and 48.98% carbohydrate in dry basis. It is highly possible to use it as good source of protein and diet fiber due to its content of high protein and diet fiber. The protein concentration obtained from red pepper seed contains 6.63% moisture, 1.52% fat, 67.00% protein, 4.59% ash, and 26.87% carbohydrate. Red pepper seed protein concentrate contains more protein than soy protein concentrate, which is a commercial product. In alkaline conditions, red pepper seed protein showed a higher solubility than red pepper flour and soy protein concentrate. Generally, solubility increased with increasing salt concentrations in all samples. The effect salt concentration on red pepper seed protein was higher than red pepper seed flour.   After this concentration, no change was observed.  Emulsion activity of red pepper seed flour and protein was 49.3-54.7% and 48.8-70.4%, respectively. And also emulsion stability was 52.9-54.3% and 47.2-64.9%, respectively. The emulsion properties of red pepper seed protein showed similar trend with solubility curves. Red pepper seed protein had higher emulsion properties than red pepper seed flour in alkaline conditions. The emulsion prepared by red pepper seed protein was more stable than prepared by red pepper seed flour. The emulsion properties of red pepper seed protein decreased with salt addition. On the other hand, the emulsion properties of red pepper seed flour and soy protein concentrate were not affected by salt addition. Keywords: Red pepper seed, protein, emulsifying properties, solubility