Ekstraksiyon süresinin ve pH değerinin kırmızı pancarda toplam fenolik madde ve antioksidan aktivitesi üzerinde etkisinin incelenmesi
Investigation of the effect of extraction time and pH value on total phenolic and antioxidant activity in red beet
Yazar: RAMA ALKAYARI
Danışman: PROF. DR. MUSTAFA KÜÇÜKİSLAMOĞLU
Sakarya Üniversitesi / Fen Bilimleri Enstitüsü / Kimya Ana Bilim Dalı / Organik Kimya Bilim Dalı
Derece: Yüksek Lisans, 2023
Konu: Kimya = Chemistry

Özet:
Bu tez çalışmasında kırmızı pancardan farklı pH değerlerinde (pH 4-10) hem 1 saatlik hem de 24 saatlik ekstraktları elde edilmiştir. Elde edilen bu ekstraktlar toplam fenolik içerikleri ve antioksidan aktiviteleri açısından değerlendirildi.
Kırmızı pancar (Beta vulgaris L.) bitkisi, doğal bir gıda boyası olan betalainler açısından o kadar zengindir ki, bu konuda yapılan birçok çalışmada hammadde olarak kullanılmıştır. Doğal renkler genellikle çeşitli botanik kaynaklardan elde edilir ve gıdaların besleyici ve duyusal özelliklerini arttırdıkları için tercih edilmektedir.
Betalainler, gıda renklendiricileri olarak yaygın olarak kullanılan ve antioksidan, anti-inflamatuar, hepatoprotektif, anti-kanser özellikleri dâhil olmak üzere çok çeşitli arzu edilen biyolojik aktivitelere sahip suda çözünür bitki pigmentleridir. Başta pancar olmak üzere çeşitli bitkilerden üretilebilirler. Artan talep ile birlikte betalain ekstraksiyonunda en yüksek verimi elde etmek ve ekstrakte edilen betalainin stabilitesini sağlamak gibi konular önem kazanmaya başlamıştır.
Antioksidan aktivite tayin yöntemleri çalışılan sistemdeki substrat, reaksiyon koşulları, konsantrasyonlar ve analizlenecek bileşiğin yapısı gibi çeşitli parametrelere bağlı olduğundan, bir bileşiğin antioksidan aktivitesini tayin etmek için standart bir metod yoktur. Bu yüzden antioksidan değerlendirmenin birkaç metod kullanılarak farklı oksidasyon şartları altında çalışılması önerilmektedir. Tez kapsamında da çeşitli metodlarla bitki ekstraktlarının serbest radikalleri giderme ve antioksidan aktiviteleri çalışılmıştır.
Çalışmamızdaki amacımız gıda olarak kullanılan kırmızı pancarın antioksidant kapasitesinin pH'ı ekstraksiyon süresine göre değeşimi incelemektedir. Kırmızı pancardan elde edilen pigment, gıda boyası olarak hem sıvı hem de toz halde kullanılmaktadır. Çalışma için kullanılacak yöntem iki aşamada gerçekleşirilecektir. Birinci aşamada kırmızı pancar (Beta vulgaris L.) blender ile parçalanacak ve renk verici pigmentler uygun Ph da su ile ekstrakte edilecektir. Elde edilen ekstrak rotari evoparatorde 50 derecede yoğunlaştırıldıktan sonra kurutulmak üzere freeze dryer cihazında vakum altında kurutulacktır. Elde edilecek toz pigmentin antioksidan özellikleri DPPH ve ABTS radikal yakalama yöntemiyle tespit edilecektir. Ekstrenin total fenolik bileşik miktarları da tayin edilecektir. 
Çalışma sonucundan kırmızı pancardan elde edilen sulu ekstraktın iyi ve güçlü bir antioksidant özellik gösterdiğini söylenebilir ve pH4 genel olarak en iyi antioksidant aktivite sahip olan ekstrakt olduğunu belirlenmiştir.

Abstract:
In this thesis study, both 1-hour and 24-hour extracts were obtained from red beet at different pH values (pH 4-10). These extracts were evaluated in terms of their total phenolic content and antioxidant activities.
Thanks to the balance between production and destruction events in the cells, our body maintains its vitality throughout life. In this cycle called metabolism, various substances taken from the outside through nutrition are converted into other products as a result of cellular destruction events, and free radicals are produced as a by-product during these events.
Free radicals and antioxidants, which are the most researched subjects of recent years, are gaining more and more importance day by day. Under normal conditions, metabolism is healthy and antioxidants and free radicals are in balance. However, when this balance changes in favor of free radicals, a predisposition to diseases caused by oxidative stress (such as heart, cancer, premature aging, etc.) is observed. Increasing sources of exogenous free radicals such as pollution, alcohol and cigarette use, forest fires and X-rays and UV rays can cause oxidation by damaging carbohydrates, fats, proteins and DNA in the human body.
In addition, some compounds in plants have a retarding effect on the oxidative stress process. These compounds, which have been studied for a long time, are called antioxidants. Antioxidants are compounds that reduce or eliminate the harmful effects of free radicals in the body. Natural antioxidants obtained from foods are one of the most important factors in strengthening the antioxidant defense system.
As we age, our defense mechanisms weaken and the free radicals in our body become unbalanced. This is due to decreased production of the endogenase enzyme, a natural antioxidant in the body. Therefore, it is important to consume all foods containing antioxidants to restore the balance. Natural antioxidants are substances found in plant and animal tissues.
Today, increasing consumer awareness and the need for healthy nutrition have increased the importance of all foods and natural ingredients used in food formulations. For this reason, people are starting to use natural dyes instead of synthetic additives in food dyes or dyes used to beautify existing colors. Dyes, which differ according to their chemical structure and source, are basically divided into two main groups as natural and synthetic.
Synthetic colorants are color materials that are not found in nature due to their chemical structure, but can be produced by chemical synthesis. Synthetic food colorants are superior to natural food colorants in terms of coloring power, color tone width, brightness, color stability and application. Synthetic colorants are highly soluble in water. Many of them are stable to heat, light, acids, alkalis and preservatives and therefore have a very long shelf life, but have adverse effects on human health.
Natural coloring agents are pigments obtained from microbial, vegetable, animal and mineral sources. These colorants, whose color range is limited, generally have poor stability and poor coloring power, are affected by heat and pH. Although natural colorants have low stability against many physical and chemical effects (heat, light, pH) and there are many problems with their use in foods, it has been noted in recent studies that their use has increased due to their positive effects on human health.
The red beet (Beta vulgaris L.) plant is so rich in betalains, a natural food coloring, that it has been used as a raw material in many studies on this subject. Natural colors are generally preferred because they come from a variety of botanical sources and enhance the nutritional and sensory properties of foods.
Produced red beet (Beta vulgaris L.) is consumed raw in meals, salads and pickles. It is used as a natural colorant in foods such as ice cream, candy, yoghurt, pudding, sherbet, milk and bakery products. Beetroot is extremely rich in antioxidants, thanks to the compounds and pigments in its structure.
100 grams of red beetroot has an average of 43 kcal, approximately 9.56 g carbohydrates, 1.5 g protein, 0.1 g fat, 78.0 mg sodium, 350.0 mg potassium, 24.0 mg magnesium, 16.0 mg calcium It contains 40.0 mg of phosphorus, 0.5 mg of zinc, 0.9 mg of iron, 0.4 µg of selenium, 3 µg of vitamin K, 10 mg of vitamin C, 0.03 mg of vitamin B1 and 11.4 µg of carotenoids.
Beetroot contains a number of bioactive compounds that can exert health-promoting effects, including betalains, ascorbic acid, flavonoids, carotenoids, polyphenols, saponins and high levels of nitrate.
Betalains are water-soluble plant pigments that are widely used as food colorants and have a wide range of desirable biological activities, including antioxidant, anti-inflammatory, hepatoprotective, anti-cancer properties. They can be produced from various plants, especially beet. In line with the increasing demand, issues such as betalain extraction with the highest efficiency and ensuring the stability of the extracted betalains are gaining importance.
Red beet is an economically important plant, with varieties such as beetroot, tubers and leaves, and sugar beet, which are usually native to a region starting from southern Sweden and the British Isles to the west of Europe and thence to the entire Mediterranean coast. In Turkey, it is mostly produced in the Aegean and Marmara regions.
Red beet is grown all over the world and is widely and frequently consumed. World beet production is estimated to be around 275 million metric tons in 2018. Betacyanins make up about 75-95% of beet pigments, the remaining 5-25% being betaxanthins. Betalain concentrations in red beet are 200–2100 mg/kg fresh weight.
Betalains are water-soluble and nitrogen-containing colored pigments known as betalaminic acid derivatives. They are generally divided into two groups: betacyanins and betaxanthins. Since the two pigments in question have different chemical structures, they have different color properties. Betaxanthins are yellow, while betacyanins are red (Özyurt et al, 2019). Structurally, betaxanthins are condensation products of betalamic acid and various amino compounds, whereas betacyanins are characterized by a cyclo Dopa structure with additional substitutions via alternating glycosylation and acylation patterns at C-5 or C-6.
Betalains were first introduced in 1960 by Dr. It was isolated by Tom Mabry at the University of Zurich and its chemical structures were discovered. Betalains were once thought to be related to anthocyanins, the red pigments found in most plants. Both betalains and anthocyanins are water-soluble pigments found in the vacuoles of plant cells. However, betalains are structurally and chemically different from anthocyanins and the two were not found together in the same plant. For example, betalains contain nitrogen while anthocyanins do not.
The most studied betalain is betanin, also called beetroot red, as it can be extracted from beetroot roots. Betanin is a glycoside and hydrolyzes to the sugar glucose and betanidine. Betanin dehydrogenation that occurs during heating leads to the formation of neobetanin, which is responsible for the color change to yellow. Cleavage can also produce yellow betalamic acid and colorless cyclo-DOPA-5-O-glucoside. Betanin color is retained upon C15-isomerization or decarboxylation, but C17-decarboxylation results in a hypsochromic shift of absorption from 538 to 505 nm maximum, which is seen as an orange-red color appearance. 2-Decarboxy and 15-decarboxy-betanins are also formed.
There is no standard method for determining the antioxidant activity of a compound, as antioxidant activity determination methods depend on various parameters in the system under study, such as the substrate, reaction conditions, concentrations, and the nature of the compound to be analyzed. Therefore, it is recommended to study antioxidant evaluation under different oxidation conditions using several methods. Within the scope of the thesis, free radical removal and antioxidant activities of plant extracts were studied by various methods.
Our aim in our study is to examine the change of antioxidant capacity of red beet, which is used as food, according to pH, extraction time. Color pigments obtained from red beet are used as colorants in foods in both liquid and powder form. The method to be used for the study will be carried out in two stages. In the first stage, beetroot (Beta vulgaris L.) will be shredded with a blender and the coloring pigments will be extracted with water at appropriate pH. The obtained extract will be concentrated in a rotary evaporator at 50 degrees and then dried in a freeze dryer under vacuum. The antioxidant properties of the powder pigment to be obtained will be determined by DPPH and ABTS radical capture method. The total phenolic compound amounts of the extract will also be determined. 
As a result of the study, it can be said that the aqueous extract obtained from red beet shows good and strong antioxidant properties and pH4 was determined to be the extract with the best antioxidant activity in general.