EVALUATION OF THE MICROWAVE DRIED ON SWEET CHERRY LEAF/STALK IN TERMS OF ANTIOXIDANT ACTIVITY


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GÖKBULUT İ.

5th The International Engineering and Natural Sciences Conference 2020 (IENSC2020), Diyarbakır, Türkiye, 5 - 06 Kasım 2020

  • Yayın Türü: Bildiri / Tam Metin Bildiri
  • Basıldığı Şehir: Diyarbakır
  • Basıldığı Ülke: Türkiye
  • İnönü Üniversitesi Adresli: Evet

Özet

  • Sweet cherry is one of the most popular temperate fruits, being highly appreciated by consumers due to its taste, color and sweetness, but also for its nutritional and bioactive properties. Sweet cherries (Prunus Avium L.) contain substantial amounts of anthocyanin and polyphenolics, and their stalk have been used in traditional medicine for centuries. Its fruit, leaves and stalks are the source of bioactive compounds and show antioxidant activity. Sweet cherry leaves contain more vitamin C and total carotenoids than other parts of the plant. The total polyphenol compound content in stalks is quite high. It contains some health benefit compounds including phenolic compounds, organic acids, and sugars, and high antioxidant activity. It is well known that phenolic compounds, particularly anthocyanin, have beneficial effects on several diseases due to their bioactive compounds. Sweet cherry contains significant levels of anthocyanin which possess antioxidant capacity in metabolic reactions owing to their ability to scavenge oxygen free radicals and other reactive species. Many anti oxidative phenolic compounds in plants, however, are usually presented in a covalent form. Therefore, reliable and practical methods of releasing natural antioxidants from plant materials are of great interest. Microwave energy can enhance the bioavailability of free pharmacologically active natural compounds by preventing the binding of polyphenols to the plant matrix.
  • Microwaves are non-ionizing waves that are part of the electromagnetic spectrum in the frequency range 300-3000 megahertz (MHz). In microwave drying, since the material is heated as a whole, the water in the material is heated in a very short time and evaporated and the moisture transfer is from the inside to the outside. Compared to conventional convective drying systems, microwave drying systems can significantly shorten the drying time without deteriorating product quality in many products. The temperature of the product dried during the microwave drying process plays a key role in obtaining a high quality dry product.
  • In this study, in which leaf and stalk of cherry (Prunus Avium L) were dried by microwave technology for 360w 3 to 6 minutes. DPPH (1,1-Diphenyl-2-picrylhydrazyl radical) and ABTS (2, 2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) antioxidant activities and Total Phenolic Content (TPC) were determined.
  • DPPH antioxidant activity value in leaf samples increased at the 6th minute. ABTS antioxidant activity values ​​increased after 3 minutes of 360w application in sweet cherry leaves and stalk, and then ABTS activity decreased when reaching the 6th minute. Similarly, the amount of Total Phenolic Compound (TPC) increased in the 3rd minute and lost activity at the end of the 6th minute.  As in all heating methods, it is reported that prolongation of heating time increases nutrient losses in the microwave heating method. After microwave treatment, while the free fraction of phenolic acids increased, bound fractions decreased and antioxidant activity increased. The content of total phenolic substances increased with strength in the first 3 minutes but was rejected in the longer irradiation time (6 minutes). This means that some phenolic substances may deteriorate.
  • The results showed that proper microwave treatment could be an effective process to release and activate bound phenolic compounds and increase the antioxidant capacity of cherry stalk and leaves.