Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
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Book Part Citation - Scopus: 1Enzyme Production From Sourdough(CRC Press, 2023) Elvan, Menşure; Harsa, ŞebnemSourdough is a traditional fermented food well known around the world. It contains a wide variety of components, such as cereals and pseudocereals, and is rich in microflora that can potentially be used for enzyme production. Sourdough is a good source of lactic acid bacteria that have high enzyme production capability. Enzymes have different roles during sourdough fermentation: mainly, amylase and xylanase enzymes have important effects in improving texture; protease and phytase enzymes increase the nutritional value of sourdough; lipoxygenase improves the shelf life of products; and esterase plays a leading role in aroma and flavor formation. Additionally, it is possible to isolate sourdough enzymes for their potential to improve the health attributes of other foods, i.e., enzymes to break down gluten, hydrolyze phytic acid, and degrade fructans. Moreover, these enzymes may also be used to improve the technological properties of grain-based foods and beverages. Currently, there are no studies on the large-scale production of enzymes based on sourdough, although microorganisms isolated from sourdough have the potential for industrial-scale food applications as the sourdough microflora and derived enzymes have Generally Recognized as Safe (GRAS) and green label status. This chapter reviews sourdough enzymes and their importance for improving the quality and shelf life of foods in different food industries and products. © 2024 selection and editorial matter, Marco Garcia-Vaquero and João Miguel F. Rocha.Book Part Discovery, Characterization, and Databases of Enzymes From Sourdough(CRC Press, 2023) Ağırbaşlı, Zeynep; Harsa, ŞebnemSourdough enzymes have not been investigated in wide scale yet. Therefore, this chapter summarizes the main strategies and techniques used for the identification of sourdough enzymes together with the compilation of this information in databases for a wide variety of applications. The chapter describes a panel of methods based on different approaches, such as biochemical and molecular techniques for the identification of several key microbial enzymes emerged from sourdough or a combination thereof. Review includes information on the enzymes in carbohydrate metabolism, protein metabolism, phenolic metabolism, and stress metabolism together with enzymatic formation of bioactive compounds in sourdough. © 2024 selection and editorial matter, Marco Garcia-Vaquero and João Miguel F. Rocha.Conference Object Citation - Scopus: 2Preparation and Characterization of Hydroxyapatite/Calcium Phosphate Powders(Trans Tech Publications, 2004) Şimşek, Deniz; Çiftçioğlu, Rukiye; Harsa, ŞebnemThe preparation of calcium phosphate based powders through chemical precipitation in order to determine the optimum conditions for the preparation of stoichiometric, thermally stable hydroxyapatite (HA) powders was investigated in this work. The effects of parameters like pH, aging time, and heat treatment temperature on the phase structure and morphology of the powders were investigated by SEM and XRD.HA was prepared at a Ca/P ratio of 1.67. The precipitation pH had a profound influence on the morphology and crystallite size of the powders in the 4-11 pH range. Relatively large 5 mum prismatic particles were obtained at low pH whereas the powders were formed from agglomerates of nano sized particles at high pH. Powders had a HA dominant phase structure above a pH of 8. Phase pure HA powders were obtained with close to theoretical yields at pH = 10 and 11. The crystallite sizes of the powders varied from about 30 nm at 90degreesC to 50-90 mn at 1250degreesC with the smallest crystallite sizes obtained for pH 10 and 11 powders at 1250degreesC. The crystallite size increased significantly with aging temperature.