Publication: Liyofilize Ekşi Hamur Starter Kültürü Üretimi için Optimum Koşulların ve Kültür Stabilitesinin Belirlenmesi
Abstract
Bu doktora tezi kapsamında ekşi hamurdan izole edilmiş ve endüstriyel olarak kullanılabileceği belirlenmiş üç laktik asit bakterisinin (Lactobacillus curvatus N19, Weisella cibaria N9, Lactobacillus brevis ED25) dondurularak kurutulması, depolama stabilitelerinin belirlenmesi, fermantasyon koşullarının optimize edilmesi ve ekşi hamur ekmeğinde kullanım potansiyelleri belirlenmiştir. Çalışmanın ilk aşamasında dondurma ve dondurarak kurutma işlemlerinde canlılık kaybının minimum olması için kriyoprotektan kullanımının optimizasyonu gerçekleştirilmiş ve belirlenen optimum kriyoprotektan formülasyonlarıyla üretilen kültürlerin dondurma ve kurutma işlemi sonrasında canlılık düzeylerinin %99'dan yüksek olduğu bulunmuştur. Liyofilize kültürler karakterize edilmiş ve toz materyaller için gerekli özellikleri taşıdıkları belirlenmiştir. Kültürlerin depolanması sürecinde hücre canlılığında az da olsa kayıp meydana geldiği ve fermantasyon yeteneklerinde de kısmi bir azalma olduğu saptanmıştır. Sıcaklığa bağlı hızlandırılmış raf ömrü testi (ASLT) sonucu kültürlerin oda sıcaklığında 18-25,8 ay saklanabileceği belirlenmiş ve ASLT'nin uzun dönem muhafaza için yeterli hassasiyette, ancak kısa dönem muhafaza için gerçek değerlerden oldukça farklı sonuçlar verdiği belirlenmiştir. Liyofilize kültürlerin metabolit üretimlerinin fermantasyon sıcaklığı ve süresinden önemli düzeyde etkilendiği tespit edilmiş ve optimizasyon çalışmaları sonucunda en uygun koşulların 28,62 ile 32 oC sıcaklık ve 23,44 ile 26,22 saat süre ile fermantasyon uygulamasının olduğu belirlenmiştir. Liyofilize kültürler kullanılarak ekşi hamurlar elde edilmiş; ardından bunlardan %20 oranında maya olarak kullanılarak ekmek üretilmiştir. Kültür kullanımıyla üretilen ekmeklerin genel kalite özellikleri kontrol örneğine kıyasla daha kabul edilebilir bulunmuştur. Kültürlerle üretilen ekmeklerin daha kompleks uçucu bileşen profiline sahip olduğu, duyusal açıdan da daha fazla kabul gördüğü saptanmıştır. Sonuç olarak optimum kriyoprotektant formülasyonu ile üretilen liyofilize kültürlerin depolama stabilitelerinin oldukça iyi olduğu ve endüstriyel anlamda ekşi hamur ekmeği üretiminde kültür olarak kullanılabileceği tespit edilmiştir. Mart 2020, 229 sayfa Anahtar kelimeler: Liyofilizasyon, modelleme, ekşi hamur, starter kültür
In the scope of this doctoral thesis, freeze-drying of Lactobacillus curvatus N19, Weisella cibaria N9, Lactobacillus brevis ED25 which isolated from sourdough was individually investigated. The storage stability, optimization of fermentation conditions and the usage potentials of them in sourdough bread making were also determined. An optimization study was carried out to minimize the loss of viability in the freezing and freeze-drying processes and it was found that the cell viability levels of the cultures produced with the determined optimum cryoprotectant formulation was higher than 99% after both freezing and drying processes. Freeze-dried cultures were characterized and it was detected that they had the ideal properties for powder materials. It was determined that there was a slight loss in the cell viability during storage and a partial decrease in the fermentation abilities of the cultures. It was stated that cultures might be preserved for 18-25.8 months as the result of accelerated shelf life storage test (ASLT) depending on temperature and it was established that ASLT resulted enough sensitively for long term preservation but quite different from the actual values for short term preservation. It was detected that fermentation metabolites of lyophilized cultures were significantly affected by fermentation temperature and time. The optimum fermentation conditions were determined between 28.62-32oC for temperature and 23.44-26.22 hours for time as the result of optimization study. Sourdough samples were obtained with using freeze-dried cultures and the bread production was realized by using 20% of sourdough samples. General quality characteristics of breads produced by using culture were found more acceptable than the control sample. It was determined that the breads produced with culture had more complex volatile profile than the control sample and sensory aspects of the breads produced by using lactic culture were more widely accepted. Consequently, it was found that freeze-dried cultures produced with optimum cryoprotectant formulation had high storage stability and could be used as starter culture for producing sourdough bread industrially. March 2020, 229 Pages Keywords: Lyophilisation, modeling, sourdough, starter culture
In the scope of this doctoral thesis, freeze-drying of Lactobacillus curvatus N19, Weisella cibaria N9, Lactobacillus brevis ED25 which isolated from sourdough was individually investigated. The storage stability, optimization of fermentation conditions and the usage potentials of them in sourdough bread making were also determined. An optimization study was carried out to minimize the loss of viability in the freezing and freeze-drying processes and it was found that the cell viability levels of the cultures produced with the determined optimum cryoprotectant formulation was higher than 99% after both freezing and drying processes. Freeze-dried cultures were characterized and it was detected that they had the ideal properties for powder materials. It was determined that there was a slight loss in the cell viability during storage and a partial decrease in the fermentation abilities of the cultures. It was stated that cultures might be preserved for 18-25.8 months as the result of accelerated shelf life storage test (ASLT) depending on temperature and it was established that ASLT resulted enough sensitively for long term preservation but quite different from the actual values for short term preservation. It was detected that fermentation metabolites of lyophilized cultures were significantly affected by fermentation temperature and time. The optimum fermentation conditions were determined between 28.62-32oC for temperature and 23.44-26.22 hours for time as the result of optimization study. Sourdough samples were obtained with using freeze-dried cultures and the bread production was realized by using 20% of sourdough samples. General quality characteristics of breads produced by using culture were found more acceptable than the control sample. It was determined that the breads produced with culture had more complex volatile profile than the control sample and sensory aspects of the breads produced by using lactic culture were more widely accepted. Consequently, it was found that freeze-dried cultures produced with optimum cryoprotectant formulation had high storage stability and could be used as starter culture for producing sourdough bread industrially. March 2020, 229 Pages Keywords: Lyophilisation, modeling, sourdough, starter culture
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