Mikrodalga pastörizatör sistemi ile organik orta nemli meyvelerin ısıl işlem koşullarının ve kalitesinin belirlenmesi
Determination of heat treatment conditions and quality of organic intermediate moisture fruits in  microwave pasteurizer system design
Yazar: DİLBER ÇAĞLAR
Danışman: PROF. DR. TANER BAYSAL
Ege Üniversitesi / Fen Bilimleri Enstitüsü / Gıda Mühendisliği Ana Bilim Dalı / Gıda Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2021
Konu: Gıda Mühendisliği = Food Engineering

Özet:
Bu tez çalışmasında mikrodalga ve geleneksel pastörizasyon yöntemleri ile organik orta nemli üzüm ve hurmanın pastörize edilmesi amacıyla hedef mikroorganizmanın ısıl direncinin saptanması ve geleneksel ve mikrodalga pastörizasyon yöntemlerinin ürün kalitesi üzerine etkilerinin incelenmesi amaçlanmıştır. Yüksek şeker içerikli gıdalarda hedef mikroorganizma olarak seçilen Zygosaccharomyces rouxii'nin ısıl direnci (D ve z değeri) her iki yöntem (sıcak suda geleneksel pastörizasyon ve mikrodalga pastörizasyon) kullanılarak belirlenmiştir. Her iki pastörizasyon yöntemi için teorik ve deneysel olarak F değerleri hesaplanmış ve karşılaştırılmıştır. Ayrıca, pastörizasyon yöntemlerinin üzüm ve hurma örneklerinde kalite özelliklerine etkisi araştırılmıştır. Hedef mikroorganizmanın ısıl direncini belirlemek için farklı zaman aralıklarında ve 60, 70 ve 80°C olmak üzere 3 farklı sıcaklıkta çalışılmıştır.

Abstract:
In this study, it was aimed to pasteurize organic intermediate moisture raisin and dates with different pasteurization methods, to determine the thermal resistance of the target microorganism and to investigate the effects of the methods on the quality.
The thermal resistance (D and z value) of the target yeast, Zygosaccharomyces rouxii that found in high sugar content foods was determined for both methods (conventional pasteurization in hot water and microwave pasteurization). Theoric and experimantal F values were calculated and compared for both pasteurization methods. Additionally, the effect of pasteurization methods on the quality properties of organic intermadiate moisture raisin and date samples was investigated. Different temperatures as 60, 70 and 80°C at different time intervals were studied for determining the thermal resistance of microorganism. The D values of Z. rouxii were found as 6.50±0.49, 2.96±0.02, 1.91±0.01 minutes for raisin samples, and as 7.19±0.18, 2.96±0.09, 2.02±0.03 minutes for dates in conventional treatment. These values were 3.46±0.31, 2.02±0.14, 1±0.01 minutes for raisin samples and 3.98±0.02, 2.01±0.01, 0.97±0.01 minutes for dates in microwave treatment at 60℃, 70℃ and 80℃ respectively. 
D and z values were found considerably lower in microwave pasteurization than conventional method also F8537 values for 5 log reduction and come up times significantly decreased by microwave pasteurization. In conventional pasteurization of raisin samples, D85 and F8537 values were found as 1.4 and 7 respectively, while in microwave pasteurization these values were determined as 0.73 and 3.65 min. Total soluble solid content, acidity and color values were preserved better by microwave treatment. Specially hydroxymethylfurfural (HMF) contents of date and raisin samples pasteurized by the conventional method were found to be approximately 2 times more than the samples pasteurized by microwave.
These ﬁndings demonstrated that microwave pasteurization can be alternatively used for the conventional method with the advantage of less heating time and protecting the quality properties better.