TAMER TURGUT

The Effect of Microwave Heating on the Some Quality Properties and Shelf Life of Yoghurt

Bu çalışma yoğurt fermantasyonu sonrası mikrodalga ısıtma kullanılarak üretilen ve 4±1°C'de 28 gün depolanan set tipi yoğurtların bazı özellikleri ve mikrodalga ısıtmanın yoğurt bakterilerinin canlılıkları üzerindeki etkisini belirlemek amacıyla yapılmıştır. Bu sayede depolama sırasında asitlik artışı geciktirilerek yoğurdun raf ömrünün uzatılması mümkün olabilecektir. Yoğurt örnekleri fermantasyondan sonra 720 Watt mikrodalga güç seviyesinde üç farklı süreyle (10, 20 ve 30 sn.) mikrodalga ısıtmaya tabi tutulmuştur. Yoğurt bakterilerinin (Lactobacillus delbrueckii ssp. bulgaricus ve S. thermophilus) depolama boyunca sayıları ve yoğurt örneklerinin bazı fiziko-kimyasal özellikleri (pH ve titre edilebilir asitlik) belirlenmiştir. Bulunan sonuçlar mikrodalga uygulamasının, canlı L. bulgaricus ve S. thermophilus sayıları üzerinde etkili olduğunu göstermiştir (P

Mikrodalga Isıtma Uygulamasının Yoğurdun Raf Ömrü ve Bazı Kalite Özellikleri Üzerine Etkisi

This study was carried out to determine the properties of set type yoghurts made using microwave heating after yoghurt fermentation during storage period of 28 d at 4±1°C. In this way, it will be possible to increase the yoghurt shelf-life, by preventing post-acidification. Yoghurts samples were subjected to three different microwave heating (10, 20 and 30 sec) at 720 Watt power level. Viability of yoghurt bacteria (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus) was assessed during 28 d of storage. Samples were subjected also physicochemical analysis (pH and titratable acidity). The results showed that microwave applications significantly affected viable counts of L. delbrueckii ssp. bulgaricus and S. thermophilus (P<0.05). The counts of L. bulgaricus and S. thermophilus increased in heated yoghurts but a delay was observed during of storage period. Also the results indicated that the microwave heating had significant effect on the titratable acidity values (P<0.05). The titratable acidity and pH showed similar patterns of increase or decrease during storage period. During refrigerated storage, decline in pH was greater in control group yoghurts than heated yoghurts. The titratable acidity increased in all yoghurt samples. However, the rate of increase was affected by the microwave heating time. The results of the study showed that the microwave heating had significant effect on the acceptability of yoghurt during shelf-life.

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