Yoghurt Powder: Processing Technology, Storage And Possible Fields of Use (Turkish with English Abstract)

Öz

The primary objective of drying the yoghurt is to preserve it in a shelf stable powder form of high quality, without a need for refrigeration. In order to extend the shelf life of yoghurt, some traditional applications such as removing of water by straining (strained yoghurt) or sun drying of yoghurt are used , however, yoghurt powder which has the longest shelf life yoghurt product is not produced in an industrial scale in Turkey. Yoghurt can be dried alternatively by spray, microwave, convective or freeze drying methods, taking into consideration the viability and activity of the yoghurt bacteria. The quality of yoghurt powder is affected mainly by the viable yoghurt starter bacteria count. Although the best method for drying the yoghurt is identified to be freeze drying in terms of survival of yoghurt starter bacteria; high cost of application is seen to be the main disadvantage of this method. On the other hand, another drying method - spray drying has advantages such as high moisture removal rate, reduced cost and short process time, compared to the freeze-drying method. Freeze-dried yoghurt can be stored for up to 1-2 years, at 4 ºC whereas spray dried yoghurt cultures, when stored under cool and dry conditions, are guaranteed to preserve its activity up to 1 year. After 1 year of storage, the powder should contain a minimum of total lactic acid bacteria counts of 106 cfu/g. Yoghurt powder can be used in dry dessert mixes, yoghurt drink mixes flavored with natural fruits, soup bases, instant drink mixes and as ingredients in bakery and confectionery industries. It can also be used in reconstituted form as fresh yoghurt. However, poor texture, gel structure and flavor of reconstituted yoghurt are the main problems of yoghurt powder technology and should be improved. In this review, it is aimed to present information on production technology, storage stability and possible fields of use of yoghurt powder and different drying methods used.

Anahtar Kelimeler

• Yoghurt powder, Streptococcus thermophilus, Lactobacillus bulgaricus, freeze-drying, spray drying, storage stability

Yoğurt Tozu; İşleme Teknolojisi, Depolama ve Kullanım Alanları

Öz

Yoğurdun kurutulmasının temel amacı yoğurdu yüksek kalitede, soğutma gereksinimi olmadan, raf ömrünü arttırarak toz formunda saklamaktır. Türkiye’de bölgesel olarak yoğurdun raf ömrünü uzatmak amacıyla süzerek suyunu uzaklaştırma (süzme yoğurt), güneşte kurutma gibi çeşitli yöntemler kullanılmakla birlikte endüstriyel düzeyde yoğurt tozu üretimi yapılmamaktadır. Yoğurdu kurutmak için dondurarak kurutma, püskürtmeli kurutma, mikrodalga kurutma veya konvektif kurutma gibi kurutma yöntemleri uygulanmaktadır. Yoğurt tozu kalitesini canlı yoğurt starter bakteri sayısı önemli ölçüde etkilemektedir. Yoğurt tozu, canlı bakteri sayısı açısından değerlendirildiğinde en iyi kurutma yönteminin dondurarak kurutma olduğu belirtilmekle birlikte, çok pahalı bir yöntem oluşu önemli bir dezavantaj olarak görünmektedir. Diğer taraftan püskürtmeli kurutma yöntemi, yüksek su buharlaşma hızı, daha düşük maliyet ve kısa işlem süresi ile dondurarak kurutma yöntemine karşı avantajlar sağlamaktadır. Dondurarak kurutulmuş yoğurt, 4 ºC’da 1-2 yıl depolanabilmekte, püskürtmeli kurutucuda kurutulmuş yoğurt ise soğuk ve kuru koşullar altında saklandığında aktif kültürler 1 yıl canlılıklarını koruyabilmektedir. 1 yıllık depolama sonrasında, yoğurt tozunun en az 106kob/g düzeyinde toplam canlı yoğurt bakterisi içermesi gerekmektedir. Toz ürün; kuru meyveli karışımlarda, meyve aromalı yoğurt içeceklerinde, hazır içecek karışımlarında, ekmekçilikte, hazır toz çorba karışımlarında kullanılabildiği gibi, rekonstitüe edilerek taze yoğurt formunda da kullanılabilmektedir. Ancak yoğurt tozu teknolojisinde karşılaşılan en önemli problem, rekonstitüe ürünün jel yapısı, tekstür ve aroma özelliklerinin zayıf olmasıdır ve bu mutlaka geliştirilmelidir. Bu derlemede yoğurt tozunun üretim teknolojisi, farklı kurutma yöntemleri, depolama stabilitesi ve kullanım alanları hakkında bilgi verilmesi amaçlanmıştır.

Anahtar Kelimeler

• Yoğurt tozu, Streptococcus thermophilus, Lactobacillus bulgaricus, dondurarak kurutma, püskürtmeli kurutma, depolama stabilitesi  

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