Pastörize keçi sütünün dondurulması ve dondurarak depolanması sırasında sütte meydana gelen değişmeler
Küçük Resim Yok
Tarih
2010
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Bolu Abant İzzet Baysal Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bu araştırmada, tam yağlı çiğ keçi sütü pastörize edilip farklı ambalaj hacimlerine aktarıldıktan sonra farklı sıcaklıklarda dondurulması ve üç ay depolanması ile mikrobiyolojik, fiziksel, kimyasal ve duyusal özelliklerinin tespiti amaçlanmıştır.Bu amaçla çiğ ve pastörize sütlerin özellikleri belirlendikten sonra farklı hacimdeki ambalajlara aktarılıp -15 ve -35°C' lerde dondurulmuş ve -18 ile -28°C' lerde üç ay depolanmışlardır. Depolama süresince (0, 30, 60 ve 90. günler) keçi sütlerinin mikrobiyolojik (toplam mezofilik aerobik ve koliform bakteri sayısı), fizikokimyasal, biyokimyasal (pH, titrasyon asitliği, vizkozite, sedimentasyon, asitlik derecesi (ADV), oksidasyon ve renk) ve duyusal özellikleri incelenmiştir.Elde edilen araştırma sonuçlarına göre; keçi sütü örneklerinde koliform bakteri sayısında depolama süresi boyunca önemli (p<0.05) azalma belirlenirken toplam mezofilik aerobik bakteri sayısında değişim belirlenmemiştir. Titrasyon asitliği ve E vitamini miktarlarında önemli değişme olmamış buna karşın pH, sedimentasyon, oksidasyon ve asitlik derecelerinde önemli artışlar (p<0.05) saptanmıştır. Renk değerlerinde ise dondurma ve depolama esnasında önemli azalmalar (p<0.05) tespit edilmiştir.Duyusal değerlendirmelerde; tüm örneklerin tadı beğenilirken 1litrelik ambalajlar daha yüksek puan almışlardır. Keçi sütlerinin kokuları ile renk ve görünüşleri depolama boyunca önemli derecede değişmemiş ancak düşük sıcaklıkta dondurulan 1 litrelik ambalajların daha çok beğenildiği görülmüştür. Yapısal açıdan değerlendirildiğinde ikinci aya kadar olumlu gelişmeler gözlenirken, ikinci aydan sonra yapıda bozulmalar belirlenmiştir. Genel olarak, duyusal değerlendirmelerde 1 litrelik ambalajlar daha çok beğenilirken, fiziksel özelliklerde 1/2 litrelik hacimli ambalajların sonuçlarının daha kabul edilebilir olduğu tespit edilmiştir.
In this research, it was aimed to determine the microbiological, physical, chemical and sensory properties of frozen pasteurized whole fat goat milk after being transferred in to two different packaging size and stored frozen at two different temperatures and stored for three months.For this purpose, firstly raw and pasteurized goat milk properties were determined then they were transferred into two different packages (1/2 L and 1 L), later frozen at -15 and -35°C and were stored at -18 and -28°C for three months. During storage period (0, 30, 60 and 90 days) goat milk samples were investigated in terms of their microbiological (total aerobic mesophilic bacteria and coliform bacteria), chemical and biochemical properties (pH, titration acidity %, viscosity, sedimentation, acid value (ADV), oxidation and colour) and sensory characteristics.According to the results obtained, while the effect of storage time on the counts of coliform bacteria were found to be significant (p<0.05), there were no difference at total aerobic mesophilic bacteria count. Although there were no significant difference at titratable acidity and amount of vitamin E, significant differences (p<0.05) found for pH, sedimentation, oxidation and acid value. At the same time, colour values were observed to be significantly reduced (p<0.05) during freezing and storage period.In sensory evaluations, all tasted goat milk samples were approved, while 1 L packages liked more. During the storage time; odour, colour and appeareance of goat milk samples were not changed. On the other hand, 1 L packaged samples froze at -35ºC prefered more compared to other samples. Textural properties of goat milks were improved up to two months of storage, then deteriorations in texture were observed. Generally in the sensory evaluations, 1 L packages prefered by the panelists whilst physical properties of 1/2 L packages were also found to be still acceptable.
In this research, it was aimed to determine the microbiological, physical, chemical and sensory properties of frozen pasteurized whole fat goat milk after being transferred in to two different packaging size and stored frozen at two different temperatures and stored for three months.For this purpose, firstly raw and pasteurized goat milk properties were determined then they were transferred into two different packages (1/2 L and 1 L), later frozen at -15 and -35°C and were stored at -18 and -28°C for three months. During storage period (0, 30, 60 and 90 days) goat milk samples were investigated in terms of their microbiological (total aerobic mesophilic bacteria and coliform bacteria), chemical and biochemical properties (pH, titration acidity %, viscosity, sedimentation, acid value (ADV), oxidation and colour) and sensory characteristics.According to the results obtained, while the effect of storage time on the counts of coliform bacteria were found to be significant (p<0.05), there were no difference at total aerobic mesophilic bacteria count. Although there were no significant difference at titratable acidity and amount of vitamin E, significant differences (p<0.05) found for pH, sedimentation, oxidation and acid value. At the same time, colour values were observed to be significantly reduced (p<0.05) during freezing and storage period.In sensory evaluations, all tasted goat milk samples were approved, while 1 L packages liked more. During the storage time; odour, colour and appeareance of goat milk samples were not changed. On the other hand, 1 L packaged samples froze at -35ºC prefered more compared to other samples. Textural properties of goat milks were improved up to two months of storage, then deteriorations in texture were observed. Generally in the sensory evaluations, 1 L packages prefered by the panelists whilst physical properties of 1/2 L packages were also found to be still acceptable.
Açıklama
Fen Bilimleri Enstitüsü, Gıda Mühendisliği Ana Bilim Dalı
Anahtar Kelimeler
Gıda Mühendisliği, Food Engineering
