MEYVE ÇEŞİDİ VE MUHAFAZA SÜRESİNİN MEYVELİ YOĞURTLARIN BAZI KALİTE KRİTERLERİ ÜZERİNE ETKİSİ

Abstract

OZET: Bu arastirmada, pastorize edilen (70oC'de 30 dak.) ve evaporatorde (450 mmHg, 60oC) kurumadde miktari %19,95'e yukseltilen taze inek sutu kullanilmistir. 43oC'de inkube edilen ve pH'si 4,7'ye kadar dusurulen sade yogurtlar, soguk hava deposunda (6oC) bir gece dinlendirilmistir. Muz puresi, cilek, portakal ve visne sularina esit oranda seker karistirilip isil islem uygulanan marmelatlar, yogurtlara %16 oraninda (% 8 meyve + % 8 seker) ilave edilerek karistirilmistir. Boylece 4 farkli meyveli yogurt cesidi, muhafaza suresi boyunca (1,3,5,7,9,11 ve 13. gunler) duyusal, fiziksel ve kimyasal ozellikler bakimindan sade ve % 8 seker iceren yogurtlarla kiyaslanmistir. Arastirma, Sansa Bagli Bloklar Deneme Desenine gore duzenlenmis ve iki tekerrurlu olarak yurutulmustur. Meyve ilavesi, yogurtlarin % kurumadde, serum ayrilmasi ve viskozite degerlerinde genel olarak yukselmeye; % yag, % asitlik ve pH'sinda dusmeye neden olmustur. Yogurt orneklerinde yapilan duyusal degerlendirme sonuclarinda, genel olarak en fazla portakalli yogurt begenilmis, bunu cilekli, visneli ve muzlu yogurtlar takip etmistir. Muhafaza suresi boyunca yogurtlarin % kurumadde, % protein, % yag ve serum ayrilmasi ile pH degerlerinde dusme; % asitlik ve viskozite degerlerinde yukselme tespit edilmistir. Arastirmanin 11. gununden itibaren yogurtlarda kuf ve alkol kokusu hissedilmistir. Bu nedenle kuf ve maya kontaminasyonunu onlemek sartiyla meyveli yogurtlarin soguk sartlarda 11 gun muhafaza edilebilecegi sonucuna varilmistir. THE EFFECTS OF DIFFERENT FRUITS AND STORAGE PERIOD ON SOME QUALITY CRITERIA OF FRUIT YOGURT SUMMARY: In this study, pasteurized (70oC, 30 min.) and evaporized (450 mmHg, 60oC) up to 19.95 % drymatter fresh cow milk was used in yogurt manufacture. Yogurts that were incubated at 43oC and its pH was adjusted to 4.7 were stored at 6oC overnight. Jams that produced from banana puree, strawberry, orange and cherry juice mixing with equal amounts of sugar, received heat treatment then were added to yogurts following cooling at 16 % rates (8 % fruit & 8 % sugar) and mixed thoroughly. The changes during storage period of 1-13 days with 1 day increments of fruit added yogurts were analyzed to compare with plain yogurt and the yogurt with 8 % sugar only in terms of sensory, physical and chemical properties. Tests were conducted according to Completely Randomised Blocks Design with two replication. Addition of fruits, generally increased % dry matter, sineresys and viscosity, but decreased % fat, % acidity and pH of the yogurt. During the sensory evaluation, yogurts with orange juice were most preferred following by the yogurts with strawberry, cherry juice and banana puree. During the storage, % dry matter, % fat, sineresys and pH decreased while % acidity and viscosity were increasing. Starting from 11 th day of the storage, mould growth appeared and smell of alcohol were perceived. The results suggested that yogurt could be preserved at least for 11 days at 6oC if mould and other contaminations are prevented.