Stevia katkılı probiyotik yoğurtlarda bakteri canlılığının ve ürün özelliklerinin belirlenmesi
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Date
2019-03-28
Authors
Eroğlu, Ezgi
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Publisher
Bursa Uludağ Üniversitesi
Abstract
Bu çalışmada Bifidobacterium animalis subsp. lactis ve Lactobacillus acidophilus probiyotik bakteri suşlarının sırasıyla karbonhidrat içermeyen TPY (Tryptone Peptone Yeast Extract) ve MRS (de Man, Rogosa and Sharpe) temel besi ortamına ilave edilen steviayı in vitro koşullarda fermente edebilme yetenekleri araştırılmıştır. Besi ortamlarına substrat olarak %0,025 ve %1 stevia, %0,025 stevia + %1 inülin, %1 stevia + %1 inülin ile %2 oranında kültür ilave edilerek 37oC'de 48 saat süreyle anaerobik fermantasyona bırakılmıştır. Karbonhidrat içermeyen örnek, negatif; %1 glikoz veya inülin içeren örnek ise pozitif kontrol olarak değerlendirilmiştir. Temel ortamda geliştirilen kültürlerden, fermantasyonun 0., 12., 24., 36. ve 48. saatlerinde örnekler alınmıştır. Bu örneklerde pH, hücre yoğunluğu (OD600), probiyotik bakteri sayısı, prebiyotik aktivite sayısı (PAS), laktik asit ve kısa zincirli yağ asitleri (KZYA) miktarı belirlenmiştir. Çalışmanın ikinci aşamasında stevia katkılı probiyotik yoğurt üretimi gerçekleştirilmiş ve stevianın potansiyel prebiyotik aktivitesi ile yoğurt özellikleri üzerine etkisi değerlendirilmiştir. Fermantasyon süresince asitlik gelişimine de bağlı olarak B. animalis subsp. lactis ve L. acidophilus'un hücre yoğunluğu değerlerinin (OD600) artış gösterdiği ve bakteriyel fermantasyonun en fazla L. acidophilus örneklerinde gerçekleştiği belirlenmiştir. Probiyotik bakterilerin en iyi gelişim gösterdiği besi ortamı %0,025 stevia ve %0,025 stevia + %1 inülin içeren ortam olmuştur. Stevia, B. animalis subsp. lactis ve L. acidophilus tarafından fermente edilebilir özellik gösterirken, ayrıca inülin ilavesi bakteri gelişimini arttırmıştır. Yoğurt örneklerinde depolama süresinin 1., 7., 14., 21. ve 28. günlerinde mikrobiyolojik, fizikokimyasal (titrasyon asitliği, serum ayrılması, renk (L, a ve b), tekstürel (sıkılık, konsistens, iç yapışkanlık ve viskozite indeksi) ile duyusal (görünüş, yapı ve tekstür, koku, renk, aroma yoğunluğu, tat, duyusal asitlik ve genel kabul edilebilirlik) özellikler incelenmiştir. Probiyotik bakteri sayısının stevia ve inülin içeren yoğurt örneklerinde depolama boyunca biyoterapötik seviyede (>7 log kob/mL) kaldığı saptanmıştır. B. animalis subsp. lactis kullanımı yoğurtların enstrümental tekstürel özelliklerini iyileştirirken, L. acidophilus içeren yoğurtlar duyusal açıdan daha çok beğenilmiştir. Sonuç olarak stevianın B. animalis subsp. lactis ve L. acidophilus türlerinin gelişimini ve aktivitesini attırdığı in vitro çalışmalar ile belirlenmiş, potansiyel prebiyotik kaynak ve şeker ikamesi olarak şeker oranı azaltılmış süt ürünlerinde kullanılabileceği saptanmıştır.
In this study, the ability utilising stevia added to non-carbohydrate containing TPY (Tryptone Peptone Yeast Extract) and MRS (Man, Rogosa and Sharpe) basal media under in vitro conditions by probiotic strains of Bifidobacterium animalis subsp. and Lactobacillus acidophilus was investigated. The basal media were supplemented with 0.025% and 1% stevia, 0.025% stevia + 1% inulin, %1 stevia + 1% inulin and 2% culture and incubated for 48 hours at 37 ° C under anaerobic conditions. The medium which contained no carbohydrate was designated as negativecontrol, whereas the media containing 1% glucose or inulin were evaluated as positive. Samples were collected from the cultures developed in basal media on the 0, 12, 24, 36 and 48 hours of fermentation. The samples were analysed for pH, cell density (OD600), probiotic bacteria counts, prebiotic activity score (PAS), lactic acid and short chain fatty acids (SCFA) content. In the second stage of the study probiotic yoğurt supplemeted with stevia was manufactured and the potential prebiotic activity of stevia and its effect on yogurt characteristcs as sugar substitute were evaluated. Depending on the acidity development during fermentation, the cell density (OD600) values of B. animalis subsp. lactis and L. acidophilus showed an increase and the highest bacterial fermentation was observed in L. acidophilus yogurt. The best growth medium for probiotic bacteria was 0.025% stevia and 0.025% stevia + 1% inulin. B. animalis subsp. lactis and L. acidophilus were able to ferment stevia whilst addition of inulin increased the bacterial growth. Microbiological, physicochemical (titritable acidity, syneresis, color (L, a and b), textural (firmness, consistency, cohesiveness and viscosity index) and sensorial (appearance, structure and texture, odor, color, aroma density, taste, sensory acidity and general acceptability) properties of yogurt samples were determined on the 1, 7, 14, 21 and 28 days of storage. The counts of probiotic bacteria remained within the biotherapeutic level (> 7 log kob/mL) during storage in yogurt samples containing stevia and inulin. Yoghurts containing B. animalis subsp. lactis have improved the instrumental textural properties, whereas yoghurts containing L. acidophilus had higher scores for sensorial attributes. Consequently, it was found that stevia improved the survival and activity of B. animalis subsp. lactis and L. acidophilus species in vitro, and could be assigned as a potential prebiotic source and sugar substitute for manufacturing of sugar-reduced dairy products.
In this study, the ability utilising stevia added to non-carbohydrate containing TPY (Tryptone Peptone Yeast Extract) and MRS (Man, Rogosa and Sharpe) basal media under in vitro conditions by probiotic strains of Bifidobacterium animalis subsp. and Lactobacillus acidophilus was investigated. The basal media were supplemented with 0.025% and 1% stevia, 0.025% stevia + 1% inulin, %1 stevia + 1% inulin and 2% culture and incubated for 48 hours at 37 ° C under anaerobic conditions. The medium which contained no carbohydrate was designated as negativecontrol, whereas the media containing 1% glucose or inulin were evaluated as positive. Samples were collected from the cultures developed in basal media on the 0, 12, 24, 36 and 48 hours of fermentation. The samples were analysed for pH, cell density (OD600), probiotic bacteria counts, prebiotic activity score (PAS), lactic acid and short chain fatty acids (SCFA) content. In the second stage of the study probiotic yoğurt supplemeted with stevia was manufactured and the potential prebiotic activity of stevia and its effect on yogurt characteristcs as sugar substitute were evaluated. Depending on the acidity development during fermentation, the cell density (OD600) values of B. animalis subsp. lactis and L. acidophilus showed an increase and the highest bacterial fermentation was observed in L. acidophilus yogurt. The best growth medium for probiotic bacteria was 0.025% stevia and 0.025% stevia + 1% inulin. B. animalis subsp. lactis and L. acidophilus were able to ferment stevia whilst addition of inulin increased the bacterial growth. Microbiological, physicochemical (titritable acidity, syneresis, color (L, a and b), textural (firmness, consistency, cohesiveness and viscosity index) and sensorial (appearance, structure and texture, odor, color, aroma density, taste, sensory acidity and general acceptability) properties of yogurt samples were determined on the 1, 7, 14, 21 and 28 days of storage. The counts of probiotic bacteria remained within the biotherapeutic level (> 7 log kob/mL) during storage in yogurt samples containing stevia and inulin. Yoghurts containing B. animalis subsp. lactis have improved the instrumental textural properties, whereas yoghurts containing L. acidophilus had higher scores for sensorial attributes. Consequently, it was found that stevia improved the survival and activity of B. animalis subsp. lactis and L. acidophilus species in vitro, and could be assigned as a potential prebiotic source and sugar substitute for manufacturing of sugar-reduced dairy products.
Description
Keywords
Probiyotik, Prebiyotik, İnülin, Stevia, Yoğurt, İn vitro, Probiotic, Prebiotic, Yogurt, In vitro
Citation
Eroğlu, E. (2019). Stevia katkılı probiyotik yoğurtlarda bakteri canlılığının ve ürün özelliklerinin belirlenmesi. Yayınlanmamış yüksek lisans tezi. Bursa Uludağ Üniversitesi Fen Bilimleri Enstitüsü.