This study attempted to investigate the possibility of using some types of probiotic bacteria in the production of ice cream and was aimed at making a contribution to the manufacture of new functional foods. For this purpose, different cream levels (5% and 10%) and different strains of probiotic bacteria (Lactobacillus acidophilus, Bifidobacterium bifidum and both) were used in ice cream production to determine their effects on the quality of the ice creams in each group. During storage of 1, 15, 30, 45, 60, 75 and 90 days, L. acidophilus, B. bifidum counts and sensory analyses were performed. The results obtained at the end of storage demonstrated that the counts of L. acidophilus and B. bifidum continued to decrease during the storage but all types of ice cream sample seemed to preserve their probiotic property even after 90 days. Higher counts of probiotic bacteria were observed in the samples with L. acidophilus, B. bifidum, and L. acidophilus and B. bifidum in double-cultured samples respectively. In general, it appeared that the ice cream samples with 5% cream content were found to be more delectable. All ice cream samples have shown good results in preserving their probiotical properties for more than 3 months. Although sensory scores of probiotic ice cream samples reduced during this time, they rated as 'tasty' throughout the storage.

This study was performed to determine the viability of Lactobacillus acidophilus and Bifidobacterium bifidum in yogurt made with strawberry marmalade (SM) and to examine the quality properties of probiotic yogurt. Acidity, pH, bacterial counts and sensory analysis of the yogurt samples were investigated on days 1, 3, 5, 7, 10 and 14 during storage at 4 °C. The survival rate of L. acidophilus was greater than that of B. bifidum. The viability of L. acidophilus decreased during the storage period, but B. bifidum numbers remained stable during the storage period. The highest L. acidophilus count (7.20 log cfu/g) was found in L. acidophilus + B. bifidum SM yogurt on day 1. The highest B. bifidum count (6.13 log cfu/g) was detected in yogurt containing L. acidophilus + B. bifidum SM yogurt on day 7. Yeast and mould counts of all yogurts increased during the storage period. Coliform bacteria and Staphylococcus aureus were not detected in the yogurt samples. The highest overall acceptance sensory score was observed in yogurts containing L. acidophilus. Considering the sensory and probiotic characteristics of all yogurt samples, this study suggested that strawberry yogurt with a suitable 5-7 day storage period can be produced with single L. acidophilus addition or single B. bifidum addition.

No abstract

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. Keywords: Yoghurt, Microwave heating, Shelf-Life, L. Lactobacillus delbrueckii ssp. bulgaricus, Streptococcus thermophilus Mikrodalga Isıtma Uygulamasının Yoğurdun Raf Ömrü ve Bazı Kalite Özellikleri Üzerine Etkisi ÖzetBu 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<0.05). Sonuçlar aynı zamanda mikrodalga ısıtmanın titre edilebilir asitlik değerleri üzerinde de önemli etkiye (P<0.05) sahip olduğunu göstermiştir. Çalışma, mikrodalga ısıtma uygulmasının raf ömrü süresince yoğurdun kabul edilebilirliği üzerinde önemli bir etkisi olduğunu göstermiştir.

This study investigated the effects of loquat (Eriobotrya japonica L.) marmalade (LM) supplementation in probiotic yogurt during a 21 days storage period. In addition, the viability of Bifidobacterium and its effect on yogurt quality were investigated. Four types of yogurt, including plain yogurt (LM0) and yogurts with 5%, 10%, and 15% LM, were prepared. On days 1, 7, 14, and 21 of storage, physicochemical properties, microbial growth, and textural and sensory properties were investigated. The addition of LM to yogurt significantly affected the total dry matter, fat, pH, titratable acidity, syneresis, water holding capacity, and color parameters (L*, a*, b*). The addition of LM caused a decrease in L* (from 87.52 to 81.78) and an increase in a* values (from −35.42 to −30.14). Yogurts containing 10 and 15% LM demonstrated lower syneresis than control samples during storage. During storage, the pH of yogurts continuously decreased (P &lt; 0.01). The viability of Bifidobacterium in yogurt was not affected by the LM addition. During storage, the viable count of Bifidobacterium ssp. decreased in all yogurt types. Lactobacillus delbrueckii ssp. bulgaricus decreased more than Streptococcus thermophilus did during storage. In all yogurt samples, coliform bacteria stayed below detectable concentrations. When a general evaluation was made by considering the physicochemical quality, sensory, and textural properties of all yogurt samples, it was revealed that LM-added yogurts can be produced and stored for 21 days.