Yogurt: Technology and Biochemistry

Tamime, A. Y.; Deeth, Hilton C.

doi:10.4315/0362-028x-43.12.939

Cited by 381 publications

(302 citation statements)

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“…Several methods are used to increase the shelf life of the product such as different packaging [15] , addition of antibiotics [16][17][18] , addition of gas [19] , application of preservatives, heat treatment after incubation [18] and carbonation process [20] .…”

Section: -10 D At <10°cmentioning

confidence: 99%

Mikrodalga Isıtma Uygulamasının Yoğurdun Raf Ömrü ve Bazı Kalite Özellikleri Üzerine Etkisi

Turgut¹

2016

Kafkas Univ Vet Fak Derg

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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.

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Section: -10 D At <10°cmentioning

confidence: 99%

Mikrodalga Isıtma Uygulamasının Yoğurdun Raf Ömrü ve Bazı Kalite Özellikleri Üzerine Etkisi

Turgut¹

2016

Kafkas Univ Vet Fak Derg

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“…bulgaricus strains were shown to be stably maintained in all combinations (10 8 e10 9 cfu/mL for each species at the end of yoghurt fermentation), and the acetaldehyde, ethanol, acetone, diacetyl and MEK contents of the yogurts were reported to be between 13.44 and 25.44 mg/L, 1.49e7.02 mg/L, 0.28e0.54 mg/L, 0.43e1.79 mg/L, and 0.04e0.11 mg/L, respectively. Acetaldehyde is considered to be the most important compound for the typical yogurt flavor (Gardini, Lanciotti, Guerzoni, & Torriani, 1999), and generally found between 17 and 41 mg/L in yoghurts (Abrahamsen, Svensen, & Tufto, 1978;Tamime & Deeth, 1980). Çelik (2007) indicated that 11 among 20 different yogurt combinations showed acetaldehyde production over 20 mg/L and the combination cTY63-2/b22 had the highest acetaldehyde content (25.444 mg/L).…”

Section: Technological Performances Of the Isolatesmentioning

confidence: 99%

High genetic and phenotypic variability of Streptococcus thermophilus strains isolated from artisanal Yuruk yoghurts

Erkuş

Okuklu

Yenidünya

et al. 2014

LWT - Food Science and Technology

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a b s t r a c tStreptococcus thermophilus is a commonly used starter bacterium in dairy industry. It reduces the pH of milk rapidly and equilibrates the medium for the growth of Lactobacillus delbrueckii subsp. bulgaricus during yoghurt fermentation. Efforts to increase the diversity of artisanal yoghurt starters are not only important to bring new strains with novel and desirable characteristics, but also for the preservation of natural diversity which diminishes with the overuse and spread of industrial starters to natural resources. In the present study, 14 artisanal yoghurt samples were processed for the isolation of promising strains for yoghurt starter culture production and 66 strains were subsequently characterized. They were all identified as S. thermophilus using species-specific PCR and 16S rRNA gene sequencing. Genotypic diversity at the strain level was investigated by pulsed field gel electrophoresis (PFGE), and 22 homology groups were obtained. Further phenotypic characterization unearthed a significant phenotypic heterogeneity within homology groups, mostly with atypical novel character. Only 7 out of 66 strains showed S. thermophilus type-strain like phenotypic traits. Majority of the isolates were determined to be protease positive and fast milk acidifier to be used as yoghurt starter culture.

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“…Assessing the innocuous nature of S. thermophilus as a food microorganism is of major importance since this bacterium is widely used for the manufacture of dairy products [1][2][3] (annual market value of B$40 billion) 3 . In consequence, over 10 21 live cells are ingested annually by the human population.…”

mentioning

confidence: 99%

Complete sequence and comparative genome analysis of the dairy bacterium Streptococcus thermophilus

et al. 2004

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The lactic acid bacterium Streptococcus thermophilus is widely used for the manufacture of yogurt and cheese. This dairy species of major economic importance is phylogenetically close to pathogenic streptococci, raising the possibility that it has a potential for virulence. Here we report the genome sequences of two yogurt strains of S. thermophilus . We found a striking level of gene decay (10% pseudogenes) in both microorganisms. Many genes involved in carbon utilization are nonfunctional, in line with the paucity of carbon sources in milk. Notably, most streptococcal virulence-related genes that are not involved in basic cellular processes are either inactivated or absent in the dairy streptococcus. Adaptation to the constant milk environment appears to have resulted in the stabilization of the genome structure. We conclude that S. thermophilus has evolved mainly through loss-of-function events that remarkably mirror the environment of the dairy niche resulting in a severely diminished pathogenic potential. Supplementary information The online version of this article (doi:10.1038/nbt1034) contains supplementary material, which is available to authorized users.

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Yogurt: Technology and Biochemistry

Cited by 381 publications

References 0 publications

Mikrodalga Isıtma Uygulamasının Yoğurdun Raf Ömrü ve Bazı Kalite Özellikleri Üzerine Etkisi

Mikrodalga Isıtma Uygulamasının Yoğurdun Raf Ömrü ve Bazı Kalite Özellikleri Üzerine Etkisi

High genetic and phenotypic variability of Streptococcus thermophilus strains isolated from artisanal Yuruk yoghurts

Complete sequence and comparative genome analysis of the dairy bacterium Streptococcus thermophilus

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