Fermentation of reconstituted milk by Streptococcus thermophilus: Effect of irradiation on skim milk powder

Microcalorimetric assays for measuring cell growth and metabolic activity: Methodology and applications

“…Especially, when opaque, solid, semi-solid or encapsulated samples are involved [68,121,122]. In food microbiology several fermentation processes take place in opaque or solid matrices such as milk or dough.…”

“…In milk or milk product, it can be difficult to monitor microbial activity or growth related to normal fermentation or to spoilage. In addition to its opacity, milk fermentation often leads to a solid (hard cheese for example) or semi-solid (yoghurt) final product [122,123]. In this context, optical methods are not applicable and plate counts are time consuming since extraction is needed.…”

“…In this context, optical methods are not applicable and plate counts are time consuming since extraction is needed. In this case, calorimetry can be used especially since often milk is used as the growth medium [122,123]. When looking for spoilage, the same methodologies as for clinical samples can be applied (see above).…”

“…Firstly monitoring growth rate and production of heat might allow comparing or typing different starter cultures [128], especially for milk products. On the other hand, if the same starter culture is used as a ''bioindicator'', one can easily compare the properties of the milk tested [122,123,129]. Similarly testing several strains of lactic acid bacteria and monitoring their growth in rye sourdough can be used to select the strains that have better industrial properties; the ones that have a higher growth rate and a higher oxygen tolerance for example [130].…”

Microcalorimetric study of the growth of Streptococcus thermophilus in renneted milk

“…The data obtained from the study of these parallel samples is used together with the microcalorimetric data. The approach was applied for the characterization of peculiarities of the growth of Streptococcus thermophilus ST12 in differently pretreated milk samples (Stulova et al, 2011 ), and in milk reconstituted from non-irradiated and irradiated at 10 kGy milk powder (Stulova et al, 2013 ).…”