Identifcation of yeasts from raw milk and selection for some specific antioxidant properties

Abstract

Eleven different species of yeasts isolated from raw milk, such as Issatchenkia orientalis, Pichia fermentans, Rhodotorula mucilaginosa and Yarrowia lipolytica were identified using an integrated approach, including phenotypic and genotypic methods and the API 20C AUX system. Eleven selected strains which tolerated low pH levels, gastric juice and bile salt were further analysed for the presence of functional traits useful for probiotic application as antioxidants. The ability to scavenge DPPH (2, 2-diphenyl-1-picrylhydrazyl) and inhibit linoleic acid peroxidation indicated that P. fermentans BY5 and HJ15 may be promising candidate strains for use as probiotics with antioxidant activity.

Identifying yeast isolated from spoiled peach puree and assessment of its batch culture for invertase production

“…Both are urease positive (Table 1, Figure 1), which matches Chen et al (2010) for the urea hydrolysis test. Beckenkamp (1997), when working with pasteurized fruit pulp samples, also identified the genera Rhodotorula & Trichosporon, while Sancho et al (2000) identified R. mucilaginosa in pear pulp.…”

“…The downside of these techniques is the effort to extract and purify the DNA. On the other hand, a simple method based on the assimilative ability of substrates known as API 20C AUX has been widely used to identify yeasts (Silva & Candido, 2005;Chen et al, 2010).…”

Galactomyces geotrichum – moulds from dairy products with high biotechnological potential

“…A test with cycloheximide showed that G. geotrichum was resistant to urea, but it was not resistant to cadaverine. Furthermore, no growth of G. geotrichum was detected on cellobiose, maltose, mellobiose, raffinose, mannitol, erythritol and α-methyl glucoside (Chen et al, 2010).…”

“…The G. geotrichum mould is able to grow at 3 to 11 pH, but the optimal is 5-7 pH (Skóra et al, 2009). Chen et al (2010) examined the yeast and moulds obtained from raw milk. Selected G. geotrichum isolates were able to grow on glucose and galactose, but could not ferment glucose and assimilate nitrate.…”

Probiotic potential of indigenous yeasts isolated during the fermentation of table olives from Northeast of Portugal

“…Similar results were also observed by Bautista-Gallego et al (2011) and Hernández et al (2007), in most yeasts isolated during fermentation of table olives. The ability of the yeast to produce this enzyme can be of great interest, since it is linked to the antioxidant capacity (Chen et al, 2010). In relation to lipase, C. tropicalis 3A, C. boidinii 32A and G. ressii 33A did not show any activity, while P. manshurica 2A and S. cerevisiae 15A and 15B showed high activity.…”