Kefir is an acidic, mildly alcoholic dairy beverage produced by the fermentation of milk with a grain-like starter culture (Koroleva, 1988). These grains usually contain a relatively stable and specific balance of microbes that exist in a complex symbiotic relationship (Obermann & Libudzisz, 1998; Witthuhn et al. 2004). The different groups of microbes present in the grains are active at different stages of the fermentation (Koroleva, 1982). The lactococci, including Lactococcus lactis subsp. lactis, Lc. lactis subsp. cremoris and Lc. lactis subsp. diacetilactis provide rapid acid development during the first hours of the fermentation (Litopoulou-Tzanetaki & Tzanetakis, 2000). As the acidity of the milk increases it provides favourable conditions for the growth of the lactobacilli (Rea et al. 1996). The yeasts, acetic acid bacteria and the aroma-producing microbes, mainly leuconostocs, have a much slower growth rate than the lactic acid producers, resulting in the slow production of the aroma compounds and the gradual increase in the concentration of these substances in the later stages of the fermentation (Koroleva, 1982).

We wish to apologise to Vivek Upadhyay for the incorrect spelling of his name on page 226 of volume 72 issue 2 of this journal.

The correct reference is given in full below.

Thom Huppertz, Mathias R Zobrist, Therese Uniacke, Vivek K Upadhyay, Patrick F Fox and Alan L Kelly

Effects of high pressure on some constituents and properties of buffalo milk. Journal of Dairy Research 72 226–233

Pathogenic microorganisms invading the mammary gland induce an inflammatory reaction which includes an increase of somatic cells in milk and activation of bacteriostatic enzymes and proteins in milk. During spontaneously occurring subclinical mastitis the somatic milk cells, mainly macrophages, secrete cytokines, eicosanoids, acute phase proteins and other immunomediators. In contrast, the bacteriostatic protein lactoferrin is mainly secreted by mammary epithelial tissue, while major milk proteins like α-lactalbumin and κ-casein are down-regulated already during subclinical infection.

Changes of the mRNA expression of various immunomediators in the mammary tissue of cows during 12 h after induction of mastitis via intramammary administration of lipopolysaccharide (LPS) in several studies are reported. Six healthy lactating cows were injected in one quarter with 100 μg Escherichia coli-LPS (O26[ratio ]B6) and the contralateral quarter with saline (9 g/l) serving as control. mRNA expression in mammary biopsy samples of various inflammatory factors and milk proteins at 0, 3, 6, 9 and 12 h after LPS administration was quantified by real-time reverse transcription-PCR.

In LPS-challenged quarters tumour necrosis factor α and cyclooxygenase-2 mRNA expression increased to their highest values (P<0·05) at 3 h after LPS-challenge. Expression of lactoferrin, lysozyme, inducible nitric oxide synthase, and of the apoptotic factors caspase-3, caspase-7 and FAS was elevated (P<0·05) and peaked at 6 h after challenge. No significant increase in mRNA expression of platelet-activating factor acethylhydrolase, 5-lipoxygenase, and insulin-like growth factor 1 was found. None of the parameters tested did change significantly in the control quarters. mRNA expression of major milk proteins did not change significantly in response to the LPS challenge (αS1-casein, αS2-CN, β-CN and β-lactoglobulin) except for α-lactalbumin which decreased (P<0·05) in LPS-treated and control quarters and for κ-CN which decreased in the LPS-treated quarters. In conclusion, mRNA expression of the majority albeit not all inflammatory factors changed within hours of LPS challenge. Decreased gene expression of α-lactalbumin and κ-CN may reduce milk yield and suitability for cheese production.

At present there is no rapid microbiological method for the detection of viable Mycobacterium paratuberculosis in milk. By combining an extensive milk sample pretreatment with solid phase cytometry as the detection technique we were able to demonstrate viable mycobacterial cells in 50 ml of artificially contaminated pasteurized milk in less than one working day.

β-lactoglobulin polymorphisms have been reported in the milk of different goat breeds, although no genetic variants affecting the protein have been characterized. In the present study, we amplified and sequenced the proximal promoter and the first six exons containing the entire coding region for the β-lactoglobulin gene in eleven goat breeds from Spain, France, Italy, Switzerland, Senegal and Asia to identify genetic variants. Fifteen polymorphisms were detected, nine in the promoter region and six in the exons of the β-lactoglobulin gene. All polymorphisms were single nucleotide substitutions with the exception of one deletion/insertion in the promoter region. The polymorphisms in the coding region did not produce any amino acid change. In addition, pyrosequencing technology was used to genotype four polymorphisms in the promoter region in 200 goats belonging to eleven breeds. Differences in allelic frequencies for these polymorphisms between breeds are described and a specific polymorphism for the Italian populations was identified. Finally, the analysis of association between these four promoter point mutations was investigated resulting in five haplotypes, GCGC being the most frequent haplotype in all breeds analysed.