The Effect of High-Pressure Processing of Caprine Milk on the Production and Properties of Yoghurt.

The aim of this study was to determine the suitability of HP-treated caprine milk for yoghurt production and to evaluate the effect of HP treatment on yoghurt properties. Reconstituted caprine milk was subjected to HP treatment (350 MPa/10 min/20 °C); a lactic acid starter culture (YC-X16, Chr. Hansen) was added. Milk was fermented at a temperature of 43 °C until pH 4.60. Bacterial counts, pH, color, rheological characteristics, texture, microstructure, and the sensory attributes of the yoghurt were determined after production and after seven days of storage at a temperature of 4 °C. HP treatment increased color saturation and whiteness index and induced a minor increase in milk pH. Minor differences in the acidification curve were noted. During storage, Streptococcus thermophilus counts were significantly higher in yoghurt from HP-treated than from untreated milk, whereas Lactobacillus delbruecki ssp. bulgaricus counts remained stable. A color analysis did not reveal differences between the experimental and control yoghurts. After storage, yoghurt made from HP-treated milk was characterized by thicker consistency and lower rheological stability than the control yoghurt. The micrographs of the yoghurts confirmed the differences in rheological parameters. Yoghurt produced from HP-treated caprine milk and stored for seven days received the highest scores in the sensory evaluation.

[Microbiological changes in edam type cheese, brined in a mixture of sodium and potassium chlorides during the ripening process]. / Zmiany mikrobiologiczne w serze edamskim, solonym w mieszaninie chlorków sodu i potasu podczas dojrzewania.

Cheese were brined in a modified brine containing a mixture of sodium and potassium chlorides (1: 1.27, w/w), following technological instruction, for 24 hours and in a shortened time of 18 h and 12 h. Edam type cheese brined for 24 h in a traditional brine served as a control. In the ripening period, the cheeses were subjected to the following microbiological analyses: total bacteria count, the number of acidifying streptococci, the most probable number (MPN) of resting spores of anaerobic saccharolytic bacteria, the count of E. coli and the number of coagulase-positive staphylococci. The cheeses were additionally subjected to chemical analyses, including the determination of acidity, water content, salt content and a panel assessment of their organoleptic traits. The microbiological analysis demonstrated an increase in the total bacteria count and a decrease in the number of acidifying streptococci coinciding with the progress in ripening. No significant changes were observed in the population of microflora examined in the cheeses brined in the modified brine, as compared those produced in the traditional brine. The type of brine used also had no significant effect on changes in the MPN of resting spores of anaerobic saccharolytic bacteria. In none of the cheeses analyzed in this study was found E. coli bacteria or coagulase-positive staphylococci.