The Effect of Lipolytic Enzymes of Bacillus spp. on Quality of Ultra-High-Temperature-Treated Milk

Lipolysis was monitored based on determining the concentration of free fatty acids in milk, on the model case of UHT milk contamination with spores of 15 B. licheniformis, B. subtilis and B. cereus strains isolated from farm environment and raw milk. Lipolysis was not recorded at storage temperature of 4 °C, whereas significant changes in levels of free fatty acids were shown at storage temperature of 24 °C. After 3 weeks of storage the initial content of 41.97 mmol·kg-1 of fat rose to as much as 1,617.22 mmol·kg-1 of fat. The extent of the change depended mainly on the Bacillus spp. species and the storage period and, to a certain degree, also on the initial number of microorganisms. Significant lipolytic activity was detected in association with B. licheniformis and B. cereus species. It was found that spores of resistant B. licheniformis strains may survive 100 °C/10 min and 135 °C/5 s heating and show lipolytic activity

The Effect of Feed and Temperature Regimen on Lipid Oxidation in Muscle of Broiler Chickens

The paper presents the effects of temperature and feed composition on the stability of lipids in breast and thigh muscles of COBB 500 meat hybrids. The chickens were reared in accordance with the technological procedure. The diet of experimental groups contained Proenergol in combination with Energol; the diet of control group chickens contained Proenergol and soybean oil. In the control groups and in half of the experimental groups, the temperature was reduced in agreement with the technological procedure, while it was kept at the constant level of 31 °C in other groups. The feeding continued up to the age of 42 days. The level of lipid oxidation was determined using malondialdehyde assays. No differences between individual groups of chickens were found in the breast muscle. In the thigh muscle, the introduction of Energol resulted in non-significant differences between the control and chickens kept in heat stress conditions. Negative correlation between lipid oxidation and live weight was established in control chickens fed soybean oil (p p < 0.05) in young male chicks fed Energol and kept at constantly increased temperature