Modelling stochastic variability and uncertainty in aroma active compounds of PEF-treated peach nectar as a function of physical and sensory properties, and treatment time.

Effects of pulsed electric field (PEF) processing on 28 aroma active compounds, and four physical and eight sensory properties of peach nectar were explored using the best-fit multiple linear regression (MLR) models and Monte Carlo simulations as a function of the treatment times of 0, 66, 131, and 210 µs. The PEF treatment time of 131 µs on average led consistently to the least loss of most compounds. Significantly enhanced or no significant changes in the sensory properties were found as a function of the PEF treatment times. The most influential sensory predictor of the 28 MLR models was flavour, while the aroma compound most influential on the sensory properties of aftertaste, flavour, sweetness, and overall acceptance was octadecanoic acid. Monte Carlo simulations were used for the probabilistic assessments of stochastic variability and uncertainty associated with aroma active compounds of PEF-treated peach nectar.

Factors affecting the adsorption of buchnericin LB, a bacteriocin produced by Lactobacillus [correction of Lactocobacillus] buchneri.

Buchnericin-LB adsorbs to gram-positive but not to gram-negative bacteria. The tested gram-positive bacteria were species of Lactobacillus, Pediococcus, Leuconostoc, Enterococcus, Lactococcus, Listeria, Bacillus, Staphylococcus; gram-negative bacteria belonged to the genera Salmonella, Escherichia, Yersinia and Pseudomonas. Buchnericin-LB adsorption depended on pH but not on time and temperature. Also some anions of salts and lipoteichoic acid reduced or inhibited its adsorption. Treatment of cells and cell walls of sensitive bacteria with detergents, organic solvents or enzymes did not affect subsequent binding of buchnericin-LB. Treatment with buchnericin-LB caused sensitive cells to lose high amounts of intracellular K+ ions and UV-absorbing materials and became more permeable to o-nitrophenol-beta-D-galactopyranoside. Buchnericin-LB (640-2560 AU/ml) decreased the colony forming units (99%) and absorbance values of Listeria monocytogenes and Bacillus cereus. These results indicate that the mode of action of buchnericin-LB is bactericidal and its lethal effect is very rapid.