No abstract

In the accompanying article, we demonstrated that a live culture of Lactococcus lactis compares favourably with antibiotics for treatment of bovine mastitis in two initial field trials. In an effort to explain the mechanism involved, this study investigated the effect of culture administration on the local immune response. In this respect we initially observed that infusion of the live culture Lactococcus lactis stimulated substantial recruitment of polymorphonucleocytes (PMN) and lymphocytes to the udder. For instance, in one assay, quarters infused with the probiotic experienced a dramatic increase (approximately 20,000-fold) in neutrophils over the first 48-h period from an average value of 83.6 cells/ml pre-treatment to 1.78 x 106 cells/ml 48 h post-infusion. Levels of the acute phase proteins haptaglobin and milk amyloid A were also elevated significantly in comparison with controls following infusion of the culture. The results of flow cytometric assays also demonstrated that while infusion of a live lactococcal culture led to an enhanced recruitment of PMN to the udder (from 1.85 x 104 cells/ml pre-infusion to 1.45 x 106 cells/ml 24 h post-infusion) cell-free supernatant from the same culture was not able to do so, indicating that live Lc. lactis can specifically trigger the mammary immune response to elicit PMN accumulation. These results suggest that the mechanism responsible for this probiotic treatment of mastitis is associated with stimulation of the host intramammary immune system.

The aim of this study was to evaluate and compare the antimicrobial properties of extracts of thirty commercial herbs and spices commonly used in the production of ready meals. Various extracts of spices were evaluated for their antimicrobial activities against Escherichia coli, Listeria innocua, Staphylococcus aureus and Pseudomonas fluorescens using a microdilution broth method. Ethanol and hexane extracts of oregano, clove, sage, rosemary and celery showed relatively strong antimicrobial activities against all bacteria tested. In contrast, water extracts displayed little or no antimicrobial activity. Flow cytometry revealed that cell membrane structures were damaged by spice and herb active extracts, while analysis of intra- and extracellular ATP contents of bacteria indicated that an increase in extracellular ATP was partially due to intracellular leakage. Extract combinations assessed using the checkerboard method did not display synergistic effects, however, some additive effects were observed when oregano was combined with sage or rosemary against L. innocua or S. aureus. This study has demonstrated that some commercial spice extracts have antimicrobial activity against food-borne bacterial species and may be considered as potential antibacterial agents for addition to ready meals.

No abstract

Salt has been used in food preparation since pre-history and is still routinely added in modern food manufacturing processes. Salt may be added at the table or during cooking; however a large amount of dietary salt originates from processed foods (~60-70% of adult daily dietary salt). Excess salt intake is strongly linked to increases in blood pressure (hypertension) and subsequently pre-disposes individuals to the onset of cardiovascular disease (CVD), a leading cause of death in developed countries. Excess dietary salt intake has also been linked to the development of kidney disease, aggravation of asthma conditions and to the onset of osteoporosis. Results from large numbers of human studies have led to worldwide initiatives being put in place in order to reduce current levels of salt consumption. Hence there is an urgent need to reduce excess dietary salt intake from processed foods in particular. Current daily consumption figures can be as high as ~10-12g NaCl per day while an intake of 4g salt per day is sufficient. Therefore a target reduction to an intake of 6g per day is the goal for a number of public health agencies worldwide. An incremental reduction in salt content in foods appears to be the best strategy to reduce population blood pressure values. However any reduction in salt content in processed foods must not impact on product safety or sensory quality. In this review various public health aspects of salt intake are considered. Additionally, the technological implications of salt reduction in foods are discussed and the possibilities for replacement of salt by addition of salt replacers, herbs, spices and other food ingredients to maintain product quality are highlighted.