Gillian M. Heard

Lactic acid bacteria associated with wine grapes from several Australian vineyards

Aims:  The detection and isolation of lactic acid bacteria by enrichment methods from wine grapes cultivated in vineyards located in New South Wales, Australia.

Application of nontraditional meat starter cultures in production of Hungarian salami.

Listeria monocytogenes and Escherichia coli O111 have been implicated in several outbreaks of food-borne disease linked to smallgoods products. Traditional meat starter cultures, containing a mixture of lactic acid bacteria (LAB) and staphylococci, are used to maintain safety and sensory properties of Hungarian salami. The present study investigated if nontraditional meat starter (NTMS) cultures can be used for improving the safety of Hungarian salami. Salami batter was inoculated with List. monocytogenes and E. coli and subsequently fermented with NTMS cultures and a commercially available meat starter. A total of 15 NTMS cultures were tested. The salami was monitored for levels of pathogen, LAB and pH. When used in conjunction with the commercial meat starter, 9 NTMS cultures reduced the E. coli O111 count by more than 2.5 log units, whereas 10 of the NTMS cultures reduced List. monocytogenes by more than 2.5 log units. The commercial meat starter alone reduced E. coli and List. monocytogenes by 1.2 and 1.3 log units, respectively. Some NTMS cultures reduced the pathogen count without affecting pH of the salami batter. All NTMS cultures survived in salami throughout fermentation and maturation. It was concluded that NTMS cultures, including Lactobacillus acidophilus LAFTI L10, L. paracasei LAFTI L26, L. paracasei 5119, Lactobacillus sp. L24 and Bifidobacterium lactis LAFTI B94, may be used to increase the safety of Hungarian salami because these cultures gave strong inhibition of both E. coli O111 and List. monocytogenes.

Evaluation of molecular methods for the analysis of yeasts in foods and beverages

The analysis of yeasts in foods and beverages involves the sequential operations of isolation, enumeration, taxonomic identification to genus and species, and strain differentiation. Although well established cultural methods are available to perform these operations, many molecular methods have now been developed as alternatives. These newer methods offer various advantages, including faster results, increased specificity of analysis, decreased workload, computer processing of data and possibilities for automation. Molecular methods for yeast analysis are now at a stage of development where they can move from the research laboratory into the quality assurance laboratories of the food and beverage industries. However, many practical questions need to be considered for this transition to progress. A diversity of molecular methods with similar analytical objectives are available. Which methods should the food analyst choose and what principles should be used to guide this choice? Food analysts are required to make judgements and decisions about the microbiological quality and safety of consignments of products often worth many millions of dollars in national and international trade. Moreover,

Microbial species associated with different sections of broccoli harvested from three regions in Australia

The microbial populations associated with the different sections of broccoli harvested from three locations in Australia were studied during storage at 5, 15 and 20 degrees C. Bacterial and yeast populations associated with the outer florets and cut surfaces of the stem were generally 10-fold or more higher than those associated with inner florets or non-cut stems, respectively. The predominating bacterial species varied with the origin of the broccoli. Pseudomonas fluorescens, Ps. corrugata and Ps. viridiflava predominated at populations of 10(5)-10(7) cfu/g on broccoli harvested from Victoria, Ps. fluorescens, Ps. mendocina and Ps. fragii and Arthrobacter spp. (10(-3) 10(6) cfu/g) were prevalent on broccoli harvested from Queensland. Broccoli harvested from New South Wales exhibited a predominance of Ps. fluorescens, Arthrobacter spp. and Enterobacteragglomerans (10(3)-10(5) cfu/g). Most species grew on broccoli during storage. Similar species were found at the different sections of broccoli, although, for some species there was evidence of strain variation at the different locations and for different temperature of storage.