English-style crumpets (pH 6--8, aw 0.97--0.99) are a popular baked product enjoyed by consumers worldwide. However, over the past few years, outbreaks of food poisoning have been caused by the growth of Bacillus cereus in crumpets. This spore forming microorganism, which originates in flour, can easily survive the baking process and grow to >106 CFU/g within 3--5 days at ambient storage temperature. Therefore, control of this pathogen is essential to ensure the safety and marketability of English-style crumpets. / Initial studies were done to determine the effect of water activity ( aw), pH, modified atmosphere packaging (MAP), UV-light, bacteriocins, organic acids and esters, alone and in conjunction with each other, on the growth of B. cereus in model broth/agar systems. / B. cereus is a difficult microorganism to control in food using conventional preservation methods. Further studies are now under way to investigate novel methods to control the growth of this pathogen, particularly in high pH crumpets. (Abstract shortened by UMI.)

Bacillus cereus has been responsible for several food poisoning outbreaks involving high moisture-high pH (aw ~ 0.98, pH ~ 8.8) English-style crumpets. Two novel methods, involving sorbohydroxamic acid (SHA) and mastic essential oil (MO), were evaluated for their potential to inhibit the growth of this pathogen and other selected spoilage and foodborne pathogens in high moisture, high pH English-style crumpets. / While sorbic acid only controlled the growth of B. cereus at pH 5 and 5.5, SHA proved effective at all pHs and concentrations under investigation. MO also failed to inhibit the growth of B. cereus when added directly to agar plates. / Products were unacceptable when counts increased from 103 CFUIg to 106 CFU/g or sensory scores reached <3 on a scale of 5. Only SHA (0.3% w/w) proved effective in high pH crumpets. (Abstract shortened by UMI.)

No description available.

No description available.

In this research, initial studies were done to determine the effect of various methods of presentation involving chemical preservatives, water activity ($ rm a sb{w}$), and modified atmosphere packaging (MAP) on mold growth in an agar model system. Results showed that preservatives could completely inhibit mold growth for 2-40d depending on concentration and pH used. Gas packaging (60% or 80% CO$ sb2$), oxygen absorbents, alone or in combination with potassium sorbate, could also inhibit mold growth for $>$40d at ambient storage temperature using a Response Surface Methodology (RSM) approach. / The effects of various methods of applying potassium sorbate into pizza crusts via direct incorporation into the batter, surface spraying, and impregnation of packaging material with potassium sorbate to control mold spoilage of pizza crusts were also investigated. Results showed that the antimicrobial effect of potassium sorbate was negligible when the packaging material was impregnated with the inhibitor but more pronounced when it was incorporated directly into the dough or sprayed onto the product's surface. The inhibitory effect of potassium sorbate increased as both the pH and the inoculum level decreased. / Shelf life studies using low concentrations of potassium sorbate (1000 and 2000 p.p.m.) and MAP, alone and in combination with each other, showed that potassium sorbate, gas packaging or oxygen absorbents (Ageless FX) could extend the shelf life of pizza crusts and decrease the growth rate of molds, bacteria and yeast. Furthermore, when pizza crusts were packaged in 60% CO$ sb2$ or with an oxygen absorbent, in combination with potassium sorbate (1000-2000 p.p.m.), a shelf life of 42d was possible without compromising the sensory shelf life of the product. (Abstract shortened by UMI.)

Initial challenge studies with spores of proteolytic Clostridium botulinum types A and B (~104 spores/g) showed that while air- and gas-packaged English-style crumpets (aw 0.990) and pizza crust (aw 0.960) were toxic after 42-days storage at ambient temperature (25°C), no neurotoxin was detected in bagels (a w 0.944). Further challenge studies with similarly packaged crumpets inoculated with C. botulinum (~102 spores/g), pre- or post-baking, demonstrated that all crumpets were toxic within 4 to 6 days at 25°C and that toxigenesis preceded spoilage. Furthermore, reformulating crumpets to pH 8.3 and packaging in 100% CO2 had little effect in delaying the growth of C. botulinum compared to crumpets formulated to pH 6.5 and packaged in 60% CO2. / Subsequent studies were directed at determining the levels of additional barriers that could be used to ensure the safety of high-moisture MAP crumpets. While ethanol vapour proved to be an effective additional barrier in crumpets (100-g, [aw 0.990, pH 6.5]) challenged with ~102 spores/g of C. botulinum, spoilage preceded toxigenesis due to absorption of ethanol from the package headspace by crumpets. Modelling studies in Trypticase Peptone Glucose Yeast (TPGY) broth confirmed the anti-botulinal nature of ethanol and showed that a level of ~4% (vol/vol) could be used for complete inhibition of this pathogen, depending on the aw and pH of the growth medium. However, while ethanol vapour could be used to inhibit the growth of C. botulinum in high-moisture crumpets, its anti-botulinal efficacy was influenced by the method of crumpet leavening (yeast v chemical). / Preliminary studies were also done to assess the potential of mastic oil, a novel inhibitor, against C. botulinum. While direct and indirect application of ethanolic extracts of mastic oil inhibited the growth of C. botulinum in vivo, they failed to do so in crumpets.

No description available.

No description available.