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Fumigation of peppercorns using black pepper essential oil
Poster abstracts
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diation there was no difference in numbers of E. coli on meat which had been modified to pH 4-3, 4.0 and 3.7 using HC1. At all irradiation doses the major effect of pH on E. coli was between pH 5-5 and pH 4.3. There was little evidence of further reduction between pH 4.0 and 3.7. An irradiation dose of 0.5 kGy resulted in a one log-cycle decrease at pH 5-5 and a two log-cycle decrease at pH 4.3, 4.0 and 3.7. An irradiation dose of 1 or 2 kGy resulted in an additional one log-cycle reduction in numbers of E. coil except at 2.0 kGy and pH 4.0, where there was a further reduction. The effect of 2.0 kGy was only marginally greater than that of 1-0 kGy. The results suggest a definite 'tailing effect' with respect to the survival of E. coli with increasing doses of radiation.
Fumigation of Peppercorns Using Black Pepper Essential Oil P.E. C o o k , a, B.S.L. J e n i e b & S. F a r d i a z b aDepartment of Food Science and Technology, University of Reading, Reading, UK, RG6 2AP. hinter University Center for Food and Nutrition, IPB, Bogor Agricultural University, Bogor, Indonesia Black pepper is often contaminated with microorganisms including sporeforming bacteria, coliforms and moulds. Many herbs and spices contain essential oils and oleoresins which possess antimicrobial properties, either directly or through the action of volatile components. The aim of the present study was to establish whether black peppercorns could be decontaminated by fumigating with black pepper essential oil. Fumigation of dry black peppercorns had no significant effect on the numbers of aerobic bacteria. Compared with the untreated peppercorns, numbers of Enterobacteriaceae and moulds were decreased, but numbers were not significantly lower than in incubated controls. Fumigation had no apparent influence on the composition of the fungal flora, which was dominated by aspergilli and mucoraceous moulds. Fumigation of rehydrated peppercorns failed to prevent the growth of aerobic bacteria and Enterobacteriaceae but significantly reduced fungal counts by three log-cycles. An agar diffusion assay suggested that the essential oil was more inhibitory towards fungi than bacteria.
The Effect of Acetate and Diaeetyl on Salmonella
typhimurium V.M. Dillon, M . H . Archer, J.D. Owens & G. Campbell-Platt Department of Food Science and Technology, University of Reading, Whiteknights, P.O. Box 226, Reading, UK, RG6 2AP The preservation of traditionally fermented foods by lactic acid bacteria is partly due to the metabolism of sugars to organic acids such as acetic and lactic acid and other antimicrobial metabolic products such as diacetyl. These antimicrobial
227
diation there was no difference in numbers of E. coli on meat which had been modified to pH 4-3, 4.0 and 3.7 using HC1. At all irradiation doses the major effect of pH on E. coli was between pH 5-5 and pH 4.3. There was little evidence of further reduction between pH 4.0 and 3.7. An irradiation dose of 0.5 kGy resulted in a one log-cycle decrease at pH 5-5 and a two log-cycle decrease at pH 4.3, 4.0 and 3.7. An irradiation dose of 1 or 2 kGy resulted in an additional one log-cycle reduction in numbers of E. coil except at 2.0 kGy and pH 4.0, where there was a further reduction. The effect of 2.0 kGy was only marginally greater than that of 1-0 kGy. The results suggest a definite 'tailing effect' with respect to the survival of E. coli with increasing doses of radiation.
Fumigation of Peppercorns Using Black Pepper Essential Oil P.E. C o o k , a, B.S.L. J e n i e b & S. F a r d i a z b aDepartment of Food Science and Technology, University of Reading, Reading, UK, RG6 2AP. hinter University Center for Food and Nutrition, IPB, Bogor Agricultural University, Bogor, Indonesia Black pepper is often contaminated with microorganisms including sporeforming bacteria, coliforms and moulds. Many herbs and spices contain essential oils and oleoresins which possess antimicrobial properties, either directly or through the action of volatile components. The aim of the present study was to establish whether black peppercorns could be decontaminated by fumigating with black pepper essential oil. Fumigation of dry black peppercorns had no significant effect on the numbers of aerobic bacteria. Compared with the untreated peppercorns, numbers of Enterobacteriaceae and moulds were decreased, but numbers were not significantly lower than in incubated controls. Fumigation had no apparent influence on the composition of the fungal flora, which was dominated by aspergilli and mucoraceous moulds. Fumigation of rehydrated peppercorns failed to prevent the growth of aerobic bacteria and Enterobacteriaceae but significantly reduced fungal counts by three log-cycles. An agar diffusion assay suggested that the essential oil was more inhibitory towards fungi than bacteria.
The Effect of Acetate and Diaeetyl on Salmonella
typhimurium V.M. Dillon, M . H . Archer, J.D. Owens & G. Campbell-Platt Department of Food Science and Technology, University of Reading, Whiteknights, P.O. Box 226, Reading, UK, RG6 2AP The preservation of traditionally fermented foods by lactic acid bacteria is partly due to the metabolism of sugars to organic acids such as acetic and lactic acid and other antimicrobial metabolic products such as diacetyl. These antimicrobial