The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Steve Labrie - One of the best experts on this subject based on the ideXlab platform.
-
metatranscriptome analysis of fungal strains penicillium Camemberti and geotrichum candidum reveal Cheese matrix breakdown and potential development of sensory properties of ripened Camembert type Cheese
BMC Genomics, 2014Co-Authors: Mariehelene Lessard, Daniel Stgelais, Catherine Viel, Brian Boyle, Steve LabrieAbstract:Camembert-type Cheese ripening is driven mainly by fungal microflora including Geotrichum candidum and Penicillium Camemberti. These species are major contributors to the texture and flavour of typical bloomy rind Cheeses. Biochemical studies showed that G. candidum reduces bitterness, enhances sulphur flavors through amino acid catabolism and has an impact on rind texture, firmness and thickness, while P. Camemberti is responsible for the white and bloomy aspect of the rind, and produces enzymes involved in proteolysis and lipolysis activities. However, very little is known about the genetic determinants that code for these activities and their expression profile over time during the ripening process. The metatranscriptome of an industrial Canadian Camembert-type Cheese was studied at seven different sampling days over 77 days of ripening. A database called CamemBank01was generated, containing a total of 1,060,019 sequence tags (reads) assembled in 7916 contigs. Sequence analysis revealed that 57% of the contigs could be affiliated to molds, 16% originated from yeasts, and 27% could not be identified. According to the functional annotation performed, the predominant processes during Camembert ripening include gene expression, energy-, carbohydrate-, organic acid-, lipid- and protein- metabolic processes, cell growth, and response to different stresses. Relative expression data showed that these functions occurred mostly in the first two weeks of the ripening period. These data provide further advances in our knowledge about the biological activities of the dominant ripening microflora of Camembert Cheese and will help select biological markers to improve Cheese quality assessment.
-
the composition of Camembert Cheese ripening cultures modulates both mycelial growth and appearance
Applied and Environmental Microbiology, 2012Co-Authors: Steve Labrie, Mariehelene Lessard, G Belanger, Daniel StgelaisAbstract:The fungal microbiota of bloomy-rind Cheeses, such as Camembert, forms a complex ecosystem that has not been well studied, and its monitoring during the ripening period remains a challenge. One limitation of enumerating yeasts and molds on traditional agar media is that hyphae are multicellular structures, and colonies on a petri dish rarely develop from single cells. In addition, fungi tend to rapidly invade agar surfaces, covering small yeast colonies and resulting in an underestimation of their number. In this study, we developed a real-time quantitative PCR (qPCR) method using TaqMan probes to quantify a mixed fungal community containing the most common dairy yeasts and molds: Penicillium Camemberti, Geotrichum candidum, Debaryomyces hansenii, and Kluyveromyces lactis on soft-Cheese model curds (SCMC). The qPCR method was optimized and validated on pure cultures and used to evaluate the growth dynamics of a ripening culture containing P. Camemberti, G. candidum, and K. lactis on the surface of the SCMC during a 31-day ripening period. The results showed that P. Camemberti and G. candidum quickly dominated the ecosystem, while K. lactis remained less abundant. When added to this ecosystem, D. hansenii completely inhibited the growth of K. lactis in addition to reducing the growth of the other fungi. This result was confirmed by the decrease in the mycelium biomass on SCMC. This study compares culture-dependent and qPCR methods to successfully quantify complex fungal microbiota on a model curd simulating Camembert-type Cheese.
-
terminal restriction fragment length polymorphism and automated ribosomal intergenic spacer analysis profiling of fungal communities in Camembert Cheese
International Dairy Journal, 2010Co-Authors: Marianne Arteau, Steve Labrie, Denis RoyAbstract:Identifying and isolating yeasts and moulds within a fungal community is challenging. The main goal of the present study was to assess a new approach for the detection and identification of fungi involved in Camembert Cheese rind formation to replace the use of traditional microbiological techniques. Two molecular methods, terminal-restriction fragment length polymorphism (T-RFLP) and automated ribosomal intergenic spacer analysis (ARISA), were adapted and compared for their potential to determine fungal composition directly from Cheese samples. The two techniques in combination with principal component analysis showed differences in the fungal composition of Cheeses when comparing surface with centre, different batches, manufacturing processes and ripening times. Moreover, Cheese stabilisation induced changes in the flora at the Cheese centre, and difference in size (150 g versus 1 kg) modified surface flora. Nine fungal genera were identified in Cheese samples: Cladosporium, Debaryomyces, Geotrichum, Kluyveromyces, Mucor, Penicillium, Pichia, Saccharomyces and Yarrowia.
Erwan Engel - One of the best experts on this subject based on the ideXlab platform.
-
interactions between non volatile water soluble molecules and aroma compounds in Camembert Cheese
Food Chemistry, 2002Co-Authors: E Pionnier, Erwan Engel, Christian Salles, J Le L QuereAbstract:Abstract Interactions between selected aroma compounds and non-volatile water-soluble molecules were studied using dynamic headspace-gas chromatography. A model water-soluble extract (MWSE), previously constructed in gustatory and physico-chemical accordance with the crude Camembert Cheese WSE, allowed the contribution of non-volatiles to the headspace composition of volatile compounds to be assessed. The presence of the MWSE increased the headspace concentration of 2-heptanone, 1-octen-3-ol and 3-methylbutanol, showing that these three volatile compounds were released by MWSE. Omission tests performed on MWSE allowed for the impact of each MWSE component on aroma compounds release to be determined. The releasing influence of minerals appeared as the main effect observed for the three volatiles, despite some retention phenomena due to other MWSE components also occurring. In the case of 2-undecanone, 2-nonanol, 2,4-dithiapentane and ethylhexanoate, which were not affected by the presence of MWSE, some significant compensatory effects were observed. Whereas amino acids had no significant effect, minerals might cause their release and the presence of peptides can either decrease or increase headspace concentration of aroma compounds. Possible antagonistic effects between MWSE components are discussed.
-
determination of taste active compounds of a bitter Camembert Cheese by omission tests
Journal of Dairy Research, 2001Co-Authors: Erwan Engel, Nadine Leconte, Chantal Septier, C. Salles, Jeanluc Le QuereAbstract:The taste-active compounds of a Camembert Cheese selected for its intense bitterness defect were investigated. The water-soluble fraction (WSE) was extracted with pure water and fractionated by successive tangential ultrafiltrations and nanofiltration. The physicochemical assessment of these fractions led to the construction of a model WSE which was compared by sensory evaluation to the crude water-soluble extract, using a panel of 16 trained tasters. As no significant difference was perceived, this model WSE was then used directly or mixed with other Cheese components for omission tests. Among the main taste characteristics of the WSE (salty, sour, umami and bitter), bitterness was found to be due to small peptides whose mass distribution was obtained by RPHPLC-MS (400–3000 Da) and whose taste properties are discussed.
-
Evolution of the taste of a bitter Camembert Cheese during ripening: characterization of a matrix effect.
Journal of agricultural and food chemistry, 2001Co-Authors: Erwan Engel, Sophie Nicklaus, Chantal Septier, C. Salles, J. L. Le QuereAbstract:The objective of this study was to characterize the effect of ripening on the taste of a typically bitter Camembert Cheese. The first step was to select a typically bitter Cheese among several products obtained by different processes supposed to enhance this taste defect. Second, the evolution of Cheese taste during ripening was characterized from a sensory point of view. Finally, the relative impact of fat, proteins, and water-soluble molecules on Cheese taste was determined by using omission tests performed on a reconstituted Cheese. These omission tests showed that Cheese taste resulted mainly from the gustatory properties of water-soluble molecules but was modulated by a matrix effect due to fat, proteins, and Cheese structure. The evolution of this matrix effect during ripening was discussed for each taste characteristic.
-
Evolution of the composition of a selected bitter Camembert Cheese during ripening: release and migration of taste-active compounds
Journal of Agricultural and Food Chemistry, 2001Co-Authors: Erwan Engel, C. Tournier, Christian Salles, Jean-luc Le QuéréAbstract:The aim of this study was to add to the understanding of changes in taste that occur during the ripening of a bitter Camembert Cheese by the evolution of its composition. Physicochemical analyses were performed on rind, under-rind, and center portions of a Camembert Cheese selected for its intense bitterness. At each of the six steps of ripening studied organic acids, sugars, total nitrogen, soluble nitrogen, phosphotungstic acid soluble nitrogen, non-protein nitrogen, Na, K, Ca, Mg, Pi, Cl, and biogenic amines were quantified in each portion. Changes in Cheese composition seemed to mainly result from the development of Penicillium Camemberti on the Cheese outer layer. Migration phenomena and the release of potentially taste-active compounds allowed for the evolution of saltiness, sourness, and bitterness throughout ripening to be better understood. Apart from taste-active compounds, the impact of the Cheese matrix on its taste development is discussed.
Hiroyuki Nakayama - One of the best experts on this subject based on the ideXlab platform.
-
tryptophan related dipeptides in fermented dairy products suppress microglial activation and prevent cognitive decline
Aging (Albany NY), 2019Co-Authors: Yasuhisa Ano, Toshiko Kutsukake, Kazuyuki Uchida, Rena Ohya, Akihiko Takashima, Yuka Yoshino, Takafumi Fukuda, Hiroyuki NakayamaAbstract:The rapid growth in aging populations has made prevention of age-related memory decline and dementia a high priority. Several epidemiological and clinical studies have concluded that fermented dairy products can help prevent cognitive decline; furthermore, intake of Camembert Cheese prevents microglial inflammation and Alzheimer's pathology in mouse models. To elucidate the molecular mechanisms underlying the preventive effects of fermented dairy products, we screened peptides from digested milk protein for their potential to regulate the activation of microglia. We identified dipeptides of tryptophan-tyrosine (WY) and tryptophan-methionine that suppressed the microglial inflammatory response and enhanced the phagocytosis of amyloid-β (Aβ). Various fermented dairy products and food materials contain the WY peptide. Orally administered WY peptide was smoothly absorbed into blood, delivered to the brain, and improved the cognitive decline induced by lipopolysaccharide via the suppression of inflammation. Intake of the WY peptide prevented microglial inflammation, hippocampal long-term potential deficit, and memory impairment in aged mice. In an Alzheimer's model using 5×FAD mice, intake of the WY peptide also suppressed microglial inflammation and accumulation of Aβ, which improved cognitive decline. The identified dipeptides regulating microglial activity could potentially be used to prevent cognitive decline and dementia related to inflammation.
-
novel lactopeptides in fermented dairy products improve memory function and cognitive decline
Neurobiology of Aging, 2018Co-Authors: Yasuhisa Ano, Toshiko Kutsukake, Kazuyuki Uchida, Tatsuhiro Ayabe, Rena Ohya, Yuta Takaichi, Shinichi Uchida, Koji Yamada, Akihiko Takashima, Hiroyuki NakayamaAbstract:Alongside the rapid growth in aging populations, prevention of age-related memory decline and dementia has become a high priority. Several epidemiological and clinical studies have concluded that fermented dairy products can help to prevent cognitive decline; furthermore, intake of Camembert Cheese prevents Alzheimer's pathology in model mice. To elucidate molecular mechanisms underlying the preventive effects of fermented dairy products, here we screened peptides from digested fermented dairy products for ability to improve memory function in a scopolamine-induced amnesia mouse model. We found that Trp-Tyr (WY)-containing peptides from whey protein improved memory function in the mice, and the effects were confirmed in aged mice. The WY-containing peptides directly inhibited monoamine oxidase-B activity and increased dopamine levels in brain tissue. Pretreatment with dopamine receptor antagonist abolished the improvement in memory function due to WY-containing peptides. These results suggest that WY-containing peptides in fermented dairy products increase monoamine levels by inhibiting monoamine oxidase-B activity, helping to prevent age-related cognitive decline.
-
preventive effects of a fermented dairy product against alzheimer s disease and identification of a novel oleamide with enhanced microglial phagocytosis and anti inflammatory activity
PLOS ONE, 2015Co-Authors: Makiko Ozawa, Toshiko Kutsukake, Shinya Sugiyama, Kazuyuki Uchida, Aruto Yoshida, Hiroyuki NakayamaAbstract:Despite the ever-increasing number of patients with dementia worldwide, fundamental therapeutic approaches to this condition have not been established. Epidemiological studies suggest that intake of fermented dairy products prevents cognitive decline in the elderly. However, the active compounds responsible for the effect remain to be elucidated. The present study aims to elucidate the preventive effects of dairy products on Alzheimer’s disease and to identify the responsible component. Here, in a mouse model of Alzheimer’s disease (5xFAD), intake of a dairy product fermented with Penicillium candidum had preventive effects on the disease by reducing the accumulation of amyloid β (Aβ) and hippocampal inflammation (TNF-α and MIP-1α production), and enhancing hippocampal neurotrophic factors (BDNF and GDNF). A search for preventive substances in the fermented dairy product identified oleamide as a novel dual-active component that enhanced microglial Aβ phagocytosis and anti-inflammatory activity towards LPS stimulation in vitro and in vivo. During the fermentation, oleamide was synthesized from oleic acid, which is an abundant component of general dairy products owing to lipase enzymatic amidation. The present study has demonstrated the preventive effect of dairy products on Alzheimer’s disease, which was previously reported only epidemiologically. Moreover, oleamide has been identified as an active component of dairy products that is considered to reduce Aβ accumulation via enhanced microglial phagocytosis, and to suppress microglial inflammation after Aβ deposition. Because fermented dairy products such as Camembert Cheese are easy to ingest safely as a daily meal, their consumption might represent a preventive strategy for dementia.
-
identification of a novel dehydroergosterol enhancing microglial anti inflammatory activity in a dairy product fermented with penicillium candidum
PLOS ONE, 2015Co-Authors: Toshiko Kutsukake, Aruto Yoshida, Ayaka Hoshi, Hiroyuki NakayamaAbstract:Despite the ever-increasing number of dementia patients worldwide, fundamental therapeutic approaches to treat this disease remain to be established. Preventive approaches such as diet, exercise and learning attract attention. Several epidemiological studies suggest that ingestion of fermented dairy products prevents cognitive decline in the elderly. These reports indicate that specific ingredients in the fermented dairy products elicit an anti-inflammatory or anti-oxidative activity that facilitates neuroprotection. The responsible components remain to be investigated. A number of studies have shown that inflammation caused by microglia is closely related to exaggeration of the pathology and cognitive decline seen in the elderly. Many researchers have proposed that controlling microglial activities could be effective in preventing and possibly curing dementia. In the present study, to elucidate specific compounds that regulate microglial activity from dairy products, repeated purification by HPLC, combined with evaluation using primary microglia, facilitated the identification of dehydroergosterol (DHE) as a novel component of the extract that enhances microglial anti-inflammatory activity. DHE contains three conjugated double bonds in a steroid ring system and is an analogue of ergosterol. Despite their related chemical structures, the anti-inflammatory activity of DHE is markedly stronger than that of ergosterol. P. candidum for Camembert Cheese produces DHE, but P. Roqueforti for blue Cheese and Aspergillus do not. DHE also induces CD11b-positive microglia cells into CD206-positive M2 type microglia. Neurotoxicity and neuronal cell death induced by excessively activated microglia is suppressed by treatment with DHE. Thus, this is the first report to demonstrate that DHE, identified as a responsible compound in dairy products, can induce microglia into a preferable phenotype for our brain environment and can be safely introduced into the body by consumption of dairy products. We believe the uptake of DHE might help to prevent the onset of dementia.
Shaowei Liu - One of the best experts on this subject based on the ideXlab platform.
-
evaluation of listeria innocua as a suitable indicator for replacing listeria monocytogenes during ripening of Camembert Cheese
International Journal of Food Science and Technology, 2009Co-Authors: Shaowei Liu, Virenda M Puri, Ali DemirciAbstract:The suitability of Listeria innocua for use as an indicator for replacing Listeria monocytogenes during the Cheese-making and ripening of Camembert Cheese was evaluated. Pasteurized whole milk inoculated with either L. innocua or L. monocytogenes was used to make Camembert Cheese, which were ripened in three stages. All Cheese was ripened in three stages: room temperature (∼20 °C) and relative humidity of 60% for 36 h; 12 °C and relative humidity of 93% for 2 weeks; and 7 °C and relative humidity of 85% for 3 weeks. Results showed that population values of L. innocua and L. monocytogenes on day 1 were 7.16 and 6.11 log 10 CFU/g, respectively, which declined to 6.54 and 5.45 log 10 CFU/g, respectively, during subsequent 20 days. Thereafter, L. innocua and L. monocytogenes populations increased to 7.38 and 6.06 log 10 CFU/g on day 35 of ripening, respectively. During ripening, surface and interior of Cheeses were analysed for populations of L. innocua and L. monocytogenes, respectively. The data were collected on day 1, 5, 10, 15, 20, 25, 30, and 35 of ripening. Generally, the growth of L. innocua and L. monocytogenes is faster in surface than in centre. Top centre, bottom centre and bottom surface locations had similar population values during ripening. There were no significant differences (P > 0.05) between batch and section of Cheese. The ripening time and locations had significant effect (P < 0.05) on the survival and growth of L. innocua and L. monocytogenes. The trends of survival and growth of L. innocua and L. monocytogenes were similar. These results indicated that L. innocua can be considered as an indicator for L. monocytogenes during ripening of Camembert Cheese.
-
ph spatial distribution model during ripening of Camembert Cheese
Lwt - Food Science and Technology, 2008Co-Authors: Shaowei Liu, Virendra M PuriAbstract:Abstract During ripening of Camembert Cheese, a soft Cheese, the pH values continually change, which impacts the growth of Listeria monocytogenes . In this study, a pH distribution model suitable for the ripening phase of Camembert Cheese was developed and verified. An experimental trend-based statistical model for pH using normalized time and normalized pH as variables was developed to determine the evolution of pH. The pH model showed good agreement with the mean pH measured values, i.e., the pH model was able to capture the magnitudes and trends sufficiently. The R 2 values for top surface, center, inner–outer side surface, and bottom surface regions’ mean measured and pH model-predicted values were 0.97, 0.95, 0.99, and 0.99, respectively.
-
dynamic growth models for l monocytogenes during ripening in Camembert Cheese
Lwt - Food Science and Technology, 2008Co-Authors: Shaowei Liu, Virendra M PuriAbstract:Abstract Population density curves for L. monocytogenes in Camembert Cheese were obtained during ripening. The pH, moisture content, and the specific growth rate values for survival and growth data for each trial were used to develop and verify three levels of accuracy Camembert Cheese Dynamic Models (CDMs) (location, region, and section-specific dynamic growth models). The location-specific dynamic growth model provided the most detailed information and had highest accuracy for the prediction of L. monocytogenes during ripening of Camembert Cheese. Experimental data had a good fit with calculated values for the three levels of CDMs: (1) for location-specific dynamic growth model, the R2 values for top center (TC), top surface (TS), center (C), bottom center (BC), and bottom surface (BS) regions were 0.92, 0.94, 0.91, 0.94, and 0.95, respectively. The standard error ranged from 0.19 to 0.24 log(CFU/g). (2) For region-specific dynamic growth model, the R2 values for two regions were 0.93 (TS and C) and 0.94 (TC, BC, and BS), respectively. The standard errors were 0.19 and 0.22 log(CFU/g), respectively. (3) For section-specific dynamic growth model, the R2 value was 0.93 with standard error of 0.27 log(CFU/g).
-
spatial moisture content distribution during ripening of Camembert Cheese
Transactions of the ASABE, 2007Co-Authors: Shaowei Liu, Virendra M PuriAbstract:Listeria monocytogenes is a foodborne pathogen that can survive and grow during ripening of Camembert, a soft Cheese. During the ripening phase, the spatial moisture content values continually change, which impacts the growth of L. monocytogenes. Toward this end, distributions and changes of moisture content during ripening of Camembert Cheese (108 mm dia., 32 mm height) were measured at six locations in two vertical cross-sections 120° apart. The moisture content values decreased continually during ripening of Camembert Cheese. On day 1, the average moisture content was 0.65 (g/g, wet basis), which decreased to 0.38 (g/g, w.b.) on day 35, the last day of ripening. Generally, the moisture content values in the top and bottom regions were lower than in the inside regions. Furthermore, the circumferential surface moisture content values were lower than in the center region. Additionally, the left center had the highest moisture content values during ripening of Camembert Cheese. Within each batch for the two 120°-apart cross-sections, the moisture content values were not significantly different (P > 0.05). However, different locations were significantly different (P < 0.05) for a given day of ripening. In addition, the ripening time had a significant effect (P < 0.05) on the moisture content values. The moisture content values measured in this research can form the basis for developing a mathematical model to predict the distribution of moisture content, which when coupled with pH and dynamic predictive growth models, will enable the prediction of survival and growth of L. monocytogenes during ripening of Camembert Cheese.
-
spatial distribution of population of listeria monocytogenes during manufacturing and ripening of Camembert Cheese
Journal of Food Safety, 2007Co-Authors: Shaowei Liu, Virendra M Puri, Ali DemirciAbstract:The spatial distribution of the survival and growth of Listeria monocytogenes during manufacturing and ripening of Camembert Cheese was studied. All Cheeses were artificially inoculated with L. monocytogenes and ripened in three stages: room temperature (∼20C) and relative humidity (RH) of 60% for 36 h, 13C and RH of 93% for 2 weeks, and 7C and RH of 85% for 3 weeks. During ripening, different locations were analyzed for population of L. monocytogenes. The data were collected on days 1, 5, 10, 15, 20, 25, 30 and 35 of ripening. Results showed that the population of L. monocytogenes on day 1 was 6.06 log 10 cfu/g, which was 1.96 log 10 cfu/g increasing over the initial inoculation of 4.08 logic cfu/g. For the subsequent 20 days, the L. monocytogenes population declined to 5.33 log1o cfuig. Thereafter, the L. monocytogenes population increased to 6.07 log 10 cfu/g on day 35 of ripening. Generally, the growth of L. monocytogenes is faster in locations near the surface than in the center. There were no significant differences between batches and sections of Cheese, whereas the ripening time and locations had a significant effect on the survival and growth of L. monocytogenes. The survival and growth data for L. monocytogenes during ripening of Camembert Cheese can be used to develop dynamic predictive models for possible use in risk assessment and Hazard Analysis and Critical Control Point implementation.
Virendra M Puri - One of the best experts on this subject based on the ideXlab platform.
-
ph spatial distribution model during ripening of Camembert Cheese
Lwt - Food Science and Technology, 2008Co-Authors: Shaowei Liu, Virendra M PuriAbstract:Abstract During ripening of Camembert Cheese, a soft Cheese, the pH values continually change, which impacts the growth of Listeria monocytogenes . In this study, a pH distribution model suitable for the ripening phase of Camembert Cheese was developed and verified. An experimental trend-based statistical model for pH using normalized time and normalized pH as variables was developed to determine the evolution of pH. The pH model showed good agreement with the mean pH measured values, i.e., the pH model was able to capture the magnitudes and trends sufficiently. The R 2 values for top surface, center, inner–outer side surface, and bottom surface regions’ mean measured and pH model-predicted values were 0.97, 0.95, 0.99, and 0.99, respectively.
-
dynamic growth models for l monocytogenes during ripening in Camembert Cheese
Lwt - Food Science and Technology, 2008Co-Authors: Shaowei Liu, Virendra M PuriAbstract:Abstract Population density curves for L. monocytogenes in Camembert Cheese were obtained during ripening. The pH, moisture content, and the specific growth rate values for survival and growth data for each trial were used to develop and verify three levels of accuracy Camembert Cheese Dynamic Models (CDMs) (location, region, and section-specific dynamic growth models). The location-specific dynamic growth model provided the most detailed information and had highest accuracy for the prediction of L. monocytogenes during ripening of Camembert Cheese. Experimental data had a good fit with calculated values for the three levels of CDMs: (1) for location-specific dynamic growth model, the R2 values for top center (TC), top surface (TS), center (C), bottom center (BC), and bottom surface (BS) regions were 0.92, 0.94, 0.91, 0.94, and 0.95, respectively. The standard error ranged from 0.19 to 0.24 log(CFU/g). (2) For region-specific dynamic growth model, the R2 values for two regions were 0.93 (TS and C) and 0.94 (TC, BC, and BS), respectively. The standard errors were 0.19 and 0.22 log(CFU/g), respectively. (3) For section-specific dynamic growth model, the R2 value was 0.93 with standard error of 0.27 log(CFU/g).
-
spatial moisture content distribution during ripening of Camembert Cheese
Transactions of the ASABE, 2007Co-Authors: Shaowei Liu, Virendra M PuriAbstract:Listeria monocytogenes is a foodborne pathogen that can survive and grow during ripening of Camembert, a soft Cheese. During the ripening phase, the spatial moisture content values continually change, which impacts the growth of L. monocytogenes. Toward this end, distributions and changes of moisture content during ripening of Camembert Cheese (108 mm dia., 32 mm height) were measured at six locations in two vertical cross-sections 120° apart. The moisture content values decreased continually during ripening of Camembert Cheese. On day 1, the average moisture content was 0.65 (g/g, wet basis), which decreased to 0.38 (g/g, w.b.) on day 35, the last day of ripening. Generally, the moisture content values in the top and bottom regions were lower than in the inside regions. Furthermore, the circumferential surface moisture content values were lower than in the center region. Additionally, the left center had the highest moisture content values during ripening of Camembert Cheese. Within each batch for the two 120°-apart cross-sections, the moisture content values were not significantly different (P > 0.05). However, different locations were significantly different (P < 0.05) for a given day of ripening. In addition, the ripening time had a significant effect (P < 0.05) on the moisture content values. The moisture content values measured in this research can form the basis for developing a mathematical model to predict the distribution of moisture content, which when coupled with pH and dynamic predictive growth models, will enable the prediction of survival and growth of L. monocytogenes during ripening of Camembert Cheese.
-
spatial distribution of population of listeria monocytogenes during manufacturing and ripening of Camembert Cheese
Journal of Food Safety, 2007Co-Authors: Shaowei Liu, Virendra M Puri, Ali DemirciAbstract:The spatial distribution of the survival and growth of Listeria monocytogenes during manufacturing and ripening of Camembert Cheese was studied. All Cheeses were artificially inoculated with L. monocytogenes and ripened in three stages: room temperature (∼20C) and relative humidity (RH) of 60% for 36 h, 13C and RH of 93% for 2 weeks, and 7C and RH of 85% for 3 weeks. During ripening, different locations were analyzed for population of L. monocytogenes. The data were collected on days 1, 5, 10, 15, 20, 25, 30 and 35 of ripening. Results showed that the population of L. monocytogenes on day 1 was 6.06 log 10 cfu/g, which was 1.96 log 10 cfu/g increasing over the initial inoculation of 4.08 logic cfu/g. For the subsequent 20 days, the L. monocytogenes population declined to 5.33 log1o cfuig. Thereafter, the L. monocytogenes population increased to 6.07 log 10 cfu/g on day 35 of ripening. Generally, the growth of L. monocytogenes is faster in locations near the surface than in the center. There were no significant differences between batches and sections of Cheese, whereas the ripening time and locations had a significant effect on the survival and growth of L. monocytogenes. The survival and growth data for L. monocytogenes during ripening of Camembert Cheese can be used to develop dynamic predictive models for possible use in risk assessment and Hazard Analysis and Critical Control Point implementation.
-
spatial ph distribution during ripening of Camembert Cheese
Transactions of the ASABE, 2005Co-Authors: Shaowei Liu, Virendra M PuriAbstract:During the ripening phase, the pH values continually change, which impacts the survival and growth of all microorganisms including Listeria monocytogenes (a foodborne pathogen). Toward this end, distribution and change of pH during ripening of cylindrical (108 mm diameter; 32 mm height) Camembert Cheese were measured at 16 locations and three vertical cross-sections 120° apart. The pH at different locations had significant differences (P < 0.05) for each day of ripening. The pH values in the top and bottom regions had higher values than in the top middle and bottom middle regions. In addition, the pH in the surface region was higher than in the center region. The day had a significant effect (P < 0.05) on the pH values during ripening. Overall, the pH values increased gradually and throughout the ripening of Camembert Cheese. The pH value was around 4.5 on day 1 and approximately 7.5 on day 35 of ripening. Within a set, the pH values had no significant difference (P > 0.05) for each batch and each section. For across-set comparisons, the set had no significant effect (P > 0.05) on the pH values during ripening. There were similar values for each batch and section on each ripening day. The pH values measured in this research can be the basis for developing a mathematical model to predict the distribution of pH, which when coupled with a dynamic predictive growth model, will enable the prediction of survival and growth of L. monocytogenes during ripening of Camembert Cheese.
