Motivasjonen for å endre undervisningsopplegg er å øke studentenes læring. For å måle effekten av... more Motivasjonen for å endre undervisningsopplegg er å øke studentenes læring. For å måle effekten av endringer eller identifisere vanlige misforståelser innen fagområdet matmikrobiologi har vi utviklet en begrepstest (Food Microbiology Concept Inventory). Testen ble videreutviklet fra lignende tester i mikrobiologi og forfatternes egne erfaringer. I tillegg ble matbransjen spurt om hvilken mikrobiologikunnskap som de mener er essensiell for en kandidat med bachelorgrad i matteknologi. En spørreundersøkelse ble utviklet og sendt ut til 268 aktører fordelt på akademia, instituttsektor, industri og forvaltning. Den totale svarprosenten i undersøkelsen var 20,5%, og 56% av respondentene var fra industrien. Uavhengig av respondentenes utdanning eller arbeidsplass var det stor enighet om de fem viktigste påstandene eller spørsmålene i undersøkelsen. Disse omhandlet overlevelse og vekst av mikroorganismer (Q21), mikroorganismenes påvirkning på produktkvalitet og mattrygghet og overvåkning av...
Arbeidslivsrelevans i høyere utdanning er avhengig av kontakt med arbeidslivet, men like viktig e... more Arbeidslivsrelevans i høyere utdanning er avhengig av kontakt med arbeidslivet, men like viktig er det å ruste studenten til en fremtid preget av livslang laering. I tillegg til fagkunnskap er arbeidsgivere opptatt av de generiske ferdighetene. Denne studien utforsker hvorvidt bruk av filmatiserte case utviklet i samarbeid med matbransjen kan bidra til at et emne som matmikrobiologi oppfattes som mer relevant for arbeidslivet av studentene. Hensikten var å trekke bransjens mikrobiologiske utfordringer inn i emneundervisningen. I tillegg ble det undersøkt om omleggingen bidro til økt studentmotivasjon og laering. For å frigi tid til caseundervisning ble en del forelesninger filmatisert for selvstudium. Studentene var gjennomgående positive til opplegget med omvendt klasserom, og de var spesielt fornøyde med fleksibiliteten som filmatiserte forelesninger gir. Casene ble oppfattet som relevante for arbeidslivet, og undervisningsformen bidro til at flere møtte forberedt enn til tradisjonelle forelesninger. Hovedutfordringen i opplegget var at studentene ble usikre på casenes relevans for emnets laeringsutbyttebeskrivelser og vurderingsform. Tydelige forventningsavklaringer er avgjørende for å sikre høy studentdeltagelse og at studentene møter forberedt til caseundervisningen. Omlegging av undervisningen bidro til signifikant bedre akademisk prestasjon enn tidligere år.
Bachelorutdanningen i matteknologi ved NTNU utdanner kandidater som kan gå inn i en rekke ulike r... more Bachelorutdanningen i matteknologi ved NTNU utdanner kandidater som kan gå inn i en rekke ulike roller innen matindustri og forvaltning; eksempelvis innen kvalitetsarbeid og analyser, innovasjon og produktutvikling, matproduksjon og forskning. Matteknologen er en allrounder. Som et ledd i å optimalisere studentenes læring og øke gjennomstrømmingen, ønsket vi å finne ut mer om hvilke oppfatninger og forestillinger studentene har om studiet. Hva er viktig i studiet i utformingen av en matteknolog? Hvilke læringsaktiviteter opplevde de som nyttige i forhold til å forstå pensum bedre? Kan læringsaktiviteter med utgangspunkt fra arbeidslivet øke forståelsen av faglige tema? Dette er spørsmål som ble stilt til studenter fra 1., 4. og 6. semester under utdanning og uteksaminerte kandidater fra bachelorutdanningen. Undersøkelsen ble gjennomført med fokusgruppeintervjuer med påfølgende tematisk analyse av data. Studentenes holdninger og forventninger, samt studiets oppbygning, vurderingsmeto...
Aims: The aim of the study was to quantify the growth kinetic parameters and spoilage-associated ... more Aims: The aim of the study was to quantify the growth kinetic parameters and spoilage-associated metabolites of an inoculated strain of Aeromonas salmonicida in pre-rigor filleted Atlantic salmon (Salmo salar L.) stored in vacuum (VP) or modified atmosphere (MAP 60/40% CO 2 /N 2) at 4 and 8°C. Methods and Results: The maximum growth rate of A. salmonicida in VP salmon stored at 4°C was 0Á56 AE 0Á04 day À1 with no detectable lag-phase and the concentration of Aeromonas reached 8Á33 log CFU per g after 10 days. The growth rates and maximum population density of Aeromonas in MAP salmon were lower but the applied atmosphere did not inhibit the growth. A selection of metabolites associated with fish spoilage were quantified using 1 H nuclear magnetic resonance (NMR) spectroscopy. The concentration of trimethylamine (TMA) was significantly affected by storage time and temperature, packaging atmosphere and inoculation with A. salmonicida (General Linear Model (GLM), P < 0Á001 for all factors). Conclusion: The study presents preliminary results on A. salmonicida as a potential spoilage organism in vacuum-packaged salmon during cold storage. The combination of refrigeration and a packaging atmosphere consisting of 60/ 40 % CO 2 /N 2 did not completely inhibit the growth but prevented the formation of TMA. Significance and Impact of the Study: Little information is available on the spoilage potential of Aeromonas spp. in minimally processed salmon products under different packaging conditions. The study clearly demonstrates the importance of hurdle technology and provides data to further elucidate the significance of Aeromonas spp. as a spoilage organism.
Biopreservation is a food preservation technology using microorganisms and/or their inherent anti... more Biopreservation is a food preservation technology using microorganisms and/or their inherent antimicrobial metabolites to inhibit undesirable microorganisms. The aim of the present study was to explore the diversity and antimicrobial activity of lactic acid bacteria (LAB) strains (n = 99) isolated from ready-to-eat (RTE) seafood (cold-smoked salmon (CSS), gravlax, and sushi) towards two strains of Listeria monocytogenes (CCUG 15527, F11), Listeria innocua (CCUG 15531) and Escherichia coli (CCUG 38079). The LAB strains were assigned to five different genera (Carnobacterium spp., Lactobacillus spp., Leuconostoc spp., Weissella spp., and Enterococcus sp.) by sequencing a 1150 bp stretch of the 16S rRNA gene. A significant association between the seafood source and the distribution of LAB genera was found (p < 0.001), of which Leuconostoc spp. were most prevalent in sushi and Carnobacterium sp. and Lactobacillus sp. were most frequently isolated from CSS and gravlax. Antimicrobial ac...
Water and salt uptake, and water holding capacity (WHC) of whole gutted Atlantic salmon superchil... more Water and salt uptake, and water holding capacity (WHC) of whole gutted Atlantic salmon superchilled at sub-zero temperatures in refrigerated seawater (RSW) were compared to traditional ice storage. Following the entire value chain, the whole salmon was further processed, and fillets were either chilled on ice or dry salted and cold-smoked. Changes in quality parameters including colour, texture, enzyme activity and microbial counts were also analyzed for 3 weeks. Our results showed that when fish were removed from the RSW tank after 4 days and further chilled for 3 days, an overall weight gain of 0.7%, salt uptake of 0.3% and higher WHC were observed. In contrast, ice-stored fish had a total weight loss of 1% and steady salt uptake of 0.1%. After filleting, raw fillets from whole fish initially immersed in RSW had better gaping occurrence, softer texture, lower cathepsin B + L activity but higher microbiological growth. Otherwise, there were no differences in drip loss nor colour (...
Minimally processed and ready-to-eat (RTE) seafood products are gaining popularity because of the... more Minimally processed and ready-to-eat (RTE) seafood products are gaining popularity because of their availability in retail stores and the consumers’ perception of convenience. Products that are subjected to mild processing and products that do not require additional heating prior to consumption are eaten by an increasing proportion of the population, including people that are more susceptible to foodborne disease. Worldwide, seafood is an important source of foodborne outbreaks, but the exact burden is not known. The increased interest in seafood products for raw consumption introduces new food safety issues that must be addressed by all actors in the food chain. Bacteria belonging to genus Aeromonas are ubiquitous in marine environments, and Aeromonas spp. has held the title “emerging foodborne pathogen” for more than a decade. Given its high prevalence in seafood and in vegetables included in many RTE seafood meals, the significance of Aeromonas as a potential foodborne pathogen a...
Aeromonas spp. are ubiquitous bacteria that have received increasing attention as human pathogens... more Aeromonas spp. are ubiquitous bacteria that have received increasing attention as human pathogens because of their widespread occurrence in food, especially seafood and vegetables. The aim of this work was to assess the species identity and phylogenetic relationship of 118 Aeromonas strains isolated from fresh retail sushi from three producers, and to characterize the isolates with respect to genetic and phenotypic virulence factors. We also evaluate the potential hazard associated with their presence in ready-to-eat seafood not subjected to heat treatment. Mesophilic Aeromonas salmonicida was most prevalent (74%), followed by A. bestiarum (9%), A. dhakensis (5%), A. caviae (5%), A. media (4%), A. hydrophila (2%), and A. piscicola (1%). All isolates were considered potentially pathogenic due to the high prevalence of genes encoding hemolysin (hlyA) (99%), aerolysin (aerA) (98%), cytotoxic enterotoxin (act) (86%), heat-labile cytotonic enterotoxin (alt) (99%), and heat-stable cytotonic enterotoxin (ast) (31%). The shiga-like toxins 1 and 2 (stx-1 and stx-2) were not detected. Moreover, there was heterogeneity in toxin gene distribution among the isolates, and the combination of act/alt/hlyA/aerA was most commonly detected (63%). β-hemolysis was species-dependent and observed in 91% of the isolates. All A. media and A. caviae strains were non-hemolytic. For isolates belonging to this group, lack of hemolysis was possibly related to the absence of the act gene. Swimming motility, linked to adhesion and host invasion, occurred in 65% of the isolates. Partial sequencing of the gyrB gene demonstrated its suitability as a genetic marker for Aeromonas species identification and for assessment of the phylogenetic relationship between the isolates. The gyrB sequence divergence within a given species ranged from 1.3 to 2.9%. A. bestiarum, A. salmonicida, and A. piscicola were the most closely related species; their sequences differed by 2.7-3.4%. The average gyrB sequence similarity between all species was 93%, demonstrating its acceptable taxonomic resolution. The presence of multiple species of potential pathogenic Aeromonas in fresh retail sushi raises new food safety issues related to the increased consumption of ready-to-eat food composed of raw ingredients.
Retail fresh sushi is gaining popularity in Europe. This study was conducted to investigate the m... more Retail fresh sushi is gaining popularity in Europe. This study was conducted to investigate the microbiological quality of selected samples of fresh sushi with a shelf life of 2 to 3 days offered as complete meals in Norwegian supermarkets. Analysis of aerobic plate counts in 58 sushi samples from three producers revealed large variations in microbiological quality, and 48% of the analyzed sushi boxes were rated as unsatisfactory (> 6.0 log CFU/g). Mesophilic Aeromonas spp. was detected in 71% of the samples. In a follow-up study, we collected products and raw materials directly from the production facility of one producer and observed a significant decrease (P < 0.01) in aerobic plate counts compared with the initial sampling. The observed difference between products purchased in stores compared with those collected directly from the factory suggests that poor temperature control during distribution and display in stores leads to reduced microbiological quality. Microbiologic...
We report that endogenously synthesized (−)-proto-quercitol (1d-1,3,4/2,5-cyclohexanepentol) and ... more We report that endogenously synthesized (−)-proto-quercitol (1d-1,3,4/2,5-cyclohexanepentol) and glycine betaine were the principal compatible solutes of Schizochytrium sp. strain S8 (ATCC 20889) and three new osmotolerant isolates of thraustochytrids (strains T65, T66, and T67). The compatible solutes were identified and quantified by use of nuclear magnetic resonance spectroscopy, and their identity was confirmed by mass spectroscopy and measurement of the specific optical rotation. The cellular content of compatible solutes increased with increasing NaCl concentration of a defined medium. (−)-proto-Quercitol was the dominating solute at all NaCl concentrations tested (0.25 to 1.0 M), e.g., cells of S8 and T66 stressed with 1.0 M NaCl accumulated about 500 μmol (−)-proto-quercitol and 100 μmol glycine betaine per g dry weight. To our knowledge, (−)-proto-quercitol has previously been found only in eucalyptus. The 18S rRNA gene sequences of the four (−)-proto-quercitol-producing st...
Motivasjonen for å endre undervisningsopplegg er å øke studentenes læring. For å måle effekten av... more Motivasjonen for å endre undervisningsopplegg er å øke studentenes læring. For å måle effekten av endringer eller identifisere vanlige misforståelser innen fagområdet matmikrobiologi har vi utviklet en begrepstest (Food Microbiology Concept Inventory). Testen ble videreutviklet fra lignende tester i mikrobiologi og forfatternes egne erfaringer. I tillegg ble matbransjen spurt om hvilken mikrobiologikunnskap som de mener er essensiell for en kandidat med bachelorgrad i matteknologi. En spørreundersøkelse ble utviklet og sendt ut til 268 aktører fordelt på akademia, instituttsektor, industri og forvaltning. Den totale svarprosenten i undersøkelsen var 20,5%, og 56% av respondentene var fra industrien. Uavhengig av respondentenes utdanning eller arbeidsplass var det stor enighet om de fem viktigste påstandene eller spørsmålene i undersøkelsen. Disse omhandlet overlevelse og vekst av mikroorganismer (Q21), mikroorganismenes påvirkning på produktkvalitet og mattrygghet og overvåkning av...
Arbeidslivsrelevans i høyere utdanning er avhengig av kontakt med arbeidslivet, men like viktig e... more Arbeidslivsrelevans i høyere utdanning er avhengig av kontakt med arbeidslivet, men like viktig er det å ruste studenten til en fremtid preget av livslang laering. I tillegg til fagkunnskap er arbeidsgivere opptatt av de generiske ferdighetene. Denne studien utforsker hvorvidt bruk av filmatiserte case utviklet i samarbeid med matbransjen kan bidra til at et emne som matmikrobiologi oppfattes som mer relevant for arbeidslivet av studentene. Hensikten var å trekke bransjens mikrobiologiske utfordringer inn i emneundervisningen. I tillegg ble det undersøkt om omleggingen bidro til økt studentmotivasjon og laering. For å frigi tid til caseundervisning ble en del forelesninger filmatisert for selvstudium. Studentene var gjennomgående positive til opplegget med omvendt klasserom, og de var spesielt fornøyde med fleksibiliteten som filmatiserte forelesninger gir. Casene ble oppfattet som relevante for arbeidslivet, og undervisningsformen bidro til at flere møtte forberedt enn til tradisjonelle forelesninger. Hovedutfordringen i opplegget var at studentene ble usikre på casenes relevans for emnets laeringsutbyttebeskrivelser og vurderingsform. Tydelige forventningsavklaringer er avgjørende for å sikre høy studentdeltagelse og at studentene møter forberedt til caseundervisningen. Omlegging av undervisningen bidro til signifikant bedre akademisk prestasjon enn tidligere år.
Bachelorutdanningen i matteknologi ved NTNU utdanner kandidater som kan gå inn i en rekke ulike r... more Bachelorutdanningen i matteknologi ved NTNU utdanner kandidater som kan gå inn i en rekke ulike roller innen matindustri og forvaltning; eksempelvis innen kvalitetsarbeid og analyser, innovasjon og produktutvikling, matproduksjon og forskning. Matteknologen er en allrounder. Som et ledd i å optimalisere studentenes læring og øke gjennomstrømmingen, ønsket vi å finne ut mer om hvilke oppfatninger og forestillinger studentene har om studiet. Hva er viktig i studiet i utformingen av en matteknolog? Hvilke læringsaktiviteter opplevde de som nyttige i forhold til å forstå pensum bedre? Kan læringsaktiviteter med utgangspunkt fra arbeidslivet øke forståelsen av faglige tema? Dette er spørsmål som ble stilt til studenter fra 1., 4. og 6. semester under utdanning og uteksaminerte kandidater fra bachelorutdanningen. Undersøkelsen ble gjennomført med fokusgruppeintervjuer med påfølgende tematisk analyse av data. Studentenes holdninger og forventninger, samt studiets oppbygning, vurderingsmeto...
Aims: The aim of the study was to quantify the growth kinetic parameters and spoilage-associated ... more Aims: The aim of the study was to quantify the growth kinetic parameters and spoilage-associated metabolites of an inoculated strain of Aeromonas salmonicida in pre-rigor filleted Atlantic salmon (Salmo salar L.) stored in vacuum (VP) or modified atmosphere (MAP 60/40% CO 2 /N 2) at 4 and 8°C. Methods and Results: The maximum growth rate of A. salmonicida in VP salmon stored at 4°C was 0Á56 AE 0Á04 day À1 with no detectable lag-phase and the concentration of Aeromonas reached 8Á33 log CFU per g after 10 days. The growth rates and maximum population density of Aeromonas in MAP salmon were lower but the applied atmosphere did not inhibit the growth. A selection of metabolites associated with fish spoilage were quantified using 1 H nuclear magnetic resonance (NMR) spectroscopy. The concentration of trimethylamine (TMA) was significantly affected by storage time and temperature, packaging atmosphere and inoculation with A. salmonicida (General Linear Model (GLM), P < 0Á001 for all factors). Conclusion: The study presents preliminary results on A. salmonicida as a potential spoilage organism in vacuum-packaged salmon during cold storage. The combination of refrigeration and a packaging atmosphere consisting of 60/ 40 % CO 2 /N 2 did not completely inhibit the growth but prevented the formation of TMA. Significance and Impact of the Study: Little information is available on the spoilage potential of Aeromonas spp. in minimally processed salmon products under different packaging conditions. The study clearly demonstrates the importance of hurdle technology and provides data to further elucidate the significance of Aeromonas spp. as a spoilage organism.
Biopreservation is a food preservation technology using microorganisms and/or their inherent anti... more Biopreservation is a food preservation technology using microorganisms and/or their inherent antimicrobial metabolites to inhibit undesirable microorganisms. The aim of the present study was to explore the diversity and antimicrobial activity of lactic acid bacteria (LAB) strains (n = 99) isolated from ready-to-eat (RTE) seafood (cold-smoked salmon (CSS), gravlax, and sushi) towards two strains of Listeria monocytogenes (CCUG 15527, F11), Listeria innocua (CCUG 15531) and Escherichia coli (CCUG 38079). The LAB strains were assigned to five different genera (Carnobacterium spp., Lactobacillus spp., Leuconostoc spp., Weissella spp., and Enterococcus sp.) by sequencing a 1150 bp stretch of the 16S rRNA gene. A significant association between the seafood source and the distribution of LAB genera was found (p < 0.001), of which Leuconostoc spp. were most prevalent in sushi and Carnobacterium sp. and Lactobacillus sp. were most frequently isolated from CSS and gravlax. Antimicrobial ac...
Water and salt uptake, and water holding capacity (WHC) of whole gutted Atlantic salmon superchil... more Water and salt uptake, and water holding capacity (WHC) of whole gutted Atlantic salmon superchilled at sub-zero temperatures in refrigerated seawater (RSW) were compared to traditional ice storage. Following the entire value chain, the whole salmon was further processed, and fillets were either chilled on ice or dry salted and cold-smoked. Changes in quality parameters including colour, texture, enzyme activity and microbial counts were also analyzed for 3 weeks. Our results showed that when fish were removed from the RSW tank after 4 days and further chilled for 3 days, an overall weight gain of 0.7%, salt uptake of 0.3% and higher WHC were observed. In contrast, ice-stored fish had a total weight loss of 1% and steady salt uptake of 0.1%. After filleting, raw fillets from whole fish initially immersed in RSW had better gaping occurrence, softer texture, lower cathepsin B + L activity but higher microbiological growth. Otherwise, there were no differences in drip loss nor colour (...
Minimally processed and ready-to-eat (RTE) seafood products are gaining popularity because of the... more Minimally processed and ready-to-eat (RTE) seafood products are gaining popularity because of their availability in retail stores and the consumers’ perception of convenience. Products that are subjected to mild processing and products that do not require additional heating prior to consumption are eaten by an increasing proportion of the population, including people that are more susceptible to foodborne disease. Worldwide, seafood is an important source of foodborne outbreaks, but the exact burden is not known. The increased interest in seafood products for raw consumption introduces new food safety issues that must be addressed by all actors in the food chain. Bacteria belonging to genus Aeromonas are ubiquitous in marine environments, and Aeromonas spp. has held the title “emerging foodborne pathogen” for more than a decade. Given its high prevalence in seafood and in vegetables included in many RTE seafood meals, the significance of Aeromonas as a potential foodborne pathogen a...
Aeromonas spp. are ubiquitous bacteria that have received increasing attention as human pathogens... more Aeromonas spp. are ubiquitous bacteria that have received increasing attention as human pathogens because of their widespread occurrence in food, especially seafood and vegetables. The aim of this work was to assess the species identity and phylogenetic relationship of 118 Aeromonas strains isolated from fresh retail sushi from three producers, and to characterize the isolates with respect to genetic and phenotypic virulence factors. We also evaluate the potential hazard associated with their presence in ready-to-eat seafood not subjected to heat treatment. Mesophilic Aeromonas salmonicida was most prevalent (74%), followed by A. bestiarum (9%), A. dhakensis (5%), A. caviae (5%), A. media (4%), A. hydrophila (2%), and A. piscicola (1%). All isolates were considered potentially pathogenic due to the high prevalence of genes encoding hemolysin (hlyA) (99%), aerolysin (aerA) (98%), cytotoxic enterotoxin (act) (86%), heat-labile cytotonic enterotoxin (alt) (99%), and heat-stable cytotonic enterotoxin (ast) (31%). The shiga-like toxins 1 and 2 (stx-1 and stx-2) were not detected. Moreover, there was heterogeneity in toxin gene distribution among the isolates, and the combination of act/alt/hlyA/aerA was most commonly detected (63%). β-hemolysis was species-dependent and observed in 91% of the isolates. All A. media and A. caviae strains were non-hemolytic. For isolates belonging to this group, lack of hemolysis was possibly related to the absence of the act gene. Swimming motility, linked to adhesion and host invasion, occurred in 65% of the isolates. Partial sequencing of the gyrB gene demonstrated its suitability as a genetic marker for Aeromonas species identification and for assessment of the phylogenetic relationship between the isolates. The gyrB sequence divergence within a given species ranged from 1.3 to 2.9%. A. bestiarum, A. salmonicida, and A. piscicola were the most closely related species; their sequences differed by 2.7-3.4%. The average gyrB sequence similarity between all species was 93%, demonstrating its acceptable taxonomic resolution. The presence of multiple species of potential pathogenic Aeromonas in fresh retail sushi raises new food safety issues related to the increased consumption of ready-to-eat food composed of raw ingredients.
Retail fresh sushi is gaining popularity in Europe. This study was conducted to investigate the m... more Retail fresh sushi is gaining popularity in Europe. This study was conducted to investigate the microbiological quality of selected samples of fresh sushi with a shelf life of 2 to 3 days offered as complete meals in Norwegian supermarkets. Analysis of aerobic plate counts in 58 sushi samples from three producers revealed large variations in microbiological quality, and 48% of the analyzed sushi boxes were rated as unsatisfactory (> 6.0 log CFU/g). Mesophilic Aeromonas spp. was detected in 71% of the samples. In a follow-up study, we collected products and raw materials directly from the production facility of one producer and observed a significant decrease (P < 0.01) in aerobic plate counts compared with the initial sampling. The observed difference between products purchased in stores compared with those collected directly from the factory suggests that poor temperature control during distribution and display in stores leads to reduced microbiological quality. Microbiologic...
We report that endogenously synthesized (−)-proto-quercitol (1d-1,3,4/2,5-cyclohexanepentol) and ... more We report that endogenously synthesized (−)-proto-quercitol (1d-1,3,4/2,5-cyclohexanepentol) and glycine betaine were the principal compatible solutes of Schizochytrium sp. strain S8 (ATCC 20889) and three new osmotolerant isolates of thraustochytrids (strains T65, T66, and T67). The compatible solutes were identified and quantified by use of nuclear magnetic resonance spectroscopy, and their identity was confirmed by mass spectroscopy and measurement of the specific optical rotation. The cellular content of compatible solutes increased with increasing NaCl concentration of a defined medium. (−)-proto-Quercitol was the dominating solute at all NaCl concentrations tested (0.25 to 1.0 M), e.g., cells of S8 and T66 stressed with 1.0 M NaCl accumulated about 500 μmol (−)-proto-quercitol and 100 μmol glycine betaine per g dry weight. To our knowledge, (−)-proto-quercitol has previously been found only in eucalyptus. The 18S rRNA gene sequences of the four (−)-proto-quercitol-producing st...
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