Optimized multilayer coating using layer-by-layer assembly method for excellent oxygen barrier of poly(lactic acid) based film

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Potato Chips Byproducts as Feedstocks for Developing Active Starch-Based Films with Potential for Cheese Packaging

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Endringer i biokjemi og kvalitetsparametre ved lagring og varmebehandling av atlantisk makrell (Scomber scombrus)

Atlantisk makrell er en pelagisk fisk som finnes i norske farvann. Makrell er rik på viktige næringsstoffer som lipider og proteiner, og er en god matressurs i et sunt kosthold. Under prosessering og lagring kan verdifulle komponenter i fiskekjøttet ødelegges eller gå tapt. For å utvikle produkter med god kvalitet og holdbarhet, er det derfor behov for å optimalisere prosessering og lagring av pelagiske råmaterialer. Dette arbeidet hadde to hovedmål. Et mål var å optimalisere kjølelagring av makrellfileter, og endringer i kvalitet og biokjemiske egenskaper ble studert gjennom kjøling på is (4°C, 7 dager) og superkjøling (-2°C, 19 dager). Fryselagring (-20°C, 1 måned) ble brukt som referanse. Et annet mål med dette arbeidet var å studere effekten av ulik varmebehandling og påfølgende lagring på endringer i ulike kvalitetsparametre. Vakuumpakkede makrellfileter ble varmebehandlet i vannbad ved 60, 75 og 90°C i 10, 15 og 20 minutter og lagret kjøling på is (4°C) i 1, 3 og 7 dager. Makrell hadde akseptabelt antall bakterier til og med dag 5 ved kjølelagring, og gjennom hele lagringsperioden ved superkjøling. Det er ønskelig å redusere drypptap under prosessering, ettersom drypp er et godt vekstmedium for bakterier og et resultat av ødelagte membraner. Drypptapet økte signifikant gjennom lagringsperioden, og kjølte fileter hadde høyere drypptap enn superkjølte. Mengde cellevevsvæske (CTF) er et mål på ødeleggelse av membraner og økte signifikant under superkjølt lagring. Superkjøling resulterte i lysere fileteer enn kjølt lagring. Kjølte makrellfileter ble lysere og mykere under lagring, mens superkjølte fileter ble hardere og hadde liten variasjon i lyshet. Fryste fileter hadde størst lyshet og var mykere enn de superkjølte. Endring i tekstur kan skyldes endring i proteinløselighet som følge av denaturering eller ødeleggelser ved frysing/tining. Mengde vannløselige proteiner ble signifikant redusert ved superkjøling, mens en ikke-signifikant reduksjon ble funnet for kjølte fileter. Denaturering av myofibrillproteiner førte til en reduksjon på 85 % i mengde saltløselige proteiner under superkjølt lagring, og på dag 19 var mengden saltløselige proteiner under 2 % av våtvekt. Proteinoksidasjon ble studert gjennom kvantifisering av karbonylgrupper. Saltløselige proteiner hadde større karbonylinnhold enn vannløselige proteiner, så myo- fibrillproteiner i løsning var mer oksiderte enn de løste sarkoplasmaproteinene. Karbonylinnholdet (nmol/mg protein) i saltløselige proteiner økte signifikant under superkjølt lagring. Proteolytiske enzymer bryter ned muskelproteiner, og i dette studiet ble proteolytisk aktivitet bestemt ved å studere aktiviteten til katepsin B+L-lignende enzymer. Den totale aktiviteten økte ved kjølelagring. Aktiviteten økte fra dag 1 til dag 9 i superkjølte fileter før den gikk ned. Økt total aktivitet skyldes trolig nedbrytning av inhibitorer. Katepsin B+L-lignende aktivitet i cellevevsvæske var stabil for kjølte makrellfiler, men økte signifikant ved superkjølt lagring. Forholdet mellom aktivitet i cellevevsvæske og total aktivitet er et mål på grad av lysosomal ødeleggelse, og superkjølt lagring førte til økt ødeleggelse av lysosomer. Proteolytisk aktivitet resulterte i signifikant økning i mengde frie aminosyrer ved både superkjølt og kjølt lagring, og fritt histidin dominerte for alle makrellfiletene. Varmebehandling har lenge vært en vanlig prosesseringsmetode for å sikre trygg og holdbar mat, og siden fisk er sensitiv mot termisk behandling, er det ønskelig å forkorte tiden og senke temperaturen. Tid og temperatur under varmebehandlingen påvirket ikke vanninnholdet til makrellfiletene, og alle prøvene hadde god mikrobiell holdbarhet gjennom lagringsperioden. Væsketapet økte med økende temperatur og tid i vannbad, men gikk ned gjennom lagringsperioden ettersom noe av væsken ble gjenabsorbert av muskelen. Høyere prosesseringstemperatur førte til lysere fileter, og lysheten økte ytterligere ved kjølelagring. Termisk denaturering av proteiner førte til lav mengde vann- og saltløselige proteiner. Mest løselige proteiner ble funnet ved 60°C. Mengde vannløselige proteiner var 1,45 % av våtvekt eller lavere, og størst mengde saltløselige proteiner var 0,63 % av v˚atvekt. Ved lagring gikk mengde vannløselige proteiner ytterligere ned, mens mindre variasjon ble funnet for mengde saltløselige proteiner. Både vann og saltløselige proteiner hadde en signifikant økning i karbonylinnhold og var derfor mer oksidert etter varmebehandling. Varmebehandling ved 60°C resulterte i makrellfileter med høyere kvalitet enn prosessering ved høyere temperaturer, med tanke på denaturering av muskelproteiner, oksidasjon av proteiner og væsketap

Recyclable mono materials for packaging of fresh chicken fillets: New design for recycling in circular economy

The focus on sustainability and circular economy is leading to a need for development of new food packaging concepts, including recyclable materials that ideally consist of a single material in a monolayer system. This research was focused on the possibility of replacing complex multilayered material [amorphous polyethylene terephthalate/ polyethylene (APET/PE)] with simple recyclable mono material [highdensity polyethylene (HDPE)] for packaging of chicken fillets in modified atmosphere packaging (CO2/N2: 60%/40%). Bacterial growth measured as total viable count (TVC), lactic acid bacteria and Enterobacteriaceae, Brochothrix thermosphacta and Escherichia coli for chicken fillets packed in HDPE mono materials was compared with chicken fillets packed in APET/PE. TVC increased during the storage period (24 days) with high level of TVC count (7 log10 CFU/g) recorded at Days 19–20 of storage in both HDPE and APET/PE material. No significant differences were recorded in off-odour between chicken stored in APET/PE compared with HDPE in CO2/N2 atmosphere during the storage period (samples were regarded as acceptable on the 24th day of storage). The drip loss increased in all samples during storage, and no significant differences between samples stored in different materials were recorded. Significant differences in bacterial growth were recorded between samples with different gas volume to product volume (G/P) ratio (Day 17), implying that higher G/P ratio is resulting in lower TVC count. The lowest G/P ratio caused the highest drip loss, whereas addition of CO2 emitter reduced the drip loss to some extent. This research is very encouraging as it provides new insight into the use of monolayer materials as well as the importance of design for recycling in circular economy.publishedVersio

Recyclable mono materials for packaging of fresh chicken fillets: New design for recycling in circular economy

The focus on sustainability and circular economy is leading to a need for development of new food packaging concepts, including recyclable materials that ideally consist of a single material in a monolayer system. This research was focused on the possibility of replacing complex multilayered material [amorphous polyethylene terephthalate/ polyethylene (APET/PE)] with simple recyclable mono material [highdensity polyethylene (HDPE)] for packaging of chicken fillets in modified atmosphere packaging (CO2/N2: 60%/40%). Bacterial growth measured as total viable count (TVC), lactic acid bacteria and Enterobacteriaceae, Brochothrix thermosphacta and Escherichia coli for chicken fillets packed in HDPE mono materials was compared with chicken fillets packed in APET/PE. TVC increased during the storage period (24 days) with high level of TVC count (7 log10 CFU/g) recorded at Days 19–20 of storage in both HDPE and APET/PE material. No significant differences were recorded in off-odour between chicken stored in APET/PE compared with HDPE in CO2/N2 atmosphere during the storage period (samples were regarded as acceptable on the 24th day of storage). The drip loss increased in all samples during storage, and no significant differences between samples stored in different materials were recorded. Significant differences in bacterial growth were recorded between samples with different gas volume to product volume (G/P) ratio (Day 17), implying that higher G/P ratio is resulting in lower TVC count. The lowest G/P ratio caused the highest drip loss, whereas addition of CO2 emitter reduced the drip loss to some extent. This research is very encouraging as it provides new insight into the use of monolayer materials as well as the importance of design for recycling in circular economy

Cooking chicken at home: Common or recommended approaches to judge doneness may not assure sufficient inactivation of pathogens

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Improved microbial and sensory quality of chicken meat by treatment with lactic acid, organic acid salts and modified atmosphere packaging

Microbial contamination and growth play important roles in spoilage and quality loss of raw poultry products. We evaluated the suitability of three commercially available organic acid based antimicrobial compounds, Purac FCC80 (l-lactic acid), Verdad N6 (buffered vinegar fermentate) and Provian K (blend of potassium acetate and diacetate) to prevent growth of the innate microbiota, reduce spoilage and enhance the sensory quality of raw chicken under vacuum, high CO2 (60/40% CO2/N2), and high O2 (75/25% O2/CO2) modified atmosphere (MA) storage conditions. Solutions were applied warm (50 °C) or cold (4 °C) to reflect treatments prior to (Prechill) or after (Postchill) cooling of chicken carcasses, respectively. Single postchill treatments of raw chicken wings with 5% Verdad N6 or Provian K solutions and MA storage enabled complete growth inhibition during the first seven days of storage before growth resumed. Enhanced bacterial control was obtained by combining Prechill lactic acid and Postchill Verdad N6 or Provian K treatments which indicated initial reductions up to 1.1 log and where total bacterial increase after 20 days storage was limited to 1.8–2.1 log. Antibacterial effects were dependent on the concentration of the inhibiting salts used, pH and the storage conditions. Bacterial community analyses showed increased relative levels of Gram-positive bacteria and with reductions of potential spoilage organisms in samples treated with the organic acid salts Verdad N6 and Provian K. Sensory analyses of raw, treated wings showed prominent lower scores in several spoilage associated odour attributes when compared with untreated chicken wings after 13 days storage. For heat-treated chicken, only minor differences for 22 tested attributes were detected between seven antimicrobial treatments and untreated control chicken. Immersion in commercially available organic acid/salt solutions combined with MA storage can reduce bacterial levels, improve microbial and sensory quality, and potentially improve shelf life and reduce food waste of chicken products

Cooking chicken at home: Common or recommended approaches to judge doneness may not assure sufficient inactivation of pathogens.

About one third of foodborne illness outbreaks in Europe are acquired in the home and eating undercooked poultry is among consumption practices associated with illness. The aim of this study was to investigate whether actual and recommended practices for monitoring chicken doneness are safe. Seventy-five European households from five European countries were interviewed and videoed while cooking chicken in their private kitchens, including young single men, families with infants/in pregnancy and elderly over seventy years. A cross-national web-survey collected cooking practices for chicken from 3969 households. In a laboratory kitchen, chicken breast fillets were injected with cocktails of Salmonella and Campylobacter and cooked to core temperatures between 55 and 70°C. Microbial survival in the core and surface of the meat were determined. In a parallel experiment, core colour, colour of juice and texture were recorded. Finally, a range of cooking thermometers from the consumer market were evaluated. The field study identified nine practical approaches for deciding if the chicken was properly cooked. Among these, checking the colour of the meat was commonly used and perceived as a way of mitigating risks among the consumers. Meanwhile, chicken was perceived as hedonically vulnerable to long cooking time. The quantitative survey revealed that households prevalently check cooking status from the inside colour (49.6%) and/or inside texture (39.2%) of the meat. Young men rely more often on the outside colour of the meat (34.7%) and less often on the juices (16.5%) than the elderly (>65 years old; 25.8% and 24.6%, respectively). The lab study showed that colour change of chicken meat happened below 60°C, corresponding to less than 3 log reduction of Salmonella and Campylobacter. At a core temperature of 70°C, pathogens survived on the fillet surface not in contact with the frying pan. No correlation between meat texture and microbial inactivation was found. A minority of respondents used a food thermometer, and a challenge with cooking thermometers for home use was long response time. In conclusion, the recommendations from the authorities on monitoring doneness of chicken and current consumer practices do not ensure reduction of pathogens to safe levels. For the domestic cook, determining doneness is both a question of avoiding potential harm and achieving a pleasurable meal. It is discussed how lack of an easy "rule-of-thumb" or tools to check safe cooking at consumer level, as well as national differences in contamination levels, food culture and economy make it difficult to develop international recommendations that are both safe and easily implemented

Cooking chicken at home: Common or recommended approaches to judge doneness may not assure sufficient inactivation of pathogens

About one third of foodborne illness outbreaks in Europe are acquired in the home and eating undercooked poultry is among consumption practices associated with illness. The aim of this study was to investigate whether actual and recommended practices for monitoring chicken doneness are safe. Seventy-five European households from five European countries were interviewed and videoed while cooking chicken in their private kitchens, including young single men, families with infants/in pregnancy and elderly over seventy years. A cross-national web-survey collected cooking practices for chicken from 3969 households. In a laboratory kitchen, chicken breast fillets were injected with cocktails of Salmonella and Campylobacter and cooked to core temperatures between 55 and 70˚C. Microbial survival in the core and surface of the meat were determined. In a parallel experiment, core colour, colour of juice and texture were recorded. Finally, a range of cooking thermometers from the consumer market were evaluated. The field study identified nine practical approaches for deciding if the chicken was properly cooked. Among these, checking the colour of the meat was commonly used and perceived as a way of mitigating risks among the consumers. Meanwhile, chicken was perceived as hedonically vulnerable to long cooking time. The quantitative survey revealed that households prevalently check cooking status from the inside colour (49.6%) and/or inside texture (39.2%) of the meat. Young men rely more often on the outside colour of the meat (34.7%) and less often on the juices (16.5%) than the elderly (>65 years old; 25.8% and 24.6%, respectively). The lab study showed that colour change of chicken meat happened below 60˚C, corresponding to less than 3 log reduction of Salmonella and Campylobacter. At a core temperature of 70˚C, pathogens survived on the fillet surface not in contact with the frying pan. No correlation between meat texture and microbial inactivation was found. A minority of respondents used a food thermometer, and a challenge with cooking thermometers for home use was long response time. In conclusion, the recommendations from the authorities on monitoring doneness of chicken and current consumer practices do not ensure reduction of pathogens to safe levels. For the domestic cook, determining doneness is both a question of avoiding potential harm and achieving a pleasurable meal. It is discussed how lack of an easy “rule-of-thumb” or tools to check safe cooking at consumer level, as well as national differences in contamination levels, food culture and economy make it difficult to develop international recommendations that are both safe and easily implemented