Fresh produce is often touted for its many health benefits; however, various items have been linked to foodborne disease outbreaks. This is especially a concern for immune suppressed individuals who are classified as severely neutropenic (white blood cell count under 500 neutrophils/μL of blood). At this degree of suppression, many are urged to follow a restrictive diet that reduces the potential of exposure to microbial populations. Currently no processing technique is used to sanitize microorganisms from fresh produce. Electron beam (e-beam) irradiation is a non-thermal process that has been approved by the FDA to treat fresh foods and is able to eliminate bacteria. Another technology used to extend shelf life is modified atmosphere packaging (MAP). The objective of this study was to evaluate the use of e-beam irradiation at current FDA-approved doses (< 1 kGy) to determine whether bioburden on fresh fruits can be reduced while maintaining sensory quality. Aerobic plate count methods were employed to determine the bioburden of treatments over a 21 day storage period under both ambient and MAP conditions. A previously identified bacterial plate count benchmark of < 500 CFU/ gram will be used to determine the applicability of the e-beam treatment. A consumer study using a 9 point hedonic scale as well as instrumentation measuring color, texture, moisture content, total soluble solids and titratable acidity were used to compare the treated fruit to the control. E-beam consistently reduced the bioburden on strawberries, fresh-cut watermelon and significantly (p<0.05) for avocado samples. Avocado, grapes and watermelon showed potential to be labeled as clean foods (below 500 CFU/gram). Fruit firmness (as measured by deformation) was not negatively affected by e-beam treatment and was preserved over storage with MAP treatment. Color was not adversely affected by e-beam or MAP, except for avocados that were significantly more grey in the presence of O_(2). Most importantly, consumers rated e-beam and MAP treated samples as acceptable (score above 5) in qualities of color, odor, flavor and firmness. E-beam proved to be an effective tool in reducing bioburden at low doses while maintaining fruit quality.

Fish products under vacuum (VAC) and/or modified atmosphere packaging (MAP) conditions can have a significantly extended shelf life. Prevention of toxin production by Clostridium botulinum is essential for processors of VAC and MAP refrigerated fishery products. The objective of this study was to determine if C. botulinum toxin development precedes microbiological spoilage and sensory rejection in fully cooked breaded and battered Alaskan Pollock or raw aquacultured flounder fillets. Aquacultured summer flounder (Paralichthys dentatus) fillets and fully cooked breaded and battered Alaskan pollock (Theragra chalcogramma) were either aerobically packed (Oxygen Transmission Rate (OTR) of 3,000 cc/m2/24h@70°F for flounder and 6,000 cc/m2/24h@70°F for Pollock), vacuum packed or MAP packaged in a 100% CO₂ atmosphere (OTR of 7.3 cc/m2/24h@70°F). Flounder fillets were stored at either 4 or 10°C while pollock portions were stored at 8 and 12°C. Based on the time to spoilage (counts >107 CFU/g), additional samples were inoculated with five strains of nonproteolytic C. botulinum and analyzed qualitatively for botulinum toxin using a mouse bioassay. For flounder at 4°C, toxin formation did not occur after 35 days in aerobically packed fillets. Vacuum packed and 100% CO2 fillets produced toxin before spoilage at days 20 and 25, respectively. In the aerobic packages at 10°C, toxin production occurred after spoilage at day 8, but before spoilage in the vacuum and 100% CO₂ packages at day 9. Sensory evaluation of toxic vacuum and 100% CO₂ packages at 4°C revealed toxin production proceeded spoilage and absolute sensory rejection. However, at 10°C toxin production was evident only after absolute sensory rejection and microbiological spoilage for aerobically packed fillets. Vacuum packages and 100% CO₂ packages were toxic during spoilage but before absolute sensory rejection. Toxin was not present in the aerobically and 100% CO₂ packed pollock samples at 8°C and the 100% CO2 packed samples at 12°C after 35 days. Aerobically packed portions stored at 12°C first produced toxin at day 25; toxicity occurred after absolute sensory rejection and before spoilage. The vacuum packed portions first formed toxin at day 25 for 8 and 12°C storage before spoilage and absolute sensory rejection. / Ph. D.

O uso de atmosfera modificada (ATM) na embalagem de cortes cárneos tem sido uma alternativa para melhorar a qualidade do produto. Diante disto, o objetivo deste trabalho foi observar a vida útil de carnes armazenadas neste tipo de embalagem. Foram retiradas 96 amostras de 4 novilhos anelorados, divididas em três tratamentos: Tratamento 1 (T1) – referente às amostras analisadas no dia da desossa; Tratamento 2 (T14) – referente às amostras analisadas aos 14 dias de armazenamento; Tratamento 3 (T28) – referente às amostras analisadas aos 28 dias de armazenamento. Cada tratamento tinha oito amostras de cada um dos quatro músculos estudados: Longissimus dorsi (Contrafilé) – LD, Quadricepis femoris (Patinho) – QF, Semitendinosus (Lagarto) - ST e Supraspinatus (Peixinho) – SS, sendo quatro delas (A, B, C e D) usadas para análises de força de cisalhamento, perdas de água ao cozimento e por exsudação, pH e cor, e as outras quatro para análises microbiológicas. As amostras foram embaladas em sacos do tipo masterpack com mistura de gases na proporção de 75% O2 e 25% CO2 e armazenadas por 28 dias em câmara de resfriamento com temperatura de 0 a 1ºC. Ao longo do período de armazenamento foi observada uma redução linear da força de cisalhamento nos músculos LD, ST e QF, e uma associação quadrática em relação ao músculo SS, com um aumento da força após 14 dias. Em relação às perdas de água ao cozimento houve uma interação significativa entre o tempo de armazenamento e os músculos, e as perdas por exsudação apresentaram uma relação linear com o tempo de armazenamento, com valores crescentes de perdas do T1 em relação ao T2 e T3. Os valores de pH apresentaram uma associação linear e quadrática em relação ao tempo de armazenamento. Para as características de cor, o tempo de armazenamento apresentou associação linear e quadrática com o croma L*, quadrática com o croma a* e linear e quadrática com o croma b*. Não foram detectadas presenças de Salmonella e de Coliformes fecais, e nem de Clostridium em nenhuma das amostras analisadas, e as contagens detectadas de Coliformes totais estão abaixo do limite especificado para carne crua. Desta forma, foi concluído que carnes armazenadas em ATM, por um período de até 28 dias, não comprometem a qualidade visual e sensorial dos produtos. / Modified atmosphere packaging and case ready beef have been used to improve quality of beef cuts. With this objective in mind this work was designed to study the shelf life of this kind of packaging on beef cuts and 24 samples from 4 Nellore steers, were collected from each muscle: Longissimus dorsi (LD), Quadriceps femoris (QF), Semitendinosus (ST) and Supraspinatus (SS) in a total of 96 samples which were packaged in masterpack bags with a MAPAX gas with 75% O2 and 25% CO2 and aged for 1, 14 or 28 days or treatment T1 samples analyzed on day 1, T14 samples analyzed on day 14 and T28 samples analyzed on day 28, respectively. Every treatment had 8 samples from every one of the 4 muscles studied (A, B, C, e D). Four samples were used for shear force, cooking losses, pH and color and, the other 4 samples for microbiological analyses. A linear decrease in shear force with aging time was observed for LD, ST and QF muscles. A quadratic association for the SS muscle was seen after 14 days of aging. For cooking losses there was a significant interaction between aging time and muscle, as exudative loss showed a linear relation with aging time, improving loss, when comparing T1 in relation to T2 and T3. Differences were observed for pH showing a linear and quadratic relation with aging time. Muscle color among treatments and results were within acceptable values for both characteristics and results. No Salmonellae, Clostridium or Fecal Coli forms were observed in any of the samples as well as total Coli forms were within acceptable ranges for raw beef.

This dissertation discusses, in brief, the production and transport property characterization of films made from the extrusion and biaxial stretching of [beta] nucleated isotactic polypropylene and the extrusion of PEBAX block copolymers. Multilayered films for modified atmosphere packaging applications were also produced by coextrusion and biaxial stretching of these two materials and similarly characterized. Current membranes for packaging applications are generally produced by coating a porous support with a polymeric solution to deposit an active layer for separation. The goal of this project is to displace membranes produced by solvent-based processes, which are environmentally hazardous and thus costly, with equivalent or superior materials produced using melt extrusion. / text

O uso de atmosfera modificada (ATM) na embalagem de cortes cárneos tem sido uma alternativa para melhorar a qualidade do produto. Diante disto, o objetivo deste trabalho foi observar a vida útil de carnes armazenadas neste tipo de embalagem. Foram retiradas 96 amostras de 4 novilhos anelorados, divididas em três tratamentos: Tratamento 1 (T1) – referente às amostras analisadas no dia da desossa; Tratamento 2 (T14) – referente às amostras analisadas aos 14 dias de armazenamento; Tratamento 3 (T28) – referente às amostras analisadas aos 28 dias de armazenamento. Cada tratamento tinha oito amostras de cada um dos quatro músculos estudados: Longissimus dorsi (Contrafilé) – LD, Quadricepis femoris (Patinho) – QF, Semitendinosus (Lagarto) - ST e Supraspinatus (Peixinho) – SS, sendo quatro delas (A, B, C e D) usadas para análises de força de cisalhamento, perdas de água ao cozimento e por exsudação, pH e cor, e as outras quatro para análises microbiológicas. As amostras foram embaladas em sacos do tipo masterpack com mistura de gases na proporção de 75% O2 e 25% CO2 e armazenadas por 28 dias em câmara de resfriamento com temperatura de 0 a 1ºC. Ao longo do período de armazenamento foi observada uma redução linear da força de cisalhamento nos músculos LD, ST e QF, e uma associação quadrática em relação ao músculo SS, com um aumento da força após 14 dias. Em relação às perdas de água ao cozimento houve uma interação significativa entre o tempo de armazenamento e os músculos, e as perdas por exsudação apresentaram uma relação linear com o tempo de armazenamento, com valores crescentes de perdas do T1 em relação ao T2 e T3. Os valores de pH apresentaram uma associação linear e quadrática em relação ao tempo de armazenamento. Para as características de cor, o tempo de armazenamento apresentou associação linear e quadrática com o croma L*, quadrática com o croma a* e linear e quadrática com o croma b*. Não foram detectadas presenças de Salmonella e de Coliformes fecais, e nem de Clostridium em nenhuma das amostras analisadas, e as contagens detectadas de Coliformes totais estão abaixo do limite especificado para carne crua. Desta forma, foi concluído que carnes armazenadas em ATM, por um período de até 28 dias, não comprometem a qualidade visual e sensorial dos produtos. / Modified atmosphere packaging and case ready beef have been used to improve quality of beef cuts. With this objective in mind this work was designed to study the shelf life of this kind of packaging on beef cuts and 24 samples from 4 Nellore steers, were collected from each muscle: Longissimus dorsi (LD), Quadriceps femoris (QF), Semitendinosus (ST) and Supraspinatus (SS) in a total of 96 samples which were packaged in masterpack bags with a MAPAX gas with 75% O2 and 25% CO2 and aged for 1, 14 or 28 days or treatment T1 samples analyzed on day 1, T14 samples analyzed on day 14 and T28 samples analyzed on day 28, respectively. Every treatment had 8 samples from every one of the 4 muscles studied (A, B, C, e D). Four samples were used for shear force, cooking losses, pH and color and, the other 4 samples for microbiological analyses. A linear decrease in shear force with aging time was observed for LD, ST and QF muscles. A quadratic association for the SS muscle was seen after 14 days of aging. For cooking losses there was a significant interaction between aging time and muscle, as exudative loss showed a linear relation with aging time, improving loss, when comparing T1 in relation to T2 and T3. Differences were observed for pH showing a linear and quadratic relation with aging time. Muscle color among treatments and results were within acceptable values for both characteristics and results. No Salmonellae, Clostridium or Fecal Coli forms were observed in any of the samples as well as total Coli forms were within acceptable ranges for raw beef.

No description available.

The antimicrobial efficacy of carvacrol, trans-cinnamaldehyde, eugenol and thyme oil (0.5, 1, 2 and 5% v/v) was evaluated against Salmonella on turkey breast cutlets as 2 min dip treatments at 4°C. Carvacrol revealed maximum efficacy against Salmonella on turkey cutlets and was selected for 30s and 60s dip treatments at 4°C. Only 5% carvacrol was effective and exhibited 1.0 and 1.8 log CFU/g reduction of Salmonella with 30s and 60s dip treatments, respectively. However, carvacrol showed synergistic activity with carbon dioxide in modified atmosphere packaging (95% CO2/5% O2) against Salmonella and Campylobacter and caused 1.0-2.0 log CFU/g reductions with lower concentrations (0.25, 0.5 and 1.0%). This combination reduced the growth of lactic acid bacteria. In the third experiment, efficacy of lauric arginate (200 and 400ppm) against C. jejuni was tested on chicken breast fillets. Both these concentrations significantly reduced C. jejuni on chicken fillets (1.0-1.5 log CFU/g) at 4°C.

Three types of dried milk (whole, nonfat, and buttermilk) were packaged in a modified atmosphere with a novel palladium-based oxygen removing catalyst and stored for eight weeks at 50°C. Powders stored in air with no catalyst and powders stored with the catalyst in an atmosphere modified to contain 5.7% hydrogen in nitrogen were evaluated by instrumental, chemical, and sensory methods. Hexanal concentrations were measured weekly using solid phase microextraction (SPME) and gas chromatography (GC) to compare the degrees of oxidation in the powders stored with the catalyst to those stored without it. Color changes were also monitored weekly using Hunter's L-, a-, and b-values. At the end of the eight-week period, a paired comparison sensory test was used to ascertain if the catalyst had an effect on odor. Anisidine values were also measured at this point to determine levels of oxidation in the powders. No significant difference was found in levels of oxidation between samples packaged with and without the catalyst in the modified atmosphere. At the end of eight weeks, the average hexanal concentration in the whole milk powder stored with the oxygen scavenger was 1.19 ± 0.20 ppm, while the average hexanal concentration in the air-packed whole milk powder was 1.06 ± 0.08 ppm. The average hexanal concentrations for the buttermilk stored with the catalyst and without were 0.84 ± 0.18 and 0.79 ± 0.15 ppm, respectively. In the nonfat milk powder, the sample stored with the catalyst had an average hexanal concentration of 0.91 ± 0.14 ppm and the sample stored in air without the catalyst had an average hexanal concentration of 0.83 ±0.20 ppm. Difference testing by volunteer sensory panelists also revealed no significant differences. It was expected that the milk powders stored with the catalyst in the modified atmosphere would have lower levels of oxidation and off-odors at the end of the eight weeks. However, the treatment ultimately resulted in no chemical or sensory differences. Thus, the catalyst proved ineffective in the given conditions. This could be due to a loss of the hydrogen required for the catalyst to function as time progressed or a lack of significant oxidation under the conditions employed. / Master of Science in Life Sciences

Numerous food-borne outbreaks of Escherichia coli O157:H7 have been linked to leafy greens in recent years. An overwhelming amount of lettuce and spinach on the market is sold in modified atmosphere packaging as ready to eat salad mixes. The objectives of this study were to determine the effects of modified atmosphere, storage temperature, and inoculum size on survival of E. coli O157:H7 on cut and whole leaf lettuce and spinach. E. coli O157:H7 H1730 was inoculated onto cut and whole leaves of leaf lettuce and spinach. Samples were held under normal atmospheric conditions or in a modified atmosphere package at either 4ºC or 10ºC to simulate display and abuse temperatures. Leaves were sampled at Days 0, 1 and every other day until visual spoilage occurred (7 days for lettuce, 9 days for spinach). E. coli O157:H7 was able to survive at 4° and 10°C regardless of atmosphere and inoculum size for 7 days on cut and whole lettuce and 9 days on cut and whole spinach. Overall, numbers of E. coli O157:H7 increased (1 log) throughout the storage period on spinach, and decreased on lettuce (1-1.5 log). Significantly higher (P < 0.05) numbers of E. coli O157:H7 were found on lettuce and spinach stored at 10ºC than when stored at 4ºC. There were no significant differences (P > 0.05) in Numbers of E. coli O157:H7 with respect to atmosphere, leaf type or inoculum size. If contamination of lettuce or spinach with E. coli O157:H7 occurred, the pathogen may survive well under typical packaging and storage conditions. / Master of Science in Life Sciences

Master of Science / Department of Animal Sciences and Industry / Melvin C. Hunt / The objective of this study was to determine the effects of Zilmax® feeding duration (7.56 g/ton Zilmax for 0, 20, 30, or 40 d) on color development and stability of crossbred beef (B) and Holstein (H) semimembranosus (SM) steaks packaged in polyvinyl chloride overwrap (PVC), high-oxygen (80% O2, 20% CO2, HiOx) modified atmosphere packaging (MAP), and low-oxygen (0.4% CO, 30% CO2, 69.6% N2, LoOx) MAP. A 7.62-cm thick portion from beef and Holstein SM muscles (n = 120 total, 30 from each feeding duration) was removed, vacuum packaged, and stored until d 21 when two, 2.54-cm thick steaks were cut, overwrapped with PVC, and placed into retail display for 0 or 3 d. On d 10, the remaining muscle of the SM was enhanced, and five, 2.54-cm thick steaks were cut and assigned to 0, 3, or 5 d (HiOx) and 0 or 9 d (LoOx) of display. Measurements taken on the deep (DSM) and superficial (SSM) portions were: pH, L*, a*, b*, hue angle, and saturation indices, initial color, display color, and discoloration. No Diet × Display Day (P > 0.05) interaction occurred for display color or discoloration scores of B steaks in PVC. On d 1, PVC 30 d H steaks were brighter (P < 0.05) than 40 d H steaks in PVC; no differences (P > 0.05) in H PVC display color due to diet occurred on d 0, 2, and 3. For steaks in HiOx, the DSM of 20 and 30 d B steaks on d 4 and the DSM of 20 d B steaks on d 5 was brighter (P < 0.05) red than 40 d Zilmax B DSM. HiOx 20 d H steaks were darker red (P < 0.05) on d 5 of display and more discolored (P < 0.05) on d 3 to 5 than HiOx H steaks from all other diet regimens. For LoOx, 30 d B steaks were brighter (P < 0.05) red than 0 or 40 d steaks on d 0 and 9 of display. The DSM and SSM of LoOx H steaks from cattle fed Zilmax tended (P > 0.05) to be brighter red than control H steaks through 9 d of display. In conclusion, both HiOx and LoOx minimized color differences due to SM muscle areas. Feeding B cattle Zilmax for 20 or 30 d yields steaks equal to or better in color traits than cattle fed 0 or 40 d when packaged in PVC, HiOx, or LoOx. H steaks in LoOx had slight benefits in color stability when cattle were fed Zilmax for any duration, whereas H steaks in PVC had color advantages with only the 20 and 30 d durations. Packaging 20 d H steaks in HiOx resulted in less desirable color characteristics than all other feeding treatments. Keywords: zilpaterol, beef, Holstein, display color, modified atmosphere packaging, semimembranosus