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The use of Pulsed Energy (Flashbasttm) Technology (PET) to extend the shelf life of fresh fish fillets was studied. Unskinned fillets from fresh sea trout (Cynoscion regalis) and hybrid striped bass (Morone chrysops x ~ saxatilis) were treated with 7.45 Joules/cm² of PET, stored individually in sterile polyethylene bags, and kept in ice for 21 days at 3°C. Sensory data showed no significant differences (pâ ¤ 0.05) in the appearance, odor, texture, or taste of cooked samples from treated and control fillets, regardless of species. Raw sea trout fillets developed "alien" odors upon treatment which disappeared within the first week of storage and were not detected in cooked samples. These off-odors were significant (pâ ¤ 0.05) in the freshwater species only during the first three days post-treatment. Microbiological analyses revealed that PET reduced bacteria growing on the flesh surface and skin at significantly higher (pâ ¤ 0.05) rates than those in the flesh. Total coliforms were the most susceptible bacteria to PET. / Ph. D.

An enzyme-linked immunosorbent assay (ELISA) using polyclonal antibodies has been developed for the detection of the fluorescing group of Pseudomonas. The assay was used as a rapid test (6h) for predicting the shelf-life of pasteurized fluid milk. Milk samples were held at 7°C and tested weekly until determined to be unacceptable by daily sensory evaluation. Sterile milk samples were inoculated with target concentrations of 0 (control), 100, and 1000 cells/ml of Pseudomonas fluorescens on day 0. Samples were tested before and after preliminary incubations. Preliminary incubations conducted include milk alone and milk with broth (1:1) for 18h at 21°C. ELISA and plate counts were performed before and after preliminary incubation to determine the number of pseudomonads present and the relationship between ELISA and plate counts. These numbers were correlated to the shelf-life of each sample, as determined by sensory evaluation. Samples undergoing a preliminary incubation with only milk gave the best correlation to shelf-life (R=0.86). / Master of Science

The effects of packaging treatments, post harvest cooling delay and storage duration on color, texture, ascorbic acid content, weight loss and glucosinolate retention in crown-cut heads of broccoli were studied. Oxygen and CO2 levels inside shrink wrap packages were also monitored. Shrink wrap packaging had a significant positive effect on hue angle (p<0.05). Packaging and post harvest cooling delay had no effect on hue difference and total color difference. While post harvest cooling delay had no effect on texture, crown-cut heads of broccoli stored in shrink wrap packaging retained firmness significantly better than ice packaged heads of broccoli (p<0.05). Ascorbic acid was retained better in broccoli held in shrink wrap packages and cooling delay had a significant negative influence on ascorbic acid content (p<0.05). Packaging and post harvest cooling delay had a significant positive effect on weight loss (p<0.05). Broccoli stored in shrink wrap film lost about 3.7% of original weight while ice packaging resulted in about 17.4% weight loss (p<0.05). No consistent trends were observed in the levels of O2 and CO2 inside shrink wrap packages. An important glucosinolate, glucoraphanin was retained significantly better in shrink wrapped heads (p<0.05). Between two cultivars, shelf life of cv.Gypsy was better than cv.Everest with respect to color, ascorbic acid retention and weight loss. But cv.Everest retained texture (firmness) better after 35 days of storage. Overall results indicate that shrink wrap packaging and shorter post harvest cooling delays protect quality of broccoli. / Master of Science

Tesis por compendio / This PhD dissertation focuses on the development of renewable and biodegradable active films based on chemically-modified wheat gliadin proteins endowed with antimicrobial capacity owing to the incorporation of naturally-occurring bioactive compounds, namely cinnamaldehyde, natamycin, and lysozyme. Gliadin proteins were treated with cinnamaldehyde at acidic pH and films were produced by casting. The resulting protein-based films presented improved functional properties (mechanical, barrier, and water resistance), and biochemical evidence of the formation of a more compact network whose degree of cross-linking increased with the amount of cinnamaldehyde incorporated into the gliadin-ethanolic solution. Free cinnamaldehyde not participating in the cross-linked reaction remained entrapped in the protein matrix at low relative humidity conditions. The sensitivity of the films to moisture owing to the hydrophilic character of gliadins provided a trigger and control mechanism for the release of cinnamaldehyde in moderate and high relative humidity environments, similar to conditions occurring in packaged food products. The antimicrobial properties of the films developed were tested in vitro by vapor diffusion assays against common food spoilage fungi (Penicillium expansum and Aspergillus niger), showing great effectiveness. Application of these active films to the preservation of two foodstuffs, sliced bread and cheese spread, gave promising results, lengthening fungal growth lag phase and minimizing fungal growth extension. / Balaguer Grimaldo, MDLP. (2015). Development of active bioplastics based on wheat proteins and natural antimicrobials for food packaging applications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48520 / Premios Extraordinarios de tesis doctorales / Compendio

Traditional plating methods for bacterial enumeration can be limited, but the development of high-throughput DNA sequencing, such as Oxford Nanopore Technologies (ONT), can provide rapid and highly specific alternative for species-level identification. In this study, ONT amplicon sequencing was applied to fresh broiler breast meat to identify their bacterial composition and monitor their dynamic changes. The sequencing data were complemented by sensory panels, physicochemical analysis, and traditional plating methods. Over time, the bacterial diversity decreased within and across samples. By the end of shelf-life, Pseudomonas fragi, Pseudomonas lundesis, and Brochothrix thermosphacta became the most prevalent species. These bacteria were associated with spoilage attributes that were reported in the sensory panels. This study demonstrated the effectiveness of Nanopore sequencing in determining the spoilage associated bacteria in chicken meat. Future research may focus on developing targeted interventions to mitigate the impact of these spoilage bacteria and extend the shelf life of chicken meat.

The purpose of this project was to evaluate the antioxidant activity in vitro and its effects at the oxidative stability of mechanically deboned poultry meat (MDPM) of five natural extracts. It was studied: the yerba mate (Ilex paraguariensis), the marcela (Achyrocline satureioides), a mixture of yerba mate (50%) and marcela (50%), green tea (Camellia sinensis) and propolis without alcohol. The synthetic antioxidant BHA (Butylated Hydroxianisole) was used as a positive control and the meat treated with no antioxidant was used as negative control. Natural extracts were evaluated in vitro for quantification of phenolic and flavonols total content, for antioxidant activity, by DPPH radicalscavenging, Phosphomolybdenum complex and Reducing Power assay methods. All antioxidants were mixed separately in different and equal portions of mechanically deboned poultry meat, as follow: 0.50% of yerba mate, marcela and the mixture, 0.05% of green tea, 0.10% of própolis without alcohol and 0.02% of BHA. Samples of MDPM were packed and storage at 0 to +4ºC for 10 days. The samples were evaluated each two days and the pH, TBARS and peroxide index were measured, as well as the Total Mesophilic Aerobic counts, Total Coliforms, E. coli, Lactic Bacteria, Clostridium perfringens, Salmonella spp and Staphylococcus aureus. Surface and internal colour ( L*, a*, b*) were measured and pictures of each treatment were done. Green tea extract showed the higher (p<0.05) phenolics contents and the higher (p<0.05) antioxidant activity in vitro compared to the other extracts. Yerba mate extract showed the higher (p<0.05) flavonols content. Propolis without alcohol extract showed the lowest (p<0.05) phenolics, flavonols and antioxidant activity in vitro. Marcela had the best oxidative inhibitory effect at the MDPM, with the lowest TBARS values. Propolis extract showed the best performance for the meat colour stability. Natural antioxidant addition do not interfere at MDPM pH and peroxide values. Salmonella spp was not detected in any of the samples evaluated and the results found to Staphylococcus aureus were in agreement with the Brazilian Mechanically Deboned Meat Legislation. The mixture of extracts showed the lowest (p<0.05) media for Total Mesophilic Aerobic counts. Propolis extract showed the lowest media count for Total Coliforms, E. coli and Clostridium perfringens. Yerba mate extract showed the lowest media count for Lactic Bacteria. The use of natural antioxidants should provide benefits in relation to the MDPM lipid oxidation and the microbiological growth inhibition. More researchs are necessary, looking for a better understanding about the action mechanisms of these extracts. / Este trabalho teve como objetivo avaliar cinco extratos naturais em relação a sua atividade antioxidante in vitro e na Carne Mecanicamente Separada (CMS) de frango. Foram estudadas a erva mate (Ilex paraguariensis), a marcela (Achyrocline satureioides), uma mistura de erva mate (50%) com marcela (50%), o chá verde (Camellia sinensis) e o própolis sem álcool. O antioxidante sintético BHA foi utilizado como controle positivo e o tratamento sem adição de antioxidante como controle negativo. Nos extratos naturais foram identificados o conteúdo total de fenólicos, flavonóides e a atividade antioxidante pelos métodos do DPPH, Fosfomolibdênio e do Poder de Redução. Todos os extratos foram aplicados separadamente em porções distintas e iguais de Carne Mecanicamente Separada (CMS) de frango, sendo os percentuais de aplicação de 0,50% de erva mate, marcela e da mistura, 0,05% de chá verde, 0,10% do própolis sem álcool e 0,02% de BHA. A CMS de frango foi mantida sob refrigeração de 0 a +4ºC durante 10 dias. As amostras foram avaliadas a cada dois dias, em relação ao pH, índice de TBARS, índice de peróxido, em relação a contagem média de Aeróbios Mesófilos Totais, Coliformes Totais, E. coli, Bactérias lácticas, Clostridium perfringens, Salmonella spp e Staphylococcus aureus. A cor objetiva (L*, a*, b*) foi medida na superfície e na parte interna da CMS de frango assim como o registro em foto de cada tratamento. O extrato de chá verde apresentou o maior (p<0,05) conteúdo de fenólicos e a maior (p<0,05) atividade antioxidante in vitro em relação aos demais extratos. O extrato de erva mate apresentou o maior (p<0,05) conteúdo de flavonóides. O extrato de própolis sem álcool apresentou os menores (p<0,05) conteúdos de fenólicos, de flavonóides e a menor atividade antioxidante in vitro. O extrato de marcela teve o melhor efeito na inibição da oxidação lipídica da CMS de frango, apresentando os menores valores médios de TBARS. O extrato de própolis sem álcool manteve por mais tempo a estabilidade da cor da carne. A adição dos antioxidantes naturais não interferiu no pH e nem no índice de peróxido da CMS de frango. Não foi detectada a presença de Salmonella spp e os resultados de Staphylococcus aureus ficaram dentro dos padrões estabelecidos pela Legislação. O tratamento com a mistura de extratos de erva mate e de marcela apresentou a menor (p<0,05) contagem média de Aeróbios Mesófilos Totais em relação aos demais tratamentos. O extrato de própolis sem álcool apresentou a menor contagem média de Coliformes totais, E. coli e Clostridium perfringens. O extrato de erva mate apresentou a menor contagem média de Bactérias lácticas. O uso de antioxidantes naturais pode trazer benefícios em relação a inibição da população microbiana da CMS de frango. Mais estudos são necessários visando um melhor entendimento dos mecanismos de ação desses extratos na carne mecanicamente separada (CMS) de frango.

Fler svenskar vill konsumera mer inhemskt producerad fisk. Scandinavian Aquasystems odlar och försöker introducera fisken tilapia på svenska marknaden. Tilapia är en fisk som precis börjat göra intåg i Europa men är stor runtomkring resten av världen. En smakprofil som berättar hur länge produkten är sensoriskt tjänlig kan vara av hjälp. Denna undersökning syftade till att skapa en sensorisk smakprofil för fisken tilapia och till att se hur smakprofilen förändrades vid lagring i vakuumförpackning. För att skapa smakprofilen användes metoden QDA. Resultatet gav många egenskapsord var av vissa kunde klassificeras som färskhetsrelaterade och vissa som förskämningsrelaterade. Det kunde även konstateras att färsk, odlad tilapia har en antydan av saftigare och mer mjäll textur. Vid lagring finns en möjlighet att tilapia får en intensivare smak av dy och metall, samt en intensivare doft av dy. / A large amount of Swedes has a desire to consume more nationally produced fish. Scandinavian Aquasystems produces and tries to introduce tilapia into the Swedish market. As a fish, tilapia has just begun making ways into Europe but is already a big commodity around the rest of the world. In addition, a sensory profile which tells how long the product remains sensorially suitable could be of help. This study aimed to create a sensory profile and to study its inherent effects of vacuum packaging over time. In creating the sensory profile, a QDA method was used. The study resulted in a variance of different attributes which of some could be categorized as either fresh related or spoilage related. It was found that fresh, farmed tilapia carried an indication of having a juicier and more tender texture. With storage there is chance of tilapia getting a more intense flavor of mud and metal, as well as a more intense odor of mud.