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Estudo sobre a perda da hermeticidade de embalagens plásticas flexíveis utilizadas no envase de carne bovina cozida e desidratada (Beef Jerky) / Study of the leaks on flexible plastic used for the packaging of dried cooked beef (Beef Jerky)Anjos, Rubem Fernando dos 15 September 2017 (has links)
O objetivo do presente trabalho foi avaliar a perda da hermeticidade do sistema de embalagens plásticas flexíveis utilizadas para o envase de carne bovina cozida e desidratada (Beef Jerky) que é realizado por meio da aplicação de vácuo, atmosfera modificada e a inserção de absorvedores de oxigênio. Durante 1 (um) mês foram realizadas avaliações dos defeitos que ocasionam a perda da hermeticidade na produção do Beef Jerky em três plantas fabris localizadas no Brasil. Os defeitos encontrados foram mapeados, identificados e avaliados por meio de análises microscópicas da estrutura do filme flexível, análises de oxigênio do espaço livre da embalagem e ensaios de verificação dos canais de solda. Os resultados apresentados nesta pesquisa demonstraram que as origens da perda da hermeticidade estão relacionadas a fatores físicos, biológicos e humanos. Após a realização de melhorias como a alteração da linha de produção e treinamento dos operadores, o aumento da espessura da solda e a redução da quantidade de vácuo aplicada, houve a redução de 33,66%, 51,32% e 43,59% de defeitos de hermeticidade respectivamente. Foi observado também que a taxa de permeabilidade ao O2 da embalagem (TPO2) pode ser reduzida e consequentemente a barreira mecânica pode ser aumentada possibilitando a redução de defeitos mecânicos nas embalagens. A substituição dos sachês absorvedores, que podem ser danificados pelo contato com o produto, por sistemas de embalagens ativas que contém o princípio ativo incorporado ao filme também foi proposta, porém não foi recomendada uma vez que o oxigênio residual não atingiu menos que 1% de oxigênio após 72 horas. O resultado preliminar demonstrou que este sistema é menos eficiente do que o atual e que novos estudos e aprimoramentos da tecnologia devem ser realizados para que a aplicação das embalagens no sistema de envase de Beef Jerky seja eficiente. / The objective of the present study was to evaluate the leakage of the flexible plastic packaging system used for the packaging of Beef Jerky, which is carried out through the application of vacuum, modified atmosphere and the insertion of oxygen absorbers. During 1 month were made evaluations of the defects that causes the leakage in the production of Beef Jerky at three plants located in Brazil. The defects were mapped, identified and evaluated through microscopic analysis of the flexible film structure, oxygen analyzes of the packaging headspace and the seal channels verification tests. The results presented in this research demonstrated that the origins of leakage are related to physical, biological and human factors. After improvements such as the alteration of the production line and training of the operators, the increase of the seal thickness and the reduction of the applied vacuum amount, there was noted a reduction of 33,66%, 51,32% e 43,59% of sealing defects, respectively. It has also been observed that the package O2 transmission rate (OTR) can be reduced and consequently the mechanical barrier can be increased enabling reduction of mechanical defects in the packages. The replacement of the absorbent sachets, which may be damaged by contact with the product, for the active packaging systems containing the active principle incorporated in the film was also proposed, but it was not recommended since the residual oxygen did not reach less than 1% of after 72 hours. The preliminary result has shown that this system is less efficient than the current one and that further studies and improvements of the technology must be made so that the application of the packages in the system of Beef Jerky packaging will be efficient.
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Validation of Texas beef jerky processingEspitia, Felicia Danielle 02 June 2009 (has links)
This study evaluated the thermal drying process commonly used by small and
very small beef jerky operations in Texas. It was intended to determine the impact of
relative humidity on the production of beef jerky and to provide documentation to beef
jerky producers to support their Hazard Analysis and Critical Control Point programs.
This project was divided into two phases: Phase I provided a low level of relative
humidity (15-25%), whereas Phase II provided a high level (100%) for 25% of the
cooking cycle. Both phases consisted of three trials, each representing one of the
treatments (n=18) applied to the samples. The first treatment served as the control group
and included samples that were non-inoculated, while the other two treatments included
inoculations of samples with a bovine fecal slurry and rifampicin-resistant Salmonella
Typhimurium. Each of the three treatments for both phases was analyzed for reduction
of microbial levels in addition to temperature and product composition.
Once the two phases had been completed and all data were analyzed, it was
concluded that there was not a statistical difference between the level of reduction for
Aerobic Plate Counts, coliforms, Escherichia coli and Salmonella provided by Phase I
with low humidity and Phase II with high humidity. Both levels of humidity provided similar levels of reduction within each trial, suggesting that the level of humidity does
not have a great impact on the level of microbial reduction achieved.
However, this study did not provide the adequate level of initial inoculation
levels to support the required 6.5 log reduction stated in 9 CFR 318.7. Inoculation levels
were lower than 6.5 logs for all three treatments in both phases, resulting in lower levels
of overall reduction. Therefore, based upon the information provided by this study, it
cannot be concluded that a low level of humidity will achieve a 6.5 log reduction as
mandated in 9 CFR 318.17.
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Combined microwave - convection drying and textural characteristics of beef jerkyThiagarajan, Ignaci Victoria 21 October 2008
Beef jerky is a dried meat snack which is rich in protein but of low calorific value. This ready-to- eat meat snack is in high demand among hikers, bikers and travelers due to its compact nature and nutritional value. The current processing methods such as smoke house and home dehydrators take 6-10 h. Increasing market for this shelf-stable meat product increases the need for alternate efficient processing method. Also, this meat snack market depends on its textural characteristics which denote the consumer acceptability. In this research, three different methods of drying beef jerky were examined.
Influences of pH and salt on different characteristics of beef jerky were investigated using combined microwave-convection drying. Also, the effects of relative humidity and airflow rates in forced air thin layer drying on jerky processing were studied. Samples of beef jerky dried using a combined microwave-convection drier and thin layer drying unit were compared with samples dried in a smoke house.
The results obtained showed that pH and salt content had a significant influence on drying, physical and textural characteristics of jerky. It was found that samples with low pH (5.15) and high salt content (3.28% (w/w)) dried faster than samples with high pH and low salt content due to their high drying rates. These samples had shown high shrinkage and weight loss compared to samples with pH 5.65 and 1.28% (w/w) salt content. Analysis of the textural characteristics such as tensile force, puncture force and texture profile showed that the samples with high pH and low salt content were comparably softer than the rest of the samples. Results of the effect of relative humidity and airflow rate in forced air thin layer drying on jerky processing showed that relative humidity and airflow rate influenced the drying, physical, chemical and textural characteristics of beef jerky. Combination of low relative humidity and high airflow rate showed desirable drying characteristics. However, samples dried at this combination showed high shrinkage and weight loss. The hardness of the beef jerky increased with increase in airflow rate and reduction in relative humidity.
A comparison of the drying methods revealed that different drying methods produced different desirable properties. Combined microwave-convection drying was found to be efficient and very rapid (8.25 min). The low shrinkage and weight losses along with high drying rate obtained using this method would pave a way to fast and efficient processing. The color and textural characteristics were different from those of samples dried in a smoke house. Surprisingly, combined microwave-convection drying method produced softer beef jerky than thin layer and smokehouse methods. However, the commercially available jerky is tougher than the one dried using combined microwave-convection drying. The samples dried in a thin layer drier had comparable color and textural characteristics with samples dried in a smoke-house. Also, forced-air thin layer drying method reduced drying time of beef jerky from 7 to 3 h. The forced air thin layer drier has the potential to produce beef jerky with similar color and textural characteristics to commercially available smoke house dried samples.
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Combined microwave - convection drying and textural characteristics of beef jerkyThiagarajan, Ignaci Victoria 21 October 2008 (has links)
Beef jerky is a dried meat snack which is rich in protein but of low calorific value. This ready-to- eat meat snack is in high demand among hikers, bikers and travelers due to its compact nature and nutritional value. The current processing methods such as smoke house and home dehydrators take 6-10 h. Increasing market for this shelf-stable meat product increases the need for alternate efficient processing method. Also, this meat snack market depends on its textural characteristics which denote the consumer acceptability. In this research, three different methods of drying beef jerky were examined.
Influences of pH and salt on different characteristics of beef jerky were investigated using combined microwave-convection drying. Also, the effects of relative humidity and airflow rates in forced air thin layer drying on jerky processing were studied. Samples of beef jerky dried using a combined microwave-convection drier and thin layer drying unit were compared with samples dried in a smoke house.
The results obtained showed that pH and salt content had a significant influence on drying, physical and textural characteristics of jerky. It was found that samples with low pH (5.15) and high salt content (3.28% (w/w)) dried faster than samples with high pH and low salt content due to their high drying rates. These samples had shown high shrinkage and weight loss compared to samples with pH 5.65 and 1.28% (w/w) salt content. Analysis of the textural characteristics such as tensile force, puncture force and texture profile showed that the samples with high pH and low salt content were comparably softer than the rest of the samples. Results of the effect of relative humidity and airflow rate in forced air thin layer drying on jerky processing showed that relative humidity and airflow rate influenced the drying, physical, chemical and textural characteristics of beef jerky. Combination of low relative humidity and high airflow rate showed desirable drying characteristics. However, samples dried at this combination showed high shrinkage and weight loss. The hardness of the beef jerky increased with increase in airflow rate and reduction in relative humidity.
A comparison of the drying methods revealed that different drying methods produced different desirable properties. Combined microwave-convection drying was found to be efficient and very rapid (8.25 min). The low shrinkage and weight losses along with high drying rate obtained using this method would pave a way to fast and efficient processing. The color and textural characteristics were different from those of samples dried in a smoke house. Surprisingly, combined microwave-convection drying method produced softer beef jerky than thin layer and smokehouse methods. However, the commercially available jerky is tougher than the one dried using combined microwave-convection drying. The samples dried in a thin layer drier had comparable color and textural characteristics with samples dried in a smoke-house. Also, forced-air thin layer drying method reduced drying time of beef jerky from 7 to 3 h. The forced air thin layer drier has the potential to produce beef jerky with similar color and textural characteristics to commercially available smoke house dried samples.
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Ocorrência de Listeria monocytogenes em linha de processamento de Beef Jerky / Occurrence of Listeria monocytogenes in Beef Jerky processing lineCoradini, Marcia Goulart Lopes 22 December 2015 (has links)
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Previous issue date: 2015-12-22 / Sem bolsa / A busca crescente dos consumidores por praticidade destaca-se dentre as principais
tendências de consumo de alimentos no mundo. Neste contexto, enquadra-se o
Beef Jerky, um produto cárneo produzido através de processo térmico, que não
necessita de refrigeração no ponto de venda. Entretanto, por ser um alimento pronto
para o consumo, deve-se garantir sua segurança e uma das bactérias patogênicas
que, uma vez presente neste alimento, pode causar danos à saúde dos
consumidores, é Listeria monocytogenes. O objetivo deste estudo foi avaliar a
ocorrência de L. monocytogenes em uma linha de produção de Beef Jerky localizada
no município de Bagé, Rio Grande do sul- Brasil. Foram realizadas sete coletas, nas
quais se avaliaram 12 pontos ao longo da linha de processamento, dentre eles a
matéria-prima, superfícies com e sem contato com o produto, bem como o produto
final. As amostras foram analisadas no equipamento Mini Vidas® bioMérieux e,
aquelas que apresentaram resultado positivo para L. monocytogenes, foram
submetidas a PCR, utilizando-se o gene prs para confirmação de gênero, e os genes
inlA, inlC e inJ para confirmação da espécie L. monocytogenes. A ocorrência global
de L. monocytogenes foi de 7,14%, sendo 21,42% em superfícies sem contato com
produto, 1,78% em superfícies de contato com produto, e 28,57% na matéria-prima,
entretanto, não se identificou o patógeno no produto final. Observa-se que a matériaprima é uma importante fonte de contaminação e introdução de L. monocytogenes
na indústria produtora de Beef Jerky e que a contaminação por esse microorganismo em superfícies de contato e sem contato com o alimento, reforça a
importância dos programas de higienização como forma de evitar contaminação
cruzada para o produto final. Entretanto, como o produto final (Beef Jerky) não
apresentou contaminação por L. monocytogenes, as etapas do processo de
produção que envolvem barreiras à multiplicação de patógenos e morte microbiana,
podem ter sido efetivas no controle do patógeno. / The growing demand of consumers for convenience, stands out among the main
trends in food consumption in the world. In this context is the beef jerky a meat
product produced by thermal process that does not require refrigeration at the point
of sale, ensuring practicality of use. However, being a food ready for consumption,
should ensure its security and one pathogenic bacteria that, once present, can harm
the health of consumers is Listeria monocytogenes. The objective of this research
was to identify the occurrence of L. monocytogenes in a Beef Jerky production line
located in the municipality of Bage, Rio Grande do Sul- Brazil. We evaluated 12
points along the processing line, including the raw materials, surfaces with and
without contact with the product as well as the final product, in seven collections.
Samples were analyzed in Mini Vidas® bioMérieux equipment and those that tested
positive for L. monocytogenes, were subjected to PCR using the prs gene for gender
confirmation and the inlA genes, inlC and inlJ to confirm the species L.
monocytogenes. The overall occurrence of L. monocytogenes was 7.14% and
21.42% on surfaces without contact with product, 1.78% on product contact surfaces,
and 28.57% in the raw material, however, it did not identify the pathogen in the final
product. It is observed that the raw material is a major source of contamination and
introduction of L. monocytogenes in producer Beef Jerky industry and the
contamination by that micro-organism contact surfaces without contact with food,
reinforces the importance of cleaning programs in order to avoid cross-contamination
of the final product. However, since the final product (Beef Jerky) showed no
contamination by L. monocytogenes, the steps of the production process involving
barriers to multiplication of pathogens and microbial death, may have been effective
in pathogen control.
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The effects of four packaging systems and storage times on the survival of Listeria monocytogenes in shelf-stable smoked pork and beef sausage sticks and whole muscle turkey jerkyLobaton-Sulabo, April Shayne S. January 1900 (has links)
Master of Science / Department of Food Science / Elizabeth A. E. Boyle / To validate how packaging and storage reduces Listeria monocytogenes (Lm) on whole muscle turkey jerky and smoked sausage sticks, four packaging systems, including heat seal (HS), heat seal with oxygen scavenger (HSOS), nitrogen flushed with oxygen scavenger (NFOS), and vacuum (VAC), and four ambient temperature storage times were evaluated. Commercially available whole turkey jerky and pork and beef smoked sausage sticks were inoculated with Lm using a dipping or hand-massaging method, respectively. There was no interaction on packaging and storage time on Lm reduction on smoked sausage sticks and an Lm log reduction of >2.0 log CFU/cm[superscript]2 was achieved in smoked sausage sticks packaged in HS, HSOS, and VAC. A >2.0 log CFU/cm[superscript]2 reduction was achieved after 24 h of ambient temperature storage, regardless of package type. NFOS was less effective in reducing Lm by more than 0.5 log CFU/cm[superscript]2 compared to HS, HSOS or VAC. After 30 d of ambient storage, Lm had been reduced by 3.3 log CFU/cm[superscript]2 for all packaging environments. In turkey jerky, Lm reduction was affected by the interaction of packaging and storage time. HS, HSOS, NFOS, or VAC in combination with 24, 48, or 72 h ambient temperature storage achieved <1.0 log CFU/cm[superscript]2. After 30 d at ambient temperature storage, Lm was reduced by >2.0 log CFU/cm[superscript]2 in HS and VAC, and could serve as a post-lethality treatment. Alternatively, processors could package turkey jerky in HSOS or NFOS in combination with 30 d ambient storage period as an antimicrobial process. Very little data has been published describing how packaging atmospheres affects Lm survival in RTE meat. The mechanism for Lm reduction under these conditions is not fully understood and additional research is needed.
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Statistics of dislocations at low temperature in pure metals with body centered cubic symmetry / Statistiques du glissement des dislocations à basse température dans les métaux de symétrie cubique centréeChoudhury, Anshuman 11 December 2018 (has links)
Les observations de microscopie électronique in situ effectuées par Daniel Caillard (CEMES, Toulouse) au cours de la déformation de cristaux de symétrie cubique centrée ont montré que les dislocations vis effectuaient des sauts de plusieurs distances inter-atomiques alors que la théorie standard de Peierls prédit des sauts de une seul distance inter-atomique. Nous avons étudié par simulation atomique le glissement d'une dislocation vis dans un cristal de fer pure. Nous montrons que la propagation de décrochement le long de la dislocation induit un échauffement local qui favorise la nucléation de décrochements supplémentaires. L'accumulation de ces décrochements permet à la dislocation de parcourir plusieurs distances inter-atomiques. Ces simulations nous permettent de proposer une théorie pour l'explication des observations de D. Caillard. / In situ straining tests in high purity α-Fe thin-foils at low temperatures have demonstrated that crystalline defects, called dislocations, have a jerky type of motion made of intermittent long jumps of several nanometers. Such an observation is in conflict with the standard Peierls mechanism for plastic deformation in bcc crystals, where the screw dislocation jumps are limited by inter-reticular distances, i.e. of a few Angstroms. Employing atomic-scale simulations, we show that although the short jumps are initially more favorable, their realization requires the propagation of a kinked profile along the dislocation line which yields coherent atomic vibrations acting as traveling thermal spikes. Such local heat bursts favor the thermally assisted nucleation of new kinks in the wake of primary ones. The accumulation of new kinks leads to long dislocation jumps like those observed experimentally. Our study constitutes an important step toward predictive atomic-scale theory for materials deformation.
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