Linguiças cozidas defumadas armazenadas a temperatura ambiente, é um produto tipicamente brasileiro, no qual são empregadas algumas barreiras para a extensão do shelf life: cozimento, defumação e embalagem à vácuo. Estudos de durabilidade comprovaram que muitas não atendem ao shelf life esperado. Na empresa estudada, somente 23% dos lotes das linguiças em estudo atenderam a 90 dias de armazenamento desejados para a indústria de alimentos e 17% dos lotes não chegaram à 45 dias. Foram realizadas avaliações microbiológicas antes do cozimento (média de 5,03 log UFC/g), após cozimento (média de 1,56 log UFC/g) e após resfriamento (média 1,54 log UFC/g) para os gomos com calibre de 40-44mm; comprimento 23-26cm; com peso variando de 260-300 gramas onde foram submetidos ao processo de cozimento e defumação por, no mínimo, 5 horas, atendendo no mínimo 71,1°C no centro térmico do gomo. Os parâmetros físico-químicos também foram avaliados e atendem a legislação, com valores de aw 0,938 e pH 6,33, favoráveis ao desenvolvimento microbiológico. Também foram realizadas análises sensoriais para avaliação dos atributos sensoriais ao longo do armazenamento a temperatura ambiente. / Smoked sausages stored at room temperature, is a typical Brazilian product, in which some hurdles are used to extend shelf life: cooking, smoking and vacuum packing. Durability studies have proven that many do not achieve the expected shelf life. In the studied company, only 23% of the lots of the sausages under study attended the 90 days of storage desired for the food industry and 17% of the lots did not reach 45 days. Microbiological evaluations were performed before cooking (average of 5.03 log CFU/g) after cooking (mean of 1.56 log CFU/g) and after cooling (mean 1.54 log CFU/g) for the caliber 40-44mm; length 23-26cm; with weight varying from 260-300 grams where they were submitted to the cooking and smoking process for at least 5 hours, attending at least 71.1°C in the thermal center of the oven. The physico-chemical parameters were also evaluated and comply with the legislation, with values of aw 0.938 and pH 6.33, favorable to the microbiological development. Sensory analyzes were also performed to evaluate the sensory attributes along the storage at room temperature.

<p>Temperature is the common accelerant that is used for shelf-life determination of shelf-stable food because it is easy to use and there are models such as Q₁₀and Arrhenius, which are available for shelf-life prediction. The accelerated shelf-life test (ASLT) still requires months of analysis time as it only uses temperature as the accelerant. Oxygen pressure as an accelerant has not been given much attention even though many studies have shown the negative impact of oxygen on the shelf-life of food. An effective analysis method with multiple accelerants has the potential for the development of a rapid shelf-life determination method. Hence, this research focused on the invention of a rapid method, named the Ultra-Accelerated Shelf-Life Test (UASLT) that combines oxygen pressure and temperature as accelerants and the development of shelf-life prediction model(s). The study hypothesized that the application of elevated oxygen pressure and elevated temperature (40C) increases the amount of oxygen diffusing into packaged food which leads to rapid degradation of nutrients that further reduces the overall shelf-life analysis time compared to the ASLT method. A custom-made high-pressure chamber with a 100% oxygen environment at 40C was designed and developed as part of the UASLT method. The impact of the application of oxygen pressure on oxygen diffusivity in polymeric food packaging materials was investigated on three packages with different oxygen permeability properties. The application of oxygen pressure significantly increased the rate of oxygen transfer and the oxygen diffusivity values for all packaging materials compared to the counterparts that were not exposed to the pressure. A shelf-stable model food fortified with vitamins A, B1, C and D3 was developed to investigate the effectiveness of the UASLT method in degrading the quality indicators in the model foods in a polyethylene terephthalate (PET) container. PET was chosen as it was the most permeable to oxygen. Model food was also subjected to ASLT conditions at the same temperature without additional pressure and at room temperature (control). A degradation of 27.1 ± 1.9%, 13.9± 2.1%, 35.8 ± 1.0%, and 35.4 ± 0.7% were seen in vitamins A, B1, C and D3, respectively, in just 50 days. Slower degradation was observed with samples kept under the ASLT conditions for 105 days and reached a degradation of 24.0 ± 2.0%, 4.9 ± 6.1%, 32.0 ± 3.1% and 25.1 ± 1.5% for vitamin A, B1, C and D3, respectively. The control samples that were studied for 210 days showed 14.9 ± 5.0%, 2.0 ± 2.2%, 13.8 ± 2.2% and 10.6% ± 0.8% degradation in vitamins A, B1, C and D3, respectively. The increase in the dE values due to browning in samples kept at the UASLT, ASLT and control conditions were 11.67 ± 0.09, 7.49 ± 0.19 and 2.51 ± 0.11, respectively. The degradation of vitamins A, C, D3 was analyzed using the 1st order kinetic and the rate constant,    (day^-1) was used to develop four prediction models. Vitamin B1 values were omitted from the kinetic analysis due to insufficient degradation. Two temperature-oxygen diffusion models were developed by correlating oxygen diffusivity and   . Comparisons were made with the temperature-based models of    and Arrhenius. The predicted    values across the models were in the range of 0.051-0.054 day^-1,0.080-0.088 day^-1 and 0.048-0.051 day^-1, for vitamin A, C and D3, respectively. The    values estimated for vitamins A, C, and D3 were 2.16, 2.63 and 2.62, respectively. The predicted shelf-life of vitamin A, C and D3 to undergo 25% reduction was in the range of 404 to 551, 321-353 and 529-583 days across all models, respectively. The shelf-life predicted from the temperature-oxygen diffusion models was close to the temperature models indicating the potential to be paired with the UASLT method. Experimental verification is needed to analyze the errors in the prediction. The addition of oxygen pressure further reduced the shelf-life analysis time by 50% compared to ASLT. Elevated external oxygen pressure can be used as an accelerant along with elevated temperatures (40C) for rapid shelf-life testing of packaged foods. This novel approach has potential application in the food industry for faster shelf-life analysis of food.</p>

The benefits of low UV dose treatment of horticultural produce – also known as hormetic treatment - have been attested to in numerous studies conducted over the last 15 years. However, commercial growers have not adopted the concept of hormesis. With increasingly stringent controls on the use of fungicides and other chemical agents the time has come to examine how hormetic treatment might be applied in the horticulture sector. The objectives of this work were firstly, to confirm UV-induced hormetic effects applied postharvest for a number of different types of produce, namely, tomatoes, broccoli, strawberries and mangoes. Secondly, to evaluate the use of rollers to ensure full surface treatment of produce, and thirdly to evaluate the possibility of treating produce preharvest. In order to investigate surface UV dose distributions, a polystyrene sphere (Diameter 70 mm) was used to simulate fruits such as tomatoes, apples, peaches etc., that have an approximately spherical form. Biodosimetry based on spores of Bacillus subtilis was employed to experimentally determine UV doses and to compare the results obtained with theoretical predictions. Good agreement was obtained and the modelling approach was extended to other types of produce. This showed the amenability of mechanical rollers to ensure full surface treatment of produce. Postharvest treatment of produce was carried using conventional low intensity UV sources principally emitting at 254 nm and also a commercially available high energy pulsed UV source. Treatment using the conventional UV source was carried out on mechanical rollers within a UV cabinet designed for this work at a fixed distance from the source and at an intensity of 1000 μW/cm2. A 5 minute conventional UV treatment of tomatoes was approximately comparable to fruit given a 3-pulsed treatment using the pulsed source (507 J/pulse of polychromatic light). The colour and texture of both groups of fruit were significantly maintained as compared with controls. The treated tomatoes also showed a significant increase in the ascorbic acid levels during storage. Similarly, a 15 minute conventional UV treatment of broccoli heads was comparable to heads given a 10-pulsed treatment using the pulsed source. Where both treatments gave rise to a statistically significant retention of green colour of treated broccoli. In addition, mangoes given a 10 minute conventional UV treatment were comparable to fruit given a 20-pulsed treatment using the pulsed source with both treatments leading to maintenance of texture as compared to control fruit. This confirmed the UV-hormetic effects. The effects of conventional and pulsed treatments are compared and discussed. Preharvest treatment of tomatoes and strawberries was carried out in commercial glasshouses. Doses of either 3 or 8 kJ/m2 were delivered to the fruits using a treatment device designed for the work, which delivered a combined intensity of 2000 μW/cm2 from two low pressure UV sources. The treated tomatoes showed a delay in development of colour as measured on the vine and after picking. Picked tomatoes were inoculated with P. digitatum and C. gloeosporioides and the results obtained showed a significant inhibition of the development of the fungi in the treated fruit during the storage period. These results suggest that the beneficial response shown by the preharvest treatment is not a localised one but a systematically induced resistance observable throughout the treated plant. This was shown by monitoring tomato fruits on treated plants which themselves where not directly exposed to the UV light. The two doses elicited different responses in the treated strawberries, with the 8 kJ/m2 dose causing the fruit to redden significantly faster than the 3 kJ/m2 treated fruits and controls. This could have significant nutritional benefit as the red colour of strawberries has been correlated with anthocyanin levels. On the other hand, treatment at the lower UV dose led to a lag in colour development. The amenability of the equipment utilised for commercial application is discussed.

Master of Science / Department of Animal Sciences and Industry / Elizabeth A. E. Boyle / Light emitting diode (LED) and fluorescent (FLS) lighting effects on enhanced pork loin chops, beef longissimus dorsi and semimembranosus steaks, ground beef, and ground turkey displayed in two retail display cases set up with similar operational temperatures were evaluated using visual and instrumental color, Enterobacteriaceae (EB) and aerobic plate counts (APC), internal product and case temperatures, and thiobarbituric acid reactive substances (TBARS). Visual discoloration of the five meat products increased (P<0.05) as display time increased. Beef longissimus dorsi steaks, ground beef, and the superficial portion of beef semimembranosus steaks had less (P<0.05) visual discoloration under LED lighting than FLS. Compared to FLS, pork loin chops under LED lighting had higher (P<0.05) L* values and a lower (P<0.05) a/b ratio. The deep portion semimembranosus steak under LED was redder (P<0.05) and the superficial portion had a lower (P<0.05) a/b ratio; LED deep and superficial portion semimembranosus steaks had higher (P<0.05) saturation index values at 5.18 and 4.47, respectively, on d 0 than FLS. Pork chops under LED lighting had lower (P<0.05) APC populations than FLS by the end of display. Enterobacteriaceae populations fluctuated throughout display on ground turkey under FLS lighting while populations remained stable under LED. APC populations increased as display time increased for pork loin chops, ground beef and ground turkey, but not beef longissimus dorsi steaks possibly due to initial case-ready postmortem age. As display time increased, EB populations increased (P<0.05) for pork loin chops, ground beef and ground turkey. The internal temperature of all products, except beef longissimus dorsi steaks, was lower (P<0.05) in the LED case. FLS case temperatures were higher (P<0.05) by 0.56 to 1.11°C than LED over the duration of the study. Pork loin chops, ground turkey, and beef semimembranosus steaks had higher (P<0.05) TBARS values by 0.06 to 0.24 mg malonaldehyde/kg under LED lighting, but lighting type did not affect (P>0.05) lipid oxidation of beef longissimus dorsi steaks or ground beef. LED lighting results in lower display case temperatures, lower internal product temperatures, and extended color life; however, lipid oxidation was increased in some cuts under LED lighting.

A preocupação constante com a inocuidade e a qualidade dos alimentos irradiados, aliada à tendência de se estudar os aspectos sensoriais desses alimentos, foram a motivação para o desenvolvimento deste trabalho que teve como objetivos verificar os efeitos da radiação ionizante produzida pelo 60Co na sobrevivência de Salmonella sp em hambúrgueres de carne de frango congelados e verificar a aceitação do produto irradiado durante o seu período de estocagem. Amostras de hambúrguer de carne de frango congelados, inoculados com quatro cepas diferentes de Salmonella sp foram expostos a níveis de radiação com doses variando entre O e 3,5 kGy para verificação da sobrevivência da população de Salmonella sp presente. Amostras não inoculadas e irradiadas com doses de 0,5 e 7 kGy foram submetidas à avaliação sensorial por painel não treinado, pelo período de 120 dias, com o intuito de se verificar o decaimento da qualidade do produto. Os valores D10 encontrados para Salmonella sp variaram entre 1,02 e 1,32 kGy, portanto, as doses de 5 e 7 kGy, utilizadas nas fases seguintes do experimento, seriam suficientes para reduzir a população de Salmonella sp no produto em 5-6 ciclos logarítmicos. A exposição às doses de 5 e 7 kGy não afetou as características sensoriais do produto. A vida de prateleira do hambúrguer de carne de frango congelado e irradiado com doses de 5 e 7 kGy foi de, no mínimo, 120 dias, ou seja, igual à do produto não irradiado. / Safety and quality of irradiated foods are still of great concern to researchers and consumers, in general. The aims of this research were to study the effects of ionizing radiation from 60Co on the population of Salmonella sp inoculated in frozen chicken meat patties as well as on their sensory characterisitcs during the storage period. Samples of frozen chicken meat patties, inoculated with a pool of four strains of Salmonella sp, were exposed to irradiation doses varying from 0 to 3.5 kGy in order to determine their sensitivity (D10). Non inoculated samples of frozen chicken meat patties exposed to 5 and 7 kGy and a non inoculated and non irradiated sample were submitted to sensory evaluation by a non-trained panel. 010 values varied from 1.02 to 1.32 kGy Samples exposed to 5 and 7 kGy did not showed appreciable changes during the storage period of 120 days. Therefore, irradiation can be applied to chicken meat patties in order to improve their safety during a storage period of, at least, 120 days.

O objetivo desse estudo foi determinar a vida útil da tilápia do Nilo (Oreochromis niloticus) inteira armazenada em gelo, usando analises sensoriais (Método do Índice de Qualidade), físico-químicas (bases nitrogenadas voláteis totais - BNVT, sustâncias reativas ao ácido tiobarbitúrico - TBARS, pH, cor, textura e microbiológicas (microrganismos mesófilos e psicrotróficos). Uma equipe de sete provadores foi treinada durante sete sessões para avaliação sensorial de frescor em peixe cru e filés cozidos. Um esquema QIM foi otimizado para tilápia inteira e outro desenvolvido para filés cozidos, com 19 e 12 pontos de demérito, respetivamente. Três lotes de tilápia foram usados e os exemplares foram armazenados durante 13 dias em gelo para avaliar as alterações dos atributos de qualidade (aparência, brânquias, olhos, parede abdominal). A vida útil da tilápia do Nilo armazenada em gelo foi determinada em oito dias com base no critério sensorial dos filés cozidos, e pode ser usada como referencia para predizer o tempo de conservação residual. O índice de qualidade apresentou uma alta correlação linear com o tempo em gelo (IQ = 1,3865 x dias + 0,7922, R2 = 0,96), assim como também todos os atributos de qualidade. As análises sensoriais mostraram ser adequadas e confiáveis para avaliar o grau de frescor da tilápia, porem é recomendado usar no mínimo quatro peixes e mais do que um avaliador. A firmeza diminuiu durante o tempo de conservação em gelo (r = -0,73). Há uma pobre correlação entre os índices físico-químicos e microbiológicos e o tempo em gelo, não sendo considerados parâmetros confiáveis para avaliação das alterações da qualidade da tilápia do Nilo. Porém, peixes com até 13 dias não representam um risco para o consumidor, considerando que não foram ultrapassados os teores limites de BVNT (< 30 mg N/100g) nem de micro-organismos mesófilos viáveis (< 107 UFC/g). / The aim of this study was to determine the shelf-life of whole Nile tilapia (Oreochromis niloticus) stored in ice, using sensory analysis (Quality Index Method), physicochemical (total volatile base nitrogen - TVB-N, thiobarbituric acid-reactive substances - TBARS, pH, color, texture and microbiological (mesophilic and psychrotrophic). A sensory panel of seven assessors was trained during seven sessions for sensory evaluation of fresh fish and cooked fillets. A QIM scheme was optimized for whole tilapia and other developed for cooked fillets, with 19 and by 12 points of demerit, respectively. Three batches of tilapia were used and the fish were stored on ice during 13 days to evaluate the changes in quality attributes (appearance, gills, eyes, abdomen). The shelf-life of Nile tilapia stored on ice was determined in eight days based on sensory analysis of cooked fillets, and can be used as reference to predict the remaining shelf life. The quality index had a high linear correlation with time on ice (QI = 1.3865 x + 0.7922 days, R2 = 0.96), as well as all quality attributes. Sensory analysis showed to be adequate and reliable for assessing the degree of freshness of tilapia, however it is recommended to use at least 4 fish and more than one assessor. The firmness decreased during the ice shelf life (r = -0.73). There is a poor correlation between the physical, chemical and microbiological indexes and the time stored on ice, whereby they\'re not considered reliable parameters for assessing changes in quality of Nile tilapia. However, fish up to 13 days do not represent a risk for the consumer, considering they were not exceeded the limits of TVB-N levels (< 30 mg N/100 g) and also not the viable mesophilic microorganisms (< 107 CFU / g).

O Estado de São Paulo vem experimentando nos últimos anos um expressivo aumento da produção, oferta e consumo de carne ovina. Com a tendência atual de procura por produtos de maior conveniência, com rapidez e facilidade de preparo, vislumbra-se a necessidade do mercado investir na oferta de carne ovina na forma de cortes resfriados. Nesse sentido, a irradiação com energia ionizante poderia ser uma alternativa viável para a comercialização dos cortes resfriados de cordeiro. O objetivo deste trabalho foi estudar a aplicação de diferentes doses de radiação gama visando estender a vida útil microbiológica da carne de cordeiro embalada a vácuo e armazenada sob refrigeração. Para isso, primeiramente foi realizado um experimento preliminar visando se estabelecer parâmetros como a dose e o tempo de estocagem. As amostras foram irradiadas com doses de 1,0, 3,0 e 5,0 kGy e submetidas a análises microbiológicas por um período de 60 dias a uma temperatura de 1 °C. De acordo com os resultados pôde-se concluir que a dose de 3,0 kGy deve ser utilizada como dose máxima. Assim, iniciou-se o experimento final, e para isso, as amostras de lombo de cordeiro foram embaladas a vácuo e irradiadas com as doses zero (controle), 1,5 kGy e 3,0 kGy e estocadas sob refrigeração a 1 °C. Foram realizadas nos tempos de zero, 14, 28, 42 e 56 dias análises microbiológicas e análises físico-químicas. Também foi realizado um teste sensorial de aceitação com 63 provadores, no qual foram avaliados os atributos de aroma, textura, suculência, sabor e qualidade global. Todos os dados foram estatisticamente avaliados através de contrastes entre as médias, com um nível de significância de 5%. Os resultados obtidos para os testes microbiológicos foram de ausência de Salmonella sp., contagens esporádicas de coliformes a 45 °C e Staphylococcus aureus (&lt; 10 (est) UFC/g) para todas as amostras. Para as demais análises microbiológicas houve efeitos significativos (p&lt;0,05) de tratamento e tempo. Entretanto, nas características físico-químicas, houve apenas efeitos significativos (p&lt;0,05) ao longo do tempo de zero a 28 dias, para pH e cor b* (amarelo), os quais decaíram e aumentaram, respectivamente. Na aceitação sensorial, as amostras não diferiram (p&gt;0,05) em nenhum dos atributos avaliados. Assim, pôde-se concluir que a irradiação gama nos lombos de cordeiro foi eficiente em diminuir a proliferação de microrganismos sem prejudicar as características físico-químicas, e ainda, que a aceitação do consumidor também não foi prejudicada pela irradiação. Ao final do experimento, foi possível afirmar que a dose 3,0 kGy foi a mais indicada, pois conseguiu estender a vida de prateleira de 14 para 56 dias do lombo de cordeiro irradiado e armazenado a 1°C. / The State of São Paulo has experienced in recent years a significant increase in production, supply and consumption of lamb meat. With the current trend of demand for products of greater convenience, with speed and ease preparation, there is the need to invest in the market supply of refrigerated lamb cuts. Accordingly, irradiation with ionizing energy could be a viable alternative for the marketing of refrigerated cuts of lamb meat. The aim of this work was to study the application of different doses of gamma radiation in order to extend the stability of lamb meat vacuum packed and stored under refrigeration. For this, first a preliminary experiment was conducted aiming to determine parameters such as irradiation dose and storage time. The lamb loins (Longissimus dorsi) were vacuum packed, irradiated with doses of 1,0, 3,0 and 5,0 kGy and stored under refrigeration in cooling chamber at 1 °C. According to the results, a dose of 3,0 kGy may be indicated as the maximum dose of irradiation. After establishing these parameters, the final experiment began, and for that, the lamb loin samples were vacuum packaged and irradiated with doses zero (control), 1,5 kGy and 3,0 kGy and stored under refrigeration at 1 °C. In predetermined periods (zero, 14, 28, 42 and 56 days) microbiological and physicalchemical analysis were carried out. Also, a sensory acceptance test was conducted, with 63 consumers, which evaluated aroma, texture, juiciness, flavor and overall quality atributes. All data were statistically evaluated using contrasts between means, with a significance level of 5%. The results obtained for microbiological testing of all samples were absence of Salmonella sp. and sporadic counts of coliforms at 45 °C and Staphylococcus aureus (&lt;10 (est) CFU/g). For other microbiological analysis there were significant effects (p &lt;0,05) of treatment, and time. However, for the physicochemical characteristics, there were only differences (p &lt;0,05) of time from zero to 28 days for pH and color b * (yellow), which declined and increased, respectively, over this period. In the sensory acceptance test, the samples did not differ (p&gt; 0,05) in any of the evaluated attributes. Thus, it was concluded that gamma irradiation in the lamb loins was effective in decreasing the proliferation of microorganisms without damaging its physical and chemical characteristics. At the end of the experiment, it was possible to say that the 3.0 kGy dose was indicated because could extend the shelf life of 14 to 56 days of loin of lamb irradiated and stored at 1 °C.

O iogurte é considerado um importante derivado lácteo para a alimentação humana. No Brasil, este produto é elaborado tradicionalmente a partir do leite bovino. A produção de iogurte, porém, constitui uma excelente alternativa para o aproveitamento do leite de búfala, embora possam ocorrer problemas na aceitação do produto devido ao elevado teor de gordura no leite original. O presente trabalho teve por objetivo avaliar a estabilidade e algumas características de qualidade do iogurte natural elaborado a partir do leite de búfala contendo diferentes níveis de gordura. Para isto, o leite foi desnatado até atingir 0,5% de gordura e misturado a volumes convenientes de leite integral, com a finalidade de obter os seguintes tratamentos: A – teor de iogurte integral, B – iogurte padronizado, contendo 3,0% de gordura e C – iogurte desnatado, contendo 0,5% de gordura. Os leites foram utilizados separadamente para a fabricação do iogurte natural batido, o qual foi embalado em frascos de polietileno de 1 L e estocado câmara fria a 5ºC por 30 dias. Amostras de iogurte foram coletadas nos dias 1, 15 e 30, após a fabricação, com vistas à realização das seguintes análises: contagem de coliformes, mesófilos e psicrotróficos; determinação do pH, acidez titulável, gordura, proteína e matéria seca; viscosidade aparente e análise sensorial, realizada através de painel não treinado. Os resultados foram analisados através de ANOVA. Os dados obtidos nas análises microbiológicas não apresentaram diferenças significantes (P > 0,05) entre os iogurtes produzidos com leite bubalino integral, padronizado e desnatado. Não foram observadas variações importantes nas características físico-químicas estudadas nos diferentes tipos de iogurte, durante o período de 30 dias de estocagem. A viscosidade também não foi influenciada (P > 0,05) pelos níveis de gordura nas análises dos dias 1, 15 e 30, indicando que a adição de leite em pó não é necessária para padronizar o teor de sólidos totais no iogurte produzido a partir de leite bubalino desnatado. Comparado ao iogurte desnatado, o iogurte produzido com leite padronizado apresentou notas significativamente maiores (P < 0,05) na análise sensorial nos dias 15 e 30. Conclui-se que todos os tipos de iogurte apresentaram características aceitáveis sob os aspectos microbiológico e físico-químico, embora o iogurte produzido com leite bubalino contendo 3,0% de gordura tenha demonstrado uma melhor qualidade sensorial, bem como uma boa estabilidade durante o armazenamento / Yoghurt is considered an important dairy product for human nutrition. In Brazil, it is traditionally manufactured from cow’s milk. Yoghurt can be also an excellent alternative for utilization of buffalo milk. However, consumers may have some acceptance problems in relation to buffalo yoghurt because of the original milk high fat content. The aim of the present study was to evaluate some characteristics and the stability of yoghurt produced with buffalo milk standardised at different fat levels. The milk was defatted down up 0.5% and mixed with adequate volumes of whole milk, resulting in three treatments: A- whole yoghurt, B- standard yoghurt with 3.0% fat content, and C- skim yoghurt with 0.5% fat content. Standardised milks were used separately for manufacture of stirred whole plain yoghurt. Yoghurts were stored in 1-L polyethylene bottles at 5ºC for 30 days. Samples were collected at 1, 15 and 30 days of storage and submitted to the following analysis: coliform, mesophile and psychrotrophic counts, determination of pH, fat and protein content, total solids and non-fat solids, viscosity and sensorial evaluation. Results were analysed using one-way ANOVA. No significant differences were observed among of treatments on microbiological (P > 0.05) after evaluation. No important variations in chemical parameters were observed during 30 days storage of all yoghurts. Viscosity was not influenced (P > 0.05) by fat content in yoghurts on days 1, 15 and 30 after manufacture, hence indicating that addition of milk powder is not necessary to standardise solid contents in yoghurt made from defatted buffalo milk. Standardised yoghurt obtained significantly (P < 0.05) higher grades in sensorial analysis at 15 and 30 days storage when compared to yoghurt produced from skim milk. It was concluded that all yoghurts present acceptable microbiological, physical and chemical characteristics. However, the product made from buffalo milk containing 3.0% fat showed better sensorial quality and good stability during storage

A embalagem desempenha uma função crucial na estabilidade dos alimentos. Neste estudo avaliou-se a estabilidade microbiológica de néctar de jabuticaba e caldo de cana pasteurizados (85 ºC/30 s), acondicionados assepticamente em garrafa de polietileno de alta densidade (PEAD) incorporada com agentes inorgânicos microestruturados com Ag/ZnO. Os lotes processados foram estocados a 5 ºC na ausência de luz. Testes físico-químicos, microbiológicos e sensoriais foram conduzidos para avaliar a estabilidade e estimar o tempo de vida útil das bebidas. Médias de notas superiores a 5 (na escala hedônica de 9 pontos) e percentagens de aceitação superiores a 60% foram estabelecidas para estimar o tempo de vida de prateleira das bebidas. Os resultados dos testes físico-químicos para o néctar de jabuticaba variaram de 3,40 a 3,76 para o pH, de 11,0 a 12,5 ºBrix para sólidos solúveis totais, e de 0,52 a 0,76% (m/m) de ácido cítrico para acidez total titulável. Para o caldo de cana, os valores de pH, sólidos solúveis totais e acidez total titulável variaram de 5,10 a 5,37; 14,3 a 24,0 ºBrix e de 0,05 a 0,13%(m/m) ácido cítrico, respectivamente, durante o período do estudo. Para o néctar de jabuticaba, as contagens de mesófilos, psicrotróficos e bolores e leveduras variaram de 1 a 1,5; &lt; 1est a 1; &lt; 1est a 1,3 logUFC/mL respectivamente, durante o período de estocagem. Para o caldo de cana as contagens variaram de &lt; 1est a 4,5 1est a 4,4; 1est a 4,0 logUFC/mL. O néctar de jabuticaba alcançou maior estabilidade microbiológica que o caldo de cana. As médias de notas para sabor, aparência e impressão global obtidas nos testes de escala hedônica variaram entre 6 a 7,1 para o néctar de jabuticaba e 5 e 7,7 para o caldo de cana. O néctar de jabuticaba e caldo de cana permaneceram microbiologicamente estáveis por um período de 120 e 50 dias, respectivamente. Os agentes inorgânicos microestruturados com Ag/ZnO não exerceram influência na estabilidade microbiológica dos dois produtos. / Packaging plays a crucial role in food stability. In this study, the microbiological stability of pasteurized (85 ºC/30 s) jabuticaba nectar and cane juice, aseptically packaged in high density polyethylene (HDPE) bottle treated with silver and zinc oxide (Ag/ZnO), was evaluated. All processed batches were stored at 5 ºC in the dark. Physicochemical, microbiological and sensory tests were conducted to evaluate the stability and estimate the beverage´s shelf life. Average scores greater than 5 (in the 9-point hedonic scale) and percentage of approval greater than 60% were both used as threshold values for estimating the product´s shelf life. As for the nectar, the pH ranged from 3.40 to 3.76; soluble solids from 11.0 to 12.5 ºBrix and titratable total acidity from 0.52 to 0.76% (w/w) citric acid. The pH values, total soluble solids and titratable acidity of cane juice varied from 5.10 to 5.37; 14.3 to 24.0 ºBrix and 0.05 to 0.13%(w/w) citric acid, respectively, during the storage. For nectar, counts of mesophiles, psychrotrophs and molds and yeasts ranged from 1 to 1.5; &lt; 1est to 1; &lt; 1est to 1.3 logCFU/mL, respectively, during the storage period. For the cane juice the counts ranged from &lt; 1est to 4.5; &lt;1est to 4.4; &lt;1est to 4.0 logCFU/mL. Jabuticaba nectar achieved longer microbiological stability than cane juice. The mean scores for flavor, appearance and overall impression obtained in the nine-point hedonic scale tests ranged from 6 to 7.1 for jabuticaba nectar and 5 and 7.7 for cane juice. Nectar and cane juice remained microbiologically stable for 120 and 50 days, respectively. The Ag/ZnO microstructured inorganic agents had no influence on the microbiological stability of both products.

O presente estudo teve por objetivo avaliar o desempenho do Teste do Cometa em confronto com métodos convencionais de avaliação de frescor e qualidade higiênica e sanitária de filés de Tilápia (Oreochromis niloticus - LINNAEUS, 1758) refrigerados, durante a vida útil comercial, correlacionando os seus resultados com aqueles obtidos nas análises físico-químicas, microbiológicas e sensorial. As análises foram realizadas nos dias zero - cinco - nove - 12 - 14 pós-processamento dos filés. Em cada dia de estudo foram processados três filés diferentes, pertencentes ao mesmo lote de produto. O protocolo foi repetido em três momentos diferentes, completando 45 amostras. Nos resultados encontrou-se no dia zero e no quinto dia útil do produto, condições impróprias para consumo com relação aos microrganismos psicrotróficos e mesófilos, respectivamente, e o tipo de cometa predominante foi o tipo 3. Aos nove dias de vida útil dos filés, a média dos parâmetros Trimetilamina, Odor e Intenção de Compra indicavam produto impróprio e no teste do cometa predomina o tipo 5. Aos 12 dias de vida útil dos filés de Tilápia, refrigerados, bases voláteis nitrogenadas totais e textura obtiveram resultados impróprios, enquanto que a aparência se revelou imprópria a partir do 14º dia. Concluiu-se que o teste do cometa se presta para o estudo de vida útil de filés de Tilápia refrigerados e apresentou correlação com os métodos convencionais de avaliação de frescor e qualidade higiênica e sanitária do pescado. A partir do 9º dia de estudo predominavam cometas do tipo 5, indicativos do grau máximo de dano celular e fragmentação de DNA das células, pelo teste do cometa, o que coincidiu com a rejeição da Intenção de Compra na análise sensorial. / The present study aimed to evaluate the performance of the Comet assay in comparison with conventional methods of assessing freshness and hygienic and sanitary quality of chilled Tilapia (Oreochromis niloticus - Linnaeus, 1758) fillets, over the shelf-life, correlating their results with those obtained in the physical-chemical, microbiological and sensory. The analyzes were performed on days zero - 5 - 9 - 12 - 14 post-processing of the fillets. In each study day were processed three different fillets, belonging to the same batch of product. The protocol was repeated at three different times, completing 45 samples. The results showed that at the zero and fifth day of the product, improper conditions for consumption, with respect to psychrotrophic and mesophilic microorganisms, respectively, and the predominant type of comet was the type 3. At nine days of the fillets shelf-life, the average of the parameters trimethylamine, odor and purchase intent indicate improper product, and at the comet assay predominate type 5. At 12 days of the shelf-life of chilled tilapia fillets, total volatile basic nitrogen and texture results obtained improper conditions, while appearance showed improper at the 14th day. It was concluded that the comet assay lends itself to the study of shelf-life of chilled tilapia fillets and correlated with conventional methods of assessing freshness and hygienic and sanitary qualities of fishery. From the 9th day of study, predominated comets type 5, indicative of maximum degree of cell damage and DNA fragmentation of the cells by the comet assay, which coincided with the rejection of Purchase Intent at sensory analysis.