Maria Teresa de Alvarenga Freire

Thermal stability of polyethylene terephthalate (PET): Oligomer distribution and formation of volatiles

Two ovenable PET (polyethylene terephthalate) samples were investigated under severe heating conditions and oligomers and volatile substances were analysed as potential migrants into foods. The samples were tested for migration into water, 3% acetic acid and 15% ethanol solution for 1 hour at 95°C. Overall migration and the specific migration of terephthalic acid, ethylene glycol and diethylene glycol were all very low. The plastics were heated at 150°C, 260°C and 270°C, for 5 minutes 30 minutes and 60 minutes. Oligomer analysis by LC/MS (liquid chromatography-MS) showed that the concentration of the second series alicyclic oligomers increased up to 15-fold on heating whereas the major oligomer fraction, the cyclic trimer, tetramer, pentamer and hexamer showed only minor concentration changes with heating. Volatiles evolved by the samples were trapped on a Tenax trap and identified by GC/MS (gas chromatography-MS). They were few in number and low in concentration and none merited migration tests. It is concluded that even when tested up to melting point, PET plastics of this type have good temperature stability and are well suited for high-temperature food contact applications. Copyright

Stability of lamb loin stored under refrigeration and packed in different modified atmosphere packaging systems

The aim of the present study was to evaluate the effect of different modified atmosphere packaging (MAP) systems (vacuum, 75% O2+25% CO2 and 100% CO2) on the stability of lamb loins stored at 1±1°C for 28 days. Microbiological (counts of aerobic and anaerobic psychrotrophic microorganisms, coliform at 45°C, coagulase-positive staphylococci and lactic acid bacteria and presence of Salmonella), physical and chemical (thiobarbituric acid reactive substances [TBARS], objective color, pH, water loss from cooking [WLC] and shear force), sensory (acceptance testing using a 9-point hedonic scale) and gas composition analyses were performed. Lamb meat remained stable with respect to the majority of the evaluated physical and chemical indexes and within the standards established by Brazilian legislation for pathogenic microorganisms throughout the storage period in all three packaging systems. However, with respect to psychrotrophic microorganisms, 100% CO2 packaging system provided increased stability despite presenting lower appearance preference.

Determination of volatile organic compounds in recycled polyethylene terephthalate and high-density polyethylene by headspace solid phase microextraction gas chromatography mass spectrometry to evaluate the efficiency of recycling processes.

A method for the determination of volatile organic compounds (VOCs) in recycled polyethylene terephthalate and high-density polyethylene using headspace sampling by solid-phase microextraction and gas chromatography coupled to mass spectrometry detection is presented. This method was used to evaluate the efficiency of cleaning processes for VOC removal from recycled PET. In addition, the method was also employed to evaluate the level of VOC contamination in multilayer packaging material containing recycled HDPE material. The optimisation of the extraction procedure for volatile compounds was performed and the best extraction conditions were found using a 75 μm carboxen-polydimethylsiloxane (CAR-PDMS) fibre for 20 min at 60 °C. The validation parameters for the established method were linear range, linearity, sensitivity, precision (repeatability), accuracy (recovery) and detection and quantification limits. The results indicated that the method could easily be used in quality control for the production of recycled PET and HDPE.

CARACTERIZAÇÃO FÍSICO-QUÍMICA, MICROBIOLÓGICA E SENSORIAL DE POLPA DE CUPUAÇU CONGELADA (Theobroma gradiflorum, Schum)

O presente trabalho visou a caracterização microbiológica, físico-química e a aceitação sensorial de polpa de cupuaçu congelada (Theobroma grandiflorum Schum). Analisaram-se 3 marcas do produto, denominadas A, B e C, fornecidas em saquinhos de polietileno de 100 g. A caracterização microbiológica foi fundamentada na quantificação de mesófilos aeróbios, bolores e leveduras, coliformes e na verificação da presença de Salmonella. Os testes físico-químicos basearam-se na determinação de extrato seco, atividade de água (Aa), cinzas totais, proteínas, lipídios, sólidos solúveis (°Brix), acidez titulável, ácido ascórbico, pH e cálculo do ratio. Os testes sensoriais da polpa foram conduzidos com o suco preparado a partir das amostras comerciais. Atributos de aparência, aroma, sabor e impressão global do suco foram avaliados por meio de testes de escala hedônica e de ordenação-preferência. As contagens médias de mesófilos aeróbios foram equivalentes a 1,6 x 102, 1,3 x 102 e 7,9 x 101 UFC.g–1 de polpa, nas marcas A, B e C, respectivamente. Para bolores e leveduras, obtiveram-se 4,9 x 101, <10 e 1,6 x 101 UFC.g–1. As contagens de coliformes a 30 e 45 °C foram inferiores a 0,3 NMP.g–1 nas três marcas. Constatou-se a ausência de Salmonella em 25 g de polpa, para todas as amostras testadas, em conformidade com a legislação vigente. Os resultados obtidos na caracterização físico-química revelaram desacordo de algumas amostras com a legislação para os parâmetros sólidos solúveis totais, acidez titulável e ácido ascórbico. Os resultados da análise sensorial não evidenciaram diferença entre as três marcas de polpa a 5% de significância para os testes de escala hedônica e ordenação-preferência. Concluiu-se que as três marcas de polpa congelada de cupuaçu apresentaram qualidades microbiológica e sensorial satisfatórias. No entanto, notou-se falta de uniformidade em relação aos padrões de identidade e qualidade, conforme determinado pela legislação nacional vigente.

Evaluation of Physicochemical, Microbiological and Sensory Stability of Frozen Stored Vacuum-Packed Lamb Meat

Abstract Nowadays, lamb meat represents only 7% of all meat produced in the world. In recent years the demand for standardized lamb meat cuts has been considered of great importance and the marketing occurs predominantly in the form of frozen cuts. Herewith, the main of this work was to evaluate the stability and safety of lamb meat during frozen storage. Meats were vacuum packed in high barrier multilayer plastic films and stored during 12 mon at (−18±1)°C. The meat stability was assessed by physical and chemical (lipid oxidation, objective color, pH value, cooking losses and instrumental texture), microbiological (total count of psychrotrophic, coliform count at 45°C, coagulase-positive staphylococci and the presence of Salmonella) and sensory analysis (acceptance test and visual evaluation). The vacuum packed lamb meat remained stable as to most physical and chemical indexes. Microbiological indexes showed good stability throughout the storage period according to Brazilian legislation standards to pathogenic microorganisms. Although a significant reduction in tenderness (shear force increase from 3 to 8 kg), it showed a good sensorial acceptance for all attributes tested, including texture, with scores of around 7 (like moderately) during the 12 mon of storage. Therefore, it can be concluded that, under the conditions applied in this study, lamb meat presents a shelf life of at least 12 mon when stored at −18°C.

Migration of residual nonvolatile and inorganic compounds from recycled post-consumer PET and HDPE

Migration of nonvolatile and inorganic residual compounds from post-consumer recycled polyethylene terephthalate (PET) submitted to cleaning processes for subsequent production of materials intended to food contact, as well as from multilayer packaging material containing post-consumer recycled high-density polyethylene (HDPE) was determined. Tests were carried out using food simulants. Nonvolatile organic contaminants from PET, determined by liquid chromatography-mass spectrometry (UPLC-QqQ/MS), showed significant migration reduction as consequence of the more complex cleaning technologies applied. However, contaminants not allowed by Brazilian and European Union regulations were identified even in deep cleaning samples. Results from multilayer HDPE showed a greater number of contaminants when compared to recycled pellets. Inorganic contaminants, determined by inductively coupled plasma mass spectrometry were below the acceptable levels. Additional studies for identification and quantitation of unknown molecules which were not possible to identify in this study by UPLC-QqQ/MS are required to ascertain the safety of using post-consumer recycled packaging material.

Estabilidade físico-química, microbiológica e sensorial de carne ovina embalada a vácuo estocada sob refrigeração

Lamb is commercialized today almost entirely in frozen form, but, considering the current trend to greater demand for convenience products, it becomes more evident the need of availability of chilled cuts of meat in the market. The objective of this study was to evaluate the stability and safety of lamb meat packed under vacuum when stored under refrigeration. The lamb meat samples were packed in high barrier multilayer plastic films and stored under refrigeration (4±1°C). The stability was evaluated by means of physical and chemical analysis (lipid oxidation, objective color, pH value, chemical composition, cooking losses and instrumental texture), microbiological analysis (total count of psychrotrophic anaerobic, coliform count at 45°C, coagulase-positive staphylococci and the presence of Salmonella) and sensory analysis (color, flavor and overall appearance). The vacuum packed lamb meat remained stable as to most physical and chemical indexes and microbiological indexes showed good stability throughout the 28 days of storage according to Brazilian legislation standards to pathogenic microorganisms. In relation to the stability evaluation of chilled sheep loin, it was detected a high increase of counts for psychrotrophic anaerobic microorganisms, reaching around 107CFU g-1 sample at 14 days storage, but the pannelists did not detect significant sensory changes during all the period. It is concluded that the shelf life of sheep loin stored at 4°C, is at least, 28 days.

Contaminantes voláteis provenientes de embalagens plásticas: desenvolvimento e validação de métodos analíticos

Plastic packaging materials intended for use in food packaging is an area of great interest from the scientific and economic point of view due to the irreversible internationalization and globalization process of food products. Nevertheless, a debate related to food safety aspects has emerged within the scientific community. Therefore, the development of analytical methods that allow identifying and quantifying chemical substances of toxicological potential in the packaging is considered essential. This article focuses on the main analytical methods, including validation parameters, as well as extraction and quantification techniques for determination of volatile organic compounds from food packaging materials.

A method to determine volatile contaminants in polyethylene terephthalate (PET) packages by HDC-GC-FID and its application to post-consumer materials

A simple and low cost method to determine volatile contaminants in post-consumer recycled PET flakes was developed and validated by Headspace Dynamic Concentration and Gas Chromatography-Flame Ionization Detection (HDC-GC-FID). The analytical parameters evaluated by using surrogates include: correlation coefficient, detection limit, quantification limit, accuracy, intra-assay precision, and inter-assay precision. In order to compare the efficiency of the proposed method to recognized automated techniques, post-consumer PET packaging samples collected in Brazil were used. GC-MS was used to confirm the identity of the substances identified in the PET packaging. Some of the identified contaminants were estimated in the post-consumer material at concentrations higher than 220 ng.g-1. The findings in this work corroborate data available in the scientific literature pointing out the suitability of the proposed analytical method.

Eating quality of meat from six lamb breed types raised in Brazil.

BACKGROUND Breed or genotype is important to consider for developing appropriate eating quality in lamb. The objectives of this study were to compare physical and chemical parameters and sensory acceptance of longissimus lumborum (LL) muscle from six lamb breed types economically important to the Brazilian sheep-raising chain. RESULTS No difference (P > 0.05) among samples was found in relation to L(*) , a(*) and b(*) parameters. However, differences were detected in shear force for the LL muscle produced by different breeds (P < 0.05), where animals without definite breed (WDB) showed higher shear force, whereas the lowest levels were observed for breed Hampshire Down, followed by Ile de France and the Dorper/Santa Inês cross-breed (Dorper/SI). In relation to sensory acceptance, no difference (P > 0.05) was detected in aroma attribute for all breed types tested. For the attributes texture, juiciness, flavor and overall quality, differences were detected (P < 0.05), Dorper/SI, Hampshire Down and Suffolk cross breeds received the best scores, while Santa Inês received intermediate evaluations, and Ile de France and WDB were the least accepted. CONCLUSION Under the conditions evaluated in this study, meat from Dorper/SI and Hampshire Down cross-breeds showed better eating quality, satisfying most consumers.