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- Measurement of oxygen transmission rate through foamed materials for bottle closuresPublication . Poças, Maria F.; Ferreira, Belmiro; Pereira, Joel; Hogg, TimThe determination of the oxygen transmission rate (OTR) through closures in glass bottles is becoming increasingly important for quality control of different batches and for development purposes. The Mocon method for measuring OTR is globally accepted and used in different applications. However, one of the major drawbacks this method presents when applied to bottle/closures systems is the long time required to obtain stable measurements when 40 mm long closures are tested. This paper describes a method to obtain OTR values with samples of reduced thickness with much shorter measurements time, since the condition of steady state during measurements is achieved faster and compares the estimated full-length commercial closure OTR with experimental values
- Safety evaluation of the food enzyme α-amylase from a genetically modified Aspergillus niger (strain NZYM-SB)Publication . EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Poças, Maria de Fátima TavaresThe food enzyme is an α-amylase (4-α-d-glucan glucanohydrolase; EC 3.2.1.1), produced with the genetically modified Aspergillus niger strain NZYM-SB by Novozymes A/S. The food enzyme does not contain the production organism or its DNA; therefore, there is no safety concern for the environment. The α-amylase is intended for use in starch processing, beverage alcohol (distilling) processes and baking processes. Residual amounts of total organic solids (TOS) are removed by distillation and by the purification steps applied during the production of glucose syrups (by > 99%). Consequently, dietary exposure was not calculated for these two uses. Based on the maximum use levels recommended for the baking processes and individual consumption data from the EFSA Comprehensive European Food Consumption Database, dietary exposure to the food enzyme–TOS was estimated to be up to 3.075 mg TOS/kg body weight per day in European populations. The food enzyme did not induce gene mutations in bacteria or micronuclei in human lymphocytes. Subchronic toxicity was assessed by means of a repeated-dose 90-day oral toxicity study in rodents. A no observed adverse effect level (NOAEL) was derived that, compared with the dietary exposure, resulted in a sufficiently high margin of exposure (MOE). Similarity of the amino acid sequence to those of known allergens was searched and two matches were found. The Panel considered that the risk of allergic sensitisation and elicitation reactions by dietary exposure cannot be excluded, but the likelihood is considered low. Based on the genetic modifications, the manufacturing process, the compositional and biochemical data, the findings in the toxicological and genotoxicity studies, as well as the estimated dietary exposure, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.
- Safety evaluation of the food enzyme endo-1,4-β-xylanase from a genetically modified Aspergillus niger (strain XEA)Publication . EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Poças, Maria de Fátima TavaresThe food enzyme is an endo-1,4-β-xylanase (EC 3.2.1.8) produced with a genetically modified strain of Aspergillus niger (strain XEA), by DSM Food Specialities B.V. The food enzyme is intended to be used in baking and brewing processes. Based on maximum use levels recommended for the food processes and individual consumption data from the EFSA Comprehensive European Food Consumption Database, dietary exposure to the food enzyme–total organic solids (TOS) was estimated to be up to 0.310 mg TOS/kg body weight per day in European populations. Genotoxicity tests with the food enzyme did not indicate a genotoxic concern. A repeated dose 90-day oral toxicity study in rodents, carried out with this endo-1,4-β-xylanase, showed no concern with respect to systemic toxicity. The allergenicity was evaluated by searching for similarity of the amino acid sequence to those of known allergens; no match was found. The Panel considers that there are no indications for allergic sensitisation and elicitation reactions by dietary exposure to the food enzyme endo-1,4-β-xylanase. Based on the microbial source, the genetic modifications performed, the manufacturing process, the compositional and biochemical data provided, the dietary exposure assessment, the findings in the toxicological studies and the allergenicity assessment, the Panel concludes that this food enzyme does not give rise to safety concerns under the intended conditions of use.
- Phytochemicals preservation in strawberry as affected by pH modulationPublication . Oliveira, Ana; Gomes, Maria Helena; Alexandre, Elisabete M. C.; Poças, Fátima; Almeida, Domingos P. F.; Pintado, ManuelaStrawberries purees are incorporated in foods and subjected to pH modulation according to the expected final food matrix. The effect of pH on strawberry polyphenols stored at 4 and 23 degrees C for 90 days was evaluated. Total antioxidant activity and total phenolics content were only affected by time according to a first order model. The pH 4.5 induced higher decrease in (-)-epigallocatechin gallate (71% and 79%) and quercetin-3-glucoside (29% and 36%), for both storage temperatures. For pH 2.5 and 3.0, ellagic acid increased 84% for 4 degrees C. and 185% for 23 degrees C. Anthocyanins concentration changes along storage were well described by first order model. The pH value of 2.5 presented the lower kinetic constant rate where cyanidin-3-glucoside, pelargonidin-3-glucoside and pelargonidin-3-rutinoside had a k = 0.04, 0.05 and 0.03 day(-1). Lower storage temperature (4 degrees C) and lower pH (2.5) were the best condition for the preservation of polyphenols in pasteurized strawberry during a 90-day storage period.
- Features and performance of edible films, obtained from whey protein isolate formulated with antimicrobial compoundsPublication . Ramos, Óscar L.; Silva, Sara I.; Soares, José C.; Fernandes, João C.; Poças, M. Fátima; Pintado, Manuela E.; Malcata, F. XavierThe goal of this research effort was to assess the efficacy of edible films produced fromwhey protein isolate (WPI) and glycerol, including incorporation of lactic acid (LA) and propionic acid (PRO), chitooligosaccharideswith nominal MW of 3 kDa (COS) and natamycin (NA) as antimicrobial agents. Their features were evaluated in vitro via agar diffusion and viable cell counting, against spoilage microflora often found contaminating cheese surfaces. The effect of incorporating the aforementioned compounds upon thickness, moisture content (MC), solubility (S), density (ρs),water activity (aw) and water vapor permeability (WVP), as well as upon tensile and optical properties of those films were also evaluated. Films formulated with LA, PRO or COS exhibited antimicrobial activity against all microorganisms tested, yet the viable cell count assay was more sensitive and reproducible. COS was the most active against Gram-negative bacteria, whereas LA was the most active against Gram-positive ones. NA was not active against bacteria, but displayed the strongest effect against yeasts. Incorporation of said antimicrobial compounds did not significantly (pN0.05) affect film thickness, yet it significantly (pb0.05) reduced tensile strength (TS). Incorporation of LA and NA in particular did not significantly (pb0.05) affect MC, S, ρs, WVP, elongation at break (EB) and Young's modulus (YM) values; however, a statistically significant increase (pb0.05) of MC, S andWVP, together with a statistically significant decrease (pb0.05) of ρs were attained upon incorporation of PRO or COS. Moreover, PRO produced the highest variation (pb0.05) in EB, TS and YM,whereas COS produced the highest change (pb0.05) in optical properties.
- Safety assessment of the active substances carboxymethylcellulose, acetylated distarch phosphate, bentonite, boric acid and aluminium sulfate, for use in active food contact materialsPublication . EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Poças, Maria de Fátima TavaresThis scientific opinion of the EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF Panel) deals with the safety evaluation of the active substances carboxymethylcellulose, acetylated distarch phosphate (FCM substance No 1071), bentonite, boric acid and aluminium sulfate (FCM substance No 1072). The mixture is intended to be used as a liquid absorber in the packaging of perishable foods to extend their shelf-life. All substances have been evaluated and approved for use as additives in plastic food contact materials and/or as food additives. Migration of boron into foods was up to 0.7 mg/kg food. Migration of aluminium was not detected (limit of detection (LOD) of 0.001 mg/kg). The CEF Panel concludes that the substances carboxymethylcellulose, acetylated distarch phosphate, bentonite, boric acid and aluminium sulfate are not of safety concern for the consumer when used as active components in moisture and liquid absorbers. The absorbent pads must be used under conditions in which direct contact between the active mixture and the food is avoided and the fluid absorption capacity of the absorber is not exceeded.
- Analysis of mathematical models to describe the migration of additives from packaging plastics to foodsPublication . Poças, Maria F.; Oliveira, Jorge C.; Brandsch, Rainer; Hogg, TimothyThe mathematical modeling of migration of additives from plastics to food simulants was studied using experimental data published in the literature, following two routes: the conventional approach using the solution of Fick’s 2nd law, and a kinetic model based on the Weibull distribution function. The objective of this comparison was to permit using a mathematically simpler model equally able to describe migration data, and that could have a generally wider applicability by describing situations more complex than those that simple diffusional phenomena can describe. The relationship between the parameters of the two models was analyzed by regression of data generated by Fick’s law using the Weibull model. The results show that the time constant parameter is related to the diffusion coefficient and the material thickness.It depends on temperature and on the molecular weight of the migrant in a similar manner to the diffusion coefficient. The activation energy presented values from 72 to 125 kJ/mol. The shape parameter is a function of the contribution of the mass transfer resistance at the interface. It was independent of temperature and of the migrant, assuming a global constant value of 0.67, for the systems and conditions studied. The results indicate that the Weibull model can be used to describe and analyze the migration of additives from plastics to foods with a meaning of the parameters in terms of the underlying physical phenomena.
- Performance of wine bag-in-box during storage: loss of oxygen barrierPublication . Fradique, S.; Hogg, T.; Pereira, J.; Poças, M .F. F.Bag-in-box system is a convenient packaging system for wine. Its barrier to oxygen relies, in many cases, in an aluminium metallized polyester film laminated between two polyethylene (PE) layers as the inner bag. One on the most frequently observed system failures is the ingress of wine into the gap between the layers of the double bag. This study aimed at verifying if that influences the barrier of the system to oxygen. The results showed that the contact of wine with this barrier layer, although through a PE layer, promotes the demetallization and consequent loss of barrier properties. The type of wine, in particular its volatile acidity, and the temperatures were two variables assessed. Results showed that wine with higher acidity and stored at higher temperatures tend to yield a higher increase in oxygen transmission rate of the film.
- Safety assessment of the process ‘Gneuss 1’, based on Gneuss technology, used to recycle post-consumer PET into food contact materialsPublication . EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Poças, Maria de Fátima TavaresThis scientific opinion of the EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids deals with the safety evaluation of the recycling process Gneuss 1 (EU register No RECYC0143). The input is washed and dried poly(ethylene terephthalate) (PET) flakes originating from collected post-consumer PET containers, containing no more than 5% of PET from non-food applications. They are extruded under vacuum into pellets or sheets. Having examined the challenge test provided, the Panel concluded that the decontamination in the extruder under vacuum degassing is the critical step for the decontamination efficiency of the process. The operating parameters to control its performance are well defined and are temperature, pressure, residence time, throughput rate, rotor speed and satellite screws speed. The operating parameters of this step are at least as severe as those obtained from the challenge test. It was demonstrated that this recycling process is able to ensure that the level of migration of potential unknown contaminants into food is below a conservatively modelled migration of 0.1 μg/kg food. Therefore, the recycled PET obtained from the process Gneuss 1 intended for the manufacture of articles made with up to 100% recycled post-consumer PET and intended for contact for long-term storage at room temperature with all types of foodstuffs is not considered of safety concern. Trays made of this recycled PET are not intended to be used, and should not be used, in microwave and conventional ovens.
- Quality changes in fresh-cut ‘Rocha’ pear as affected by oxygen levels in modified atmosphere packaging and the pH of antibrowning additivePublication . Gomes, M. Helena; Fundo, Joana F.; Poças, M. Fátima; Almeida, Domingos P. F.Respiratory behavior of fresh-cut ‘Rocha’ pear suggests that optimization of O2 concentration inside modified atmosphere packages (MAP) is of limited benefit. To test this hypothesis, packages were designed to achieve three equilibrium O2 partial pressures. Fresh-cut ‘Rocha’ pear was treated with 250 mM calcium ascorbate solutions buffered at pH 3.0 and pH 7.0, packaged under the three MAP conditions, and stored at 5 ◦C for 20 d. Actual O2 levels (mean ± confidence interval at 95%) during the experiment were 16.7 ± 0.2, 1.8 ± 0.2 and 0.25 ± 0.04 kPa with corresponding CO2 levels of 1.3 ± 0.1, 4.3 ± 0.2 and 6.5 ± 0.4 kPa. Changes in quality attributes related to fruit metabolism, namely firmness, titratable acidity, pH, and soluble solids content were not affected by O2 levels. Overall changes in water activity, levels of ascorbate, and microbial growth were also independent of O2 levels. Oxygen partial pressure inside the packages affected browning, which was more intense at 16.7 kPa O2. Sensory analyses performed after 8 d in storage confirmed that panelists perceived the differences in color but did not detect differences in firmness or taste among the samples under different O2 levels. Browning was more intense at pH 3.0 than at pH 7.0 but the kinetics of other quality attributes were not affected by pH. No significant improvements of quality attributes dependent on the physiology of respiration of fresh-cut ‘Rocha’ pear can be obtained by reducing O2 partial pressure inside the packages.