Ana Cristina Correia

Activity and batch operational stability of Candida rugosa lipase immobilized in different hydrophilic polyurethane foams during hydrolysis in a biphasic medium

Abstract The aim of this study was to investigate eventual relationships between some physico-chemical properties (e.g. porosity, aquaphilicity, partition coefficient for oleic acid and drying curves) of relatively hydrophilic polyurethane foams and the activity and batch operational stabiliy of Candida rugosa lipase immobilized within these foams. Two biocompatible polyurethane pre-polymers (“HYPOL FHP 2002TM” and “Hypol FHP X4300TM” from Hampshire Chemical GmbH, Germany) were tested as immobilization supports. The model reaction was the hydrolysis of crude olive residue oil in a biphasic aqueous/n-hexane medium.Drying curves under normal and reduced pressures suggested that water molecules are more strongly bound to the “FHP 2002” than to “FHP X4300” foams. This is in agreement with the higher aquaphilicity value estimated for the “FHP 2002” foam (3.7 vs 2.8).For every enzyme loading tested, hydrolysis efficiency was considerably higher for the lipase in “FHP X4300” foam when compared to the other counterpart. However, internal mass transfer limitations seem to be more severe with “FHP X4300” foams.Operational stability was evaluated in 10 consecutive batches (1 batch = 23 hours) for both immobilized preparations. A fast deactivation was observed for both biocatalysts. However, a slightly higher operational stability was observed for the lipase in “FHP 2002” foam. For the lipase in “FHP X4300” foam, the activity decay can be explained by a dramatic lipase leakage from the foam observed along successive batches. For the lipase in “FHP 2002” foam, no significant enzyme loss was observed along the reutilizations probably due to a higher number of multi-point attachment between the lipase and its support.In fact, activity and operational stability of Candida rugosa lipase in “FHP 2002” and “FHP X4300” foams appear to be related with the strength and/or the number of covalent binding between the enzyme and the support rather than to the physico-chemical properties evaluated in this work.

Antioxidant capacity, scavenger activity, and ellagitannins content from commercial oak pieces used in winemaking

In 2005, the European Union authorized the use of oak wood pieces in winemaking, and consequently, the addition of oak chips has been generalized. Thus, the antioxidant capacity, scavenger activity, and ellagitannins content from fourteen different commercial oak wood pieces (Quercus spp.) that can be found on the Portuguese market as alternatives to barrels for aging wines were studied. Commercial oak wood pieces samples from Quercus petraea had significantly higher antioxidant activity values than the pieces from Quercus alba species. In general, antioxidant capacity and scavenging activity decrease with the toasting level of the oak wood pieces samples analyzed. A similar effect was detected in the individual ellagitannin content studied. On the other hand, with the toasting process, the total phenolic content and the ellagic acid concentration increased. Finally, a correlation analysis revealed that ellagitannins contribute to the antioxidant capacity of oak wood pieces studied. From the data presented in this paper, antioxidant capacity and ellagitannin content of the oak wood pieces studied have been clearly related either to the oak wood species used, particle size, or to toasting levels.

Proanthocyanidin content, antioxidant capacity and scavenger activity of Portuguese sparkling wines (Bairrada Appellation of Origin)

BACKGROUND The main object of the present study was to investigate the different proanthocyanidin fraction (monomeric, oligomeric and polymeric fraction) contents, antioxidant capacity and scavenger activity of the most important and representative commercial sparkling wines available in Bairrada Portuguese Appellation of Origin. RESULTS The white commercial sparkling wines tested had much less total phenolic, proanthocyanidin content, antioxidant capacity and scavenger activity than the sparkling red wines. For all white and red sparkling wines the polymeric fraction of proanthocyanidins was the most abundant fraction quantified. The antioxidant capacity was positively correlated with the different proanthocyanidin fractions studied. However, in general, higher correlations between total polyphenols, different proanthocyanidin fractions and antioxidant capacity were found only for red sparkling wines. CONCLUSION The results confirm that Portuguese sparkling wines from Bairrada Appellation of Origin are good sources of antioxidants when compared with other wines elaborated from other grapes varieties and from other regions. At same time, good linear correlations between the levels of each different proanthocyanidin fractions and total polyphenols with antioxidant capacity were found for the commercial sparkling wines analysed.

Relationship Between Antioxidant Capacity, Proanthocyanidin and Anthocyanin Content During Grape Maturation of Touriga Nacional and Tinta Roriz Grape Varieties

To investigate antioxidant capacity in seeds and skins during grape maturation and its relationship with anthocyanin and proanthocyanidin content, two Portuguese red grape varieties, Touriga Nacional and Tinta Roriz (Vitis vinifera L.) were studied. Two analytical methods were used for antioxidant capacity analysis: the DPPH and ABTS methods. Proanthocyanidins from seeds and skins were separated into monomers, oligomers and polymers, while 13 individual anthocyanins from the skins were also evaluated by HPLC. For both grape varieties studied, antioxidant capacity from the skins and seeds was characterised during grape maturation by a general decrease, mainly in the first weeks after veraison, followed by stabilisation and a slight increase in the values in the last three weeks of ripening. A similar tendency was observed for the amount of all the different proanthocyanidin fractions quantified. Our results also showed that seeds are an important source of proanthocyanidins with respect to the grape berry skins. Seeds were also the grape berry fraction with the highest antioxidant capacity when compared to the antioxidant capacity content of the skins. For the 13 individual monomeric anthocyanins quantified during grape maturation, evolution was generally characterised by a continuous increase in the values. However, for some of the individual anthocyanins, the continuous increase was followed by stabilisation or a decrease in the values in the last weeks of ripening. Finally, there was a positive relationship between the different proanthocyanidin fractions and antioxidant capacity of both grape varieties studied; while a negative relationship during grape maturation was obtained for individual anthocyanins.

Study About the Knowledge and Attitudes of the Portuguese Population About Food Fibres

The association between dietary fiber, health benefits and healthy food has been studied in recent years. The food industry, to accompany the strong interest shown by consumers, has placed at their disposal new products, rich in dietary fiber. This work intended to make a statistical analysis of the knowledge of the Portuguese population about fibres, and for that a survey was conducted of a sample of 182 individuals. Some topics covered included consumption habits, knowledge about fibres, means of dissemination and information, food labelling or the relationship between fibres and health, among others. The most relevant results indicate that only 13% of respondents eat two meals a day with vegetables and/or salads and 9% eat at least 3 pieces of fruit. Whole grains are never consumed by only 41% and 18% do so at least once a week. Around 35% of respondents know about the origin of fibres whereas 70% say there is a greater amount of fibre in legumes, fruit with skin and whole foods. The consultation of food labels is of interest to 80% of respondents, although the fibre content is not of interest for 43% of respondents. The vast majority (90%) of respondents have the notion that fibre intake contributes to the prevention and treatment of diseases. With this work it was concluded that the individuals in the survey reveal an insufficient level of knowledge about dietary fibre and that, although they give great importance to the role of fibres in treatment and prevention of diseases, the level of intake is too low.

Evaluation of Textural Properties in Apples of Regional Varieties

Regional varieties of apples present an endogenous patrimony that should be preserved and promoted to guarantee biodiversity of genetic resources. In the present work, Texture Profile Analysis (TPA) was performed to apples of fourteen different regional varieties, having in consideration the spatial geometry of the fruits, and the textural parameters: hardness, adhesiveness, springiness, cohesiveness, and chewiness were assessed. The samples to perform the TPAs were obtained from different locations in the fruit–external and internal–and considering axial and radial orientations. The results of these analysis performed allowed us to conclude that the apples from regional varieties showed different textural properties among themselves. Furthermore, it was generally observed that hardness does not vary much according to the internal or external location of the sample, but varies quite significantly according to the orientation, being generally higher for the axial measurements. From the present work, it was possible to conclude that, in terms of textural properties, the varieties studied showed important differences.

Antioxidant capacity, radical scavenger activity, lipid oxidation protection analysis and antimicrobial activity of red grape extracts from different varieties cultivated in Portugal

The aim of this study was to investigate the antioxidant capacity, radical scavenger activity, lipid oxidation protection and antimicrobial activity of grape extracts from 12 different red grape varieties cultivated in Portugal. The mean values of total phenolic content quantified in grape extracts varied from 833.7 to 2005.6 mg/L gallic acid. Antioxidant capacity results showed different values for each grape variety ranging from 3.96 to 32.96 mm/L Fe(II). The scavenger activity values ranged from 15.99% to 54.82% for the superoxide radical and from 11.79% to 29.67% for the hydroxyl radical. The grape extracts with the highest antioxidant capacity had a positive effect on the lipid oxidation protection and induced low peroxide values in butter samples. Finally, concerning antimicrobial activity, grape extracts from Touriga Nacional and Tinta Roriz grape varieties had significant antimicrobial activity, especially notable for total mesophilic aerobics.

Mercury levels in parturient and newborns from Aveiro region, Portugal

ABSTRACT Since the outbreak of methylmercury (MeHg) poisoning in Japan and Iraq, mercury (Hg) is classified as well-established teratogen. The Portuguese region of Aveiro faced some decades ago an environmental Hg contamination due to activities from a chlor-alkali plant. Until now, no apparent evaluation was conducted regarding prenatal exposure to Hg in this area. The main objectives of this study were to: i) assess maternal and fetal exposure to Hg in the Aveiro region using noninvasive biological matrices; ii) examine the influence of variables that may contribute to Hg exposure during pregnancy; and iii) improve knowledge regarding metal accumulation and distribution over the maternal–fetal–placental unit. This study was performed in 50 mother–newborn pairs from the Aveiro district. Total Hg (THg) was quantified in maternal scalp hair, placenta, amniotic membrane, and umbilical cord. Maternal hair presented THg levels with a mean value of 900 ng/g, which is lower than the USEPA and WHO acceptable threshold. Regarding THg levels in placenta and umbilical cord, mean values were similar (decidua basalis: 32.84 ng/g; chorionic plate: 30.18 ng/g; umbilical cord: 30.67 ng/g). The amniotic membrane presented the highest THg levels with a mean concentration of 42.35 ng/g, reaching a maximum of 134.1 ng/g. Further, a significant positive correlation was noted between THg levels found in hair, and all matrices analyzed reinforcing the use of hair in biomonitoring studies with respect to maternal exposure to Hg. In general, levels of THg found in our study were lower than those in previous studies performed in Europe. Consumption of fish rich in selenium and bottled water was negatively correlated with THg levels. Finally, data demonstrated that Hg is capable of crossing the placental barrier and accumulate in placental tissues. Amniotic membrane seemed to play a role in metal detoxification, but further investigations are necessary to examine whether this catabolic process affects Hg accumulation.

Analysis of factors influencing the physical, chemical and sensorial properties of Serra da Estrela cheeses

The objective of this study was to evaluate the chemical, color, textural, and sensorial characteristics of Serra da Estrela cheese and also to identity the factors affecting these properties, namely thistle ecotype, place of production, dairy and maturation. The results demonstrated that the cheeses lost weight mostly during the first stage of maturation, which was negatively correlated with moisture content, being this also observed for fat and protein contents. During maturation the cheeses became darker and with a yellowish coloration. A strong correlation was found between ash and chlorides contents, being the last directly related to the added salt in the manufacturing process. The flesh firmness showed a strong positive correlation with the rind harness and the firmness of inner paste. Stickiness was strongly related with all the other textural properties being indicative of the creamy nature of the paste. Adhesiveness was positively correlated with moisture content and negatively correlated with maturation time. The trained panelists liked the cheeses, giving high overall assessment scores, but these were not significantly correlated with the physicochemical properties. The salt differences between cheeses were not evident for the panelists, which was corroborated by the absence of correlation between the perception of saltiness and the analyzed chlorides contents. The Factorial Analysis of the chemical and physical properties evidenced that they could be explained by two factors, one associated to the texture and the color and the other associated with the chemical properties. Finally, there was a clear influence of the thistle ecotype, place of production and dairy factors in the analyzed properties.

Composition of regional Portuguese apple cultivars in different harvest years.

In the present study, apples of regional cultivars originating from Portugal were compared in terms of some chemical properties during three consecutive harvest years. It was possible to conclude that these regional cultivars of apples were generally sweeter and contained more minerals than other cultivars described in the literature. The data revealed that the acid, protein, and mineral content depended on the apple cultivar. The acid content varied notably with the 2004, 2005, and 2006 harvests. For total sugar or protein content, the variations observed were comparatively smaller. In the 2004 and 2005 harvests, the sugar and protein contents were similar but differ from the 2006 harvest. In respect to mineral content, the 2004 harvest registered the highest differences, and this was also the year when the apples had the highest maturation index, calculated as the sugar/acid ratio.