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- Effect of Drying Temperature on the Physical-chemical and Sensorial Properties of Eggplant (Solanum melongena L.)Publication . Guiné, Raquel; Correia, Paula; Correia, Ana Cristina; Gonçalves, Fernando; Brito, Mariana; Ribeiro, JéssicaBackground: Eggplant is an important crop, being cultivated and consumed in many countries. However, like other vegetables, is highly perishable and has a short shelf life. Objective: The objective of this study was to evaluate the effect of hot air drying on some physical, chemical and sensorial properties of eggplant. Methods: Eggplant samples were dried in convective chambers at constant temperatures of 50, 60, 70 and 80°C. The fresh and dried samples were evaluated for moisture, water activity, vitamin C, total phenolic compounds, antioxidant activity, colour and texture. To complement the study, a sensorial evaluation was made by a consumer panel. Results: The results showed that drying decreased importantly the contents of vitamin C and phenolic compounds as well as antioxidant activity. Moreover, the negative impact was higher for higher drying temperatures. Drying also altered the colour, turning the samples darker. The textural properties were similarly considerably altered by drying, although the temperature did not show significant influence. Regarding the sensorial evaluation, even though it allowed establishing the sensory profiles of the dried samples, it was not possible to clearly distinguish among them, particularly the global appreciation. Conclusion: It was concluded that the drying operation substantially changed the physical, chemical and sensory properties of eggplant. Furthermore, the drying temperature had higher effect on the chemical components and colour and nor so much on the texture.
- Physical properties of frozen ewe’s cheesePublication . Correia, Paula; Rodrigues, Melania; Mendes, Rita; Guiné, RaquelThis work evaluates the effect of freezing and storage time in ewe´s cheese. Ewe´s cheeses were subject to two different conservation conditions: frozen at -60 C, with storage at -18 C (Frozen), and refrigeration at 7 C, with a RH (relative humidity) of 47% (Control). The initial values of moisture and water activity (a w ) were high and similar between the analysed samples, 62.2-61.3 % and 0.91-0.92 respectively, with a decrease of moisture during the storage, being lower in the Frozen sample. The cheeses presented an light colour (L* = 69.0 and 74.6), which decreased during storage. The a* and b* coordinates showed negative and positive values, respectively, meaning that the predominant colours were green and yellow, and generally during storage they diminished. The texture of cheeses, in the first day of storage, presented similar values for Control and Frozen cheeses: 9.8 and 9.9 N for crust firmness; 3.6 and 3.9 N for flesh firmness; -2.6 and -2.8 N for stickiness; -22.7 and 24.7 N.sec for adhesiveness. Finally, after 120 days of storage for these cheeses, the crust firmness, the stickiness and the adhesiveness decreased more about three times.
- Hazelnuts: a valuable resourecePublication . Guiné, Raquel; Correia, PaulaHazel (Corylus avellana L.) nutshell is one of the most consumed and most appreciated nut fruit all over the world. It is believed to have constituted a basic food in early prehistory, in temperate zones of the globe, such as for example Europe. Presently the hazelnut production is mainly concentrated on the Black Sea coast of Turkey, but other countries are also important producers, like for example Portugal, situated on the western Europe, in the Iberian Peninsula. The objective of this talk is to make a review about the worldwide importance of hazelnut, their usages, including gastronomic and industrial applications, as well as some ways that allow adding value to this fruit, making it an even more valuable resource. The advantages include higher income for produces, lower environmental impacts and valorisation of residues improving sustainability and providing valuable products for consumers and/or ingredients to incorporate into those products.
- Artificial neural network modelling of the chemical composition of carrots submitted to different pre-drying treatmentsPublication . Barroca, Maria João; Guiné, Raquel; Calado, Ana Rita P.; Correia, Paula; Mendes, MateusThe effect of various pre-drying treatments on the quality of dried carrots was evaluated by assessing the values of moisture, ash, protein, fibre, sugars and col- our. The pre-drying treatments under investigation were dipping, either in ascorbic acid or sodium metabisulphite at different concentrations and pre-treatment times, as well as blanching. The experimental data was analysed using neural networks, so that relevant patterns in the data were found and conclusions drawn about each variable. The results showed that the type of pre-drying treatment (chemical or physical) had variable impact on the nutri- tional composition of the dried carrots but not on the colour parameters, which were found to be mostly unaffected by the pre-treatment procedure. Pre-treatment with chemical agents such as ascorbic acid or metabisulphite seem to have the least impact on the parameters studied. The results of the analysis by artificial neural networks confirmed these findings.
- Physical properties of frozen ewe’s cheesePublication . Correia, Paula; Rodrigues, Melania; Mendes, Rita; Guiné, RaquelThis work evaluates the effect of freezing and storage time in ewe´s cheese. Ewe´s cheeses were subject to two different conservation conditions: frozen at -60C, with storage at -18C (Frozen), and refrigeration at 7C, with a RH (relative humidity) of 47% (Control). The initial values of moisture and water activity (a w ) were high and similar between the analysed samples, 62.2-61.3% and 0.91-0.92 respectively, with a decrease of moisture during the storage, being lower in the Frozen sample. The cheeses presented a light colour (L* = 69.0 and 74.6), which decreased during storage. The a* and b* coordinates showed negative and positive values, respectively, meaning that the predominant colours were green and yellow, and generally during storage they diminished. The texture of cheeses, in the first day of storage, presented similar values for Control and Frozen cheeses: 9.8 and 9.9 N for crust firmness; 3.6 and 3.9 N for flesh firmness; -2.6 and -2.8 N for stickiness; -22.7 and 24.7 N.sec for adhesiveness. Finally, after 120 days of storage for these cheeses, the crust firmness, the stickiness and the adhesiveness decreased more about three times.
- Development of Jelly Gums with Fruits and Herbs: Colour and Sensory EvaluationPublication . Guiné, Raquel; Correia, Paula; Florença, SofiaThis work aimed to evaluate the colour and sensory properties of jelly gums made with fruits and herbs. The colour was measured by a colorimeter in the Hunter lab coordinates (L*, a* and b*). Sensory evaluation comprised preference tests and profile analysis. The results showed that the colour of gums with blueberry was considerably different than other fruits (strawberry and raspberry). The sensory preference test allowed choosing 4 from the 16 prototypes developed (Blueberry & Mint, Raspberry & Mint, Strawberry & Mint, Strawberry & Anise), which were then characterized in terms of colour and sensory properties. The sensorial profile showed that Blueberry & Mint gums had visual aspect indicators as well as a better aroma to herb. However, for most of the attributes evaluated, the gums made with Strawberry & Anise got higher scores, including global appreciation. The results of colour evaluation revealed that the Blueberry & Mint gums were substantially different from the others. Hence, the results indicated that two of the gums developed, Blueberry & Mint and Strawberry & Anise, might have success when launching on commercialization.
- Chemical and physical characterization of samosas with shiitake mushroomPublication . Guiné, Raquel; Correia, Paula; Gonçalves, InêsOwing to the increasing demand for shiitake mushrooms, a substantial amount of by-products is produced on a daily basis. Hence, to investigate ways to value this resource is of wide interest. In that way, the aim of this work was to develop new valued foods incorporating shiitake mushroom, to utilize the products that do not comply with standards for commercialization, thus avoiding waste. For this, a filling for samosas was produced and the final products were analyzed for their chemical composition, color, texture and sensorial attributes. The results showed that the shiitake samosas had a somewhat balanced chemical composition, with protein and minerals, but not forgetting fat, present due to the frying operation. The color varied between samples, although on average both sides of the samosas were of practically the same color. The textural measurements indicated that the shiitake samosas were soft and with low chewiness, with moderate resilience and cohesiveness and high springiness. The sensory panel appreciated both the dough and the filling, as well as the whole shiitake samosas, by attributing them high scores (about 4, on a scale from 1 to 5). Finally, some significant correlations were found between some specific sensorial evaluations and instrumental measurements.
- Development of products with Shiitake mushroom: chemical, physical and sensory characterizationPublication . Guiné, Raquel; Correia, Paula; Florença, Sofia G.; Gonçalves, InêsShiitake mushrooms are much appreciated and therefore their production has increased. However, an important quantity of by-products and residues, are also generated and which are considered as waste materials. In this way, the aim of this work was to develop new foods incorporating shiitake mushrooms that do not comply with standards for commercialization, thus providing additional sources of income for the farmers. For this, a filling with mushroom was produced for rissoles and pies, and the final products were analysed for their chemical composition, colour, texture and sensorial attributes. The results showed that the shiitake products presented an interesting chemical composition, rich in protein and minerals, and poor in salt. It was also observed that the frying operation induced more colour changes in the rissoles than the oven baking of the pies. The textural measurements indicated that the rissoles were much softer when compared to the pies, being also more cohesive and elastic. The sensory panel attributed high scores to both products (around 4.5, on a scale from 1 to 5), thus indicating that these may constitute an additional source of income to the farmers and at the same time reducing waste.
- Evaluation of some physical and chemical properties of hazelnutsPublication . Guiné, Raquel; Rodrigues, Cláudia; Correia, Paula; Ramalhosa, ElsaIn this work were evaluated some physical and chemical properties of hazelnuts from two varieties (Buttler and Longa), namely colour, texture and density at the physical level and moisture, total fat, fat oxidation, ash, protein and crude fibre as concerns the chemical composition, following established procedures. The results obtained showed that the colour of the hazelnuts varied according to the point of measurement and also depending on the variety, being the Longa clearer in all points except for the core, in which the colour was equal to Butler. Regarding texture, the Butler was harder in the shell but softer in the core as compared to Longa, which in turn showed higher friability. Regarding density, no visible differences were found between varieties, but the bulk density was naturally lower than the true density in all cases, i.e., for measurements made with and without the shell, respectively. The moisture content was higher for Butler variety, 7.13%, and this also had the highest water activity. The fat content was high, as expected, around 60% in both cases, and the time for fat oxidation was lower for the Butler variety, thus indicating a lower stability to oxidative degradation. The ash content was higher for Longa variety, which was also richer in terms of protein, 15.60 %. The fibre content, however, was higher for Butler variety, 11.11%.