ESAV - DIA - Artigo em ata de evento científico nacional
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- Comparative study of the influence of microwave and hot air drying on mass transfer and qualitative aspects of pomegranate (Punica granatum L.) arilsPublication . Kaveh, M.; Golpour, I.; Guiné, Raquel P. F.Despite being an ancient method for food preservation, drying is still nowadays one of the most widely used techniques to extend shelf life of food products. There are numerous methods for drying, either isolated or in combination.1 In the case of microwave drying, the microwave energy penetrates the food and has the capacity to generate heat inside the sample. This quick energy can easily penetrate the inside layers, causing water elimination through an exterior flux of rapidly escaping vapour. Hence, microwave drying method can be faster and produce a higher quality final product, as compared, for example, with conventional hot air drying. 2 In this study, the drying time, effective moisture diffusivity, specific energy consumption, shrinkage, and color properties of the pomegranate arils were compared when dried by convective drying (CVD) and microwave drying (MW). The experiments were conducted at air temperatures of 50, 60 and 70°C and air velocities of 1 m/s for the convective dryer and at power levels of 270, 450 and 630 W for the microwave dryer. The results showed that increasing air temperature and microwave power increased the effective moisture diffusivity. The calculations demonstrate that the maximum effective moisture diffusivity value for pomegranate arils was achieved under microwave drying (630 W). Additionally, the analysis specifies that maximum specific energy consumption for pomegranate arils in the convective dryer was 145.12 kWh/kg whereas it was found to be 35.42 (kWh/kg) when using the microwave dryer. The lowest values for total color change and shrinkage observed were 14.77 and 66.5%, respectively, and they occurred for microwave drying. Comprehensive comparison of the various dryers (microwave and convective) revealed that microwave drying performed best for the drying of pomegranate arils, taking into consideration the drying time, effective moisture diffusion, specific energy consumption, color and shrinkage.
- Phenolic Compounds and Antioxidant Activity Modeling in Strawberry by using Artificial Neural Networks (ANNs) TechniquePublication . Golpour, I.; Gonçalves, Fernando; Correia, Paula; Guiné, Raquel P. F.Extraction constitutes a vital procedure when attaining bioactive compounds from plant matrices. Conventional extraction using solvents is highly dependent on variables such as time, temperature, solid to liquid ratio or type of solvent, among others, leading to the need for optimising process variables in order to increase the yield.1,2 This research study focuses on the evaluation of total phenolic compounds (TPC) and antioxidant activity (AOA) of strawberry fruits according to different experimental extraction conditions by application of Artificial Neural Networks (ANNs) technique. The experimental data was applied to train ANNs using feed and cascade forward back propagating models by Levenberg-Marquardt and Baysian regulation algorithms. Three independent variables (solvent concentration, volume/mass ratio and extraction time) were used as ANNs inputs whereas the three variables of total phenolic compounds, DPPH and ABTS Antioxidant Activities were considered as ANNs outputs. The results demonstrated that the best neural network cascade and feed forward back-propagation topologies for the prediction of total phenolic compounds and DPPH and ABTS antioxidant activity factors were the 3-9-1, 3-4-4-1 and 3-13-10-1 structures with the training algorithm of trainlm, trainbr, trainlm and threshold functions of tansig-purelin, logsig-tansig-tansig and tansig-tansig-purelin, respectively. The best R2 value for the predication of total phenolic compounds and DPPH and ABTS antioxidant activity factors were 0.9806 (MSE=0.0047), 0.9651(MSE=0.0035) and 0.9756 (MSE=0.00286), respectively. According to the comparison of ANNs, the results showed that cascade forward back propagation network had better performance than feed forward back propagation network for the prediction of TPC as feed forward back propagation network in predicting the DPPH and ABTS antioxidant activity factors had more precision than cascade forward back propagation network. According to the obtained results, it was possible to predict TPC and AOA as a function of extraction time, volume/mass ratio, solvent concentration and volume.
- Valorization of Halimione portulacoides as food ingredient Biological and Nutritional StudiesPublication . Pires, A.; Agreira, S.; Ressurreição, S.; Marques, J.; Guiné, Raquel P. F.; Barroca, Maria João; Silva, A. M.The prospect of global warming and freshwater reduction leads to an increase of saline and dry conditions of the land and leads to an enhanced need for salt-tolerant crops. Halimione portulacoides (sea purslane) is an halophyte plant found on coastlines and salt marches around the coasts of North Africa, South-West Asia and Europe. In Europe is one of the most productive and abundant species in salt marshes. H. portulacoides (sea purslane, “gramata branca” or “beldroega do mar” in Portuguese) is dispersed along the coast of the Iberian Peninsula. In this study, the leaves of sea purslane, collected in salt marshes of Figueira da Foz (Portugal) were characterized at nutritional and mineral composition. Total phenolic compounds (Folin Ciocalteu method) and antioxidant activity (-carotene/linoleic acid, metal chelating ability, FRAP and CUPRAC method) were also assessed in methanolic extracts obtained from the leaves. Moreover, was developed an enriched food (butter) with sea purslane powdered dried leaves and the sensorial evaluation (colour, flavour, scent, texture and overall acceptance) of the novel food was performed by a consumer panel. The butter was prepared according to standard procedure, controlling butter´s moisture content up to 16%. A portion of butter was salty with NaCl (1.0%) and the other with 0.8 % of dried leaves of sea purslane. After salting, the butter was worked vigorously to ensure even distribution of the salt or sea purslane powder. The butter enriched with H. portulacoides is presented in Figure 1. Figure 1. Butter enriched with H. portulacoides. From a nutritional point of view, sea purslane leaves may be considered as a good source of dietary fibre, protein, natural minerals such as sodium, calcium, magnesium and manganese. The intake of 100 g of fresh leaves sea purslane provides 24%, 28%, 74% and 78%, respectively, of the daily value recommended for calcium, magnesium, manganese and sodium. Due to their content in sodium, sea purslane can be viewed as a good candidate to be a food ingredient to replace salt (NaCl). On the other hand, leaves showed a high level of total phenolic compounds and a considerable antioxidant. Concerning the food sensory evaluation, butter with the incorporation of H. portulacoides had the higher scores in all organoleptic characteristics. Thus, it was verified that the use of H. portulacoides can be considered a promising salt substitute in butter and a good alternative to enhance the nutritional and sensorial characteristics of products, with additional health benefits.
- Produção de farinha de larvas e pupas de zângãoPublication . Correia, Paula; Vouga, C.; Coelho, C.; Guiné, Raquel P. F.; Costa, Cristina Amaro DaA técnica da remoção dos quadros de zângão, utilizada no controlo do ácaro Varroa destructor, pode proporcionar uma fonte alternativa de alimento, sendo para isso necessário desenvolver técnicas simples e viáveis de extração e utilização das larvas e pupas. Este trabalho teve como objetivo testar dois métodos de extração, o método de extração a frio e a quente. Após a recolha os quadros foram congelados para garantir a sua conservação. Seguiu-se a extração das larvas e pupas através de métodos de extração a frio e extração quente (imersão em água a ferver). A extração a frio foi realizada manualmente com duas condições: sala fria (61ºC); superfície fria. Os rendimentos de extração variaram entre 62,57,5% e 84,94,0%, respetivamente para a superfície fria e para a extração a quente. Os tempos de extração mais elevado foi para a extração a frio em sala fria (336,342,4 segundos) e o mais baixo para a superfície fria (246,830,1 segundos). As larvas e pupas foram submetidas a dois tipos de desidratação: vaporização e liofilização. A vaporização escureceu demasiado as larvas e pupas não se revelando um bom processo de secagem. Deste modo, a farinha foi produzida a partir da trituração das larvas e pupas secadas por liofilização (até peso constante). Nutricionalmente as farinhas apresentaram-se ricas em proteína e gordura. Este novo produto poderá proporcionar o aumento do rendimento da atividade apícola, benefícios nutricionais e usos na produção de novos produtos à base de farinha de zângão.
- Liquefaction optimization of peel of potato Solanum tuberosum L. var Monalisa.Publication . Dulyanska, Y.; Cruz-Lopes, Luísa; Esteves, Bruno; Guiné, Raquel P. F.; Ferreira, José; Domingos, IdalinaThe potato (Solanum tuberosum L.) is native to South America, in the Andes Mountains where it was consumed by native populations 1. According to the Food and Agriculture Organization of the United Nations (FAO), there has been a large increase in potato production in Latin America and Asia, especially China, that in 2018 was the largest producer followed by India. These two countries represented almost a third of the potatoes consumed in the world 1. In Portugal, the most widely planted potato is Solanum tuberosum L. var Monalisa, that is used by potatoes’ processing industry, generating tons of potato peel waste annually. The waste from the potato industry accounts for approximately 27% of total production. The objective of this work was to evaluate the potentiality of potato industrial residues to be liquefied by polyhydric alcohols and the chemical transformations observed in this process with subsequent use to produce polyurethane foams. Potato peel waste (PPW) was dried in an oven, crushed in the Retsch SMI mill and sifted in a vibratory sieve model Retsh 5657 HAAN 1 for 30 minutes. The fractions obtained were > 35 mesh, 35-40 mesh (0.500-0.425 mm); 40-60 mesh (0.425-0.250 mm); 60-80 mesh (0.250-0.180 mm) and 80 mesh (< 0.180 mm). The liquefactions were made in an oil-heated double-shirt reactor with a mixture of glycerol and ethylene glycol 1:1, catalyzed by 3% sulfuric acid. The effect of particle size (<80 mesh at >35 mesh) temperatures (140 oC - 180 oC), ratio material/solvent (1:5, 1:7, 1:10, 1:12) and times (15-60 min) were studied. The Fourier Transform Infrared Spectroscopy by Attenuated total reflection (FTIR-ATR) was used to evaluate the functional groups present in the original sample of PPW, in the liquefied sample and in the solid residue obtained. Liquefaction percentage with increased temperature, time, material/solvent ratio and granulometry is presented (Figure 1). Results show that liquefaction performed at 180 oC with a 1:10 material/solvent ratio, increases along time, reaching a maximum at 60 min. Similarly, liquefactions made during 60 min with a 1:10 material/solvent ratio show that there is an increase in liquefaction yield with the increase in temperature until 180 oC. A higher temperature could increase the liquefaction yield but would lead to a higher energy consumption in the process. There seems to be no significative advantage in increasing material/solvent ratio above 1:7, although the liquefaction yield increases for higher ratios. Granulometry testing shows that the smaller the particle the best is the liquefaction percentage. It was concluded that the best liquefaction yield, of approximately 90%, was obtained with a temperature of 180 oC, for 60 min and particle size <80 mesh for PPW. This material has good properties to be converted in a liquid mixture that can be used later, on the production of polyurethane foams (Figure 1). The PPW spectrum exhibits the common bands for agricultural materials (Figure 2). The main differences between the solid material and the liquefied material is the high OH band with a peak at around 3300 cm-1 for both the original material and the liquefied, while the peak for the solid residue is at higher wavenumbers. The liquefied sample has a considerable higher OH peak than the solid samples, which is probably due to the polyalcohols used for the liquefaction. The band at 1740 cm-1 (non-conjugated C=O bonds) is higher in the solid residue spectrum and smaller in the liquefied material. Similarly Jin et al. 2 observed the absence of C=O groups after the liquefaction of enzymatic hydrolysis lignin. The highest peak in the original and in the liquefied material spectra is the peak at 1100 cm-1 which has been attributed to C–O stretching vibrations in carbohydrates. This is in accordance with several chemical compositions reported for PPW 1. In the liquefied material a new peak appears at around 860 cm-1, which can be due to stretching in the pyranose ring as stated before 3.
- The impact of extraction temperature and solution concentration on the antioxidant activity of sweet cherry seeds’ extractsPublication . Dulyanska, Y.; Cunha, Margarida; Lima, M. J.; Correia, Paula; Ferreira, Manuela; Fragata, Anabela; Cardoso, Ana Paula; Barroca, Maria João; Silva, A.; Cruz-Lopes, Luísa; Esteves, Bruno; Ferreira, José; Domingos, Idalina; Guiné, Raquel P. F.Sweet cherry seeds, a valuable lignin-cellulose raw material for the production of polyurethane foams 1, are also a significant source of different phenolic compounds 2 and can be a good source of natural antioxidants, which can play an important role in preventing the formation of free radicals and protection against degenerative diseases. Considering sustainability, the main objective of this project was the use of cherry by-products (seeds) to produce extracts rich in antioxidant compounds. In this work, the seed extracts were obtained with the addition of different combinations of ethanolic solution (water:ethanol ratios - 50:50; 60:40; 80:20; 100:0 v:v) and at different temperatures (35, 50, 70 and 80 °C), all under magnetic stirring for 40 minutes. Then, the antioxidant activity of the extracts was evaluated through spectrophotometric methods, using the DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-di-(3-ethylbenzthiazoline sulfonic acid)) radicals, and also the Ferric Reducing Antioxidant Power Assay (FRAP). All measurements were replicated at least in triplicates and were expressed as mg Trolox equivalents per gram (mg TE/g). Statistical analysis was performed using the JAVA software. ANOVA tests show that there is a statistically significant effect of temperature, water percentage and temperature on the antioxidant activity evaluated by the three methods used (p> 0.001 in all tests). The percentage of water is the variable that most contributes to this effect. Individual Post Hoc comparisons show, for all tests, that in general the temperatures induce differences in antioxidant activity, except 70 °C and 80 °C in DPPH and FRAP, and 80 °C and 50 °C in ABTS. Regarding the percentage of water, it was found that all samples are different from each other, except the FRAP, in which no significant differences between 50 and 60% of water were found. In conclusion, no major differences between the ABTS, DPPH and FRAP methods were found. Temperature and percentage of water have a significant effect on the concentration of antioxidant activity in all methods. In that way, the cherry pit is a good by-product to produce extracts with high content of antioxidant activity, being that the 70° C with 50:50 and 60:40 water:ethanol solutions are the most favorable conditions to potentiate the antioxidant activity.
- Estudo Internacional do nível de conhecimento sobre insetos comestíveisPublication . Guiné, Raquel P. F.; Florença, Sofia De Guiné E; Ferreira, Manuela; Costa, Cristina Amaro Da; Correia, Paula; Cardoso, Ana Paula; Campos, Sofia; Anjos, Ofélia; Chuck-Hernandez, C.; Saric, M.; Papageorgiou, M.; Baro, J.; Korzeniowska, M.; Bizjak, M.; Bartkiene, E.; Tarcea, M.; Boustani, N.; Djekić, I.; Klava, D.; Damarli, E.Resumo: Introdução – O consumo de insetos é uma prática tradicional ao longo da história humana, mas o seu consumo é muito variável de acordo com a região do globo. Objetivos – Pretendeu-se investigar o nível de conhecimento sobre insetos comestíveis numa amostra de participantes de treze países. Métodos – Os dados foram recolhidos em 2021 por questionário online. Obtiveram-se 6899 respostas válidas. Para a análise dos dados usou-se análise fatorial, análise de clusters e testes qui-quadrado. Resultados – Foram usados 27 itens para medir o conhecimento, utilizando uma escala do tipo Likert de cinco pontos. Aplicando análise fatorial obteve-se uma solução que explica 55% da variância total observada. Esta inclui 4 fatores que retiveram 22 dos 27 itens iniciais: F1 = Sustentabilidade (8 it); F2 = Nutrição (8 it); F3 = Fatores de Produção (2 it); F4 = Preocupações com a Saúde (4 it). A análise de clusters produziu três grupos de participantes (indivíduos 'receosos', 'agricultores' e 'ecológicos'). A caracterização dos clusters revelou que a idade não influenciou a inclusão nos clusters, enquanto sexo, escolaridade, país, meio onde reside, área profissional e rendimento influenciaram a composição dos clusters. Conclusões – O nível de conhecimento sobre insetos comestíveis é altamente variável de acordo com as características individuais e localização geográfica. Por outro lado, a segmentação permitiu identificar 3 tipos de indivíduos, 'receosos', 'agricultores' e 'ecológicos'.
- Estudo Comparativo sobre o consume de produtos alimentares sustentáveis em Portugal e na turquia durante a pandemia de Covid-19Publication . Guiné, Raquel P. F.; Costa, D.; Celik, S.; Florença, Sofia De Guiné E; Ferreira, Manuela; Cardoso, Ana Paula; Cetin, S.; Costa, Cristina Amaro DaResumo: Os sistemas de agricultura biológica são sugeridos para substituir a agricultura convencional de forma a minimizar o impacto ambiental e preservar a biodiversidade. Pretendeu-se investigar as tendências dos consumidores e os hábitos de consumo de alimentos obtidos através da agricultura biológica em Portugal e na Turquia. Foi utilizado um inquérito por questionário online. Para o tratamento de dados, foram utilizadas técnicas estatísticas básicas complementadas com uma classificação em árvore destinada a avaliar a influência de fatores sociodemográficos no conhecimento sobre este tipo de alimentos. Os resultados mostraram que os padrões de consumo são semelhantes em ambos os países, com muitos participantes a consumir alimentos biológicos, especialmente vegetais e frutas, consumindo-os na sua maioria 2 ou 3 refeições por semana. As motivações mais fortes para consumir incluem benefícios para a saúde humana e menores impactos ambientais, enquanto a razão mais substancial para não consumir é o preço. Em ambos os países as pessoas têm bons conhecimentos sobre as vantagens dos alimentos biológicos em relação aos convencionais. Finalmente, a perceção do valor atribuído pela sociedade aos alimentos biológicos foi consideravelmente maior em Portugal. Estes resultados confirmam as tendências atuais dos consumidores para fazer escolhas alimentares mais sustentáveis, motivadas pelo percecionado impacto negativo da agricultura convencional nos ecossistemas e na saúde humana.
- Evaluating phenolic compounds in ethanolic extracts of cherry pitPublication . Dulyanska, Y.; Lima, M. J. Reis; Correia, Paula; Ferreira, Manuela; Fragata, Anabela; Cardoso, Ana Paula; Barroca, Maria João; Silva, A.; Cruz-Lopes, Luísa; Esteves, Bruno; Ferreira, José; Domingos, Idalina; Guiné, Raquel P. F.The climatic conditions in Portugal favoured the adaptation of the cherry tree allowing its cultivation in several regions of the country. Studies made by the Portuguese Bureau of Statistics – INE 1, showed that the Portuguese sweet cherry production has an implemented area of 6,387 ha, producing 9,241 tons of this fruit. Its production extends mainly to two regions: the North (area of 3,099 ha and production of 6,586 tons) and the Centre (3,177 ha and 2,510 tons), while the rest of the country and islands accounts for only 1.6% of the cherry production. There are several varieties of cherry in Portugal, and the most important traditionally cultivated are: “Saco da Cova da Beira”, “Saco do Douro”, “Lisboeta”, “São Julião”, Big Burlat, Maring, Napoleon-big-foot and Big Windsor, being the first four varieties native from Portugal. Cova da Beira is the most important cherry production area in Portugal, either in terms of production volume, or also in area. Additionally, the evolution of technological indicators associated with culture reveals a high degree of specialization of the “new” farms, almost always associated with other fruit crops, which coexist in a very significant number of smaller farms, of a family type, that constitute the historical legacy of cherry production on the hillside north of the Serra da Gardunha. Sweet cherry seeds result from processing sweet cherry for sweets, juices and jams’ production. Generally, seeds are considered a production waste, which gains a strong interest due to the environmental aspects related to waste disposal 2. Additionally, it is well documented that production waste, such as peels, seeds, and pomace, contain high-value bioactive compounds 3. Hence, the present work investigated the extraction of some bioactive compounds from cherry pits that originate from food manufacturing industries. The waste management company Nutrofertil, located in Portugal, namely in the district of Viseu (Tondela), provided the Seeds of Sweet Cherry (SSC) for this study. The seeds were milled and dried for stability and then used for extraction with ethanolic solutions at different percentages (from 50 to 100% water v/v). Variable temperatures were also tested and the extracts were used for quantification of phenolic compounds through spectrophotometric techniques. The material was analysed to verify that it was exempt of hydrocyanic acid. Statistical techniques were used to treat the data: (a) Hierarchical cluster analysis using squared Euclidean distance and average linkage between groups method; (b) Principal component factor analysis with Varimax rotation. The results indicated that extraction at 40 ºC with magnetic stirring and using aqueous solutions of ethanol (water:ethanol ratio = 80:20, % v/v) constitute a separate cluster. Also, extracts obtained with similar conditions but for the temperature of 35 ºC constitute another isolated cluster. Factor analysis revealed a grouping structure with four clearly distinct clusters (Figure 1). Group G1 accounts for the samples with water:ethanol 80:20 (% v/v) and a temperature of 35 ºC, corresponding to the extraction of higher amounts of anthocyanins. Group G3 includes the extractions with 100% water at 70 ºC (G3), with lowest contents of anthocyanins and flavonols. The remaining groups are divergent according to the values of total phenolic compounds. In group G4 are included samples in which were quantified high values for total phenolic compounds, flavonoids, proanthocyanidins, ortho-diphenols and phenolic acids, while G2 corresponds to samples with smaller amounts of those compounds. In conclusion, investigating the extraction potential of different conditions it was allowed to optimize the experimental conditions more favourable to maximize the recovery of certain bioactive compounds, which can have multiple applications as antioxidant substances after rigorous quality control regarding possible concentrations of hydrocyanic acid.
- Chemical properties and microbiological quality of three hazelnut varieties cultivated in PortugalPublication . Ferrão, A. C.; Guiné, Raquel P. F.; Silva, M.; Correia, PaulaHazelnut is a dried fruit that stands out for its organoleptic and nutritional characteristics and therefore is highly appreciated globally. Worldwide, there are several hazelnut varieties, and their characteristics are dependent on the genotype, agricultural techniques, post-harvest practices, geographic location and climatic conditions. In addition, the physicochemical characteristics influence the quality and shelf life of this fruit [1]. Therefore, the aim of this study was to analyse some chemical properties and also the microbiological quality of three hazelnut varieties (Grada de Viseu, Tonda de Giffoni and Butler) cultivated in Portugal. For that purpose, hazelnut kernels were analysed for moisture, water activity, fat, protein, ash and the specific extinction coefficients (K232, K268 and ΔK which is calculated from the values of the specific extinction coefficients at 264 and 272 nm). It was also performed a quantification of microorganisms at 30⁰C and of moulds and yeasts at 25⁰C. The results showed that fat was the major component for all the varieties, ranging from 70.14±1.75 g/100 g (var. Butler) to 66.46±5.33 g/100 g (var. Tonda), with no significant differences between the varieties. All analyses were done in triplicate. The fruits of the variety Grada had a higher moisture content (6.01±0.26 g/100 g), while the fruits of the var. Tonda (4.78±0.40 g/100 g) presented the lowest value, but in this case with statistically significant differences (p=0.004). According to the recommendations of the European Union, moisture content of hazelnut kernels should not exceed 6.0% [2] Regarding the water activity, the lowest value was observed for the var. Tonda (0.54±0.01), followed by the var. Butler (0.55±0.01) and finally the var. Grada (0.56±0.01), with no significant differences between them. The var. Grada was the one with the highest ash (2.73±0.08 g/100 g), fibre (6.35±0.25 g/100 g) and protein content (18.00±0.34 g/100 g), with statistically significant differences between the varieties in the three cases. Specific extinction coefficients are related to oxidation processes and provide information about the quality of the oil extracted from hazelnuts, as well as its state of conservation. The fruits from the var. Grada presented the lowest value of K232 (0.54±0.01), followed by the var. Butler (0.59±0.01) and in last the var. Tonda (0.80±0.08), which means that the fruits of the var. Tonda had more primary oxidation products, being the results for this var. statistically different from the others. As for the K268, all the varieties presented values close to zero (Var. Grada=0.03±0.00, var. Tonda=0.04±0.00 and var. Butler=0.03±0.00), meaning that all the samples had low levels of secondary oxidation compounds. Furthermore, there were no significant differences between the varieties (p=0.373). The values of the ΔK ranged from 0.004±0.00 for the varieties Grada and Butler and 0.003±0.00 for the var. Tonda, again with no statistically significant differences, which means that it is a fresh and well-preserved oil. Regarding the microbiological results, as it can be observed in Table 1, all the varieties presented a satisfactory microbiological quality in accordance with the limits established for the count of microorganisms at 30⁰C and mould and yeast by the National Health Institute Doutor Ricardo Jorge [3] (<106 CFU/g for microorganisms at 30⁰C, <105 CFU/g for yeast and <5x102 CFU/g for moulds). Moreover, there were found statistically significant differences among the varieties under study. It is important to highlight that var. Grada was that one that presented more microorganisms at 30⁰C and also more moulds and yeast, when compared to the other varieties. This may be due to the higher moisture content of this variety.The results of this study provided important information about the chemical properties and microbiological quality of the most representative hazelnut varieties cultivated in Portugal.