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Abstract(s)
Em Portugal existe grande tradição na produção de azeite e azeitona de mesa, sendo Trás-os-Montes uma das principais regiões produtoras. No País estão reconhecidas duas Denominações de Origem Protegida (DOP) para azeitona de mesa, uma delas situada a sul da região transmontana designada “Azeitona de conserva Negrinha de Freixo” e outra no Alentejo, principal região produtora, designada “Azeitona de conserva de Elvas e Campo Maior”. No sentido de valorizar estas azeitonas, no presente trabalho pretendeu-se obter farinhas a partir da “Azeitona de conserva Negrinha de Freixo”. Para tal procedeu-se à sua secagem por convecção com ar quente, a vácuo e liofilização, fazendo para cada método a caracterização físico-química (atividade de água (aw), cor, teor de humidade, gordura e cinzas, e composição em ácidos gordos). De entre os três métodos, a liofilização foi o processo mais rápido, ao contrário do vácuo, além de originar a farinha com a melhor aparência visual. Verificou-se também que durante o processo de secagem, só se detetou um período de velocidade decrescente, não tendo sido observado um período de velocidade constante. Procedeu-se ainda à modelação dos três processos de secagem, tendo-se aplicado 11 modelos descritos na literatura, tendo-se obtido bons ajustes para alguns deles, designadamente o de Verma et al..
As farinhas obtidas por convecção de ar quente 48 horas, vácuo 96 horas, e liofilização 24 horas apresentaram valores de aw iguais a 0,234; 0,420 e 0,459, inferiores a 0,6 indicador de estabilidade microbiológica. De entre estas farinhas, a liofilizada durante 24 horas foi a que se destacou, apresentando a melhor aparência visual. Contudo, esta farinha apresentava-se demasiado salgada, tendo-se optado por realizar uma demolha de 3 a 5 dias às azeitonas utilizadas como matéria prima. Verificou-se que a demolha só diminuiu o teor em sal, de 9,65 a 5,48, correspondendo às situações sem e com demolha de 5 dias, respetivamente. Em relação aos outros parâmetros avaliados (aw, cor, humidade, gordura, proteína, cinzas, sal, hidratos de carbono, valor energético e ácidos gordos) não se observou qualquer efeito.
Este produto pode ser utilizado, na elaboração de pratos ou como matéria-prima de novos produtos a desenvolver a partir da “Azeitona de Conserva Negrinha de Freixo”
In Portugal there is great tradition in the production of olive oil and table olives, with Trás-os-Montes region being one of the main producing areas. In this country, two Protected Designations of Origin (PDO) for table olives are recognized, one located in the south of Trás-os-Montes region called "Azeitona de Conserva Negrinha de Freixo" and other in Alentejo, the main producing region, named "Azeitona de Conserva de Elvas e Campo Maior". In order to valorize these olives, in the present work it was intended to obtain flours from the “Azeitona de Conserva Negrinha de Freixo”. For this purpose, it was dried by convection with hot air, vacuum and lyophilization, making for each method the physicochemical characterization (water activity (aw), color, moisture content, fat, ashes and fatty acid composition). Among the three methods, lyophilization was the fastest process, unlike vacuum, in addition to giving flour the best visual appearance. It was also found that during the drying process only a decreasing velocity period was detected and no constant velocity period was observed. The three drying processes were also modeled and 11 models described in the literature were applied and some good adjustments were obtained, namely Verma et al.. Flours obtained by 48-hour hot air convection, 96-hour vacuum and 24-hour lyophilization had aw values of 0,234; 0,420 and 0,459, less than 0.6 indicator of microbiological stability. Among these flours, the freeze-dried for 24 hours was the one that stood out, presenting the best visual appearance. However, this flour was too salty, so it was decided to soak 3 to 5 days for the olives used as raw material. It was found that the soaking only decreased the salt content from 9,65 to 5,48, corresponding to situations without and with 5 days soaking, respectively. Regarding the other parameters evaluated (aw, color, humidity, fat, protein, ashes, salt, carbohydrates, energy value and fatty acids) no effect was observed. This product can be used in the preparation of dishes or as raw material for new products to be developed from the “Azeitona de Conserva Negrinha de Freixo”.
In Portugal there is great tradition in the production of olive oil and table olives, with Trás-os-Montes region being one of the main producing areas. In this country, two Protected Designations of Origin (PDO) for table olives are recognized, one located in the south of Trás-os-Montes region called "Azeitona de Conserva Negrinha de Freixo" and other in Alentejo, the main producing region, named "Azeitona de Conserva de Elvas e Campo Maior". In order to valorize these olives, in the present work it was intended to obtain flours from the “Azeitona de Conserva Negrinha de Freixo”. For this purpose, it was dried by convection with hot air, vacuum and lyophilization, making for each method the physicochemical characterization (water activity (aw), color, moisture content, fat, ashes and fatty acid composition). Among the three methods, lyophilization was the fastest process, unlike vacuum, in addition to giving flour the best visual appearance. It was also found that during the drying process only a decreasing velocity period was detected and no constant velocity period was observed. The three drying processes were also modeled and 11 models described in the literature were applied and some good adjustments were obtained, namely Verma et al.. Flours obtained by 48-hour hot air convection, 96-hour vacuum and 24-hour lyophilization had aw values of 0,234; 0,420 and 0,459, less than 0.6 indicator of microbiological stability. Among these flours, the freeze-dried for 24 hours was the one that stood out, presenting the best visual appearance. However, this flour was too salty, so it was decided to soak 3 to 5 days for the olives used as raw material. It was found that the soaking only decreased the salt content from 9,65 to 5,48, corresponding to situations without and with 5 days soaking, respectively. Regarding the other parameters evaluated (aw, color, humidity, fat, protein, ashes, salt, carbohydrates, energy value and fatty acids) no effect was observed. This product can be used in the preparation of dishes or as raw material for new products to be developed from the “Azeitona de Conserva Negrinha de Freixo”.
Description
Keywords
Inovação Valorização Secagem Modelação Propriedades físico-químicas.