Browsing by Author "Hmida, Khalil"
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- Aplicação de revestimentos comestíveis em castanha (Castanea sativa): efeito nas propriedades físico-químicas e microbiológicasPublication . Ramalhosa, Elsa; Hmida, Khalil; Salem, Asma Bem; Díaz, Javier Sánchez; Pereira, ErmelindaA castanha é um fruto muito consumido. No entanto, a qualidade do fruto pode ser afetada durante o seu armazenamento devido ao desenvolvimento de bolores e perda de peso. O presente trabalho teve como objetivo testar diferentes revestimentos comestíveis, nomeadamente Proallium®, Foodcoat® e a combinação de ambos, revestimentos comerciais da Empresa DOMCA, ao nível das propriedades físico-químicas e microbiológicas, ao longo de 3 meses de armazenamento, em câmaras industriais refrigeradas. Foram determinadas a perda de peso, cor, atividade da água e contagens de microrganismos a 30 ºC e bolores e leveduras. Durante os três meses de armazenamento, os parâmetros de cor da casca não apresentaram diferenças significativas entre os tratamentos, com algumas exceções. O Foodcoat foi o revestimento com melhor desempenho ao nível da perda de peso (aprox. 5%). Pelo contrário, para as castanhas revestidas com Proallium e Proallium+Foodcoat obtiveram-se perdas de peso na ordem dos 10%. Contudo, a aplicação dos revestimentos comestíveis não teve efeito significativo sobre a atividade da água. Em relação aos microrganismos a 30 ºC e os bolores e leveduras, o revestimento Proallium foi o mais eficiente durante dois meses. Em conclusão, a aplicação de revestimentos comerciais pode prevenir de forma significativa a perda de peso e o crescimento microbiano.
- Effect of commercial edible coatings on the shelf life of chestnut (Castanea sativa) subjected to long-term storagePublication . Hmida, Khalil; Ramalhosa, Elsa; Pereira, Ermelinda; Ben Salem, AsmaThe chestnut fruit is very consumed worldwide. However, three main types of problems can be stated in the postharvest and during chestnut storage, namely insect worms and the development of filamentous fungi, and weight loss. Thus, the search for methodologies that minimize these problems is fundamental. The purpose of this present work was to test different commercial edible coatings, namely Proallium, Foodcoat and the two combined, to apply to chestnuts to increase their long-term storage. Thus, the main objective of this work was to check the effect of these edible coatings on the physic-chemical and microbiological properties of the fruit along its storage to evaluate the food quality and safety. All coated and uncoated samples were stored in refrigerated industrial chambers for four months. The weight loss, color, texture, water activity (aw), moisture content, titratable acidity, total soluble solids, reducing sugars, individual sugars, starch contents, and microbiological analysis were determined. During the four months of storage, the color parameters of the shell and kernel showed no significant differences between the treatments, with some exceptions. For the texture parameters (skin strength, elasticity and work required to penetrate the chestnut tissue), no significant differences were found between the treatments for a specific storage time. Nevertheless, a decrease in the maximum force and the area below the curve were detected along the storage period for each treatment. For the control, Proallium, Foodcoat, and Proallium + Foodcoat, a decrease in the area under the curve was observed after four months of storage compared to the beginning. Concerning the weight loss, after storage, Foodcoat was the coating with the best performance with the lowest weight loss (5 to 6%). On the contrary, chestnuts with Proallium and Proallium+Foodcoat achieved weight losses of around 14%. The application of the edible coatings had no significant effect on the moisture content and water activity, while the coatings had increased the titratable acidity. The total soluble solids increased in the first month for both coated and uncoated (control) fruit; however, no significant differences were observed between the treatments, suggesting that the different coatings applied did not change the TSS of the chestnuts significantly, with some exceptions. For the reducing sugars, significant differences were only observed after four months. The highest content was determined in control (553 ± 48 mg/100 g d.m.). The starch contents were determined only at the beginning and after four months. The values varied between 48.9 and 51.2%, with no significant differences between treatments and both times. For the individual sugars, the sacharose+maltose were the main free sugars present in the chestnuts. No significant differences were observed between treatments and storage time for raffinose and sacharose+maltose. On the contrary, a decrease in glucose and fructose contents was observed in Foodcoat after four months. In Proallium, this decrease was only determined on fructose. For aerobic mesophiles and the moulds and yeasts, the Proallium was the most efficient during two months. On the contrary, in the control and other treatments, the counts increased along storage time. In conclusion, the application of commercial edible coatings may significantly prevent weight loss and microbial growth.