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- Study of the effect of freezing on the visco-elastic properties of strawberriesPublication . Fundo, J.; Brandão, Teresa R. S.; Quintas, M.; Silva, C. L. M.The objective of this work was to study the influence of freezing on the visco-elastic properties of strawberries. Food structure plays an important role in food quality and functionality. It is important for the consumers to find an identical sensation when they eat a fresh strawberry and when the strawberry is defrosted. The visco-elastic properties of a food product are an indirect measure of its structure. Experimental measurements of these properties may correlate to changes on the physical attributes of the product. In this work, a dynamic mechanical analyser was used to assess changes on loss (E’’) and storage (E’) modulus, applying a compressive test with a Ø1.5 cm parallel plate geometry. Strawberries were acquired in a local market and frozen in a blast and fluidized bed freezer at –30 ºC for 1 hour. Samples were stored at –30 ºC in freezing chambers. Analyses were performed on fresh strawberries, after freezing and during storage. The samples were cut in small cylinders (1.5cm x 1.5cm) and left to relax during 1 hour at room temperature. Preliminary tests were performed in order to evaluate the linear visco-elastic region and the loss and storage modulus were determined. A dynamic frequency sweep test was also performed. Results showed that the behaviour of fresh strawberry sample varies significantly when compared with a defrosted sample. The influence of the storage still cannot be evaluated and is currently under study. Overall, it can be concluded that the freezing process greatly influenced the visco-elastic properties of the strawberries.
- Storage stability of a safer ovos moles formulation: texture and microbiological assessmentPublication . Fundo, J.; Quintas, M.; Brandão, Teresa R. S.; Silva, C.
- Innovating portuguese traditional pastry – on the use of pasteurised egg yolk in “ovos moles”Publication . Fundo, J.; Quintas, M.; Brandão, Teresa R. S.; Silva, C. L. M.“Ovos moles” is a renowned traditional Portuguese sweet that is confectioned with egg yolk, sugar and water. In this work a safer and easier to manipulate raw material - pasteurised liquid egg yolk - is proposed to substitute the intact shell eggs used in traditional “ovos moles” production. Due to previous heat treatment, pasteurised liquid egg yolk presents different sensorial, nutritional and physical properties. These changes may alter the final product’s characteristics. In order to develop a safer formulation, using pasteurised raw products, with minimised differences from the traditional product, a study on adding pasteurised egg white (as bulking agent) to the pasteurised liquid yolk was carried out. Samples made with normal shell eggs and with pasteurised liquid eggs were compared in terms of rheological parameters. Results allow characterising the physical properties of traditional ovos moles and of alternative formulations, using pasteurised egg yolk and white. A new formula, with rheological properties identical to the traditional one, was developed.