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Products: Dried Grapes, Raisins

Comparison of Microwave Short Time and Oven Heating Pretreatment on Crystallization of Raisins.

Authors: Alvarez, L., Urrutia, P., Olivares, A., Flores, A., Bhandari, B., & Almonacid, S.
  • Journals: Foods.
  • Pages: 39
  • Volume: 10(1)
  • Year: 2021
Crystalline material can develop on the surface of raisins during storage and transport, affecting the final acceptability of the product. In this work, a mild thermal pretreatment was applied to raisins to melt the pre-existing crystals and the effect of such thermal treatments on the development of crystals over a storage period was investigated. The raisins selected for this study were of the Thompson seedless variety from one Chilean company. The thermal pretreatment of raisins at 50 °C and 70 °C for 20 min in an oven and microwave (800 W) irradiation for 15 s resulted in a reduction in the percentage of crystallized raisins (w/w) from more than 50% in the control samples to less than 10% after 35 days of storage at 15 and 25 °C in a 57% relative humidity environment. The results showed that some textural parameters, such as cohesiveness and chewiness, were not affected by thermal treatment and were independent of storage temperature.