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Temperature and weight loss profiles of vacuum cooling of sliced cooked carrot.

Author(s) : ZHANG Z., SUN D. W.

Summary

Carrot samples were cooked in saturated steam for 30 min. Carrot slices with a thickness of about 3 mm were laid out perpendicularly (stacked) during vacuum cooling. At least 6 replicates were carried out for each situation. Through comparison of vacuum cooling of whole cooked carrot of about 100 g and cooked carrot slices from carrot with size similar to the whole one, it was found that cooling time needed by the whole one (16.91 min) was much longer than that of the stacked carrot slices (2.23 min), significantly (p < 0.001). Weight loss of the former (20.04%) during vacuum cooling was also much higher than that of the latter (12.14%), significantly (p < 0.05). Nevertheless, weight loss of the former was lower by about 0.3 g moisture/g dry solid, significantly (p < 0.05), during the first minute of vacuum cooling, which was proved to be a stage at which most vapour was created, by observation with the naked eye in torchlight. This implied that moisture transfer rate from interfaces of slices to vacuum chamber was much faster than that within the matrix of cooked carrot, and evaporation of moisture occurred at the interfaces. Nevertheless, about 120 g press from the top of the stacked carrot slices would prolong the cooling time by about 1.6 min (p < 0.05). It was concluded that during vacuum cooling, vapour was created in the interface and flowed out to vacuum chamber even if slices were pressed. Temperature at the lower part dropped down more slowly, and it should be monitored during vacuum cooling to decide when vacuum cooling ended.

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Details

  • Original title: Temperature and weight loss profiles of vacuum cooling of sliced cooked carrot.
  • Record ID : 2004-2867
  • Languages: English
  • Source: 21st IIR International Congress of Refrigeration: Serving the Needs of Mankind.
  • Publication date: 2003/08/17

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