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Title: Deep-fat frying : novel stategies for lowering oil uptake and minimising oil quality deterioration
Author: Tarmizi, Azmil Haizam Ahmad
ISNI:       0000 0004 2742 9894
Awarding Body: University of Reading
Current Institution: University of Reading
Date of Award: 2012
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This thesis represents a study on the application of vacuum during post-frying stage with the aim of lowering oil content in fried food. Using potato chips as an illustrative product, several protocols were initially screened, either towards the end of frying or after frying. Lowering the pressure when the product was removed from the oil resulted in a significant reduction in oil uptake. Applying vacuum triggered a continuous water vapour release from the product as a result of lower water saturation temperature, and this prevented the surface oil from penetrating into the product structure. The image generated by con focal laser scanning microscopy showed a visible boundary between the core and the crust regions, and the oil distribution was only concentrated in the crust with insignificant trace of oil in the core region. Despite the amount of oil being absorbed into fried food, the ability of oil to withstand high temperatures at the extended frying period must also be taken into consideration. Interestingly, vacuum drainage significantly inhibited the free fatty acid formation while the total oxidation value was slightly lowered, which in turn showed minimal reductions in the total colour difference value, viscosity and polar compounds. We also explored the possibility of combining moderate vacuum frying with high vacuum drainage to lower the oil uptake in fried food. As expected, high vacuum drainage significantly lowered the amount of oil taken by the potato chips, regardless to the vacuum frying conditions applied. It was also noted that the head space temperature also plays a significant role in the continuous release of water vapour from the product, aside from the product temperature. An attempt to develop fat free product was accomplished when sorbitol was used to substitute oil as frying medium. In sorbitol fried French fries, a crust was formed, similarly to oil fried product and the colour and texture developments were comparable
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available