Vacuum frying of fish tofu and effect on oil quality usage life

Atmospheric frying (165 degrees C) and vacuum frying (120 degrees C at 21 kPa) conditions for the processing of fish tofu made from surimi were compared. The application of vacuum frying showed that it could be used to reduce the final oil content of the fish tofu. A high atmospheric frying temperature caused a high rate of increase of temperature toward the center of fried fish tofu and caused microstructure destruction. It could be a concern that changes to the moisture content was obstructed after 60 s. On the other hand, surface collapsing caused an increase of oil uptake because of adsorption into the damaged areas. The result could be due to a change in the structure that affected the oil adsorption of the fish tofu being fried. High temperature and oxidation caused dark coloration and affected the chemical properties of the frying oil. The b*, and E values increased and a yellowing of the oil was observed as the number of frying batches increased. The PV and TBA indicated a high deterioration in the atmospheric frying oil quality. In contrast, the vacuum frying condition helped preserve the frying oil quality, while the light color of the product was maintained. The results supported the use of the vacuum frying process as a method for frying high quality fish tofu and conserving the quality of oil in the fish tofu. Practical applicationsThe objective of this study was to evaluate the influence of vacuum frying on oil degradation when frying fish tofu made from surimi, or fish meats pastes. There are extensive reports on the benefits due to the vacuum frying process but until now it has not been reported how the vacuum frying process influences oil degradation of value-added surimi. Thailand is one of the largest producers of surimi and fish tofu is one of the most popular export products. The process of frying under vacuum may be an alternative to replace the atmospheric frying of fish tofu and may result in long lifetime of frying oil. This study is a development together with entrepreneur to evaluate the benefits arising from the use of the vacuum frying process for the instant food from surimi. The result of the present study shows that a reduction in color and changes in oil quality factors were observed for the vacuum frying using the raw materials directly from the industry. The results of this study are beneficial for development into a test in large scale in the future. The quality of fish tofu improved using the new frying technique under vacuum and vacuum frying is an alternative frying method for conserving the quality of cooking oil.