Polydimethylsiloxane Shows Strong Protective Effects in Continuous Deep-Frying Operations

Polydimethylsiloxane (PDMS) was previously reported to show no protective effect in continuous deep-frying. In this study, we used canola oil with/without added PDMS to deep-fry shredded potato at 180°C either continuously or with 10-, 20-, or 30-min intervals between frying sessions for 6 h. In continuous deep-frying in canola oil not containing PDMS, far more oil vapor was generated from the oil and the water in the potato compared to frying with 20- and 30-min intervals between sessions and the oil in the fryer accordingly had a lower polar compound content (PC). The longer the oil was used to deep-fry potato, the more steam was generated from potato. Thus, polar compounds evaporated into the air in the steam, resulting in a low PC value of oil in the fryer. In contrast, both thermal deterioration and oil vaporization were remarkably inhibited in canola oil containing PDMS regardless of the frying pattern, and the PC value of the oil in the fryer increased in proportion to the amount of potato deep-fried. Canola oil with/without added PDMS was heated at 180°C for 6 h to confirm the effect of water released from potato on the oxidation of oil. A large increase in PC was observed in canola oil not containing PDMS when heated without water but this increase was inhibited to some extent when water was supplied continuously. On the other hand, the PC of canola oil containing PDMS was far lower than that of oil not containing PDMS, but the addition of water promoted an increase in PC. In conclusion, we observed superior protective effects of PDMS regardless of the deep-frying pattern employed, but the PC value nonetheless increased as the amount of food deep-fried increased. In addition, we confirmed that water in potato strongly correlates to PC increase of oil in the fryer.