Continuous injection of water and antioxidants possible roles on oil quality during frying

- Water injection was utilized to continuously deliver one or more antioxidants at different pH.
- It improved the overall oil stability during simulated deep-fat frying.
- Selection of buffer and/or neutralizing chemical and antioxidant is of high importance.
- Catechin optimal concentration is a function of its antioxidant or pro-oxidant activities.
- Foodservice and restaurants could significantly benefit from continuous water injection.

Frying is an important process in cooking a wide spectrum of food products in homes, restaurants and the food industry due to the unique sensory characteristics of fried foods combined with a relatively low-cost operation. Due to health and nutritional concerns however, novel approaches are being sought to reduce oil uptake and minimize deleterious oil degradation. This study investigated the potential of utilizing water injection and as a vehicle for continuous delivery of one or a combination of antioxidants at different pH values. Selected antioxidants were tested during simulated frying at 180 °C by monitoring commercial canola oil quality indices. Water injection increased free fatty acids (FFA) during frying, while simultaneously enhancing oil stability as indicated by conjugated diene value, radical-scavenging activity and p-anisidine value. It was demonstrated as an effective carrier for continuous incorporation of antioxidant, which maintained a low concentration of FFA during deep-fat frying. Selection of buffer and/or neutralizing chemical and antioxidant is of high importance. Catechin had both antioxidant and pro-oxidant activities, highlighting the need for system optimization. The protective role of water injection could be significant for foodservice and restaurants where the frying oil is maintained idle at high temperatures for relatively long periods.