BATCH VACUUM FRYING SYSTEM ANALYSIS FOR POTATO CHIPS

ABSTRACT Vacuum frying is a process used to produce high‐quality fruits and vegetables. However, the final oil content (OC) of the vacuum chips holds a major concern for health and food safety. Therefore, more information is needed before a vacuum frying system can be designed effectively to produce lower OC snacks. Potato slices were fried at 120 and 140C oil temperatures and 1.33 kPa pressure. The temperatures of the fryer headspace and the center of potato slices were monitored during frying. The effects of varying the speed of the de‐oiling mechanism and the pressurization rates on the oil absorption of potato chips were evaluated in detail. The convective heat transfer coefficient was calculated using the lumped capacity method for varying frying loads. The de‐oiling system removed up to 81% of the chip's surface oil when centrifuged for 40 s at 750 rpm (84% at 300 rpm). Short frying time and/or longer centrifuging time combinations would maximize oil removal from the chip's surface during the process. Less oil was absorbed by the potato chips when the fryer was pressurized at lower rate (25% open released valve) than at faster rate. The heated oil convective heat transfer coefficients (h) were 217 ± 13 W/m2 K (120C) and 258 ± 37 W/m2 K (140C). The h values increased up to 3.6 times during the boiling period. PRACTICAL APPLICATIONS These results are useful for an effective design and modeling of vacuum frying systems for high‐quality fruits and vegetables.