Frito-Lay has been granted a US patent for its low pressure processing method to make reduced oil potato chips.
The method centers on use of low pressure frying and deoiling to reduce the content of oil on a snack food products including potato or tortilla chips and other fried food products, Frito-Lay said.
Processing pressure the crucial detail
The snack player said that differential pressures throughout the processing steps were key to improved oil reduction in the end product.
The patent detailed that potato slices must be fried in hot oil (between 320⁰F and 380⁰F) at atmospheric pressure in a continuous fryer, batch, semi-batch or semi-continuous fryer.
The potato chips are then removed for a deoiling step in a vacuum centrifuge at a lower pressure. It is this lower pressure that is the crucial detail, Frito-Lay explained.
“When food pieces have been fried at atmospheric pressure and then subjected to a low pressure centrifugation step, the oil content of the fried food pieces is dramatically and surprisingly lower than when an atmospheric centrifugation step is used.”
“Without being limited by theory, applicants believe that the vacuum draws oil out from the interior spaces of the potato slices to the surface, thereby allowing the centripetal force exerted on the slices by the centrifuge to remove it from the surface of the potato slices. Additionally, the vacuum maintains a positive pressure differential between the internal spaces of the potato slice to the outside, which resists further oil absorption during the centrifugation step.”
These deoiled potato chips have a mouthfeel similar to chips that have not been deoiled under vacuum conditions, Frito-Lay explained, because oil that was previously trapped inside the fried food is drawn to the surface.
Bigger oil reductions with different pressure
Frito-Lay conducted experiments that showed a significant difference in oil reduction when pressures were altered throughout processing.
It found that processing unwashed chips in a centrifuge at atmospheric pressure, oil content by weight was reduced on average by 7.3%. This figure was more than doubled to 16.8% average oil reduction when the centrifugation system used a pressure lower than atmospheric.
In addition to pressure control, Frito-Lay said that the time the chips are spun inside the vacuum centrifuge and lag time between when the product exits the fryer and enters the vacuum can also impact oil removal.
Frito-Lay said the removing and transferring steps in the production line can be heated – as this prevents the chips from cooling and absorbing oil.
Frito-Lay other work on oil reduction
Frito-Lay filed a separate patent at the end of 2012 for a different method it had developed to reduce the oil content of potato chips. The continuous-frying process that uses changing temperatures can reduce oil content by up to one-third, the snack major claimed.