The research published in the Journal of Food Engineering found that use of a de-oiling system after vacuum frying was crucial to slashing oil content in potato chips.
“The use of the de-oiling system, before pressurization, removed up to 52% of the surface oil content of potato chips, proving that it is a necessary device to produce high-quality and healthier snacks by vacuum frying,” the researchers wrote.
The de-oiling mechanism used in the study was a centrifuging system - used on the sweet potato chips for 40 seconds after vacuum frying.
Two-stage process improves chips
The researchers also investigated how processing variations could improve the texture and appearance of the reduced-fat potato chips.
A two-stage frying process – where the chips are fried for one minute at atmospheric pressure before two minutes under vacuum – ensured the most palatable and appealing chips, they found.
“The atmospheric frying prior to vacuum frying helped the starch to gelatinize thus producing a better product in terms of texture, oil content, and flavor,” they said.
The chips were lighter and more yellow in color than the chips just fried under vacuum - a single-stage process.
However, they did note that a two-stage frying process meant that overall oil content was slightly higher than chips just vacuum cooked.
The sweet potato chips cooked under vacuum (single-process) were fried at three different oil temperatures – 120, 130 and 140⁰C using canola oil. The de-oiling mechanism (centrifuging system) was applied for 40 seconds after frying.
For the two-stage process, the sweet potato chips were fried at 130⁰C for one minute atmospheric and two minutes vacuum. The product was centrifuged for the same amount of time (40 seconds) as the single-stage process.
Use for regular potato chips?
The researchers cited a previous study on regular potato chips that reduced oil content by 80-90% using the same processing technique - vacuum frying followed by de-oiling.
Source: Journal of Food Engineering
Published online ahead of print, doi: 10.1016/j.jfoodeng.2013.03.032
“Two-stage frying process for high-quality sweet-potato chips”
Authors: Y. Ravli, P. Da Silva and RG. Moreira