This article needs additional citations for verification. (November 2020)
Vacuum fryers are fit to process low-quality potatoes that contain higher sugar levels than normal, as they frequently have to be processed in spring and early summer before the potatoes from the new harvest become available. With vacuum frying it is easier to maintain natural colors and flavours of the finished product. Due to the lower temperatures applied (approximately 130 °C (266 °F)), the formation of suspected carcinogen acrylamide is significantly lower than in standard atmospheric fryers, where the frying temperature is approximately 170 °C (338 °F). The fat absorption of the products is also reported to be lower than in atmospheric fryers. In South East Asia (mainly Philippines, Thailand, China and Indonesia) batch type vacuum fryers are mainly used for the production of fruit chips. However, these machines are only appropriate for relatively small production companies.
Vacuum fryer works on the principal of simple physics that as the pressure decreases below atmospheric pressure the boiling point of the water also reduces below 100 degree Celsius. All vacuum fryer are designed to achieve these goal so that heat sensitive foods can be fried at lower than 100 degree celsius which would otherwise have burned in normal deep frying process.
Continuous vacuum fryers
For larger production quantities, continuous vacuum fryers are available. In these installations, the vacuum frying pan is installed in a stainless steel vacuum tube. The infeed of the raw product is carried out through a rotary airlock. Depending on the application, the frying pan itself is designed to meet the different product specifications. A transport belt takes the finished product out of the fryer and towards the outfeed system. A lock chamber at the exit of the vacuum tube prevents air from entering the vacuum zone, and a belt system takes the product from one zone to another.
In batch fryers, the frying oil has to be replaced quite often as it is sensitive to temperature changes. Continuous vacuum fryers lead to a longer lifetime of the frying oil and therefore lower the production costs. Vacuum fryers can also reduce oil content in fried foods. The amount of reduced oil content, usually 1–3%, depends on the type of vacuum fryer.
- Granda, C.; Moreira, R.g.; Tichy, S.e. (1 October 2004). "Reduction of Acrylamide Formation in Potato Chips by Low-temperature Vacuum Frying". Journal of Food Science. 69 (8): E405–E411. doi:10.1111/j.1365-2621.2004.tb09903.x. ISSN 1750-3841.
- "91C-19 Vacuum frying of potato chips". 11 March 2012. Archived from the original on 11 March 2012. Retrieved 8 December 2016.
- "Airfryer, gezonder frituren - alle informatie op airfryervergelijken.nl". Airfryervergelijken.nl (in Dutch). Retrieved 8 December 2016.
- Journal of Food Engineering Volume 55, Issue 2, November 2002, Pages 181-191, "Vacuum frying of potato chips" By Jagoba Garayo & Rosana Moreira, Department of Biological and Agricultural Engineering, Texas A & M University, College Station - TX - 77843-2117, USA Received 31 October 2001, Accepted 5 February 2002, Available online 12 March 2002. https://doi.org/10.1016/S0260-8774(02)00062-6
- "Harvest Bay uses vacuum frying for snack products". The World of Food Science. Institute of Food Technologists. 8 November 2002. Archived from the original on 6 February 2013. Retrieved 17 September 2012.
- Henry C. Dethloff, Stephen W. Searcy (2015). Engineering Agriculture at Texas A&M: The First Hundred Years. ISBN 978-1623492892. Retrieved 8 December 2016.