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Fact frying

Frying medium is a hotly contested subject so we asked fish and chip shops what it is they want to know about the fat or oil they fry in. Here’s what they came back with along with advice from our industry experts

Q: Apart from assessing the colour, what methods can I use to quantify the level of breakdown of my medium - other than using a Testo or similar device? And are there signs when it is solid?

“Although a very dark colour indicates the oil has broken down, it can be broken down and still be white/clear (if solid/liquid). It’s not really possible to assess the condition when in a solid state, but there are lots of signs when in use that it’s broken down: foaming when frying chips, very fine bubbles when frying battered and other products, “scum” forming in the corners of the pan, rancid odour and smoking at frying temperature. Also the food will quickly go soggy after being cooked and will be far more greasy than normal.”

Mark Drummond, Towngate Fisheries, Idle, Bradford

Q: I sell a lot of breaded items and my oil darkens quite quickly. Is there anything I can do apart from filtering and skimming to maintain the oil for longer?

“Selling breaded items is a really great addition to the traditional fish and chip menu. It helps to accommodate the customers who aren’t too thrilled with battered products - these can simply be too heavy for them, which may deter them from using your business. The downside is, of course, the “after-burn” of the breadcrumb. Try to look at some of the following ideas: Turning the pan down. I fry breaded products at 167ºC on a high efficiency frying range, whereas battered products I cook at 180-185ºC. Buy a pan divider/separator if available for your frying range (Kiremko offers one) as this will reduce the volume of oil being destroyed. Also, buy a basket liner which deters any crumbs from entering the pan oil as they are contained within the basket. Again, Kiremko offers this. This will enable you to fry as much breaded product as you like within a basket, great for isolation. And, finally, ensure you are using enough egg white or batter to enable all the breadcrumb to stick. Not enough will result in the breadcrumb falling away when entering the oil. My process is to finely dust the fish with rice flour, thinly batter, press and cover the fish in breadcrumb before frying at 167ºC for the required time.”

Nigel Hodgson, Hodgson’s Chippy, Lancashire

Q: I use vegetable fat, but have tried other frying mediums too, and I still find the oil goes a dark/black colour by the end of the day. The temperature is set at 178ºC and I filter twice a day using inbuilt filtration on my three year old Florigo. What causes this rapid darkness and how can I slow it? We are busy, we go through about 25 boxes of oil per week, so there’s a lot of volume been cooked, but that also means every day several new blocks are been added, so lots of fresh going in.

“It sounds strangely familiar and it could be a few things but, because the oil is fresh and it is filtered, I think it’s more likely it could be to do with the starch levels in the potatoes. Starch levels in potatoes can vary depending on the season but also where and how long they are stored for. You would need to monitor the starch levels. If you’re using Drywite, monitor that too and increase the time to see if that helps. If you are still having problems always get in touch with your supplier either directly or via your distributor. Most oils, regardless of what product is used, are pretty robust and designed for this application.”

Gary Lewis, director, fats and oil, Silbury Oils

Q: I’ve heard other friers talk about oil rotation, but what is it and how does it work?

“In days gone by, friers would alternate fish and chip frying to maximise the life span of the frying oil and to keep the fried products at their very best. The pan used to fry fish would then be used to fry chips and vice versa, this works because the chips absorb any debris left from the fish frying and the pan is clean again to fry battered products. Nowadays, friers tend to have dedicated fish pans and dedicated chip pans. We still need to maintain the quality of our products and the longevity of our oils so we need to adopt a new system, or rather revamp an old one. Moving oil or ‘cascading’ oil from one pan to another is simple and effective. As the chip oil levels go down due to use, the oil levels need to be maintained and replenished, so moving oil from the fish pan to the chip pan mimics the old alternating system whereby the chips help to clean the oil, making it last longer to fry chips as the fish oil is replenished with new oil. In turn, this keeps the battered product fresh and crisp. Haven’t young friers got it easy these days?”

Gordon Hillan, KFE sales manager, Scotland

Q: Smoking medium is never good, but do I need to get rid of it all or can I simply remove a percentage and top up with fresh?

“Adding fresh fat/oil to the used frying medium helps to extend the frying life of the fat/oil, however, when a frying medium is already smoking it indicates that it has seriously degraded (there is a high amount of free fatty acids) and it is better to replace it completely.”

Stephen Bickmore, UK commercial manager - margarines, culinary oils and fats, Vandemoortele

Q: What’s the best temperature to filter my oil at?

“Filtration should be completed as often as possible but no less than twice a day with one always at the end of the day so that particles are not left in the pan overnight. Pans should always be switched off prior to filtering and left for about 10-15 mins to allow the heat from the burner to disperse from the bottom of the pan, otherwise the heat may affect the durability of the metal used for pans. Built-in filtration is obviously safer than external because the hot oil is confined within the pipework of the frying range.

The minimum temperature of the oil/fat should be about 120ºC. The maximum temperature is relevant to type of filtration fitted. As an example, the lifespan of a miroil filter bag will be reduced by high temperatures. It is very important that the pan is switched off for a period to allow the heat in the metal to cool.

Always wear long sleeves and heat resistant gloves and only use the filtration system when trained to do so.”

Paul Williams, managing director, KFE


What can breakdown your frying medium?

•  Heat

•  Water and starch from chips as well as ice from frozen products

•  Build up of carbon caused by food particles in the oil burning

•  Oxidation - exposure to air and dust

•  Detergent from pans and utensils


Top frying tips

•  Ensure you are frying at the right temperature; if it’s too high it can increase the rate of oxidation and the oil will break down more quickly. Ideally, you should be aiming for around 175ºC with 185ºC being the maximum.

•  Watch what you’re putting into the fryer. Potatoes should be free from starch and water while frozen products should be free of ice particles. Any salt or spices should be added to food well away from the oil. All these are potential contaminates which can result in a reduction in the fry life of around 30%.

• Regularly skim and filter the oil to remove food and debris. Investing in carbon pads which feature a combination of specific activated carbon and cellulose fibres, along with other activated absorbents, will help to ensure the frying oil is filtered cleaner.

•  Using a thinner batter will not only absorb less oil but it will also produce a less greasy product.

• Ensure there are no traces of cleaning chemicals in your pans or on your utensils as one single drop can be enough to ruin a whole pan of oil.

•  Ensure the volume of oil reflects the quantity of food in your pan, a ratio of one part food to six parts oil is recommended.

•  Cover your pans when not in use to protect from air, light and dust, all of which can degrade the oil.

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