Shakan, not stirred
Some things are better shaken, not stirred. For 007, it was his martini. But for the food industry, it is canned and bottled products such as soups, sauces, vegetables, baby foods, milk drinks and ready meals that can taste better when shaken.
A technique developed in the UK 10 years ago that shakes cans, jars, bottles and pouches during sterilisation is finally about to hit the world's food processors. Two leading retort manufacturers have just launched the first production versions of sterilisation retorts using the patented Shaka process.
By shaking cans and jars during sterilisation, the Shaka process dramatically cuts down the time it takes to sterilise canned and bottled foods. A 400g can of soup, say, can be sterilised in six or seven minutes instead of the usual hour and a half. Result? The Shaka process eliminates the overcooking associated with conventional canned and bottled food. The food tastes much fresher with better retention of colour, texture, and nutrients and with less need for additives and starches. And the cost? Pennies more for a can of soup, perhaps, but nothing like the premium price of £2 or more for a pot of soup from the chilled cabinet.
If you want to give that just-cooked, home-made flavour to your soup, carbonara sauce, curry sauce, baby food, or chilli con carne, and avoid that burnt taste in your milk drink, then you have to process it and pack it for a short shelf-life in the chilled cabinet. The Shaka machines will now allow food manufacturers to produce products in cans, jars and pouches that have long shelf-lives at ambient storage temperatures, but will compete on taste with the premium products in the chilled cabinet.
So what is the Shaka process? In the two production machines coming on the market, a basket of cans, jars or pouches in the sterilisation retort is vigorously shaken back and forth by a reciprocating actuator, thoroughly mixing the contents and allowing very rapid heat transfer.
Until Shaka came along, there was no way of stirring up the contents of cans, jars and pouches in retorts in order to get convection to speed up the transfer of heat into the contents. Most of the heat transfer in sterilisation is via conduction. And that takes time - an hour and a half for a 400g can of soup, and up to eight hours for a 3.5kg catering can of gravy.
Rotating the cans and jars can introduce some convection and speed up sterilisation a bit. But essentially, conventional retort sterilisation overcooks the food. It can taste overcooked; it can look overcooked; and it can feel overcooked. Starches and other additives are often added to maintain flavour, consistency, texture, and colour.
But all that could change as Allpax in the US and Steriflow in France launch their first production machines incorporating the Shaka process. They are both single-basket machines. But because sterilisation time is cut so dramatically, the machines will have a similar throughput to that of conventional multi-basket retorts.
The inventor of Shaka is Richard Walden, a former research scientist at Metal Box. He developed the process there 10 years ago, but it was put on the shelf. Then about three years ago, Walden started up his own business, Zinetec, bought back the rights to his invention, and started turning it from an idea into a commercial process.
Shaka processed licensed
Shaka has now been licensed to Allpax and Steriflow. The Allpax machine is now on sale and Steriflow will have a production machine this month, says Walden. "A single-basket Shaka retort, which is what Steriflow and Allpax are building, holding something like 700 to 900 400g cans, has got the same production capacity of a four-basket rotary or an eight-basket static retort."
Walden says the process is quick. "It can take 10-20 minutes from start to finish to heat the product up, sterilise it, and cool it. In a static process, 400g cans of soup can take three hours from start to finish.f
"It's all about product quality. Because the process is much shorter you do not overcook the product. Conventional canned soup is not of the same quality as, say, New Covent Garden soup from the chilled cabinet.
"Shaka is an alternative to chilled. With a number of customers we have taken their own product from the chilled cabinet and reprocessed it through Shaka and shown them it makes very little difference. We have done taste tests with the major supermarkets and they couldn't tell the difference. "Companies should be able to produce much better quality at prices only marginally greater than the existing long shelf-life ambient stored product. Take a can of soup, which may be 60p now. Shaka may make it a little more expensive - maybe 70p or 80p - but it won't be the £2 that New Covent Garden is charging for its soups out of the chilled cabinet.
"Another issue is green labels. With Shaka, the process is far gentler so you don't necessarily need all the stabilisers and additives. You can make much cleaner labels using Shaka technology."
John Emanuel is chairman of technology transfer firm, Utek Europe, which is advising Zinetec on the commercialisation of Shaka. "Most of the big names - Nestlé, Heinz, Unilever - have got pilot plants. The production models now going on sale will be aimed at the premium products of big companies and at the speciality companies.
"It is a different type of product and the brand people are scratching their heads about how to dress it up so that consumers recognise it as a different type of product. One plan is to have a Shaka quality mark that will tell the consumer that this is not like the old stuff in cans or bottles. This is new stuff."
Validation of ovens
Many of the trials on Shaka were done on a pilot machine installed at the Campden BRI food research labs. But Robin Thorn in the department of food manufacturing technology, who was involved with the trials, is now also looking at ways of shaking up attitudes to basic oven controls. Most supermarkets and retailers use the British Retail Consortium's (BRC's) audit process to assess the basic safety and hygiene of their food suppliers, and the cooking process which is a control point in a food manufacturer's hazard analysis critical control point plan, and must be validated. Firms need to control their ovens to ensure their cooking process is an effective control point, says Thorn.
"As a result of the BRC audits, we are being called in by food processors to validate their ovens to make sure they are cooking effectively, that there are no cold spots, and that products are all adequately cooked and safe to eat.
"At Campden BRI we have recently bought a heat-resistant data logger that can sit in the oven while it is heating up and monitor the temperature of the products throughout the heating process. Normally most data loggers will go to about 150°C - above that their batteries explode! The new system is heat shielded so that we can monitor temperatures in an oven to 250°C to 300°C. It is 40mm high and so it can go through a biscuit oven or a bread oven. And we have used it for meat products cooked in a continuous oven.
"It is a good tool for regularly monitoring your oven - looking at the heating pattern within the oven to see if there are any hot spots or cold spots. You can tell very quickly whether a fan isn't working, or whether it's a heating element or a distribution problem within the belt.
"We have done some work with a major snack manufacturer looking at the temperature profile within a baking oven. We found that by increasing the temperature at the front end of the oven, the manufacturer could cut down the baking time of the product by 10-15%, or speed up the baking process so that they got much higher throughout from the oven."
The problem with ovens, says Thorn, is that many of them are old. "Some are 20-30 years old, if not older. And many have control systems of an equal age." So people generally err on the side of safety, especially with meat cooking ovens, he says. "That's not a bad thing, but you will generally find that if you look at the heating times used, they can be reduced.
"You may reduce the safety margin. But if you have confidence in your oven, confidence in what you are putting into your oven, and confidence that you can control everything, then you can reduce your heating time without compromising safety. You can cut down cooking time for bulk meat products from around eight hours to six hours without any major issues," he suggests.
"If a product is overcooked, it will tend to lose water and lose weight. If you minimise the amount of cooking time you can minimise water loss and so improve your yield." FM
Key Contacts
Allpax 00 1 985 893 9277
Campden BRI 01386 842000
Steriflow 00 33 1 40 37 08 45
Utek Europe 020 7482 4226
Zinetec 01367 240650
