Wiley's senior process engineer Martin Bevis describes two innovative new developments that could change the game for ready meal makers.
Chillin’ out on the shelf
The latest European innovation for chilled ready meals is manufactured on a continuous production line and claims it can extend shelf life up to 45 days.
The technology was invented in Sweden by a company called Micvac. In Australia, a range of ready meals products using this process, the Whistling Chef brand, is already being manufactured and is on sale in Coles.
This innovation is significant given that the chilled meal generally commands a premium consumer perception over frozen ranges and it also commands a premium market price, and so its popularity amongst manufacturers is increasing.
Current processing methods like pasteurisation and modified atmosphere packaging (MAP) offer limited shelf life of up to 14 days and 10 days respectively. The Micvac process, on the other hand, claims to extend the shelf life of these meals by 30 to 45 days under industry standard chilled storage conditions while maintaining the quality of their pasteurised equivalents.
The technique is designed to fully cook the product in the plant by the use of a continuous industrial microwave tunnel, instead of alternatives such as a spiral oven. This renders segregated high risk/low risk divisions within the plant as unnecessary, as the raw ingredients can be assembled into the tray. The tray is then sealed, and the contents fully cooked within the microwave tunnel.
All product leaving the plant has therefore been fully cooked in a sealed tray, and is sterile. The microwave oven provides a very rapid and thorough cook within a small footprint, the cooking performance of which cannot be matched by a spiral oven.
It should be noted that some hydrated products such as rice and pasta require partial cooking prior to assembly due to the differing cooking characteristics of the components of the meal.
This is more than just another microwave cooking technology. The clever part of the process is the patented Micvac one-way valve which is attached to the film that seals the top of every meal. This valve allows the cooking steam to escape from the pack during the rapid microwave cooking process and therefore prevents the pack from exploding.
Once the meal is cooked, the valve closes during cooling to ensure the pack remains fully purged and no outside air is allowed back in.
The novel, multi-purpose nature of this valve allows it to be used in the initial cooking process and then as a cooking timer for the consumer reheating the meal in their microwave at home.
Once the meal has been heated up, the Micvac valve emits a loud whistling noise to indicate that the meal is ready. This is due to the passage of hot steam through the valve, exactly as it occurred during the factory cooking process.
Micvac also makes and supplies a number of the unique elements of this new technology, all of which can be implemented into any standard ready meal manufacturing process.
Outside of these process particulars, any standard ready meal plant would already have the necessary equipment in use to manufacture this product.
Saucy new development
A major component of any ready meal is the quality of its sauce. The finish, colour, smell and flavour of the sauce are all critical factors in the commercial and culinary success of the finished product.
In a ready meals facility, the sauce production will usually be carried out in steam jacketed vessels known as kettles. Milk or cream-based sauces are very heat sensitive and a great degree of care is required to prevent these products being spoiled through burn-on, which is the unwanted caramelisation of the product by the intense heat of the kettle heating surface.
A common method of preventing this product damage is to heat the sauce using direct steam injection. Reduced pressure, five micron-filtered steam is sourced from the factory main to achieve the necessary culinary quality supply. This steam is injected via a nozzle, or series of nozzles, located on the inside wall of the kettle. The sauce heats up as it absorbs the hot steam.
Steam condensate creates additional moisture which will dilute the sauce and has to be compensated for in the sauce recipe.
While this is a well-established and effective process, it can be improved upon. A major UK cooking equipment manufacturer has reviewed this heating process and developed a number of new advanced features which it calls Jet Cook. One of these innovations is the steam-injection nozzle design. The new design differs from a standard nozzle as the steam injection head is manufactured in the shape of a deep profile ring.
The direct injection steam is fed into this ring in such a way that it creates a venturi effect of sufficient strength to continually draw the sauce through the ring, and at the same time blend the injection steam into the sauce being drawn through. Combined with the action of the agitator, this rapid mixing ensures the minimum temperature differential between the hot input steam and the sauce. This results in rapid heating times, and importantly, no burn-on.
The use of Jet Cook is not restricted to dairy-based sauces and provided the recipe is adjusted to accommodate the additional water, it can be used as a rapid heating method for any sauce. The manufacturer claims that the process will heat up a 500kg batch of sauce from cold to 95°C in eight minutes.
A further application of the design is the stand-alone Jet Cook station where sauce can be reheated, for instance, during a mid-run production line breakdown. It maintains food safe temperature conditions and prevents further downtime and product wastage.
About the author
Martin Bevis is one of Wiley’s senior process engineers and has worked on a diverse range of food manufacturing projects in the UK, Europe and Australia. He can be contacted on 1300 385 988 or email connect@wiley.com.au
