Blanching is an age-old method used in preparing food and an essential step in the food processing industry. But methods and equipment are always changing and we list some of the latest developments.

So, which is best for your job – do you go for immersion or deluge, steam, air or infra-red? Each process has something going for it, so it is up to the processor to decide what application he needs, does product stick? Is it all evenly blanched? Is this a power-sapping part of the process?
These questions need to be answered.
Kiremko tells us that everyone in the food processing industry using belts in their processing lines are aware of the problems associated with product sticking on dryer belts and dirt hanging on belt supports in belt blanchers and steam cookers.
Ensuring a clean belt, says Kiremko is ensured with the company’s Delta-Link – a cantilevered wire link belt.
By combining a wire link belt with small contact surface with the well known model of cantilevered perforated sheet belt, Kiremko have come up with a belt which has a free air passage and optimum cleaning possibilities for the food processing industry.
A large percentage of a belt opening gives better heating or cooling possibilities in processes such as drying, cooking, cooling and blanching.
The absence of belt supports prevents dirt build up. The whole belt can be cleaned during processing on the return part, and the product is prevented from sticking due to the small contact surface.
Also in the Netherlands, BMA claim the screw blancher with a Ferris wheel is the answer.
The product is blanched in a horizontal cylinder, partly filled with water.
It is then transported through the machine to the discharge side by a screw auger which is equipped with perforated flights, to prevent water accumulation.
Product retention time is adjustable via a frequency controller. The combination of retention time and water temperature (adjustable between 15-95C) ensures that each product receives the correct heat treatment in the blancher.
Water is heated by steam injection and pumped continuously through the machine with circulation ensuring a uniform temperature treatment.
Optimum product quality management is ensured by the combination of retention time and temperature control.
The product is discharged and dewatered via a Ferris wheel. Inspection hatches at the top facilitate access for inspection and cleaning.
This system, says BMA, offers a maintenance-free machine, constant water temperature, and the option of high temperature blanching with short retention time or low temperature blanching with long retention time.
Another Dutch company, Food Technology Noord Oost Nederland (FTNON) says its innovative steaming, blanching and cooking processes are designed to ensure that the product’s natural characteristics are maintained while utilising low energy consumption and a high degree of control.
“Our blanching techniques are working with the help of water, air, steam and/or infrared. Moreover, the processes can be carried out continuously or batch-wise,” said a company spokesman.
For the potato chip or crisp process, Sweden’s Rosenqvists have introduced a Counter Flow Zone Blancher uses hot water.
Each product slice is separated and treated individually in the machine which has four parts – the hood with a paddle belt, a pan with multiple water intake and outlets in the bottom (water is injected along both sides), a bottom belt for use when there is no need for blanching and three temperature zones.
As the slices enter the first zone of the blancher, the paddle belt ensures that a constant amount of slices are conveyed through the machine. All slices are treated uniformly and for the same amount of time.
The injectors create a turbulent water flow which separates the slices resulting in even heat treatment. The water in the different zones can be heated by either thermo oil or direct injected steam.
Fresh water is added via a spray ramp above the discharge section.
The water discharge is placed at the in feed. Due to the counter flow main water stream and the three temperature zones, the water in the process is used with optimal efficiency.
The Zone Blancher also saves energy as different temperatures can be set along the length of the unit.
Over in North America, Gem Equipment of Oregon, say belt blanchers use water to leach sugars, gelatinise starch, kill enzymes, and improve surface texture of cut fries – an important process.
Engineering manager Chris Imdieke blanching potatoes uses two resources: water and energy.
“Gem belt blanchers are designed with water volume in mind. The blancher tank has a sloped flume down the centreline that collects return water and returns it to the pumps.
“This allows adequate suction pressure at the recirculation pumps without filling the entire blancher tank. It also allows the tank under the belt to be very shallow, minimising volume during immersion mode.”
Imdieke said system volume can also be minimised by good blancher sizing and zoning.
Also US-based company, Heat and Control says the Potato Slice Injection Blancher offers uniform blanching through its use of multiple water inlet jets located across the width of the bottom of its pan .
Unike blanchers that inject water from the sides, compressing slices into a tightly centred pack, the bottom-up water injection process separates the slices, exposing more of their surfaces.
Slices are spread across the discharge conveyor for thorough dewatering.
Surface water and particles are removed by Heat and Control’s patented AirSweep vacuum/blow-off system to maintain clean, fuel-efficient fryer operation.
This also deposits a uniform flow of individual slices into the fryer to produce finished chips with uniform moisture content and to eliminate uncooked clusters of chips.
And, from Nova Scotia, Canada, comes ABCO with its advanced two-stage blanching process which they claim, provides the best in energy efficiency, reduced effluent and product quality.
The key to ABCO’s unique and patented Heat/Hold blanching process is the short time that fresh product needs to be exposed to steam. Blanching, or heat penetration to the core of any product, is a function of temperature and time.
The shorter the duration in the heat medium, the better retention of colour, solids and nutrients will be as the leeching action is reduced accordingly.
Says Abco: “Traditional steam blanchers and hot water blanchers retain product in the heat medium until such time as the desired centre core temperature is achieved.
“This is not an efficient use of energy.
“Furthermore such inefficient steam usage wastes energy and overcooks the product.”
The Heat/Hold System transfers, in the heat section, only sufficient energy to the surface of the product to allow the blancher to do its job.
This surface heat is then allowed to equilibrate throughout the product in the Hold Section, thus raising the centre core temperature to the desired blanch level without the addition of more steam.
This very short exposure to heat in the ABCO system leads to noticeable improvement in colour, flavour, solids and nutrient retention, when compared with other blanching methods.
The improvement in product quality will reflect positively in increased consumer demand.
ABCO also offer a tray blancher ideal for the ready made meals and potato salad industry, where many products need to be prepared on the same day without cross contamination.
It uses combinations of steam, hot water and chilled water to maximise the quality of each individual product.
Colour, texture and flavour retention is vastly improved, which is critical to consumer acceptance. The machine is fully PLC. controlled and one can readily switch from one product to another with minimal effort.
Energy saving is shown by the fact that the ABCO Heat/Hold process only requires 4.5 minutes to achieve the desired effect while, in conventional steam blanchers, a full 12 minutes is needed.