High quality and easy preparation of meals, especially ready-to-serve meals, are increasingly important criteria which the consumer expects from the manufacturers. To cater for this demand a system has been developed and perfected during the last few years to permit coating frozen foods with seasoning and sauces using a “Günther tumbler” such that a savoury, evenly coated final product is obtained. Lumps in the sauce coating or even floury breakage are a thing of the past.
The deep-frozen, loosely rolling base material (meat, vegetables, rice, pasta etc.) is fed into the tumbler drum for example by conveyors and/or lift loaders. However, in the latter case the temperature should be in many cases already about -18°C to -20°C.
The material is mixed and sprayed with liquid nitrogen in the tumbler. The liquid nitrogen then passes into the gas phase and subcools the base material to e.g. – 50°C. The subcooled material is sprayed with sauce as it tumbles in the drum. Due to the large difference in temparature the sauce solidifies at once to form an uniform coating.
- Drum speed to influence the mixing quality, the surface to be sprayed and the duration of the process.
- Throughput of liquid nitrogen or sauce to control the spraying effect and the required time, depending on the pressure, number and shape of the nozzles, and the viscosity/ temperature of the sauce.
Liquid nitrogen as an ideal refrigerating agent
The refrigerating agent nitrogen is not only easy to apply and environment-friendly, but has also been approved by the German food law as a substance that does not have to be declared. Nitrogen is gained from the ambient air, is non-toxic and inert (no reactions with the product) and free from colour, odour and taste. When used for cooling and freezing foods, liquid nitrogen can be brought into direct contact with the product. Liquid nitrogen is an ideal coating agent because CO2 (carbon dioxide) snow is often trapped in the coating and then sublimated so that part of the coating separates again. In summary, the “Günther tumbler technology” in conjunction with technical gases is the smart solution to individual requirements pertaining to the coating and freezing of convenience products, ensuring efficiency of the process