Hot fill technology for drinks

The Colombian beverage group Postobón is using a NitroHotfill process for its drink bottling. The process injects nitrogen into the filled bottles shortly before they are capped - an alternative to the conventional hotfill concept. The Krones PET line featuring NitroHotfill technology was commissioned in May 2010.

The NitroHotfill line, rated at 30,000 containers an hour, serves for filling ‘Hit’ fruit juices and squashes with a fruit juice content of 36 to 51%, and fruit juice beverages containing 8% of fruit juice, in a variety of flavours like orange/pineapple, mango, pear or tropical fruit, as well as Mr. Tea ice teas and Squash sports drinks, into 500 mL and 1.5 L PET bottles.

The hotfill bottles are produced in a Contiform H18 RC (relax cooling) directly linked to a volumetric filler in a monobloc configuration. What’s special about this filler is a function for dosing nitrogen into the filled bottle by means of a droppler that has been integrated into the transfer starwheel between the filler’s carousel and the capper. This injection of liquid nitrogen gives the capped bottles extra stability, thus rendering the use of hotfill containers with special stabilising panels superfluous. And so the 0.5 L container manages with a weight of just 25 g.

The full bottles are cooled down to ambient temperature in a LinaCool flow-type cooler, after which the containers’ walls are dried before the bottles can be labelled. For this purpose, Postobón has two options: either wraparound labelling with a Contiroll HS (High Speed) or alternatively, sleeving in a Sleevematic Inline followed by a downstream steam tunnel.

In the NitroHotfill process, using a nitrogen injection unit installed shortly before the capper, the bottles are pressurised with 1.5 to 2 bar. Dosing in nitrogen after the filling operation requires accurate metering. The head-space volume in the bottle, somewhat larger with this process, is filled by the evaporating nitrogen, so that no microbiological disadvantages are entailed. Recooling after bottling would normally cause the product volume to shrink. But this shrinkage is compensated for by the positive bottle pressure created by the nitrogen injected beforehand, thus reliably preventing bottle deformation due to underpressure. The panel design, previously essential for PET containers so as to counteract the vacuum pressure with hot-filled products, is thus rendered superfluous. The NitroHotfill technology is claimed to provide a material savings of up to 30% for the PET bottle, for enhanced performance in the stretch blow-moulding process and for an improved line output overall. It also optimises storage conditions and enables flushing-air consumption to be reduced in the Contiform, thanks to lower flow rates and shorter flushing times. Also, it opens up an option for using aluminium moulds with a shell system in the Contiform H, which can be more affordable than conventional moulds.

Postobón’s President, Dr Héctor Fernando García Ardila says: “During the preliminary phase of this project, we did, of course, also address the option of aseptic filling. But this filling technology is continuously changing. We’re one of the first plants worldwide to use the NitroHotfill process, and we’re very satisfied with it. It works, and it saves us money, since we don’t need panel-stabilised hotfill containers.

“The monthly efficiency levels we’re achieving are between 85 and 90%. The goal is to reduce the bottle weight still further. Here, we quite definitely see another window for optimising cost-efficiency. But this has to go hand in hand with bottle stability and product quality.”