Superchilled sustainability

6 January 2022 | Greg Jones, Microbiology Training Specialist

Superchilling has positive impacts on shelf-life and energy consumption

In lieu of some of the recent COP21 debates, it is important to find ways to effectively reduce energy consumption whilst ensuring that the global demands for fresh and high-quality food can be met. A recent case-study by Lyon Seafood explored the use of superchilling to do just that. This technology, when used to preserve food, can use blast chillers to lower the temperature of food to around –1.5°C to–2°C. At this temperature range, a partial fraction of the water in the product freezes however enough liquid remains to limit freeze damage.

Superchilling can maintain freshness and quality of food, whilst suppressing the rate of appearance of microbiological and chemical spoilage defects. In comparison to conventional chilling (>3°C to 8°C), superchilling extends shelf-life without affecting sensory attributes. In addition, it can reduce the need for freezing and thawing processes, increasing yield, energy use, as well as labour and transport costs (Kaale et. al., 2011).

So, how is superchilling better than freezing?

Anyone that cooks will know that freezing and the formation of ice crystals in seafood and meat can have an impact on the quality of the product. It can cause tissue juices when meat is thawed (drip loss), softening, and other textural changes, due to the expansion and rupture of the cell walls. The size of the ice crystals and therefore the impacts of ice crystals can be reduced if a product is frozen swiftly. Superchilling causes ice crystals to form in the extracellular spaces (areas outside cells) and results in little change in product quality. The technique can quite easily be undertaken with a standard blast freezer and can be achieved by leaving a product in there for a slightly longer time than usual, before moving it into a standard cold storage area that is running at a slightly lower temperature than usual.

Case in point: Superchilling prawns

Lesley Galpin, Head of Technical at Lyons Seafoods, headed up a team who wanted to experiment with superchilling one of their cooked prawn products. The outcome was exciting for the team, with results demonstrating an increased minimum life on receipt and a 20% reduction in water and electricity. Indeed, the benefits of superchilling became clear for Lyons Seafoods when Christmas – usually the busiest period for the company – came around.

When asked, Lesley Galpin explained how superchilling had improved things:

“The day-to-day impact of superchilling was shown by our experience last Christmas. Like most FMCG manufacturers, Christmas is usually a stressful time with increased volumes. Last Christmas felt like we had lower volumes due to the process being much more streamlined, with less stopping and starting. To our surprise, when we looked at the figures, we had produced more than usual. Superchilling allows us to supply from a buffer stock, and so makes production more predictable and efficient.”

The use of superchilling by Lyons Seafoods, has proven effective by:

• Saving time and resources that can be invested to, for example, introduce new lines
• Ability to cook bigger batches less often to:
• Decrease product waste and reducing production starts and stops
• Reduce the line running times reducing the labour requirement
• Increase cooking yield
• Reduce hygiene costs due to less production line usage
• Decreasing effluent usage (approx. 20%)
• Saving time and money with fewer batches which results in fewer EOL (end of life) sampling and microbiological analysis
• Yielding improved EOL microbiology results, in terms of total viable counts (TVCs).

There can be additional cost savings in relation to transportation, with the removal of the need for ice, resulting in a reduced demand for water and energy, and the creation of extra space for more product.

What about food safety, and are there any challenges?

The experimental findings of Lyons Seafoods, with regards to food preservation, is aligned with previous research, which for the most part has been focussed on fish, with little data on other product types. Current data suggests that superchilling can extend shelf life of fresh products, by slowing down the rate at which microflora grows.

Our experiments have shown that superchilling is safe. We have conducted experiments previously demonstrating that Listeria does not grow at superchill temperatures. Although it is known, as stated above, that the technique suppresses rather than halts microbiological activity. This is also interesting in relation to products impacted by phychrotrophic Clostridium botulinum, which is well below its minimum growth temperature in superchilled conditions. The implication of this is that superchilled food is no more dangerous in terms of pathogen growth than standard chilling, and the usual application of HACCP will address safety risks to these products throughout their life cycle.

The main challenge with superchilling is defining that point at which a product is partially frozen and not totally frozen. Indeed, as with any refrigerated product, it is important to maintain traceability, ensuring that superchill temperatures meet the correct parameters, whilst in storage and moving through the supply chain. At present retailers and consumers would need to invest in new chilling equipment to maintain the correct temperature, which is an unrealistic expectation. To overcome this a superchilled product would need to be tempered to standard chilled conditions before retail. We examined this practice and found that cook-chill prawns packaged in a modified atmosphere showed positive results in terms of sensory perception and microbiological shelf life, when superchilled at -2°C and then stored at 5°C. The findings indicated that the standard 10-day chilled shelf life can be kept after six days superchilled storage. The chilled shelf life starts to decrease as superchill shelf life is increased, so a balance must be obtained between an increase in superchill shelf life at the production site, whilst maintaining an acceptable chilled shelf life once released from the site.

Final thoughts for future experimentation

Superchilling offers a simple method of extending shelf life, with a need to tailor the technique and therefore get the most favourable outcome for different products. So far, there has been a bias towards assessing superchilled fish and meat. Further thought needs to be given the ready-to-eat products. At present, the use of this technique can be employed by manufacturers to manage stock before release to retailers. It is an effective solution that addresses the constant demand for extended shelf life. We would advise that companies undertake the usual risk assessment and trials for their own product types.

With over 10 years’ experience helping the industry super chill their products, we’re the food and drink sector’s preferred choice for help with superchilling. Get in touch today to find out how we can help you.

To read more on this topic follow the link to our article on Extending the shelf-life of meat and fish products with superchilling, written by one of our microbiology experts, Greg Jones.

Video: Superchilling to improve quality and shelf-life

Grg Jones discusses improvements to product quality and shelf-life when superchilling

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