CSIRO: four new technologies for food processing

When people think of the Commonwealth Scientific Industry Research Organisation, or CSIRO as it is affectionately known, most have images of boffins in white coats working in laboratories with Petri dishes, beakers and Bunsen burners busily inventing new gizmos and gadgets for an array of industries. And while this is accurate to a degree, it also is a multi-faceted institution that has more than 5,000 dedicated staff spread around 57 sites throughout the continent.

It has more than 690 patents including the one that encapsulates its most famous invention, wi-fi, and covers many research spectrums, including mining, manufacturing and food. Most recent figures state that it returns about $4.5 billion to the Australian economy annually, and partners with more than 1200 SMEs per year. It’s a very busy place, and one that attracted Irish research scientist Ciara McDonnell to Australia.

McDonnell works at one of the three food sites CSIRO has set up throughout Australia. They’re at Werribee in Melbourne, North Ryde, Sydney and Coopers Plains, Queensland, where she is based. She spoke at a seminar at the recent FoodTech Expo held in Queensland. She talked about four food technologies that could have a lasting impact on the food industry.

“Coopers Plain is home to one of our food pilot plants that we share with the Department of Agriculture and Fisheries,” she said. “At that pilot plant, CSIRO has an emphasis on meat processing, so we have a suite of conventional pilot scale meat processing equipment. This can enable food processors to conduct trials at reduced batch sizes until the process is ready for scale-up. Then we assist companies with that scale up to ensure the best route to commercialisation. When we do R&D, we do take a multidisciplinary approach. We have a lot of expertise in house and we understand the importance of each aspect – from safety, nutrition, processing, food chemistry and more.”

Future trends are very important in the institution’s work because CSIRO want to conduct research with impact for current and future markets. And what are some of the pressing issues in the food and beverage space at the moment?

“We can certainly say that environment, sustainability, health, clean label and minimal waste are some of the top food trends that we drive towards,” said McDonnell. “CSIRO sees itself as bridging the gap between academic research and commercialisation into industry. We have access to a large suite of novel processing technologies ranging from pulse electric fields, spray drying, advanced convection, high pressure processing – the list goes on. In addition, we look after pilot scale conventional processing technologies as well.”

One way of gauging where a technology is at in terms of its development towards commercialisation is the Technology Readiness Level (TRL). This can be 1 or 2, which means it is at the beginning of its research level, and goes up to 9 or 10 where it is being commercialised.

High-Pressure Processing
High-pressure processing (HPP), which it is now commercialised for many food applications, was on the radar almost 20 years ago. What exactly is HPP?

“HPP can offer an alternative to pasteurisation by inactivating micro-organisms. A pre-packaged product is placed into a liquid-filled chamber where it gets treated but there’s no re-opening of the pack, so no recontamination,” said McDonnell. “Pressure is applied instantaneously and uniformly so it is evenly transmitted throughout the product, usually at about 600 megapascals (MPa) for less than five minutes. The process is dependent on the product type and its different properties like pH and water activity. It is important to note that there are different microbial cell sensitivities to HPP; Gram-negative bacteria can be more sensitive than Gram-positive, for example.”

What makes HPP so attractive is that the high pressure affects non-covalent bonds only. This means that small covalent molecules that give consumers health benefits, nutrients, colour to the product and the flavour molecules, are unaffected. HPP offers a means of maintaining the fresh-like characteristics of the product – better colour, extended shelf life –

it fits with the clean label and fewer additives trend that is now part of the food and beverage landscape. Currently, there are more than 1.5 million tonnes of HPP products produced per year globally. It is estimated that the industry will be worth about $80 billion by 2025. It is broadening into new product sectors, with its main application being shelf-life extension of refrigerated products.

However, McDonnell points out there is a catch. The technology doesn’t inactivate bacterial spores, whereas thermal pasteurisation can.

“So for those foods – low acid food, mainly with a pH greater than 4.6 – it will not work at reducing spore-forming bacteria,” said McDonnell. “Any manufacturer that is interested in making products where spore control is required would have to limit the shelf-life, add preservatives; or the alternative is to heat the product, which could result in reduced flavour and nutritional value.”

McDonnell’s colleagues then started to experiment with a combination of heat and pressure, or high-pressure thermal processing (HPTP). They simultaneously applied moderate heat and pressure and reduced the spore load with less overall thermal load than would typically be required to pasteurise or sterilise a product. What they found was that if they applied a HPT process of 550 MPa for one minute at 87.5°C, they could achieve the same inactivation of Clostridium Botulinum spores as a thermal-only process of 10 minutes at 90°C. They refer to this phenomena as HPTP synergy.

“You have less thermal load, so you are maintaining the nutritional molecules while achieving a threefold reduction in Clostridium botulinum,” said McDonnell.

But there was another catch. As mentioned, the CSIRO sees itself as bridging the gap between research and commercialisation. And it knows that many companies that have invested in HPP have units without heating ability, and this limits the scope of products it could potentially process.

“In order to commercialise the HPTP process, we need some processing adaptation,” said McDonnell. “My CSIRO colleague, Dr Kai Knoerzer, developed an insulated HPP canister that, after a pre-heating step, can be inserted into a conventional HPP unit to deliver a HPTP process. It is also able to withstand compressionable heat caused by HPP. And it doesn’t lose that heat either. This is something that is going to be licensed by CSIRO and it will allow HPP units to be adapted.”

Ultrasound
Another technology finding its feet within the food industry is power ultrasound. It has commercial application in several processes in the food sector including mixing, emulsifying, homogenising and degassing products.

How does it work? Power ultrasound typically occurs at frequencies in the range of 20 to 100 kHz. As the soundwave travels, it oscillates above and below atmospheric pressure. When this occurs through a medium at power ultrasound frequencies, any microscopic gas bubble present in that medium will go through the cycles where it expands and contracts until it reaches an unstable size. It then goes through a final compression cycle and this causes the bubble to implode on itself. This is known as cavitation. It is not visible to the eye, but it is a very destructive microscopic mechanism.

“My colleagues at CSIRO were interested in whether it could be applied to help with accelerated drying, specifically of apple slices,” said McDonnell. “They used a novel approach known as airborne acoustics, and they got a 57 per cent reduction in drying time and 54 per cent reduction in energy consumption through the drying of apple slices. It is an example of how technologies can be adapted and applied to new applications.”

Pulse Electric Fields
Next are pulse electric fields (PEF), which are based on placing the food between two oppositely charged electrodes.

“If you imagine a bacterial cell filled with charged ions – positive and negative – and we apply very short pulses of very high voltage so we don’t get heat generated. Typically, this is about 20 kilovolts per microsecond – this results in the ions moving towards the oppositely charged electrode until they permeate the cell membrane of the bacterial cell,” said McDonnell. “Just like HPP, it is a way of targeting those micro-organisms without affecting any molecules that contribute to the flavour, colour and nutritional value of a product.”

It is high on the TRL scale as it has already been commercialised for fruit juices. It can extend shelf-life for preservative-free juices while preserving nutrients. In, has also helped companies achieve up to six per cent increase in extraction yield.

‘’We’ve looked at other applications, like non-terminal milk pasteurisation and improving the texture and quality of meat.”

Shockwave
Shockwave technology is the most novel of all those discussed by McDonnell because it is at proof-of-concept stage. It is the CSIRO’s newest investment, with the government entity having acquired a second commercial prototype, the first outside of Europe.

The idea of shockwave technology for meat applications first arose around 1997 when scientists decided to put pre-packaged meat under water and detonate explosives to see if they could get significantly high pressures to tenderise meat.

“When I spoke about HPP I was talking about hundreds of megapascals,” said McDonnell. “With shockwave technology, I am talking gigapascals. It is for a shorter time – microseconds. In previous studies, 100gms of explosives, placed underwater, were used to tenderise meat. Scientists thought, ‘This is great, but how can we commercialise something with explosives?’ For that reason the speed at which the idea progressed has been slow because, as you imagine with explosives, there were a lot of safety concerns.”
In 2001, dielectric discharge came into being, which helped recreate the shockwave. The technology uses two electrodes to generate a similar effect to the explosives. The scientists put voltage through the electrodes and the arc causes very high pressure under water.

“We have a commercial prototype, which can allow for continuous processing by a conveyor system. We put a product on it, allowing it to go into the water tank, undergo the high pressures, and come out at the other side,” she said. “At the moment, we have a lot of concepts to prove with the technology. We think it might cause tissue disintegration, so we could accelerate the tenderisation of meat. The first application we are studying it for is meat processing through an Australian Meat Processor Corporation-funded project.”

McDonnell said that when it came to modelling and pressure, the scientists aimed to understand pressure distribution in the treatment chamber and to identify the area of maximum impact.

“We used the information from the modelling and conducted trials with meat. We had a tenderisation effect which was measured objectively using a Warner Bratzler shear test, where the peak force required to cut through treated meat samples is recorded,” she said. “And now we are working towards optimising this effect.”

The end result behind the technology is that it could offer processors reduced aging time if scientists can accelerate the aging by shockwave treatment. This is because it can take around 14-21 days to tenderise certain steak cuts.

McDonnell is hopeful that a lot of these technologies will come to fruition. Some will take longer than others to be realised, but that is the nature of science and discovery.

“There is a future for some of these novel technologies as they provide an opportunity for clean labelling, either by changing the food structure or inactivating microbes,” she said. “Certain applications have already been commercialised, and there are good opportunities for all these technologies to be taken up by the food industry.

“Who knows what else is to come from TRL 1 when new ideas are generated in research? They all certainly fit with the trends we are aware of, and they could help with things like having less waste. It could allow us to have more food for increased food demand.
“Also, with globalisation we need extended shelf life to reach new markets, so it will really help us on the supply chain and yield, as well as having healthier products and more efficient and sustainable processes.”