New techniques to give fresh produce a longer shelf life

‘Fresh’ frozen rocket will soon be available

What would it be like if we could freeze types of lettuce like rocket in such a way they could retain their freshness, lovely appearance and structure? It will be possible in future, according to Eda Demir from the Swedish Optifreeze. “We are currently working on the research, and results are looking very positive.” The organisation is specialised in three different things: OptiFreeze, OptiFresh and OptiDry. One of the company’s important objectives is limiting food waste. Eda talked about this during the International Strawberry Congress.

Top: Rocket before and after applying OptiFreeze. Bottom: Mango before and after applying OptiFresh.
Growing frozen market
The number of frozen products is growing. The global market for frozen products will be valued at 290 billion euro around 2020. The international market for frozen fruit and vegetables is expected to amount to 28.2 million tonnes in 2020. The EU is the largest market for frozen fruit and vegetables. The most important suppliers are Belgium, Poland, the Netherlands, Spain and France.
Frozen fruit
“A problem for frozen fruit is that the product often doesn’t look nice after defrosting. It becomes soft, mushy and no longer looks fresh. The products crystallise during the freezing process. This causes damage to the cell membrane, and nutrients and structure of the products are lost. They also leak upon defrosting.”
New technologies
New technologies are regularly developed in the frozen world. These are developed to retain, for example, quality of the product after defrosting. OptiFreeze has both solutions for the frozen and for the fresh cut fruit and vegetable sectors. They also have techniques for drying herbs. There are various processes, but all three concepts use PEF.
Electric pulse
The company Optifreeze was founded by researchers of the University of Lund in 2011. They have a patent on the process of freezing and defrosting fruit and vegetables with the OptiCept technique. Natural sugars from plants are added by means of vacuum impregnation. The product then receives a short electric pulse with a high voltage. This technique is called PEF (Pulsed Electric Field). This opens the cell membrane, and the natural sugars can enter the cells. Because of the shock, they build a much stronger cell membrane.

“Advantages for the customers are that structure and bite are retained, as well as colour, aroma and flavour. Besides, more of the original product is kept, so there’s less food waste. The process has no negative effect on health.” Eda Emir showed various other examples of products before and after treatment with OptiFreeze or OptiFresh. For example, untreated mangoes without treatment looked brown after 13 days, and with treatment they had a lovely and fresh colour. The company is currently testing OptiFresh on strawberries, raspberries, blackberries, lettuce and tomatoes.

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