Innovations in Perishable Food Processing

There are a variety of factors that make our food systems vulnerable, ranging from increasing losses in crop biodiversity to climate change. The food processing industry aims to prolong the life of perishable foods by preserving them, which requires the elimination of microbes, and that is typically done using heat or by using chemical additives. However, heat breaks down valuable molecules like vitamins, and consumers are growing more concerned with the use of chemical additives in their food. 

High-pressure processing (HPP) is a promising method of pasteurization that operates without the use of heat to inactivate microbes by subjecting the food to pressures above 415 MPa. The challenge with HPP is preserving the food’s original nutrients and freshness, as well as its sensory qualities like taste, smell, and colour so that they are accepted by consumers. Researchers at the University of Guelph reviewed the effects of HPP on the quality and consumer acceptability of fruit juices and purees.

High-pressure processed foods retain higher quality

Dr. Ashutosh Singh is an Associate Professor at the University of Guelph’s School of Engineering, and in his Agri-Food Engineering Research Lab he investigates the molecular dynamics of food as it relates to successfully developing new food processes, like HPP. Singh conducted an analysis on the existing HPP studies to identify knowledge gaps in the research. Consumer trends have recently favoured use of natural ingredients such as colours and flavours in their processed foods, so Singh noticed the lack of research surrounding HPP’s ability to enhance the colours, aromas, and flavours of fruit juices and purees. 

Singh’s research found that in comparison to thermally processed foods, the quality of HPP-pasteurized foods is comparable to their fresh alternatives, while also offering an extended shelf life. This is partly because high-pressure, compared to high temperature, has minimal impact on the low molecular weight molecules in foods, such as flavours, vitamins, and pigments, eliminating the need for artificial flavours and colours. However, HPP can directly and indirectly affect plant enzymes that contribute to “off-flavours” in foods, so there is still debate around the amount of pressure to apply in these processes. 

Further research required before HPP is mainstream

Singh found that while HPP not only preserves the natural colours and flavours of foods, but it also enhances them as the high pressure breaks the cell wall, releasing the colourful pigments and flavour molecules into the fruit juice or puree. This also means that HPP makes nutrients and vitamins more bioavailable because it is pulling those low-molecular weight molecules out of the cells. Because HPP can both infuse and pasteurize, supplemental artificial flavouring would not be required like it is for current infused beverages after they have been pasteurized. Singh also found that conducting HPP at a higher temperature, and then storing those foods at a lower temperature, significantly deactivates the number of enzymes in the product, helping to preserve the taste and smell of the product. 

“Despite the benefits of HPP it still has its challenges. Our analysis of the existing research provides valuable insights for researchers and manufacturers to understand the potential of HPP for preserving and enhancing fresh produce quality,” says Singh.

Goraya R.K., Singla M., Kaura R., Singh C.B., Singh A. Exploring the impact of high pressure processing on the characteristics of processed fruit and vegetable products: a comprehensive review. Crit. Rev. Food Sci. Nutr. 2024 July 2. doi: 10.1080/10408398.2024.2373390