The creation of a safe food, especially a baby food, relies on processing to completely destroy harmful micro-organisms or at least reduce their levels to the point where they prove of no consequence. Conventional thermal processing relies on the employment of significantly high enough heating for pasteurisation or sterilization to bring about such safe food. High pressure processing (HPP) has developed as a credible alternative to conventional thermal processing. High-pressure thermal sterilization (HPTS) builds on both technologies by combining the benefits of both heat and high pressure to be effective.
As well as destroying the micro-organisms which cause harm in themselves, there are also considerations over the products formed during heating. These include Maillard browning products as well as more toxic components such as carcinogens. Generally, carcinogen production during food production using conventional methods is well below the safety limits but it appears HPTS can help minimise production of some of these even further.
A very recent study conducted by a team of food scientists from the Technische University Berlin (Germany) demonstrated how effective HPTS is in treating a model baby food (Sevenich et al., 2014). The scientists examined two spore strains to evaluate the process and a particularly noxious substance, furan which is formed during food heating. Furan is produced in closed systems such as jars and cans where oxygen levels are reduced. Baby food is often packaged in these containers. Levels of furan found in baby food usually vary depending on the ingredients used. The mean concentrations of furan in baby food products were 9.2, 37.0, and 49.6 µg/kg for fruit-, vegetables-, and meat-containing baby foods, respectively (Jestoi et al., 2009).
The test medium was a typical baby food puree and ACES-buffer. The growth and survival levels of the two test species, Geobacillus stearothermophilus and Bacillus amyloliquefaciens were examined over the temperature range of 90–121°C at 600 Mega Pascals (MPa) using HPTS. The treatments at 90°C and 105°C showed that G. stearothermophilus was more pressure-sensitive than B. amyloliquefaciens.
Perhaps of greatest significance was the reduction in the production of furan compared to their conventional thermal treatment which involved retorting. The amount of furan was reduced by 81 to 96% in comparison to retorting for the tested temperature pressure combination. This was even at sterilization conditions with an F0-value in 7 min.
The team subsequently examined another test organism, Bacillus amyloliquefaciens in a scaled-up system – 55 litres with a model baby food. The team used temperature and time combinations at 600 MPa of between 100 and 115 °C, and 0.45 to 28min. They also looked at furan levels and found similar benefits with the scaled-up food system.
The significance of their processing studies is that HTPS could significantly improve the quality of food for especially vulnerable groups such as babies, toddlers and infants. The researchers want to assess this promising technology on a larger scale and understand a lot more about how the process works.
References
Jestoi, M., Järvinen, T., Järvenpää, E., Tapanainen, H., Virtanen, S., & Peltonen, K. (2009). Furan in the baby-food samples purchased from the Finnish markets–Determination with SPME–GC–MS. Food Chemistry, 117(3), pp. 522-528
Sevenich, R., Bark, F., Kleinstueck, E., Crews, C., Pye, C., Hradecky, J., … & Knorr, D. (2015). The impact of high pressure thermal sterilization on the microbiological stability and formation of food processing contaminants in selected fish systems and baby food puree at pilot scale. Food Control, 50, pp. 539-547.
Sevenich, R., Kleinstueck, E., Crews, C., Anderson, W., Pye, C., Riddellova, K., … & Knorr, D. (2014). High‐Pressure Thermal Sterilization: Food Safety and Food Quality of Baby Food Puree. J. Food Sci., 79(2), M230-M237.
Leave a Reply