High-pressure processing impacts health-promoting attributes of orange juice.

Scientists in Spain wanted to examine the impact that high-pressure processing would have on freshly squeezed orange juice. Specifically, they wanted to see if the high-pressure (HP) conditions would negatively affect the juice's health-promoting properties.

The investigators studied the bioactive compound stability of freshly squeezed juice from oranges--Citrus sinensis, L.--after it was subjected to HP treatment. They did so by measuring flavanone content and antioxidant activity.

As you know, high hydrostatic pressure is a preservation technique used as an alternative to traditional heat treatments. Therefore, it is essential to assess the impact of HP on bioactive compounds and the related health-promoting attributes of orange juice. Researchers tested several processes that combined HP treatment with heat treatment for various time periods. The control used was fresh juice that did not undergo any treatment. Treatment One was performed at 100 MPa at 60 C for 5 minutes. Treatment Two was performed at 350 MPa at 30 C for 2.5 minutes. Treatment Three was performed at 400 MPa at 40 C for 1 minute.

Fresh and treated samples were kept chilled at 4 C for 10 days. After applying HP during the chilled period, researchers accomplished the qualitative and quantitative determination of flavanones (naringenin and hesperetin) by using HPLC. Also, the radical scavenging activity of juices was assessed by analyzing the 2,2-diphenyl-1-picrylhydrazyl stable radical.

Flavanones are polyphenols specific of citrus fruits, in which they are present in high amounts. They may be linked to reduced risk for cancer, heart disease and other age-related degenerative diseases. The second and third treatments led to an increase in the extraction of flavanone content. Flavanone content after the 10-day chilled storage period resulted in no significant quantitative changes. Radical scavenging activity was unchanged immediately after HP treatments and over the period of chilled storage, except in the case of the first treatment, in which case it was depleted.

So, the tested upper range--350 MPa to 400 MPa--of HP-treated orange juice led to an increase in the extraction of flavanones. In addition, the process retained the fresh-like quality of freshly squeezed orange juice during the chilled storage period tested, as well as the potential health-promoting attributes in the juices.

Further information. M. Pilar Cano, Department of Plant Foods Science and Technology, Instituto del Frio, Consejo Superior de Investigaciones Cientificas (CSIC), Jose Antonio Novais, 10, Ciudad Universitaria, 28040 Madrid, Spain; phone: [phone]; fax: [phone]; email: [e-mail].