Adding a touch of rosemary to minced meat before high-pressure processing could stop the flavour loss associated with this anti-microbial treatment, say Brazilian and Danish researchers.
"Addition of 0.1 per cent dried rosemary to minced chicken thighs or breasts prior to high-pressure processing inhibit lipid oxidation during subsequent cooking and could form the basis for product development," wrote lead author Neura Bragagnolo in the journal Innovative Food Science and Emerging Technologies (doi: 10.1016/j.ifset.2006.04.005).
Although the rosemary extract market is growing, one problem is that the ingredient is still considered to be a flavour and not an antioxidant, even though it is often used as such. Many producers believe that this should be changed to reflect current market practices. Some authorities such as the French have recognised this fact, though European legislation has been slow to catch up.
"High-pressure processing has a great potential for microbial control of raw chicken meat as a "fresh" chill-stored, convenience product for wok cooking," explained Bragagnolo.
"While raw chicken meat is oxidatively stable, high-pressure treatment at 600 MPa and above induces lipid oxidation resulting in off-flavors during subsequent cooking."
The researchers, from the State University of Campinas in Brazil and the Royal Veterinary and Agricultural University in Denmark, investigated the effect of a high pressure processing treatment and subsequent cooking (95 degrees Celsius) on the formation of lipid oxidation products of minced chicken thigh and breast meat with and without prior addition of rosemary (0.1 per cent, Thorslunde, Denmark).
Electron spin resonance (ESR) spectroscopy was used to quantify lipid oxidation in the minced chicken meat.
After 10 hours of storage, the researchers found that the level of lipid oxidation was significantly lower in the rosemary treated meats. For the thigh meat, addition of rosemary was associated with a 55 per cent reduction, according to the ESR signal, while breast meat with rosemary was associated with a 42 per cent reduction, compared to the meat without rosemary.
"Rosemary showed accordingly a clear antioxidative effect in pressure-processed samples after a subsequent heat treatment and rosemary was found both to inhibit the radical formation and the subsequent lipid peroxidation and oxygen consumption," reported the researchers.
The differences between the cuts of meat can be explained, say the researchers, by the fat content of the specific cuts. Breast meat is reported to have a higher content of polyunsaturated fatty acids than the thigh meat.
"It may now be concluded that addition of rosemary to the product prior to high-pressure treatment is effective in protecting against formation of "pressed-over-flavor" upon subsequent cooking," said the researchers.
The antioxidant activity of the herb is attributed to the phenolics diterpene compounds in the rosemary.
The market for rosemary extracts is already healthy. Suspicion over chemical-derived synthetic preservatives has pushed food makers to source natural preservatives such as rosemary extract instead, and market analysts Global Information pitch the global food preservative market at €422.7bn, reaching €522bn by 2008.