"In recent years, naturally occurring antimicrobial and antioxidant compounds have been preferably employed in meats because of their potential health benefits and safety compared with synthetic preservatives, such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT)," explained lead researcher Juhee Ahn from Ohio State University.
Indeed, according to a 2003 report by Frost and Sullivan, the synthetic antioxidant market is in decline, while natural antioxidants, such as herb extracts, tocopherols (vitamin E) and ascorbates (vitamin C) are growing, pushed by easier consumer acceptance and legal requirements for market access.
The new study, published in the Elsevier journal Food Microbiology (Vol. 24, pp. 7-14), gives a boost to the natural sector by reporting that grape seed extract (ActiVin) and pine bark extract (Pycnogenol) performed better that BHA and BHT in retarding the microbial contamination by E. coli, Listeria, and Salmonella of freshly ground beef.
The same extracts also performed better at reducing oxidation of the beef than the synthetic alternatives after nine days. Oxidation processes in food can lead to organoleptic deterioration in taste, colour and texture.
The use of such natural additives has the extra advantage of the health benefits associated with the extracts. The antioxidant activity of grape seed extracts has been linked to boosting cardiovascular health by limiting oxidation of LDL (bad) cholesterol, while Pycnogenol has been claimed to have beneficial effects on a wide range of medical conditions from diabetes to asthma, from boosting male fertility to improving the memory of mice.
These findings were based on data from experiments that added 0.2 per cent BHA/BHT, 1.0 per cent ActiVin, or 1.0 per cent Pycnogenol to half a kilo of ground beef. The beef was subsequently cooked at 75 degrees Celsius, packed in sterile plastic bags, and then stored for nine days.
It was found that E. coli populations on the meat decreased by only five per cent for the BHA/BHT additive, but decreased by 33 and 35 per cent for the meat with added ActiVin and Pycnogenol. No change in Salmonella populations were observed for the BHA/BHT meats, while the grape seed and pine bark extracts reduced the bacterial population by 19 and 23 per cent, respectively.
Only Listeria populations increased in the meat, rising by 60 per cent for the BHA/BHT meat, and by 40 and 18 per cent for the grape seed and pine bark extract treated meat.
Measures of oxidation, and therefore spoilage of the meats, were also significantly less for the grape seed and pine bark extract treated meats than for the synthetic meats, with measures decreasing for the plant extracts after nine days, while the measures increased by over 200 per cent for the synthetic additives.
"Results of this work show that ActiVin and Pycnogenol are promising additives for maintaining the quality and safety of cooked beef," said the researchers.
The extracts also had a profound effect on the colour of the meats, report the researchers, with the grape seed and pine bark extracts reducing the lightness of the cooked meat, and the extracts increased the redness of the meat.
"The retention of the red colour of cooked beef treated with ActiVin and Pycnogenol may result from their antioxidative effects and their contribution of pigments. The fact that ground beef treated with ActiVin and Pycnogenol retained more redness during cooking may result in consumers avoiding consumption of undercooked meat," they said.
The researchers noted that use of such extracts in high concentrations may impact detrimentally on the organoleptic properties of the meat products, and called for further research to determine the effective concentrations that would achieve the antioxidant and antimicrobial activities without impacting on the flavour and aroma.