The authors, in a study published in the journal Food Control, explain that the use of tannic acid in combination with high and low oxygen MAP exhibited a strong inhibitory effect on the growth of psychrophilic bacteria which were dominant at refrigerated storage temperature.
MAP systems with a high oxygen (80 per cent) level are widely used in retail meat markets because the bright red colour of meat this ensures encourages consumers to purchase, but high oxygen levels can increase the incidence of oxidative changes in the meat, thus negatively affecting meat quality characteristics.
To alleviate such a drawback, the Thailand based researchers claim that the use of antioxidants, especially phenolic compounds, could be an effective means to prevent lipid oxidation in high oxygen packaging.
Tannic acid is affirmed as Generally Recognized as Safe (GRAS) by the US Food and Drug Administration (FDA) for the use as a direct additive in some food products including meat products and the authors said that previous studies have reported that the ingredient exhibited superior radical scavenging and lipid oxidation activities in fish.
Chemical, microbiological and sensorial changes of ground beef treated without and with tannic acid (200 mg/kg) and stored in air and under MAP conditions involving packed under MAP with low oxygen concentration (10 per cent) and high oxygen concentration (80 per cent) were monitored during 15 days of storage at 4°C.
Chemical and sensory analyses were taken every three days over the storage duration, with microbiological analysis conducted at day 0 and 15.
The researchers said that ground beef treated tannic acid samples kept under MAP with high oxygen exhibited lower metmyoglobin in comparison with non-treated counterparts after 15 days of refrigerated storage.
And they also found that during the period, samples treated with tannic acid and kept under all packaging conditions contained lower peroxide value (PV) and thiobarbituric acid-reactive substances (TBARS) with coincidental lower non-haem iron content, compared with non-treated counterparts.
“The sample packed in high oxygen MAP treated without and with tannic acid had the higher oxymyoglobin values and received the higher likeness scores for colour, whereas the samples stored in air and under low oxygen MAP showed the lower values, regardless of tannic acid treatment,” said the researchers.
After 15 days of storage, they said that myosin heavy chain (MHC) and actin of all tannic acid treated samples underwent less degradation than those without tannic acid treatment for all packaging conditions but they noted that degradation of MHC was more pronounced in samples kept under MAP with high oxygen.
Meanwhile, they also found that psychrophilic bacterial count (PBC) of all tannic acid treated samples was lower, compared with that of non-treated sample regardless of packaging condition.
The researchers thus concluded that, despite the noted degree of protein degradation progression, the combination of tannic acid treated ground beef samples stored under high oxygen MAP could maintain the red colour and retard lipid oxidation and microbial growth of ground beef during refrigerated storage.
Source: Food Control
Published online ahead of print: doi: 10.1016/j.foodcont.2010.02.018
Title: Preventive effect of tannic acid in combination with modified atmospheric packaging on the quality losses of the refrigerated ground beef
Authors: S. Maqsood, S Benjakul