Indian scientists are looking into the potential of green tea polyphenols to stop the oxidation of fat in meat products, thereby extending shelf-life and preventing off-flavours.
The research is one of the few studies that look beyond the health benefits of green tea extracts and reports a food formulation application for the polyphenols.
"Reports on the use of GTE in preserving foods… is not much elucidated in the literature," explained the researchers, from the Defence Food Research Laboratory in Mysore.
The potential health benefits of tea, which have mainly focused on green tea, have been receiving considerable levels of study, with scientists reporting a wide range of effects, including a lower risk of certain cancers, improved heart health, weight loss, and protection against Alzheimer's.
But new research reports that the polyphenols may also have a role in food formulation.
"Since green tea is consumed by people as a daily beverage all over the world, extracts of green tea may be safe to use in food systems to extend the shelf life," wrote the researchers in the peer-review journal Food Chemistry.
Green tea contains between 30 and 40 per cent of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3 and 10 per cent.
The four primary polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG), epigallocatechin, epicatechin gallate, and epicatechin (EC).
The new study used ethanol to produce a green tea extract (GTE), and tested the extract on fresh mutton stored at ambient conditions of 25 degrees Celsius and 85 per cent relative humidity.
Lead author K.V. Kumudavally reports that the polyphenol-rich extract inhibited microflora spoilage by up to four days, without adversely affecting the sensorial and physical quality of the meat.
Moreover, levels of free fatty acids, associated with spoilage, were significantly lower after four days in the meat preserved with the green tea extract than the control sample - 1.5 versus 4.1 grams per 100 grams, respectively.
"GTE treatment could be effectively used to extend the shelf life of fresh mutton for up to four days in Indian climatic conditions, since it significantly inhibits the formation of these lipolytic [fat] and proteolytic [protein] degradation products, which are responsible for sensorial spoilage," wrote the researchers.
"Studies show that GTE had a profound bacteriostatic effect on meat spoilage organisms including certain pathogens, indicating that the antibacterial component of GTE supports its practical use for extending the shelf life of fresh mutton for up to four days, at room temperature, without adversely affecting its physical, chemical and organoleptic parameters," they concluded.
In 2006, scientists from the University of Minnesota reported the potential of green tea polyphenols to stop the Maillard reaction in thermally processed dairy to prevent dark colours and off-flavours (LWT - Food Science and Technology, doi: 10.1016/j.lwt.2006.09.009).
Source: Food Chemistry (Elsevier) 1 March 2008, Volume 107, Issue 1, Pages 426-433, doi: 10.1016/j.foodchem.2007.08.045
"Green tea - A potential preservative for extending the shelf life of fresh mutton at ambient temperature (25 degrees Celsius)"
Authors: K.V. Kumudavally, H.S. Phanindrakumar, A. Tabassum, K. Radhakrishna and A.S. Bawa