The antioxidant activity of grape polyphenols or extracts has been verified in fish oil and frozen fish , cooked pork patties and cooked turkey stored under retail display conditions.
Green tea derivatives (at least 200 g/kg) have been added to increase the shelf life of raw, frozen and cooked meat patties.
The derivatives showed effective antioxidant activity, similar to that of such additives as BHA/BHT, although lower than that of rosemary extract.
Other studies have suggested that grape extracts and green tea extracts may have an antibacterial effect in vitro, although little information in this respect exists for meat products.
It was thought that the addition of tea and grape extracts might increase the shelf life of raw patties and other meat products stored under retail display conditions. Preliminary studies had shown that green tea and grape seed extracts do not delay the colour deterioration of raw beef patties, and that it is necessary to add sulphite.
However, the use of sulphite in food has been questioned due to its relation with certain health problems, including allergies, thiamine absorption deficit and disruption of carbohydrate metabolism.
EU Directive 95/2/EC (1995) restricts the use of sulphite in burgers and other raw meat products (maximum 450 mg SO2 per kg of meat).
The FAO–WHO (1986) established a maximum permissible daily ingestion of 0–0.7 mg SO2 per kg of body weight and considered it especially important that SO2 be minimized in food with high thiamine content, such as red meat.
The objective was to study the preservative properties of green tea and grape seed extracts for increasing the shelf life of low sulphite beef patties.
The antioxidant and antimicrobial activities of both extracts were compared with that of ascorbate.
The sensory contribution of both extracts to cooked patties was also studied.