Effects of Grape Pomace Powder Alone and in Combination with Pomegranate Peel Extract and Lactic Acid to Prolong the Shelf Life of Chicken Nuggets.

In this study different strategies have been adopted to promote the shelf-life prolongation of fresh chicken nuggets. Two different by-products, grape pomace powder (GPP) and pomegranate peel extract (PE), alone and in combination with lactic acid, were suggested as meat preservatives. The antioxidant properties measured by different assays confirmed the presence of bioactive compounds in both by-products. To test their effects on meat samples, a control nugget without any compounds and a nugget with sole lactic acid were also used for comparison. During a refrigerated storage of about 2 weeks, microbiological stability and changes in sensory properties were monitored to assess the product shelf life. Results demonstrated that GPP promoted a good preservation of meat, and its combination with other compounds further increased the effectiveness. The control without any active agent remained acceptable for less than 1 day, the control with lactic acid for less than 2 days ( > 0.05). The other active samples lasted longer depending on the combinations of active compounds. When the sole GPP was used, about 3 days of shelf life were recorded ( < 0.05). While the combination of GPP with PE promoted only a slight increase of shelf life by 1 day (2.9 vs. 3.9 days), the combination of GPP with LA prolonged the shelf life to more than 6 days (2.9 vs. 6.58 days) ( < 0.05). The best results were found when both LA and PE were combined with GPP because the nuggets lasted about 10 days ( < 0.05). To better highlight the single and combined effects of the tested active agents, a proper index ∆%, comprising the normalized percent difference between the shelf life of the sample with the most antimicrobials and that of the sample with the least antimicrobials, was calculated, thus comparing the various samples and demonstrating the potential synergic effects among them.