Inhibition of Lipid Oxidation and Rancidity in Precooked Pork Patties by Radical-Scavenging Licorice (Glycyrrhiza glabra) Extract



This study investigated the efficacy of licorice extract (LE) to curtail lipid oxidation and protect sensory attributes of ground pork during refrigerated and frozen storage. Pork patties (20% fat) were formulated with 0%, 0.02%, 0.05%, and 0.1% (meat basis) LE or rosemary extract (RE) as comparison or 0.01% (fat basis) BHA with 0 or 1.5% NaCl. Raw and precooked (75 °C) patties were packaged in polyvinylchloride overwrapped trays and stored at 2 °C up to 7 and 14 d, respectively, or at –20 °C up to 6 mo. Lipid oxidation (thiobarbituric acid-reactive substances [TBARS]) and sensory attributes of stored patty samples were evaluated, radical scavenging activity of the LE was measured, and the active phenolic compounds were identified. Cooking yield (<85%) was similar among antioxidant treatments, and lipid oxidation was minimal in refrigerated or frozen raw samples. However, TBARS values in refrigerated precooked control patties (0.22 mg/kg) rose to 9.3 to 9.4 mg/kg after 14 d, compared to 3.4 to 4.4 and 4.4 to 6.9 mg/kg in patties treated with 0.1% LE and RE, respectively. In frozen precooked samples, TBARS (0.22 mg/kg) increased to 1.3 mg/kg (P < 0.05) in control patties after 6 mo and had no significant change in patties treated with 0.1% LE or 0.01% butylated hydroxyanisol. Sensory panel evaluation confirmed strong inhibition of rancidity production by LE, corroborating its remarkable antiradical activity due to the presence of multiple phenolics. The results indicate that licorice has great potential as a natural antioxidative additive to extend the shelf-life of precooked pork.

Practical Application

Licorice has been used for centuries as a food additive and medicinal ingredient around the world. The discovery of many active phenolic compounds and terpenoids present in licorice extract has spurred considerable global interest to explore antioxidant benefits of this nontraditional material for food preparation. Our present study showed licorice was strongly inhibitory of lipid oxidation and improved sensory acceptability of cooked pork patties. Radical scavenging activity was implicated in the process. The promising results indicate great potential of licorice as a natural additive to improve oxidative stability of muscle foods.