The effects of irradiation on quality of injected fresh pork loins Kathy J. Davis a , Joseph G. Sebranek b,c, * , Elisabeth Huff-Lonergan b , Dong U. Ahn b , Steven M. Lonergan b a Burke Marketing Corp., 1516 South D Ave., Nevada, IA 50201, USA b Department of Animal Science, 215 Meat Laboratory, Iowa State University, Kildee Hall, Ames, IA 50011 USA c Department of Food Science and Human Nutrition, 215 Meat Laboratory, Iowa State University, Kildee Hall, Ames, IA 50011, USA Received 16 June 2003; received in revised form 10 November 2003; accepted 10 November 2003 Abstract A comparison of irradiation effects on injected and uninjected fresh pork loin quality was conducted. Sixty pork loins from pigs of similar genetics were obtained from a pork harvesting facility immediately prior to processing. Thirty loins were injected with a brine composed of 2.17% salt/3.04% phosphate/20.8% lactate brine while thirty were not injected. Injected loins were pumped to 13% added weight. Ten loins of each group of thirty were not irradiated while an additional 10 loins were irradiated at 2.2 kGy and the final ten loins were irradiated at 4.4 kGy. Lipid oxidation, color, purge, volatiles, and tenderness were measured on sections of the treated loins after 0, 7, 21, and 35 days of refrigerated storage. Lipid oxidation was minimal for the 0 and the 2.2 kGy-treated loins, but was significantly greater (P < 0:05) at day 35 for the loins treated with 4.4 kGy. Warner–Bratzler shear (WBS) force measurements were significantly lower (P < 0:05) for the injected loins, but irradiation did not have an effect on shear force. Purge was significantly lower for the uninjected loins irradiated at 2.2 kGy than for those irradiated at 0 and 4.4 kGy. The injection treatment did not alter the effects of irradiation on the quality characteristics measured. Ó 2003 Elsevier Ltd. All rights reserved. Keywords: Irradiation; Injected pork; Tenderness; Lipid oxidation 1. Introduction Safety and quality are of utmost importance to the meat industry. Treatments that have potential to ensure safe, consistent, high-quality products have been a ma- jor priority for recent research. Use of ingredients and processing technology such as irradiation appear to have excellent potential, particularly in combination, to achieve both safety and quality improvements. Among the popular products in the meat case today are injected or Ômoisture-enhancedÕ pork. Several ingredients are injected in a brine formulation to improve the consis- tency and quality of pork and other meat products. The ingredients most commonly included are salt, polyph- osphates and lactate. Salt added to the whole muscle meat products is known to increase water retention by increasing myo- fibrillar spacing. The chloride ion increases electrostatic repulsion between filaments which allows for more water to be absorbed and retained in the filament lattice (Offer & Trinick, 1983). Phosphates work synergistically with salt and allow meat processors to achieve equiva- lent water-holding capacity with reduced amounts of salt (Offer & Trinick, 1983). Sheard, Nute, Richardson, Perry, and Taylor (1998) found that polyphosphates improved water-holding, tenderness, and juiciness in pork loins. Furthermore, phosphates allow cooking pork to a higher temperature to ensure food safety while still maintaining desirable texture and flavor. While salt and phosphate have been shown to im- prove tenderness and water-holding capacity in meat, lactate has been included in many formulations as a bacteriostatic agent. Sodium lactate added at 3% low- ered aerobic plate counts in comparison to controls at 42 and 84 days in beef top rounds (Papadopoulos, Meat Science 67 (2004) 395–401 MEAT SCIENCE www.elsevier.com/locate/meatsci * Corresponding author. Tel.: +1-515-294-1091; fax: +1-515-294- 5066. E-mail address: sebranek@iastate.edu (J.G. Sebranek). 0309-1740/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.meatsci.2003.11.011