Effect of immunological castration on color stability, shelf life, and sensory characteristics of fresh and further processed pork

Improvest® (Zoetis, Kalamazoo, MI) an immunological product for intact male pigs that stimulates the production of antibodies against gonadotropin-releasing factor (GnRF), temporarily blocking its activity and causing temporary castration. Use of Improvest delays castration, taking advantage of increased feed efficiency and lean gain of intact male pigs, without the negative sensory characteristics associated with boar taint. Fresh loin muscle quality has been extensively studied and immunological castration does not negatively affect loin muscle quality. However, more information is needed regarding the potential effects of immunological castration on other aspects of pork quality and in other products. To date, all data on loin muscle (LM) quality have been collected within a few days postmortem, but on average, pork loins and loin chops are stored for 7-14 days then display for 3-5 days prior to purchase causing discoloration. Thus, it is important to characterize and differences between immunologically castrated (IC) and physically castrated (PC) pigs with regard to color stability in pork chops. Furthermore, enhancement is a common practice in the meat industry to improve the sensory characteristics of fresh meat and it is important to characterize any potential differences between IC and PC pigs. Finally, most pork is consumed as further processed products. Thus, it is also important to characterize any effect immunological castration may have on the shelf life and sensory characteristics of pork sausage. Therefore, the objectives of these studies were to evaluate the effects of immunological castration on the color stability of fresh pork chops, the sensory characteristics and quality of enhanced pork chops, and the color stability, shelf life, and sensory characteristics of fresh sausage. To evaluate the effect of immunological castration of pigs on color changes during storage and the sensory characteristics of enhanced and non-enhanced loins, two studies were conducted. In study 1, chops from IC pigs, IC pigs fed ractopamine (IC+RAC), PC pigs, intact males, and gilts were evaluated for sensory characteristics and instrumental tenderness (Warner-Bratzler Shear and star probe). In study 2, chops from IC pigs fed 0.55% and 0.65% SID lysine and PC pigs fed 0.55% SID lysine were displayed over 7 days and color changes were evaluated. After chops for color stability were removed, remaining loin sections were enhanced with a salt and phosphate solution and evaluated for sensory characteristics. In both studies, there were no differences between IC and PC pigs for sensory characteristics or instrumental tenderness of enhanced or non-enhanced loins. In study 2, there were also no differences in the discoloration of chops from IC and PC pigs. These data suggest immunological castration does not affect color stability of fresh pork chops or the quality of enhanced loins. To evaluate the effect of immunological castration of pigs on fresh sausage characteristics, sausage patties were evaluated for color stability, sensory characteristics, thiobarbituric acid relative substance (TBARS), textural properties and cooking loss over 3 storage times. In the first study, Boston butts (NAMP #407) from PC pigs fed 0.55% SID lysine and IC pigs fed 0.55% and 0.65% SID lysine were made into sausage patties. In a second study, sausage was formulated from IC and PC pigs targeting 25% fat. Overall, sausage discolored during display and lipid oxidation increased with increasing storage time. However, there were minimal differences between IC and PC treatments with regard to sensory or textural characteristics. Lipid oxidation did not differ between IC and PC pigs in study 1, but lipid oxidation was reduced overall in IC pigs compared with PC pigs in study 2. However, within each storage period, lipid oxidation did not differ between castration methods. Overall, immunological castration does not negatively affect the color stability, sensory characteristics, or quality of fresh pork sausage. Therefore, similar to previous studies using fresh loins, these data suggest that meat from IC pigs can be used similarly to meat from PC pigs as immunological castration is not detrimental to meat quality of fresh or enhanced loins or fresh sausage