Pork eating quality was not improved by extended ageing for 14 days

Industry effort is being directed to establish a pathway-based system for pork to improve its quality and consistency. Channon et al. (2003) showed that ageing for 7 days and constant current electrical stimulation (ES) of pig carcases can improve pork tenderness without detrimentally affecting drip loss or colour. However, recent data has suggested that both ageing period and constant current electrical stimulation may not be effective in improving eating quality consistency when commercially used in two different supply chains (Channon et al. 2015a, 2015b). This study aimed to determine the effect of gender, electrical stimulation, ageing for 14 days, and moisture infusion of five cut × cooking method treatments on pork eating quality. It was hypothesised that an extended ageing period of 14 days, rather than 7 days, together with electrical stimulation may be needed for fail rates of less than 10% to be achieved and be comparable to fail rates observed following moisture infusion.

A total of 69 entire male and 68 female Large White × Landrace pigs were managed on-farm, within gender. All male pigs were immunised against gonadotrophin releasing factor (GnRF) using Improvac^® (Zoetis Ltd, USA), with injections administered at 13 and 17 weeks of age (IM). At 22 weeks of age pigs were penned with familiar pigs for transport, and held in lairage with access to water within gender groups for 22 hours before slaughter. Pigs, within gender, were randomly selected for electrical stimulation (none or 150 mA applied for 30 sec at 2 min after exsanguination; ES). A total of 25 pigs per gender, within carcass specifications of 60–75 kg (Trim 1) and 8–13 mm P2, were selected within ES treatment in the chiller at 60 min after slaughter and sides were then allocated to ageing period (2 or 14 days) (n = 10 sides per treatment). Moisture infusion was only applied to no ES, 2-day-aged cuts at a rate of either 0% (no-MI) or 10% brine solution (MI). Cut × cooking treatments used and overall liking and fail rate was determined as described by Channon et al. (2015a, 2015b). Data were analysed by ANOVA.

The OL of pork from IM and F pigs was comparable (57.7 vs 56.8, respectively; SED 1.50, P = 0.542), with an equivalent FR also observed (19.1% for both genders). Ageing for 14 days did not improve OL compared with 2 days (56.0 versus 55.1, respectively; SED 1.58, P = 0.943. The response to ES, as well as MI, differed (P < 0.05) between cut × cooking method treatments (Table 1). This indicated that the response to pathway interventions imposed is not necessarily consistent between different cut types, even when from the same muscle. Across all cuts evaluated, MI achieved a fail rate of 10.8%. Differences in the effectiveness of ES and ageing on eating quality between this study and those of Channon et al. (2015a, 2015b) highlights that each supply chain may need to consider different pathway interventions to enable consistent production of high quality fresh Australian pork.

Table 1.  Electrical stimulation (ES) and moisture infusion (none or 10% infusion) effects on fail rate (%) and overall liking scores^A of five pork cut × cooking treatments