Factors Influencing the Prevalence of PSE Like Destructured Zones in Top Side Muscles from Fresh Hams – A Growing Industrial Problem

Research Article

Austin Food Sci. 2020; 5(1): 1034.

Factors Influencing the Prevalence of PSE Like Destructured Zones in Top Side Muscles from Fresh Hams – A Growing Industrial Problem

Kurt E, Klont E*, Wisse S, Ergun O and Klont R

Istanbul Esenyurt University, Turkey

*Corresponding author: Ediz Klont, Istanbul Esenyurt University, Turkey

Received: December 19, 2019; Accepted: January 14, 2020; Published: January 21, 2020

Abstract

PSE like zones in topside ham muscles are a problem for the cooked ham industry. In this study two experiments were carries out. In two different trials [1] the effects of carcass pH and temperature decline curves and [2] different ham weights on the incidence of destructured PSE-like zones in the deeper regions of fresh hams were studied. Experiment 1 showed that low preslaughter stress leading to a slower pH decline and preferably a higher ultimate pH are important to reduce the incidence of PSE like zones in ham muscles. A faster carcass chilling will help to improve pork quality. The core temperature of the hams will chill, however, at the slowest rate in the carcass. In experiment two it was shown that conditions to form PSE zones inside the core of the ham is significantly higher in heavier hams compared to smaller hams. Growing carcass weights will lead to larger ham weights and continue to increase the incidence of PSE likes zones in the core of the hams.

Keywords: Pork quality; Destructured meat; PSE; Carcass chilling; Colour; Topside ham muscle

Introduction

Pork quality is influenced by the interaction between pig genetics, the entire system of live animal production, processing and chilling of the carcass [3], and finally storage and handling of the meat and derived case-ready and further processed products [1,4]. Pork quality characteristics like drip loss and colour are determined by the interaction between the rate and extent of postmortem pH fall and temperature in the muscle. High postmortem muscle temperature in combination with a low pH can cause denaturation of muscle proteins and a decrease in the electrostatic repulsion between myofilaments. The subsequent increase in light scattering properties and the extent of lateral shrinkage of the myofibrils provokes the meat to become Pale, Soft, and Exudative [2,5]. PSE-like zones of destructured meat in deep regions of fresh hams, mainly top side muscles (M. semimembranosus and M. adductor) represent a serious economic problem for the cooked ham industry [6]. These destructured zones will result in a lower yield and cohesiveness of the finished cooked product, which becomes unsuitable for mechanical high speed slicing [7-9]. The incidence of PSE like zones in hams still appears to increase across the entire pork industry. Increasing carcass weights and more muscular and well conformed hams may have slowed down the temperature decline in the deeper regions of a ham. The higher core temperatures in combination with lower post mortem pH values may locally cause PSE conditions.

The influence of different pig processing conditions and carcass chilling levels in combination with rate of pH fall on general pork quality characteristics like drip loss and colour has been shown in a number of studies [6,10,11]. Vautier et al. [12] studied the prediction level of meat quality characteristics on “PSE-like zones” in pig hams and concluded that the ultimate pH seems to be a reliable predictor of the defect. Several studies have shown that an increase in the chilling rate of the ham will reduce the incidence of destructed zones within a ham [3,13] developed a standardized method to study the pH and temperature decline curves of carcasses in a commercial pig processing plant in relation to drip loss and color of loin samples.

The objective of this study was to review the effects of carcass pH and temperature decline curves and different ham weights on the incidence of destructured PSE-like zones in the deeper regions of fresh hams.

Material and Methods

Two different and separate experiments were carried out at the same commercial pig processing plant on different slaughter days. This commercial slaughterhouse processes around 450 pigs per hour using a CO2 stunning system, with 90-92 % CO2 at the bottom of the pit, and a cycle of 220 seconds. Pre-slaughter treatment of the pigs was optimal without use of electrical prods in the stunning area and low noise and stress levels. Pigs were bled and exsanguinated within 45 sec after stunning. Slaughterhouse had a rapid chilling/ cooling system, where carcasses enter a freeze chiller at 45 minutes postmortem. They remain in the chiller for 1 hour and 45 minutes with an effective air temperature of about –12°C around the carcasses. After the chiller the carcasses are stored overnight in the cooling area at 3°C. In the first trial we determined the relationship between postmortem temperature and pH decline curves and the occurrence of destructured meat in random pig carcasses from different pig suppliers. In a second experiment hams were selected into different weight groups, according to their AutoFOM carcass information, to determine the effect on the occurrence of destructured meat in the topside muscles of these hams.

Experiment 1

Relationship between postmortem pH and carcass temperature decline and the occurrence of PSE like zones in topside muscles.

A total of 175 carcasses were randomly selected on one processing day from 6 different pig suppliers. Hot carcass weight was collected for each of the selected carcasses. The pH at 45 minutes after slaughter was measured in the loin (Musculus longissimus dorsi) of each carcass at the height of the 3rd and 4th rib. Temperature probes (Model Scientific Multi-Use, Temprecord International, New Zealand) were inserted in loin muscles of 12 carcasses around 40 min after stunning at the height of the 10th rib. Six temperature probes were attached to carcasses (around the ham) to measure the cooling air temperature around the carcass during the chilling/cooling process. The temperature loggers were set to measure every 2 minutes. Loin pH measurements were carried out at 3 and 6 hours in the cooling room. Core temperatures in the ham were measured manually with a hand-held thermometer (Testo 925, Sensortype K, Netherlands) at 45 minutes, 3, 6, and 24 hours after slaughter.

The day after slaughter one loin per carcass was collected for measurements of ultimate pH, and Minolta L*, a*, and b* colour values. A boneless loin sample of more than 100 gram was taken from the blade end of the loin, which was weighed in and stored in a case ready meat tray that contained a meat juice absorbing layer. The loin samples were weighed back after 48 hours storage at 4°C for the determination of the drip loss percentage. Hams from all selected carcasses were collected and deboned, after which the top sides were visually categorized in three different quality classes (1. Normal, 2. Potential/slight destructuring, and 3. Destructured zone within the topside (see Figure 1).