Resting time before slaughter restores homeostasis, increases rigor mortis time and fillet quality of surubim Pseudoplatystoma spp.

Abstract

This study assesses the respiratory dynamics related to stress parameters and resting time before slaughter, in the quality of surubim (Pseudopatystoma spp.) fillets. A completely randomized design was conducted using five treatments: resting time before slaughter of 0, 2, 4, 8 and 24 hours, with 15 fish sampled per treatment. Time 0 corresponded to the treatment without resting time, where the fish were slaughtered immediately after arriving at the processing plant. The resting time did not affect the electrolyte balance, hemoglobin, plasma, hepatic glycogen, myofibrillar fragmentation index (MFI) and water holding capacity (WHC) of surubins. However, with increased resting time, there was a significant decrease in muscle glycogen and an increase in blood pH and blood bicarbonate levels. Additionally, respiratory parameters showed an increase in pO 2 and, consequently, in O 2 saturation and a decrease in pCO 2 .The hematocrit and MCV values of the surubins after 24 hours of resting decreased significantly. In the first hours of resting, the highest values of erythrocytes and CHCM were observed. The lowest level of stress was observed for fish having 24 hours of resting. Fish having longer resting periods (8 and 24 hours) presented fillets with a higher pH (P <0.05) and the rigor mortis establishment time was shorter for the first 2 hours and 24 hours of resting time. There was a linear decrease in fillet lightness and an increase in the intensity of red (CIE a*) color up to 24 hours when resting was increased. In CIE b*, a linear decrease (P <0.05) of the yellow intensity of the fillets was observed as the surubim resting time increased. A resting time of 4 to 8 hours before slaughter is effective in reestablishing homeostasis after transporting surubim, providing fillets with higher quality and a greater length of the pre-rigor mortis period.

Chemical, physical, microbiological and sensory analyzes of fillets of hybrid sorubins

“…Literature reports ranges from 53.94 to 62.53% to fillets of captured Pseudoplatystoma corruscans (Lara et al, 2010), 59.95 to 63.59% of WHC for fillets of farmed Pseudoplatystoma spp. (Fantini et al, 2015(Fantini et al, , 2020, and proximately 68% for fillets of Pseudoplatystoma sp. obtained from the commerce (Honorato et al, 2014).…”

Effect of different stocking densities on pre-slaughter stress based on respiratory parameters in Nile tilapia (Oreochromis niloticus)

“…Sodium (Na + ), Potassium (K + ), and Chloride (Cl -) ions were measured. Respiratory blood parameters, such as pH, H + , bicarbonate (HCO -3), partial oxygen pressure (PO 2 ), partial carbon dioxide pressure (PCO 2 ), and functional oxygen saturation (SO 2 ), were also determined (Fantini et al 2020) Evaluation of biochemical parameters: Glucose and creatinine analyses were conducted in blood samples collected by vena caudal puncture using 3 mL heparinized syringes. These analyses were performed using commercial kits (Gold Analisa Diagnóstica®), according to the manufacturer's instructions, and readings of results were conducted on a semi-automatic spectrophotometer (BIOPLUS S200).…”

“…The handling care of fish, from removal from the tank to transport, and during the period before slaughter, directly affects the well-being that can reflect the fillet's sensory quality (Fantini et al 2020). If pre-slaughter procedures are not carried out with technical criteria, stressing conditions can be increased, reducing the product's shelf life .…”

“…The timeline of the management of fish farming before the slaughter begins with capture in the tank, transport, arrival at the slaughterhouse, unloading, resting before slaughter, and finally, the stress of the slaughtering process. In these steps, the resting period can be crucial for restoring fish homeostasis (Fantini et al 2020); however, densification can promote changes in the stress responses in Nile tilapia, which, consequently, can change the quality of the fillet (Hong et al 2019). The increase in density causes changes due to stress mainly for Nile tilapia, fish of importance in aquaculture worldwide (Goes et al 2018).…”

“…However, the physiological and biochemical characteristics, such as mobilization of energy reserves in muscles and liver and changes in blood acid-base balance (Gatica et al 2010) are not yet described in each of these stages. The physiological responses to stress depend on the nature of the stress (Ferreira & Barcellos 2008); changes in heart rate, oxygen absorption, mobilization of energy substrates, and disturbance of the hydromineral balance (Fantini et al 2020) can lead to exhaustion (Bagni et al 2007;Goes et al 2019). The changes promoted by the pre-slaughter are measured by the blood indirect indicators and reveal to us if there are conditions to obtain quality of meat of great quality (Anders et al 2020;Venturini et al 2018).…”