Abstract
This study evaluated associations of heat shock proteins (HSP) and an oxidative stress protein, protein deglycase (DJ1), with beef quality and tenderness. Samples from the longissimus thoracis (N = 99) were collected pre-rigor (day 0) and after 14-d aging. Warner-Bratzler shear force (WBSF), myofibrillar fragmentation index (MFI), and a trained sensory panel were used to determine meat quality. Protein abundance of DJ1 and 2 HSP—HSPβ1 and HSPA—were assessed. Regression analyses demonstrated that DJ1 abundance after 14 d of aging is a predictor of WBSF (P < 0.001), MFI (P = 0.02), and sensory panel tenderness (P < 0.001). Abundance of HSPβ1 after 14 d of aging is also a predictor of MFI (P = 0.03). Additionally, abundance of both HSPβ1 and DJ1 pre-rigor are predictors of juiciness (P < 0.05). Abundance of HSPβ1 pre-rigor was correlated with WBSF (R = 0.67), sensory panel tenderness (R = −0.44), juiciness (R = −0.30), and umami (R = −0.20). Abundance of DJ1 pre-rigor was also correlated with WBSF (R = 0.72), sensory panel tenderness (R = −0.44), juiciness (R = − 0.24), and umami (R = −0.31). After 14-d aging, HSP β 1 abundance was cor- related with WBSF (R = 0.66), sensory panel tenderness (R = −0.34), juiciness (R = −0.34), umami (R = −0.33), and brown/ roasted (R = −0.30). Abundance of DJ1 after 14-d aging was also correlated with WBSF (R = 0.68), sensory panel tenderness (R = −0.41), juiciness (R = −0.21), and umami (R = −0.28). These results demonstrate that abundance of HSPβ1 and DJ1 both pre-rigor and after 14 d of aging are correlated with meat tenderness and end-product quality as assessed by a trained sensory panel. Regression analyses further reveal that abundance of DJ1 and HSPβ1 after 14 d of aging is causative in development of beef tenderness and juiciness, respectively. Taken together, these results suggest that abundance of DJ1 is a predictor of tenderness, whereas abundance of HSPβ1 is related to meat quality but cannot be used to predict tenderness.
Highlights
Consumers consider tenderness to be one of the most important qualities of beef and are willing to pay a premium price for a product with guaranteed tenderness (Miller et al, 2001; Koohmaraie et al, 2002; Laville et al, 2009; Lucero-Borja et al, 2014)
In samples collected after 14 d of aging, abundance of DJ1 was found to be a predictor of Warner-Bratzler shear force (WBSF) (P < 0.001), myofibrillar fragmentation index (MFI) (P = 0.02), and sensory panel tenderness (P < 0.001) (Table 3)
DJ1 protein abundance was found to predict tenderness. These results indicate that abundance of both DJ1 and HSPβ1 are correlated with tenderness and DJ1 can be used to predict tenderness, whereas HSPA was not shown to have a relationship with tenderness
Summary
Consumers consider tenderness to be one of the most important qualities of beef and are willing to pay a premium price for a product with guaranteed tenderness (Miller et al, 2001; Koohmaraie et al, 2002; Laville et al, 2009; Lucero-Borja et al, 2014). The process of tenderization occurs during the conversion of muscle to meat as a result of proteolysis of myofibrillar and associated structural proteins within the muscle (Laville et al, 2009) Proteolytic systems, such as calpains, cathepsin, caspases, and the proteasome have each been studied to some extent and are known to play a role in the postmortem tenderization process (Sentandreu et al, 2002; Koohmaraie and Geesink, 2006; Ouali et al, 2013). Members of the HSPB, including HSP27 (HSPβ1), are upregulated in response to stress and are thought to act as molecular chaperones, protecting myofibrillar proteins from degradation during events in which the muscle tissue is stressed, such as postmortem conditions (Mymrikov et al, 2011; Balan et al, 2014; Lomiwes et al, 2014). DJ1 has previously been identified as being involved in quality grade (Thornton et al, 2017) and carcass growth (Picard et al, 2017) but is not known to be related to any other carcass characteristics
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