Broiler Meat Quality Issue De-mystified31 March 2013
White striping is a recently recognised defect of chicken breast meat that could affect acceptance by consumers. This article reviews the work done to investigate the condition at the University of Arkansas, showing that the condition is associated with large fillets. The cause of the degenerative myopathy remains illusive but there appears to be no link between white striping and cooked meat quality.
Researchers at the University of Arkansas in the US describe white striping as a condition in broiler chickens characterised grossly by the occurrence of white striations, seen parallel to the direction of muscle fibres, on broiler breast fillets and thighs.
Led by C.M. Owens of the Department of Poultry Science, the Arkansas University team has investigated this meat quality defect, together with other partners, and they have published a series of papers in the journal, Poultry Science, with V. Kuttapan as the first author.
Among their first papers was an investigation into the marketing impacts of the white striping (1). As the severity of white striping increased, acceptance decreased among US consumers. More than half of those asked said they would probably not, or definitely not, buy breast fillets with moderate or severe white striping. This highlights the potential negative impact of this defect on the chicken meat market.
This study was followed by others investigating the possible causes of white striping. The Arkansas-based team found that faster growing broilers tended to have an increased occurrence of higher degrees of white striping in the breast fillets (2). Furthermore, white striping of broiler breast meat was more prevalent and more severe in heavier fillets (3).
The degree of white striping was associated with changes in the chemical composition of the breast fillets (2). Vitamin E levels in the diet have been shown in previous research to affect meat quality issues but feeding the birds higher levels of vitamin E had no significant effect on white striping (3).
Working with other institutions, the Arkansas team turned their attention to the pathological changes in the breast muscle associated with white striping in broiler breast muscles (4). They examining the changes in histology as well as proximate composition occurring in the fillets that were classified as normal, or with moderate or severe white striping.
Major histopathological changes were observed in the moderate and severe samples. Microscopic lesions for degenerative or necrotic lesions, fibrosis and lipidosis increased as the degree of white striping increased from normal to severe.
The results from the histopathological study were supported by the findings from proximate analysis, which revealed that the muscle fat content increased and the protein content decreased as the white striping was more severe.
The researchers concluded that the histopathological changes occurring in white striping indicate a degenerative myopathy that could be associated with increased growth rate in birds, as previously observed.
Investigating the issue further, the Arkansas team compared the haematological and serological profiles of birds with normal and severe degrees of white striping in the breast fillet (5).
Live, fillet and liver weights, as well as fillet yield, were higher in birds with severe white striping than normal birds. There were no differences in various haematological parameters, including the differential leukocyte count. Overall, no systemic infectious or inflammatory condition was found to be associated with white striping. The elevated serum enzyme levels confirm the muscle damage associated with the degenerative myopathy in severe cases.
No Effect on Cooked Meat Quality
For the most recent study (6), the Arkansas researchers joined forces with Auburn Univeristy and University of Illinois, Urbana-Champaign in aiming to reproduce the defect under experimental conditions. Broilers aged 59 to 63 days of four different commercial high-yielding strains (both males and females) were fed according to standard industrial or phase-feeding regimens.
The carcasses were deboned at either four or six hours post-mortem, and the fillets were scored for the degree of white striping at 24 hours post-mortem.
About 56 per cent of the birds used in the study showed some degree of white striping with the moderate and severe categories as 47.5 and 8.3 per cent, respectively.
Once again, the higher degrees of white striping were related to higher cranial fillet thickness and ready-to-cook weights. Fillets with severe white striping had increased b* values (yellowness) of the meat. The differences were not linked to feeding regime or chill time.
The degree of white striping was not associated with any of the various meat quality parameters measured, which included pH, lightness, red colour and cook loss.
The cause of and therefore prevention/treatment methods for white striping of broiler breast meat remain elusive. However, the results of this latest study confirm that there is a greater chance of higher degrees of white striping associated with heavier birds. Despite consumers stated aversion to affected products, it appears that the condition is unrelated to changes in cooked meat quality.
1. Kuttappan V.A., Y.S. Lee, G.F. Erf, J-F.C. Meullenet, S.R. McKee and C.M. Owens. 2012. Consumer acceptance of visual appearance of broiler breast meat with varying degrees of white striping. Poult. Sci., 91(5):1240-1247. doi: 10.3382/ps.2011-019
2. Kuttappan V.A., V.B. Brewer, J.K. Apple, P.W. Waldroup and C.M. Owens. 2012. Influence of growth rate on the occurrence of white striping in broiler breast fillets. Poult. Sci. 91(10):2677-2685. doi: 10.3382/ps.2012-02259
3. Kuttappan V.A., S.D. Goodgame, C.D. Bradley, A. Mauromoustakos, B.M. Hargis, P.W. Waldroup and C.M. Owens. 2012. Effect of different levels of dietary vitamin E (dl-α-tocopherol acetate) on the occurrence of various degrees of white striping on broiler breast fillets. Poult. Sci., 91(12):3230-3235. doi: 10.3382/ps.2012-02397
4. Kuttappan V.A., H.L. Shivaprasad, D.P. Shaw, B.A. Valentine, B.M. Hargis, F.D. Clark, S.R. McKee and C.M. Owens. 2013. Pathological changes associated with white striping in broiler breast muscles. Poult. Sci., 92(2):331-338. doi: 10.3382/ps.2012-02646
5. Kuttappan V.A., G.R. Huff, W.E. Huff, B.M. Hargis, J.K. Apple, C. Coon and C.M. Owens. 2013. Comparison of hematologic and serologic profiles of broiler birds with normal and severe degrees of white striping in breast fillets. Poult. Sci., 92(2):339-345. doi: 10.3382/ps.2012-02647
Kuttappan V.A., V.B. Brewer, A. Mauromoustakos, S.R. McKee, J.L. Emmert, J.F. Meullenet and C.M. Owens. 2013. Estimation of factors associated with the occurrence of white striping in broiler breast fillets. Poult. Sci., 92(3):811-819. doi: 10.3382/ps.2012-02506