title: Nitrite-cured color and phosphate-mediated water binding of pork muscle proteins as affected by calcium in the curing solution.
abstract: Calcium is a mineral naturally present in water and may be included into meat products during processing thereby influencing meat quality. Phosphates improve myofibril swelling and meat water-holding capacity (WHC) but can be sensitive to calcium precipitation. In this study, pork shoulder meat was used to investigate the impact of calcium at 0, 250, and 500 ppm and phosphate type [sodium pyrophosphate (PP), tripolyphosphate (TPP), and hexametaphopshate (HMP)] at 10 mM on nitrite-cured protein extract color at various pH levels (5.5, 6.0, and 6.5) and crude myofibril WHC at pH 6.0. Neither calcium nor phosphates present in the curing brines significantly affected the cured color. Increasing the pH tended to promote the formation of metmyoglobin instead of nitrosylmyoglobin. The ability of PP to enhance myofibril WHC was hampered (P < 0.05) by increasing the calcium concentration due to PP precipitation. Calcium also decreased the solubility of TPP but did not influence its enhancement of WHC. On the other hand, HMP was more tolerant of calcium but the soluble Ca-HMP complex was less effective than free HMP to promote water binding by myofibrils. The depressed muscle fiber swelling responding to added calcium as evidenced by phase contrast microscopy substantiated, to a certain extent, the deleterious effect of calcium, suggesting that hardness of curing water can significantly affect the quality of cured meat products.
  
  
  CONCLUSIONS
  Although not affecting nitrite-cured color, calcium hampers the efficacy of phosphates to promote water binding by muscle proteins, underscoring the importance of water quality for brine-enhanced meat products.
authors: Dept of Animal and Food Sciences, Univ. of Kentucky, Lexington, KY 40546, USA.
authors: Jing
authors: J
authors: Zhao
authors: Youling L
authors: YL
authors: Xiong
mesh_terms: D000818:Animals; D002118:Calcium / Q000737:chemistry*; D003116:Color; D011756:Diphosphates / Q000737:chemistry; D005511:Food Handling / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D008461:Meat Products / Q000032:analysis*; D009124:Muscle Proteins / Q000737:chemistry / Q000187:drug effects*; D009210:Myofibrils / Q000737:chemistry / Q000187:drug effects; D009211:Myoglobin / Q000737:chemistry; D009573:Nitrites / Q000032:analysis / Q000737:chemistry*; D010710:Phosphates / Q000032:analysis / Q000737:chemistry*; D011122:Polyphosphates / Q000737:chemistry; D012492:Salts; D012995:Solubility; D012996:Solutions / Q000737:chemistry; D013552:Swine; D014867:Water / Q000032:analysis / Q000737:chemistry; D060753:Water Quality
chemical_list: D011756:Diphosphates; D009124:Muscle Proteins; D009211:Myoglobin; D009573:Nitrites; D010710:Phosphates; D011122:Polyphosphates; D012492:Salts; D012996:Solutions; C017082:brine; C031560:myoglobin nitroxide; D014867:Water; C005692:triphosphoric acid; C003319:sodium pyrophosphate; D002118:Calcium