inosinic-acid and ribose-5-phosphate

The formation of ATP breakdown products in chicken M. pectoralis major post-slaughter is reported. The concentrations of metabolites were followed in chicken breast throughout the carcass processing post-slaughter and during chilled storage. The concentration of glucose remains similar throughout the period whilst that of glucose-6-phosphate decreases linearly. Glucose and glucose-6-phosphate concentrations were inversely related to the pHu of the breast meat throughout chilled storage. Rapid post-mortem glycolysis and high pHu values suggest the occurrence of stress at and pre-slaughter. Whilst ATP, ADP and AMP were rapidly broken down, the concentration of IMP rose rapidly and remained high. Concentrations of inosine, ribose and hypoxanthine increased gradually post-slaughter but an initial increase in ribose phosphate was not sustained. Most of the potential ribose present in chicken meat, believed to be important for flavor formation, remains bound in the form of inosine and IMP. There is evidence that additional breakdown pathways for ribose and ribose-5-phosphate may deplete the concentrations of these precursors.

Topics: Abattoirs; Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; Chickens; Cold Temperature; Diet; Dietary Sucrose; Glucose; Glucose-6-Phosphate; Glycolysis; Humans; Hydrogen-Ion Concentration; Hypoxanthine; Inosine; Inosine Monophosphate; Meat; Muscle, Skeletal; Phosphorylation; Postmortem Changes; Refrigeration; Ribose; Ribosemonophosphates; Stress, Psychological; Taste

The headspace volatiles produced from buffered and unbuffered cysteine model systems, containing inosine 5'-monophosphate, ribose 5-phosphate, or ribose, were examined by GC-MS. Sulfur compounds dominated the volatiles of all systems and included mercaptoketones, furanthiols, and disulfides. The inosine monophosphate systems produced much lower quantities of volatiles than ribose phosphate or ribose systems. In the systems buffered with phosphate or phthalate buffers, both ribose and ribose phosphate systems gave similar quantities of sulfur volatiles. However, in the absence of buffer, the ribose system was relatively unreactive, especially for volatiles formed via the 2,3-enolization route in the Maillard reaction, where 4-hydroxy-5-methyl-3(2H)-furanone is a key intermediate. A number of keto-enol tautomerisms, which are known to be acid-base-catalyzed, occur in the 2,3-enolization route. This may explain the catalysis of the ribose systems by the buffers. In the ribose phosphate systems, however, Maillard mechanisms probably played a less important role, because ribose 5-phosphate readily dephosphorylated to give 4-hydroxy-5-methyl-3(2H)-furanone on heating and thus provided an easier route to aroma compounds than the Maillard reaction.

Topics: Cysteine; Hot Temperature; Hydrogen-Ion Concentration; Inosine Monophosphate; Odorants; Phosphorylation; Ribose; Ribosemonophosphates; Sulfur; Volatilization

Topics: Inosine Monophosphate; Nucleotides; Phosphates; Ribose; Ribosemonophosphates