Pulsed-vacuum immersion of chicken meat and skin in acid solutions. Effects on mass transfers, colour and microbial quality

Decontaminating chicken skin by immersion in an organic acid solution at low temperature (7 °C) led to 3.7, 2.5, 2.4 and 2.0 decimal reductions in total viable counts, Enterobacteriaceae, total coliforms and Escherichia coli, respectively. Lactic acid was a more effective decontaminating agent than citric acid. This decontaminating effect was very closely correlated with solution pH and chicken-skin pH variations. The use of pulsed vacuum immersion (PVI) increased mass transfers (water gain and acidification) and the decontamination effect, especially with respect to total viable counts. In PVI conditions, the skin-solution contact area was increased as a result of solution infiltration into microfolds and feather follicles, but the skin colour was modified (yellowing and greening) as the intensity of the acid treatment increased. In contrast, the results of a triangular test revealed that chicken sausages produced with acid-treated skins did not differ from those made with untreated skins.