The effects of dry-cured ham initial water activity on Tyrophagus putrescentiae infestations

Abstract

A 5 × 2 × 2 factorial arrangement within a completely randomized design was used to evaluate the effect of aw (0.65, 0.70, 0.75, 0.80, and 0.85), RH (65% and 75%) and temperature (24 °C and 28 °C) on Tyrophagus putrescentiae growth, on ham cubes in two separate experiments, one for treated nets (infused with propylene glycol (PG) + propylene glycol alginate (PGA) + carrageenan (CG) + water) and one for untreated control nets. For treated nets, water activity and temperature did not affect mite growth. When control nets were used, there was no difference due to aging temperature, but there were more mites (P < 0.05) at 65% RH than at 75% RH. In addition, ham cubes with 0.85 aw had more mites (P < 0.05) than at 0.70 and 0.65 aw, and ham cubes with 0.80 and 0.75 aw had more mites (P < 0.05) than at 0.65 aw. The only treatment combinations that controlled mites were the ham cubes with 0.65 aw that were stored at 75% RH at both temperatures, with average mite counts below the initial inoculum level of 20 mites. Overall, results indicated that the treated nets were effective at controlling ham mites, regardless of ham cube aw, storage temperature, and RH. However, if only untreated barrier nets were used, mites were only controlled when ham cubes had a aw of 0.65 or 0.70 and were stored at 75% RH. These conditions may not be practical since drying to 0.65 or 0.70 aw would result in more moisture loss, lower yields, and less product that could be sold.