Synergistic Antifungal Activity of Sodium Hypochlorite,Hydrogen Peroxide, and Cupric Sulfate against Penicillium digitatum

CERIONI LUCIANA; RAPISARDA, VIVIANA A.; HILAL, MIRNA; PRADO, FERNANDO E.; RODRÍGUEZ MONTELONGO, LUISA

JOURNAL OF FOOD PROTECTION

INT ASSOC FOOD PROTECTION

Lugar: USA; Año: 2009 vol. 72 p. 1160 - 1665

0362-028X

Oxidizing compounds such as sodium hypochlorite (NaClO) and hydrogen peroxide (H2O2) are widely used in food sanitation for their antimicrobial effectiveness. We applied these compounds and metals to analyze their antifungal activity against Penicillium digitatum, the causal agent of citrus green mold. Minimal inhibitory concentration was 300 ppm for NaClO and 300 mM for H2O2 when they were individually applied by 2 min on conidia suspensions. In order to minimize the concentration of these compounds, we developed and standardized a sequential treatment on the conidia that produces the loss of viability on plate and infectivity on lemons. The in vitro treatment consists of a pre-incubation with 10 ppm NaClO, followed by an incubation with 100 mM H2O2 and 6 mM CuSO4. The combination of NaClO and H2O2 in the presence of cupric salt produces a synergistic effect (fractional inhibitory concentration index 0.36). The sequential treatment applied in situ on lemons peel, 24 h after fruit inoculation with conidia, produces a significant delay on the fungal infection. The in vitro treatment was effective on both imazalil sensitive and imazalil resistant strains of P. digitatum and Geotrichum candidum, the causal agent of citrus sour rot. Although with P. italicum (citrus blue mold) this treatment produced an inhibition of 90% of mycelial growth. These results indicate that the sequential treatment may have a potential application for postharvest disease control of citrus fruits.