Postharvest decontamination of fresh black truffle (Tuber melanosporum): Effects on microbial population and organoleptic qualities

Truffles usually contain a high microbial load and establishing a decontamination strategy without affecting the organoleptic features of fresh truffles before any postharvest processing is an imperative. In this study, the im-pacts of decontamination treatments including ozonated water (3 mg/L and 6 mg/L) and citric acid (5% and 10%) on the microbiological populations (total aerobic, total anaerobic, and Pseudomonas spp. counts) and organoleptic characteristics (firmness and colour) of fresh truffles were investigated. Furthermore, the effect of time of exposure (5, 10, 15, and 20 min) to each treatment was assessed. Treatment that demonstrated the most effective microbial reduction without compromising the colour and firmness of truffles was deemed preferred and its impact on the key volatile profile of truffles was assessed. Truffles treated with different concentrations and exposure times of ozonated water showed no significant changes in microbial counts, firmness, or colour compared to the control. A significant microbial reduction without compromising the colour and firmness of truffles was observed with citric acid treatments. In particular, the antimicrobial effect of citric acid against Pseudomonas spp. was improved significantly with increasing concentration and exposure time. Truffles treated with 10% citric acid treatment for 15 min promoted about 1.0 log CFU/g of reduction for the total aerobic and anaerobic microbes and the Pseudomonas spp. count was reduced from 6.18 +/- 0.19 log CFU/g (control) to < 3.48 log CFU/g. The key volatile profile of the selected treatment was not significantly different from the control. The overall finding shows that a single-step washing with citric acid could be a promising decontamination treatment for fresh truffles before any postharvest processing.

Automated summary

This study investigated the effects of ozonated water and citric acid on the microbial populations and organoleptic characteristics of fresh truffles. The results showed that citric acid treatment significantly reduced the microbial counts without affecting the color and firmness of truffles. Therefore, a single-step washing with citric acid could be a promising decontamination treatment for fresh truffles before any postharvest processing.