Generation of trihalomethanes with chlorine-based sanitizers and impact on microbial, nutritional and sensory quality of baby spinach

• Trihalomethane (THM) levels in the process water after washing baby spinach with chlorine-based sanitizers were close to the limits for drinking water.
• THM levels in baby spinach were very low and became undetectable after rinsing.
• Quality of baby spinach was not affected by any of the chlorine and non-chlorine sanitizers tested.
• Chlorine-based sanitizers used in the fresh-cut industry have a low potential risk of THM generation.

The potential generation of trihalomethanes (THMs) during washing of vegetable products as a consequence of the use of chlorine has become one of the main concerns for researchers, industry and regulatory agencies. However, only scarce information is known about the actual THM formation in process wash water and in the final product to establish the real risks associated with it. The aim of this work was to evaluate the THM formation in process wash water after washing baby spinach with chlorine-based sanitizers such as sodium hypochlorite and electrolyzed oxidizing water with and without the addition of salt (EOW + NaCl and EOW, respectively). Additionally, the impact of these chlorine-based sanitizers on the microbial, nutritional and sensory quality of baby spinach was compared with a non-chlorine based sanitizer such as peroxyacetic acid. The total THM levels of the process wash water treated with sodium hypochlorite and EOW + NaCl were over the authorized limit fixed by the European legislation and USEPA (100 and 80 μg L−1, respectively) for drinking water. However, the THM levels after treatment with EOW did not exceed these established limits. In baby spinach, THMs were detected in low levels in sodium hypochlorite and EOW washed samples because the rinsing step reduced them to levels below the detection limit. Chlorine and non-chlorine based sanitizers such as peroxyacetic acid, did not affect the quality and shelf-life of the product. After washing and during storage in modified atmosphere packaging, similar headspace gas concentrations, microbial and sensory quality, instrumental texture and colour measures and electrolyte leakage were observed for all sanitizers. The results provide evidence that, under these specific experimental conditions, chlorine-based sanitizers do not represent a risk for THM formation during baby spinach leaf processing. In our opinion, current experimental data does not support banning the use of chlorine-based sanitizers in the fresh-cut vegetable industry because of THM generation in commodities such as spinach.