Evolution of Physical–Chemical Parameters, Microbial Diversity, and VOCs Emissions of Tomato Pomace Exposed to Ambient Conditions in Open Reservoirs

Tomato pomace is a by-product produced in the agro-industrial processing of tomatoes. This waste is commonly stored in open-air conditions stabilizing for long periods, producing Volatile Organic Compounds (VOCs) responsible for malodors and environmental pollution.

In this work, samples of Malloa variety tomatoes were collected and stored in plastic containers of 20 kg in three different storage conditions: Open-Air, Under-Roof, and Oxygen-Free. Containers in open-air and Under-Roof conditions were kept with the lid open, and exposed to the atmosphere while containers stored in Oxygen-Free conditions were vacuum sealed and opened only for sample extraction. The production of VOCs in tomato pomace was studied by TD-GC/MS analysis, establishing a direct relationship to changes in physicochemical (ash, moisture, total phenols, pH, proteins, fibers, oils, fats) and biological (bacteria and fungi) parameters over time. The study was carried out for 8 months.

Data showed a progressive increment in odorant VOC concentrations and microbial diversity due to natural chemical and biological transformation processes. The main compounds responsible for the unpleasant odors of this waste are esters, aldehydes, and hydrocarbons, which at the end of the study period increased by an average of 16, 22, and 12%, respectively. Of the three storage methods, Under-Roof conditions presented the lowest VOC concentrations (148.34 mg/kg) in the eight month, followed by Open-Air (321.52 mg/kg) and Oxygen-Free (678.36 mg/kg) conditions.

Based on these results, the most practical storage method is Under-Roof. Waste management strategies were suggested to reduce the production of unpleasant odors. The information provided in this study is relevant for managing tomato agroindustry wastes that can affect the quality of life of nearby communities.