Assessment of Green Processes for Tomato Waste Biovalorization: Spotlight on the Innovative Pulsed Electric Field–Laccase Synergy for Enhanced Sugar and Phenol Extraction Yields

Abstract

Tomato waste (TW) is a plentiful lignocellulosic resource, mainly composed of seeds and skins, that can be converted into high-value compounds. This study explored the enhancement of TW enzymatic and fungal biovalorization using novel ecofriendly approaches, including advanced technology, pulsed electric fields (PEF). Crude laccase first produced on TW was used for enzymatic treatment, and the white rot fungus Trametes versicolor K1 was used in fungal treatment under SmF (submerged) or SSF (semi-solid) fermentation conditions. The physical PEF treatment had increased tenfold sugar extraction yield (83.4 mg/g) and twofold polyphenol extraction yield (4.43 g/g), with respect to the control. PEF–laccase innovative combination, reported for the first time, has enhanced significantly sugar extraction yield (100.6 mg/g), twofold higher than those released from TW after laccase treatment alone. However, the PEF treatment had no effect on polyphenol extraction yield when combined to laccase or fungal treatments. The treated TW was subjected to polysaccharide enzymatic hydrolysis. The combination of PEF with laccase or fungal treatment did not impact sugar yields; however, it allowed polyphenol liberation. During fungal treatment (i.e., T. versicolor K1 grown on TW), comparable maximal laccase activities of 2574.28 U/L and 2577.06 U/L were measured in the culture supernatants, in SmF and SSF conditions, respectively. The findings demonstrate the high potential of PEF for recovering phenols and sugars. When combined to fungal treatment, it offers high yields of valuable products, making it a potential cost-effective approach, providing new prospects for TW valorization.