Review article : Effect of different thermal processing on bioactive compounds and antioxidant capacity of tomato ( Solanum lycopersicum L.)

Tomatoes (Solanum lycopersicum L.) contain bioactive compounds such as carotenoids, phenolics, and L-ascorbic acid that increase their antioxidant capacity. Thermal processing frequently influences the bioactive compounds in tomatoes. The effects of common heat-processing techniques (boiling, roasting, microwave cooking, pressure-cooking, oven drying, stir-frying, steaming, and sun or solar drying) on tomato bioactive content and antioxidant activity are compiled and critically assessed in this review. Moderate heat treatments often enhanced phenolic release, carotenoid bioaccessibility, and antioxidant capacity due to cell wall rupture, enzyme inactivation, and increased extractability. However, excessive thermal processing caused carotenoid degradation, particularly in matrices that were high in lipids. Under mild to moderate conditions, lycopene was commonly heat-stable and occasionally increased because of isomerization. Phenolic compounds decreased when exposed to severe thermal treatment but they were increased at moderate temperatures. L-ascorbic acid was the most heat-labile compound with significant losses under the majority of processing methods. Antioxidant capacity often increased despite of reductions in some bioactives, suggesting the importance of structural modifications and heat-induced antioxidant products. These findings show that processing time, temperature, and technique have a major impact on tomatoes' nutritional content, and that maximizing health-promoting properties requires regulating thermal and processing conditions.