Increasing the Bioaccessibility of Antioxidants in Tomato Pomace Using Excipient Emulsions

Abstract

Plant-based foods contain numerous bioactive constituents (nutraceuticals) that have beneficial effects on human health. However, their oral bioavailability is often relatively low, which limits their potential efficacy. The bioavailability of nutraceuticals can be increased through the utilization of excipient foods whose compositions and structures are specifically designed to increase the amount of nutraceuticals absorbed in an active form. In this study, olive oil excipient emulsions were designed to increase the bioaccessibility of lycopene and other natural antioxidants in tomato pomace. These emulsions consisted of 8 wt% olive oil and 1 wt% Tween 20 or Tween 80 and were prepared using a microfluidizer operated under different processing conditions (12,000 or 20,000 psi; 3 or 5 passes). Changes in particle size, charge, and bioaccessibility were assessed when tomato pomace-emulsion mixtures were exposed to simulated gastrointestinal digestion. The mean particle diameter of the particles in the excipient emulsions increased after digestion (416 to 446 nm) compared to the values before digestion (200 to 220 nm). The presence of excipient emulsions significantly increased the bioaccessibility of lycopene in tomato pomace compared to oil-free control samples. For instance, lycopene bioaccessibility was > 82% when the tomato pomace was mixed with excipient emulsions but only 29% when it was mixed with oil-free buffer solutions. The presence of excipient emulsions also increased the total phenolic content of the tomato pomace. For instance, the phenolic content was considerably higher in the presence of excipient emulsions (1489 to 2055 mg GAE /100 g FW) than in their absence (939 mg GAE /100 g FW). However, the excipient emulsions did not increase naringenin bioaccessibility, which was attributed to the fact that it was not strongly hydrophobic. The efficacy of the excipient emulsions was only modestly dependent on emulsifier type and homogenization conditions. In conclusion, excipient emulsions can be designed to enhance the bioaccessibility of strongly hydrophobic nutraceuticals in tomato-based products, which may boost their healthiness.