ABSTRACT
Lichens have great potential as food, functional food additives or flavourings. The presence of specific substances with multiple biological activities is one of the characteristics of lichens. However, research on lichens as a food source or functional food additive is limited. The present study simulated, for the first time, the potential bioaccessibility of active compounds from 6 lichen species in simulated gastric and intestinal conditions. An in vitro digestion showed that the lichen substances had different bioaccessibility and stability during digestion. It was found that the application of some metabolic modulators significantly altered the accumulation of metabolites in most species. In addition, the study demonstrated the antimicrobial activity of the tested extracts as well as of 14 isolated lichen metabolites. These multi-directional studies demonstrate the potential of lichens in terms of their use as antimicrobial functional food additives.
ABSTRACT
The study examined the effect of fortification of bean paste with onion skin phenolics. The antioxidant potential and in vitro digestibility of nutrients in the light of phenolic-food matrix interactions were studied. Bean paste was supplemented with onion skin extracts in the range of 5-50 mg of phenolics per 100 g of bean (C, O5-O50). Fortification increased the phenolic level and antioxidant activity of bean paste; however, the experimental values, in most cases, were significantly lower than those predicted. The digestive tract acted as an effective extractor of phenolics from the functional products but, surprisingly, the amounts of introduced phenolics had no significant effect on its determined levels. Additionally, after in vitro intestinal digestion a significant increase in the ability to quench free radicals was only observed in samples enriched with the highest amounts of phenolics (O50). After gastric and intestinal stages of digestion no significant effect of fortification on the albumin digestibility was observed. Contrarily, digestibility of globulins had decreased from 70% (C) up to 55% (O50) after gastric digestion and from 93% (C) up to 80% (O50) after intestinal digestion. These results were confirmed by SDS-PAGE analysis, which indicates the presence of indigestible complexes after supplementation with phenolics. Moreover, a significant decrease in starch digestibility from 43% (C) to 21% (O50) was found. In conclusion, fortification improves the health-promoting properties of bean paste; however, the interactions of phenolics with the food matrix play an important role in the creation of the nutraceutical and nutritional quality of products.
