Peel from unripe plantain is obtained when the pulp is used for the next production process as starch isolation or dry flour. Plantain peel flour (PPF) was obtained and its chemical composition, composition of the dietary fiber (DF), polyphenol content, antioxidant capacity, and functional properties were studied. PPF had more relevant amounts of protein, ash, total starch, and total dietary fiber (TDF). The main component of DF was the insoluble fraction, with a higher level of cellulose than hemicellulose and lignin. In the insoluble fraction uronic acid was the most predominant acidic monosaccharide, while mannose was in the soluble fraction. Extractable polyphenols were found in the lowest amount, but showed the highest antioxidant capacity. Water- and oil-holding capacity values increased when the temperature of the test increased. The PPF with high DF content, high antioxidant capacity, and functional characteristics could be used as a functional ingredient for the elaboration of food products.

The microstructure of cooked gluten-free pasta depends on the ingredients used, and this microstructure affects the starch hydrolysis (SH), the release of phenolic compounds (PC) and their antioxidant capacity (AC). The aim of this study was to evaluate the SD and bioaccessibility of PC during in vitro gastrointestinal digestion of gluten-free pasta and its relationship with the microstructure. The highest SH was during the intestinal phase (≈60%), but pasta with the highest content of unripe plantain and chickpea presented the lowest release of PC (≈60%). The insoluble dietary fibre could be responsible (≈12.5%) for these effects. The cooked pasta showed high AC in the intestinal phase. Regions with gelatinized starch granules in a less dense protein network and other regions with intact or swollen granules surrounded by a protein network were observed. The starch digestion and bioaccessibility of PC were related to the structure of the matrix.