The effects of mulberry polyphenols on the digestibility and absorption properties of pork myofibrillar protein in vitro

Precise evaluation of batch adsorption kinetics of plant total polyphenols based on a flow-injection online spectrophotometric method

Efficient evaluation of adsorption kinetics of plant total polyphenols is essential for the design of adsorption separation of bioactive compounds. The conventional method uses manual sampling with poor reproducibility. Here, we developed a new method for on-line determination of total polyphenol content (TPC) in plant extracts by applying the Folin-Ciocalteu method in flow-injection analysis (FIA). The FIA parameters were optimized and a standard curve with excellent linearity was established. Precise determination of TPC with a satisfactory sample throughput of 20 h-1 was achieved for the adsorption kinetic study. The pseudo-second-order kinetic model was found to better describe the kinetic parameters of the batch adsorption/desorption process. The developed method proved to be accurate compared with the conventional method. The FIA method holds significant promise for studying and monitoring adsorption processes, due to its automatic on-line nature, low consumption of reagents and samples, and the ability to generate large quantities of highly accurate adsorption data.

Whole Flour of Purple Maize as a Functional Ingredient of Gluten-Free Bread: Effect of In Vitro Digestion on Starch and Bioaccessibility of Bioactive Compounds

The growing demand for gluten-free products requires the study of alternatives to produce nutritionally and technologically favorable foods. The aim was to evaluate the content and antioxidant capacity of gluten-free bread enriched with whole flour of purple maize (PM) and how starch and bioaccessibility of antioxidant compounds were modified during in vitro digestion. Gluten-free bread was prepared with the addition of 34%, 50%, and 70% PM, and white maize bread served as control. The content of total polyphenols, anthocyanins, and antioxidant capacity through FRAP and TEAC was measured. Specific volume, crumb texture, and starch digestibility were determined in the breads. Simultaneously, in vitro digestion and dialysis by membrane were performed to evaluate the bioaccessible and potentially bioavailable fraction. Bread with 34% PM had a similar specific volume and crumb texture to the control, but higher content of polyphenols (52.91 mg AG/100 g), anthocyanins (23.13 mg c3-GE/100 g), and antioxidant capacity (3.55 and 5.12 µmol tr/g for FRAP and TEAC, respectively). The PM breads had a higher antioxidant content and capacity and higher slowly digestible and resistant starch than the control. These parameters increased as the PM proportion rose. After digestion, anthocyanins were degraded, polyphenols and antioxidant capacity decreased, but they remained potentially bioavailable, although to a lesser extent. Bread with 34% shows acceptable technological parameters, lower starch digestibility, and contribution of bioactive compounds with antioxidant capacity. This indicates that purple maize flour represents a potential ingredient to produce gluten-free bread with an improved nutritional profile.