This study determined for the first time the structure of the peptides (i.e., peptidomics) in soy protein hydrolysates and elucidated their effects on an oil’s oxidative stability during frying cycles. The oil investigated was palm olein during 0, 4, 8, and 12 frying cycles of plantain banana chips. Proteins were extracted and hydrolyzed with two proteases. Trypsin hydrolysate (HTRY) exhibited higher anti-radical activity (DPPH, 70.2%) than the control (unhydrolyzed proteins, 33.49%) and pepsin hydrolysate (HPEP, 46.1%) at 200 µg/mL. HPEP however showed a 4.6-fold greater reduction of ferric ions (FRAP) while also possessing a higher peroxyl radical scavenging ability (716 ± 30 µM Trolox Eq/g) than HTRY (38.5 ± 35 µM Trolox Eq/g). During oil oxidative stability tests, HPEP improved the oxidative stability of the palm olein oil after 8 and 12 frying cycles, characterized by lower concentrations of hydroperoxides, and carbonyl and volatile compounds. HTRY however exerteda pro-oxidant activity. Structural data from SDS-PAGE and tandem mass spectrometry showed that the mechanism for the greater activity of the pepsin hydrolysate occurred due to unique structural features and a higher percentage of short-chain peptides. This was justified by a 25, 31, and 48% higher contents of tryptophan, histidine, and methionine, respectively (important amino acids with hydrogen atom transfer and electron-donating capacities) in the peptides identified in the pepsin hydrolysate.

Nixtamalization is a process used in the production of tortillas. This process offers many advantages, such as improving the rheological, nutritional, and textural properties of the masa. This process is carried out under different steps which affect the quality of the final product such as the cooking and soaking conditions and the quantity of ash. In addition, the fragility of the masa makes the tortillas brittle. The present work was initiated with the aim of determining the nixtamalization conditions that would improve the textural, rheological, and nutritional properties of masa. The response surface methodology, using the central composite design was applied to three factors including the ash content and cooking and soaking times, and the responses evaluated were the adhesiveness, cohesion, final viscosity, and gelatinization temperature of masa obtained from two varieties of maize (Atp-Y and Kassaï). The optimums masa flours obtained were characterized using standard methods. Results showed that, the masa made from Kassaï variety needed a cooking time of 51.21 min and soaking time of 16.10 h in the presence of 0.80 g of ash. For the Atp-Y variety, the conditions included a cooking time of 49.17 min and a soaking time of 23.4 h in the presence of 0.24 g of ash. The responses obtained showed an adhesiveness of 0.10 kg/f and 0.05 kg/f, cohesion of 1.08 kg/f and 1.23 kg/f, final viscosity of 1504.80 cP and 1328.30 cP, gelatinization temperature 73.50 °C and 71.50 °C, and finally retrogradation 435.50 cP and 316 cP, respectively, for Kassaï and Atp-Y. Chemical characterization of the optimum masa showed that the white masa had a high protein content (10.50%), carbohydrates (71.70%), and fiber (2%) while the yellow masa presented the highest lipid content (5.47%). These finding demonstrated that Kassaï (white) maize‐masa flour obtained in optimal conditions can be recommended for the production of good quality tortillas because tortillas made with this masa are less crumbly and more elastic.