Phytochemical content and antioxidant activity of extruded products made from yellow corn supplemented with apple pomace powder

Abstract

The aimed of this study was quantified total phenols content, total flavonoids, and antioxidant activity in extruded ready-to-eat products made from yellow corn added with apple pomace powder. A central composite rotatable experimental design was used. The variables tested were exit die temperature (140-180 °C), feed moisture (14-20 g/100 g) and apple pomace concentration (0-30 g/100 g). The effect of the process variables on the total contents of phenols, flavonols, flavanols and flavonoids and antioxidant activity was evaluated using the response surface methodology. The data of each response were fitted to a second-order model with determination coefficients ≥ 0.71. The extruded product with no added apple bagasse showed the lowest values of the evaluated phytochemicals but had higher antioxidant activity by DPPH. The addition of apple pomace increased the phytochemical content and antioxidant activity in extruded ready-to-eat products made with yellow corn. This makes it possible to obtain a formulation of an extruded food rich in phenolic compounds with potential to contribute to prevention of oxidative stress, while making use of agro-industrial waste from apple juice extraction.

Fruit Waste as a Matrix of Health-Promoting Compounds in the Production of Corn Snacks

“…The addition of apple pomace to these extrudates resulted in a 2-fold to 12-fold increase in flavonoids relative to control. Leon et al [ 23 ] also confirmed an increase in polyphenols in extruded products with yellow corn supplemented with apple pomace powder and a significant increase in flavonoids ranging from 15 to 200% relative to the control.…”

“…The addition of apple pomace to these extrudates resulted in a 2-fold to 12-fold increase in flavonoids relative to control. Leon et al [23] also confirmed an increase in polyphenols in extruded products with yellow corn supplemented with apple pomace powder and a significant increase in flavonoids ranging from 15 to 200% relative to the control. Analyzing the phenolic profile of corn extrudates with a share of apple pomace by UPLC-PDA-MS/MS method, it could be observed that even the control obtained from corn grits (sample EI CONTROL) contains high level of phenolic acids, which are partially endogenous acids originating from corn, namely, caffeoylglycerol, p-coumaroylquinic acid, 2-Op-coumaroylglycerol, and feruloylquinic acid, which due to the applied processing parameters are freed from the cell walls of the cereal, which is why their level in the sample is high.…”

“…Li et al [ 22 ] determined the content of polyphenols in apple pomace at the level 556 mg of gallic acid/100 g d.m. Leon et al [ 23 ] estimated the content of polyphenols in apple pomace to be 327.60 mg of gallic acid/100 g d.m. The content of polyphenols in plant material depends not only on extraction procedure but also on the expression of the results (e.g., different phenolic compounds used to calculate the amount of polyphenols) [ 6 ].…”

“…According to Ćetković et al [ 18 ], the level of flavonoids in apple pomace ranges between 45 and 119 mg of rutin/100 g d.m. According to Leon et al [ 23 ], the content of flavonoids in apple pomace equals 75.6 mg of rutin/100 g d.m.…”

“…Additionally, the amounts of quercetin derivatives were highly correlated with ABTS ( R 2 = 0.98) and DPPH ( R 2 = 0.93) and the level of chlorogenic acid with ABTS ( R 2 = 0.99) and DPPH ( R 2 = 0.92), because correlation coefficients were especially high. Analyzing the abovementioned antioxidant potential, it should be stated that its values were mainly the result of the content of polyphenols in analyzed raw material; however, it could be possible that new compounds with antioxidant properties formed during extrusion, e.g., products of Maillard reaction or more active forms of polyphenols, could also influence the final results [ 23 , 45 ]. The range of increase of antioxidant potential after the introduction of apple pomace to extrudates was from a few percent to three times in comparison to control ( Table 4 ).…”