PHYSICAL, MECHANICAL, AND WETTABILITY PROPERTIES OF CASSAVA STARCH-BASED FOAM TRAYS REINFORCED WITH PASSION FRUIT PEEL FLOUR

Passion fruit peel is an agro-industrial byproduct rich in pectin that can act as a natural reinforcing agent to improve packaging properties. This study evaluated the effect of passion fruit peel flour on the properties of cassava starch-based foam trays. Trays were produced by thermopressing (for each tray, 120g of the formulation was used, ~156 °C, 80 bar, 20 degassing cycles) using a matrix of cassava starch (100g), glycerol (12g), magnesium stearate (3g), and guar gum (2g) (all per 100g starch), under four treatments: Control (C: 110mL water, 1g sodium bicarbonate); Passion Fruit (PF: 2.5% peel flour, 110mL water, 1g sodium bicarbonate); Without Bicarbonate (WSB: 85mL water); and With Sodium Bicarbonate (SB: 85 mL water, 1g bicarbonate) (ratios per 100 g starch). Trays were characterized for mechanical properties (TA.TX Plus texture analyzer), moisture, and wettability. Moisture content was slightly higher for C (11.7 ± 0.2%) and PF (11.9 ± 0.0%) than WSB (10.9 ± 0.1%) and SB (10.7 ± 0.2%). Tensile tests showed maximum tensile strength (MTS) values of 2.0 ± 0.2 MPa (C), 4.4 ± 0.3 MPa (PF), 5.0 ± 0.8 MPa (WSB), and 4.7 ± 0.3 MPa (SB), with corresponding Young's modulus of 176.2 ± 25.0 MPa (C), 328.0 ± 9.1 MPa (PF), 505.6 ± 8.8 MPa (WSB), and 518.7 ± 30.4 MPa (SB). Elongation at break varied among C (1.5 ± 0.3%), PF (1.7 ± 0.2%), WSB (1.1 ± 0.2%), and SB (1.5 ± 0.1%). In puncture tests, PF exhibited the highest maximum penetration force (MPF) (52.8 ± 2.6 N) and MPF/thickness ratio (16.8 ± 1.8 N/mm), followed by WSB (38.2 ± 1.1 N; 15.5 ± 0.1 N/mm), SB (32.9 ± 0.8 N; 14.2 ± 1.1 N/mm), and C (17.9 ± 0.6 N; 7.2 ± 0.7 N/mm). Finally, contact angles were 47.89 ± 5.25° (C), 45.25 ± 4.57° (PF), 60.71 ± 3.99° (WSB), and 59.77 ± 2.13° (SB). Therefore, the trays produced using passion fruit peel flour demonstrated potential for enhancing foam trays.