Starch nanocrystals (SNCs) are insoluble platelet particles with multifunctional properties. SNCs production is mainly based on acid hydrolysis of cornstarch with low yield. This study focuses on investigating the effect of pretreatments (heat‐moisture‐treatment [HMT], annealing [ANN], and sonication [SNT]) on unconventional pinhão starch to produce SNCs by acid hydrolysis to improve the yield and SNCs properties. All starches hydrolysis is described by a first‐order model reaction and shown two phases related at k values. The faster hydrolysis is from SNT (k = 0.61 day−1) and the slower one is at ANN (k = 0.40 day−1). Furthermore, the acid hydrolysis is described by a rapid (0–2 days) phase, followed by a slow phase lasing 3–7 days. The HMT increases the yield of the SNCs (14.7%) but promotes losses in the RC (47.34%) as compared with the native starch (yield 10.23%; RC 52.23%). The ANN improves crystallites perfection, protecting them from acid attack. The pretreatments allow pinhão starch to be used as promising feedstock to produce SNCs with good yield and RC. In addition, ANN can be useful to improve the thermal stability and SNT to speeding up the hydrolysis for SNCs production, while HMT can increase the hydrolysis yield.

The growing concern on environment preservation and the impact of the packaging from the non‐renewable materials improve the interest at biodegradable and active packages development for food applications. The aim was to develop starch films with yerba mate extract (YME) made with water: ethanol (50:50% vol/vol) at 50°C followed by characterization. The YME was applied to the cassava starch films (control, 5, 10, 15, and 20%). The thickness, water vapor permeability (WVP), tensile strength, elongation as well as the Young’s Modulus, water solubility, phenolic compounds, antioxidant activity (DPPH•), color and opacity and sorption isotherms of the films were characterized. The starch films decrease tensile strength, Young’s module and elongation increased as the YME concentration increased. In addition, the sorption isotherms were adjusted to the GAB model (R2 > 0.96). The moisture absorption by the samples of starch films with 5, 10, and 15%, had similar moisture absorption, higher than the control samples. Practical applications In this research, we developed a biodegradable active film with Yerba mate extract (YME), which is in good agreement with the growing concern in the preservation of the environment through minimization of the environmental impact of packaging from the non‐renewable raw material. YME increased the phenolic compounds and antioxidant activity of the starch films. This behavior is good for fatty food applications, since fat acids may undergo oxidative processes and change sensorial and nutritional characteristics; and antioxidants will slow down these reactions. The YME also promoted a plasticizing effect in the cassava starch films, decreasing tensile strength and increasing the elongation. This behavior allows the application of systems that do not need high mechanical efforts.

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In this work, ion exchange experimental data were obtained in batch operation for the binary systems Cu 2+ -Na + , Zn 2+ -Na + , and Zn 2+ -Cu 2+ and for the ternary system Cu 2+ -Zn 2+ -Na + . The ionic exchanger employed was the cationic resin Amberlite IR 120. The experimental data for the binary systems and the ternary system were obtained at total concentrations of (1, 3, and 5) mEq • L -1 . The total exchange capacity of the Amberlite IR 120 resin was obtained by the column technique. All experiments were carried out at 25 °C. To model the ion exchange equilibrium, the Mass Action Law was used. The model considered both ideal and nonideal behavior to represent the experimental data. The nonideality in the solution phase and in the resin phase was described by Bromley's model and by Wilson's model. Wilson's model interaction parameters and the thermodynamic equilibrium constants were obtained from the experimental data for each binary system, from which ternary system ion exchange equilibrium was predicted. On the basis of the results obtained to represent the ion exchange equilibrium for the binary systems, a prediction was made using only the nonideal Mass Action Law. Good agreement was obtained between the calculated and measured values of the resin phase composition.