The improper disposal of plastics is a growing concern due to increasing global environmental problems such as the rise of CO2 emissions, diminishing petroleum sources, and pollution, which necessitates the research and development of biodegradable materials as an alternative to conventional packaging materials. The purpose of this research was to analyse the properties of biodegradable polymer blends of thermoplastic potato starch (TPS) and polylactide, (PLA) without and with the addition of citric acid (CA) as a potential compatibilizer and plasticizer. The prepared blends were subjected to a comprehensive physicochemical characterization, which included: FTIR-ATR spectroscopy, morphological analysis by scanning electron microscopy (SEM), determination of thermal and mechanical properties by differential scanning calorimetry (DSC), water vapour permeability (WVP), as well as biodegradation testing in soil. The obtained results indicate an improvement in adhesion between the TPS and PLA phases due to the addition of citric acid, better homogeneity of the structure, and greater compatibility of the polymer blends, leading to better thermal, mechanical and barrier properties of the studied biodegradable TPS/PLA polymer blends. After conducting the comprehensive research outlined in this paper, it has been determined that the addition of 5 wt.% of citric acid serves as an effective compatibilizer and plasticizer. This supplementation achieves an optimal equilibrium across thermal, mechanical, morphological, and barrier properties, while also promoting material sustainability through biodegradation. In conclusion, it can be stated that the use of thermoplastic starch in TPS/PLA blends accelerates the biodegradation of PLA as a slowly biodegradable polymer. While the addition of citric acid offers significant advantages for TPS/PLA blends, further research is needed to optimize the formulation and processing parameters to achieve the desired balance between mechanical strength, thermal and barrier properties and biodegradability.
Starch is a polysaccharide that is widely used in food and other industries; therefore, due to its great potential, it is attempted to be maximally isolated from various foods rich in starch. Commonly, potatoes are used for starch production due to the relatively high starch content in tubers, and the process itself is complex and includes several steps. The aim of this study was to isolate and characterize starch from eight potato varieties. First, the basic chemical composition of the potato samples was determined, and then the isolation was carried out under laboratory conditions. The isolated starch was air dried, then ground and sieved through a 400 µm sieve. The basic chemical composition, amylose content, starch color, swelling capacity and solubility index, clarity of starch pastes, texture of starch gels and thermo-physical properties (gelatinization and retrogradation) were determined in the obtained starch samples. The results showed that the SL 13–25 potato variety had the lowest starch content, while the Stilleto variety had the highest starch content. The content of protein, fat, ash and crude fiber was relatively low in all of the isolated starches, indicating their high purity. Also, the difference in the color of the isolated starches was difficult to see. The highest amylose content had starch from Saprodi, while the lowest was observed in starch from SL 13–25. Starch from the cv. Dartiest had the highest, while starch from the cv. Sereno had the lowest gel strength. The starch of the cv. Dartiest also had the highest clarity value. The retrogradation transition temperatures and enthalpies were lower compared to the gelatinization temperatures and enthalpies. With the increasing temperature, both the swelling capacity and the solubility index of all the samples increased. According to the obtained differences, this study confirmed the significant influence and role of different cultivars on starch characteristics.
Starch extracted from the domestically cultivated Scala potato variety was explored as a renewable resource for the formulation of biodegradable thermoplastic starch (TPS)/polylactic acid (PLA) blends intended for environmentally friendly food packaging applications. The isolated starch underwent comprehensive physicochemical and structural characterization to assess its suitability for polymer processing. TPS derived from Scala starch was compounded with PLA, both with and without citric acid (CA) as a green compatibilizer to enhance phase compatibility. The resulting polymer blends were systematically analyzed using Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR–ATR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) to evaluate thermal and structural properties. Mechanical performance, water vapor permeability (WVP), water absorption (WA), and biodegradability in soil over 56 days were also assessed. The incorporation of citric acid improved phase miscibility, leading to enhanced structural uniformity, thermal stability, mechanical strength, and barrier efficiency. Bio-degradation tests confirmed the environmental compatibility of the developed blends. Overall, the results demonstrate the potential of Scala-based TPS/PLA systems, particularly those modified with citric acid, as viable candidates for sustainable food packaging, while highlighting the importance of further formulation optimization to balance functional and biodegradative performance.
This paper analyzed the influence of the addition of Zn- and Se-fortified wheat flour to corn extrudates on viscosity, total starch content, starch damage, and bioavailability of zinc and selenium. Fortified wheat flour was added to corn grits in 90:10, 80:20, 70:30, and 60:40 ratios at three extrusion temperature profiles: 140/170/170 °C, 150/180/180 °C, and 160/190/190 °C. Viscosity values decreased significantly at different extrusion temperature profiles and at different proportions of wheat. The extrusion process increased the starch content, regardless of the extrusion temperature, and decreased it by adding different proportions of flour enriched with zinc and selenium. The starch damage increased with extrusion, without significant changes with extrusion temperature increment. The addition of different proportions of Zn- and Se-fortified wheat flour reduced starch damage values proportionally to the added content of enriched wheat. Increasing the temperature and the proportions, the total zinc content in the extrudates increased. Zinc bioavailability increased with increasing extrusion temperature. As for selenium, the total content increased by proportion increment but decreased with an increase in the extrusion temperature, though there were no significant differences in selenium bioavailability regardless of changes in extrusion temperature or the proportion of enriched wheat.