No abstract

Thermoplastic starch (TPS) offers an alternative to petrochemical-based plastics because as well as being a final product in itself, TPS can be used as a precursor for the production of new materials. In addition to high temperature and shear, the presence of plasticizers is essential in the TPS production process, to break the strong inter-and intra-molecular interactions of the starch chains. The properties of these plasticizers-their functional groups, molecular weight, thermal stability, and compatibility with the polymer, among others-play an important role in the production of TPS. This work therefore brings together research evaluating starch-plasticizer molecular interactions and their effect on the structure, polymer properties, retrogradation, and processing of TPS obtained by extrusion; in addition, it collects and analyzes information on the process conditions used in the extrusion of different starches in the presence of different plasticizers. The objective of this review is to provide a clear description of the importance of the effect of plasticizers on the properties of TPS obtained by extrusion, indicating the potential of some plasticizers to broaden the field of application of TPS.

No abstract

The protein, carbohydrate, and fat characteristics of quinoa grains reflect in their techno-functional potential. This aspect has been little studied in quinoa, while some physicochemical and rheological characteristics have been generalized for all cultivars under all primary production conditions. The aim of this research is to determine the agro-industrial potential of different quinoa cultivars evaluated under different environments through physicochemical and rheological responses. This study has a factorial design with a first level corresponding to cultivars and a second level to production zones. The results showed that the cultivars present high compositional variability. It was also found that the altitudinal gradient changes protein and starch composition, protein secondary structure, and starch structural conformation. In addition, significant variations were found in viscosity, breakdown, and dispersion setback for all treatments. However, there were no differences between treatments before heating/cooling and after heat treatment.

In this study, amaranth starch was extracted by high-impact wet milling and its structural and thermal properties and the effect of NaOH and SDS concentrations on extraction yield were evaluated. The best condition was 55 g of starch/100 g of amaranth, with a decrease from 2.5 to 3.5 kJ/g using different milling energies. The decrease in the protein content of the starch granule is due to an effect of the interaction between surfactant and alkali, preventing the destruction of granules. All starches presented a degree of crystallinity between 21 and 28%. The internal structural changes of the starch granule were monitored by attenuated total reflectance - Fourier-transform infrared (ATR-FTIR) in the region of 990 to 1060 cm−1. Spectra showed significant differences between the peaks at 1032 and 1005 cm−1, corresponding to the crystalline/amorphous region of the starch structure. Changes in viscosity profiles were observed between 0.302 and 1.163 Pa s.