Effect of the Addition of Fique Bagasse Cellulose Nanoparticles on the Mechanical and Structural Properties of Plastic Flexible Films from Cassava Starch

One of the activities most representative of the agricultural sector in Colombia is the production of biodegradable fique fiber. The efficiency of the defiberization process of the fique leaves is very low since a mere 4% of the total weight of the leaf (cabuya) is used and marketed. The remaining 96%, composed of fique juice and bagasse, is considered to be waste and discarded, impacting the environment. The aim of this work was to study fique bagasse as a source of cellulose nanoparticles (CNCs). CNCs were obtained by acid hydrolysis and added at 10% to films made from cassava thermoplastic starch (TPS) by the casting method. Structural changes in the CNCs, TPS, and their mixtures were characterized by FTIR-ATR and their morphology and particle size by SEM and TEM microscopy, respectively. Thermal properties were analyzed using DSC and TGA, along with their effect on mechanical properties. Changes in the FTIR spectra indicated that the chemical method adequately removed hemicellulose and lignin from the fiber surface of fique bagasse. The CNCs showed a diameter and length of 7.5 ± 3.9 and 52.7 ± 18.1 nm, respectively, and TPS 10% CNC obtained an increase in mechanical strength of 116%. The obtainment of CNCs from lignocellulosic materials can thus be viewed as a favorable option for the subsequent reinforcement of a polymeric matrix.

Physicochemical, rheological and structural properties of flours from six quinoa cultivars grown in Colombia

Background

Inclusion of quinoa in the diet of consumers has generated a challenge for quinoa producers and food processors, which involves the study of new cultivars and the functional properties of their flours.

Methods

Six quinoa cultivars (Titicaca, Blanca real, Soracá, Pasankalla, Puno and Nariño) were analyzed for their proximate composition using the methodologies proposed by the Association of Official Analytical Collaboration, AOAC. A rheological analysis was carried out with flours from each cultivar. A sequential test including a flow test, a pasting test and another flow test was programmed to evaluate the flow behavior before and after a heating process. In addition, the structural properties of the cultivar flours were evaluated by Fourier Transform Infrared spectroscopy (FTIR).

Results

It was found that the Pasankalla, Titicaca and Soracá cultivars had a higher (p < 0.05) protein content, while the Puno, Pansakalla and Blanca real cultivars stood out for their higher (p < 0.05) lipid content. On the other hand, it was found that before heating, all quinoa flour dispersions had a dilatant flow (n > 1), but after heating, all of them showed a decrease of index values, where the flours of the Titicaca and Pasankalla cultivars were more affected with a tendency toward a Newtonian flow (n ≈ 1). The pasting test showed that the viscosity varied according to the cultivar tested. It is noteworthy that both Titicaca and Soracá presented a high peak viscosity (0.16 ± 0.01 and 0.13 ± 0.02 Pa·s respectively) and different setback values on cooling (0.100 ± 0.028 and 0.01 ± 0.01 Pa·s respectively). Spectroscopic analysis showed a direct relationship between the intensity of the peaks and the nutritional content of the flours. In addition, secondary protein structures such as β-sheet, β-Turn, α-Helix and Random Coil were identified after deconvolution of the spectra. The differences in the protein structures of each cultivar could allow their identification by this methodology.

Conclusion

It can be concluded that quinoa flours from the six cultivars could be used for the formulation of different food products, such as beverages, baked goods, snacks, pasta and others, acting as nutritional improvers and modifiers of rheological, textural and functional properties.

Preliminary Characterization of Structural and Rheological Behavior of the Quinoa Hyperprotein-Defatted Flour

Protein functional properties are related to physical and chemical parameters that influence protein behavior in food systems during processing, storage and consumption. The structural and rheological properties of three quinoa hyperprotein flours (without defatting, WD, chemically defatted, CD, and mechanically defatted, MD) were evaluated. The values of the fluidity index (n) were significantly different (p < 0.05), which was associated with changes in protein or starch structures due to solvent treatments or heating of the flour during pressing. In addition, a strong dependence of the consistency index (k) on the shear rate was observed. For dispersions with a concentration of 12% (w/v), CD and WD had a significantly lower setback value than MD. The viscosity peak was affected by the presence of lipid molecules. Greater changes were evident in the β-sheet (1,610 and 1,625 cm−1) and β-spin (1,685 and 1,695 cm−1) structures. The changes identified in these structures were associated with the defatting treatment. Consequently, the intensity ratio 2,920/1,633 cm−1 was more sensitive to changes in the fat content of the flours. It was shown that defatting conditions increase the protein adsorption kinetics and that the viscoelastic properties of the protein increase when the flour has a lower fat content. Hyperprotein quinoa flour could be used to improve the protein content of products such as snacks, pastas, ice cream, bakery products, meat extenders, among others, due to its foaming, gelling or emulsifying capacity. The objective of this work was to study the effect of two types of defatting of hyperprotein quinoa flour on its structural and rheological properties.

Physicochemical Characterization of Quinoa (Chenopodium quinoa cv. Nariño) Co-products Obtained by Wet Milling

In recent years, great interest has been shown in pseudocereals for their high nutritional value. Wet milling has been used to obtain macromolecules such as proteins and starches. However, the co-products obtained from this food industry have been studied little. A factorial design Box-benhken was used to study the effect of surfactant concentration (SDS), sodium hydroxide (NaOH) concentration and maceration temperature on structural and colorimetric properties. Structural properties were evaluated by infrared spectroscopy (FTIR-ATR) and color changes by the CIElab tristimulus method (L*, a*, b*). A decrease in temperature and NaOH causes a decrease in lightness (L*), resulting in lower starch content and higher protein content in the co-product. This behavior was correlated with the infrared spectroscopy (FTIR-ATR) spectra. The spectra show a possible structural change in the amylose/amylopectin ratio of the starch granule at 1,012 cm−1, 1,077 cm−1, and 1,150 cm−1 bands, which are associated with glycosidic bonds, these bonds were sensitive to NaOH concentration. While those bands assigned to Amide II (1,563 cm−1) and Amide I (1,633 cm−1), were sensitive to the effect of NaOH and maceration temperature, evidencing that protein content in the co-products is variable and depends significantly on the extraction conditions. The co-products obtained by wet milling could be used in the development of functional foods, such as bread, snacks, pasta and other products.

Structural Characterization and Antioxidant Capacity of Quinoa Cultivars Using Techniques of FT-MIR and UHPLC/ESI-Orbitrap MS Spectroscopy

The existence of more of 16,000 varieties of quinoa accessions around the world has caused a disregard on their structural and phytochemical characteristics. Most of such accessions belong to cultivars settled in Colombia. The goal of this research was to evaluate the structural attributes and antioxidant capacities from six quinoa cultivars with high productive potential from central regions in Colombia. This study used middle-range infrared spectroscopy (IR-MIR) to determine the proteins, starch and lipids distinctive to quinoa grains. Ultra-high-performance liquid chromatography electrospray ionization Orbitrap, along with high-resolution mass spectrometry (UHPLC/ESI-Orbitrap MS), were also used to identify the existence of polyphenols in cultivars. The antioxidant capacity was determined through DPPH, ABTS and FRAP. The spectrums exhibited significant variances on the transmittance bands associated with 2922 cm-1, 1016 cm-1 and 1633 cm-1. Moreover, the intensity variations on the peaks from the secondary protein structure were identified, mainly on the bands associated with β-Sheet-1 and -2, random coil α elice and β-turns-2 and -3. Changes found in the ratios 996 cm-1/1014 cm-1 and 1041 cm-1/1014 cm-1 were associated with the crystalline/amorphous affinity. Regarding the antioxidant capacity, great differences were identified (p < 0.001) mainly through FRAP methods, while the phenolic acids and flavonoids were determined by UHPLC/ESI-Orbitrap MS techniques. The presence of apigenin and pinocembrin on grains was reported for the first time. Titicaca and Nariño were the most phytochemically diverse quinoa seeds.