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Total starch granule-associated proteins (tGAP), including granule-channel (GCP) and granule-surface proteins (GSP), alter the physicochemical properties of starches. Quinoa starch (QS) acts as an effective emulsifier in Pickering emulsion. However, the correlation between the tGAP and the emulsifying capacity of QS at different scales remains unclear. Herein, GCP and tGAP were selectively removed from QS, namely QS-C and QS-A. Results indicated that the loss of tGAP increased the water permeability and hydrophilicity of the starch particles. Mesoscopically, removing tGAP decreased the diffusion rate and interfacial viscous modulus. Particularly, GSP had a more profound impact on the interfacial modulus than GCP. Microscopically and macroscopically, the loss of tGAP endowed QS with weakened emulsifying ability in terms of emulsions with larger droplet size and diminished rheological properties. Collectively, this work demonstrated that tGAP played an important role in the structural and interfacial properties of QS molecules and the stability of QS-stabilized emulsions.

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High hydrostatic pressure (HHP) treatment was combined with octenyl succinic anhydride (OSA) modification of quinoa starch (QS) to improve esterification efficiency. The modified QS was used as a stabilizer to prepare a Pickering emulsion. The results showed that the HHP treatment disrupted the morphology and crystalline structure of QS, exposed numerous hydrophilic hydroxyl groups, and added esterification reaction sites. The degree of substitution (DS) and esterification efficiency (RE) of OSA-HHP-QS were significantly (p < 0.05) increased compared with OSA-QS. In addition, the short-range ordering, relative crystallinity, and thermal stability of OSA-HHP-QS decreased with increasing treatment pressure. Except for OSA-HHP200-QS, the starch granules treated at 200 MPa were annealed, resulting in molecular recrystallization. The Contact angle, emulsion stability index (ESI), and emulsion activity index (EAI) indicated that the emulsions stabilized with OSA-HHP-QS were highly stable. Therefore, HHP can be used as a novel technology to assist OSA modified starches in stabilizing Pickering emulsions.

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Small-granule starches (SGSs) have technological advantages over starches of conventional sizes for many applications. The study compared the granular characteristics of three SGSs (from amaranth, quinoa, and taro) with those of maize and potato starches and revealed their molecular basis. The results indicated that the supramolecular architecture of starch granules was not necessarily correlated with granule size. Acid hydrolysis of amaranth and quinoa starches was fast due to not only their small granule sizes but also the defects in the supramolecular structure, to which short external and internal chain lengths of amaranth and quinoa amylopectins contributed. By comparison, the granular architecture of taro starch granules was more stable partly due to the longer external chain length of taro amylopectin. Comparison of the molecular composition of branched subunits (released by using α-amylase of Bacillus amyloliquefaciens) in amylopectins and that in lintnerized starches suggested a significant heterogeneous degradation of amaranth and quinoa starches at supramolecular levels.

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BACKGROUND: Starch is the main component of quinoa seeds. However, quinoa starch has poor solubility in cold water and poor mechanical resistance and is easily aged, which limit its application. Therefore, modification of its structure to improve its functional properties is necessary. RESULTS: This research used acetic anhydride and sodium trimetaphosphate to modify the structure of starch molecules and investigated their influence on bread quality. The results showed that both esterification and crosslinking prevented the aggregation behavior of starch molecules. Moreover, they both decreased the gelatinization enthalpy change and relative crystallinity of the starch. Compared with native starch, modification significantly decreased the gelatinization temperature from 57.01 to 52.01 °C and the esterified starch exhibited the lowest enthalpy change with a 44.2% decrease. Modified starch increased the specific volume and decreased the hardness and chewiness of bread. Modification did not influence the moisture content in bread but impacted the water retention capacity, depending on the degree of modification. Low and medium degrees of modification improved the water retention capacity during storage. By contrast, a high degree of modification (10 g kg-1 crosslinking agent) decreased the water retention capacity. The dually modified quinoa starch (esterified and crosslinked) showed no influence on the textural properties of bread. CONCLUSION: This study demonstrated that both esterification and crosslinking significantly improved the functional properties of quinoa starch. Crosslinked or esterified quinoa starches have the potential to improve the textural properties of bakery products. © 2024 Society of Chemical Industry.

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This research supplied a "cleaner-production" way to produce "clean-label" quinoa starch-based Pickering emulsifier with excellent emulsifying properties. The effects of dry ball-milling time and speed on the multi-scale structures and emulsifying properties of quinoa starch were studied. With increasing ball-milling time and speed, particle size first decreased and then increased, the crystallinity, lamellar structure and short-range ordered structure gradually decreased, and contact angle gradually increased. The increased contact angle might be related to the increased oil absorption properties and the decreased water content. The emulsification properties of ball-milled quinoa starch (BMQS)-based Pickering emulsions increased with the increase in ball-milling time and speed, and the emulsions of BMQS-4 h, 6 h, 8 h, and 600 r reached the full emulsification state. After 120 days' storage, the oil droplets of BMQS-2 h (BMQS-400 r) deformed, the oil droplets increased, and the emulsification index decreased. The emulsification index and the oil droplets of BMQS-4 h, 6 h, 8 h and 600 r-based emulsions did not show obvious changes after storage, indicating the good emulsifying stability of these BMQS-based emulsions, which might be because that the relatively larger amount of starch particles that dispersed in the voids among the oil droplets could act as stronger network skeletons for the emulsion gel. This Pickering emulsifier was easily and highly efficiently produced and low-cost, having great potential to be used in the food, cosmetic and pharmaceutical industries.

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This study prepared type 3, type 4, and type 5 quinoa resistant starch (QRS3, QRS4, and QRS5) from quinoa starch (QS), compared their structural and physicochemical properties and evaluated their noodle-making potential. The results showed that the molecular weight of QRS3 decreased, the number of short-chain molecules increased, and its crystal type changed to B-type after gelatinization, enzymatic hydrolysis, and retrogradation. QRS4 is a phosphorylated cross-linked starch, with a surface morphology, particle size range, and crystal type similar to QS, but displaying modified thermodynamic properties. QRS5 is a complex of amylose and palmitic acid. It displays typical V-type crystals, mainly composed of long chain molecules and primarily exhibits a block morphology. The noodles prepared by replacing 20 % wheat flour with QS, QRS3 and QRS5 have higher hardness and are suitable for people who like elasticity and chewiness. QRS4 noodles are softer and suitable for people like elderly and infants who prefer soft foods. In conclusion, significant differences were evident between the fine structures, crystal types, physicochemical properties and potential applications of QS and the three QRSs. The results may expand the application of QS and QRS in the food and pharmaceutical industries.

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Nanoencapsulation of native potato bioactive compounds by spray-drying improves their stability and bioavailability. The joint effect of the inlet temperature and the ratio of the encapsulant (quinoa starch/gum arabic) on the properties of the nanocapsules is unknown. The purpose of this study was to determine the best conditions for the nanoencapsulation of these compounds. The effects of two inlet temperatures (96 and 116 °C) and two ratios of the encapsulant (15 and 25% w/v) were evaluated using a factorial design during the spray-drying of native potato phenolic extracts. During the study, measurements of phenolic compounds, flavonoids, anthocyanins, antioxidant capacity, and various physical and structural properties were carried out. Higher inlet temperatures increased bioactive compounds and antioxidant capacity. However, a higher concentration of the encapsulant caused the dilution of polyphenols and anthocyanins. Instrumental analyses confirmed the effective encapsulation of the nuclei in the wall materials. Both factors, inlet temperature, and the encapsulant ratio, reduced the nanocapsules' humidity and water activity. Finally, the ideal conditions for the nanoencapsulation of native potato bioactive compounds were determined to be an inlet temperature of 116 °C and an encapsulant ratio of 15% w/v. The nanocapsules obtained show potential for application in the food industry.

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There is increasing interest in developing quinoa products due to their unique nutritional value. Starch and protein are the primary components in quinoa, and the interaction between them affects the quality of quinoa products. This study extracted the starch and protein from quinoa and simulated the thermal processing of quinoa to investigate the effects of starch on the solubility and structure of quinoa protein isolates during heat treatment. The structure of quinoa protein isolates was characterized by fluorescence spectroscopy, Fourier transform infrared spectroscopy, laser particle size analysis, and scanning electron microscopy. The results showed that starch decreased protein solubility, and the maximum solubility was obtained after heating for 5 min. After starch addition during heat treatment, the surface charge distribution of protein changed, the degree of protein aggregation increased, the particle size of proteins increased, the thermal stability increased, and the ß-sheet ratio of the proteins increased, suggesting that the protein structure is more ordered, which is the structural foundation of protein solubility decreasing. The research about the interaction between starch and protein and the effects on the solubility of protein could provide a reference for quinoa products processing.

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Granule size is a critical parameter affecting starch processing properties. Ultrasound treatments of up to 22 h were applied on two starches differing in granule size (quinoa starch and maize starch). The two starches showed significantly different trends in both structural and physicochemical aspects affected by the ultrasound treatments. For the small granule starch (volume-weighted mean particle size of 1.79 µm), short-term ultrasonication caused an increase of swelling power. As the treatment time increased, the physicochemical properties were influenced by the degradation of amylopectin external chains. The X-ray diffraction results showed a decrease of relative crystallinity and changes of peak areas with long-term treatment. On the other hand, a balance between amylose leaching and surface damages was seen for the large granule starch (volume-weighted mean particle size of 18.3 µm). The effect of ultrasound modification on starches with different molecular and granular structures was discussed. A possible mechanism of the ultrasound effect was proposed.

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In this study, quinoa starch was subjected to microwave and heat moisture treatment (MHT) with various moisture content (15 %, 25 %, 35 %) and microwave power (4.8, 9.6, 14.4 W/g), and its structure and digestibility were investigated. SEM and particle size analysis indicated that MHT caused the agglomeration of starch granules and increased the particle size. Moreover, MHT increased the short-range order structure and relative crystallinity, except for MHT with moisture content (35 %). DSC results demonstrated that the gelatinization temperature and gelatinization enthalpy had a slight improvement after MHT. Moreover, MHT increased the amylose content to some extent. It was worth noting that the digestibility of quinoa starch significantly decreased. After MHT, a part of rapidly digestible starch (RDS) was converted into slowly digestible starch (SDS) or resistant starch (RS). Particularly, when moisture content was 25 %, the starch had a highest SDS + RS content. Thus, this study provided a potential approach using MHT to modulate the digestibility of starch.

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Quinoa starch nanoparticles (QSNPs) prepared by nanoprecipitation had a uniform particle size of 191.20 nm. QSNPs with amorphous crystalline structure had greater contact angle than QS with orthorhombic crystalline structure, which can therefore be utilized to stabilize Pickering emulsions. QSNPs-based Pickering emulsions prepared by suitable formulations (QSNPs concentration of 2.0-2.5 %, oil volume fraction of 0.33-0.67) exhibited good stability against pH of 3-9 and ionic strength of 0-200 mM. The oxidative stability of the emulsions increased with increasing starch concentration and ionic strength. Microstructural and rheological results indicated that the structure of the starch interfacial film and the thickening effect of the water phase affected the emulsion stability. The emulsion had excellent freeze-thaw stability and can be produced as a re-dispersible dry emulsion using the freeze-drying technique. These results implied that the QSNPs had great potential for application in the preparation of Pickering emulsions.

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The effects of different dosage of NaCl and sucrose on the structural and functional properties of debranched quinoa starch-oleic acid complexes (DQS-OA) under baking were investigated. The results showed that the resistant starch content of the baked DQS-OA increased by 17.15 % than DQS-OA. The addition of NaCl destroyed the thermal stability, short-range molecular order and crystalline structure of the complexes. The results of particle size, SEM and amylose content showed that NaCl accelerated the degradation of starch granules, which reduced the enzyme resistance of starch. In contrast, the enthalpy (7.28 J/g-7.78 J/g) and crystallinity (54.29 %-56.69 %) of the samples with sucrose significantly increased, and the molecular structure of the complexes became more ordered. Furthermore, with the increase of sucrose concentration, the resistant starch content also increased from 28.80 % to 31.41 %.

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BACKGROUND: A starch-lipid complex is a new type of resistant starch, which is of great importance for the prevention of chronic diseases such as diabetes. Most starch-lipid complexes usually need to be treated by heating to make them suitable for a variety of applications, and starch-based foods are generally not edible without a heat-treatment process. However, the digestion and structural properties of the starch-lipid complex will be changed after heating. In this study, microwave and conventional heating were used to treat debranched quinoa starch-oleic acid complexes (DQS-OA) with different water addition conditions, and the effects of the two methods on the physicochemical, digestive, and structural properties of DQS-OA were compared. RESULTS: The results of in vitro digestibility showed that the resistant starch content (235.34-269.55 g kg-1 ) of the conventional heating-treated samples was significantly higher than that the microwave-treated samples (141.51-157.99 g kg-1 ). Moreover, after microwave treatment, the short-range molecular order and crystalline structure of DQS-OA were destroyed and the particle size became smaller. In contrast, the thermal stability, enthalpy, and crystallinity of the complexes after conventional heating were improved. The ratio at 1047/1022 cm-1 of complexes has also been increased. CONCLUSION: This study demonstrated that conventional water-bath heating was better than microwave heating in increasing digestion resistance, improving the short-range and long-range molecular order, and promoting the formation of DQS-OA. With an increase in water addition, the influence of microwave or water-bath treatment on the properties of DQS-OA became greater. © 2022 Society of Chemical Industry.

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The purpose of this study is to investigate the effects of starch extraction methods (alkali, wet-milling, and enzymatic) on the multi-scale structures and functional properties of quinoa starch. When the enzymatic method was compared with alkali and wet-milling, it showed higher protein content (2.4%), larger mean size of aggregated granules (44.1 µm), higher relative crystallinity (29.0%), scattering intensity (17.8 α.u.), absorbance ratio of 1047/1022 (0.9), single and double helical content (8.2% and 23.1%), FWHM ratio (1.5), and average molecular weight and radius of gyration (1.58 × 107 g/mol and 106.8 nm), respectively. Similarly, quinoa starch by enzymatic extraction had a higher onset (82.1 °C), peak (83.8 °C), and conclusion (86.3 °C) temperatures, as well as an enthalpy change (6.8 J/g). It further showed maximum hardness (238.8 N), gumminess (105.6 N), chewiness (80.2 N), SDS content (7.5% of raw and 4.8% of cooked), and RS content (15.4% of raw and 13.9% of cooked), whereas it contained minimum RDS content (77.1% of raw and 81.9% of cooked). The results suggest that extraction of starch by the enzymatic method could be a viable approach to retain the native structure of starch and may eventually improve the glycemic response.

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Both the effects of enzymolysis condition on the microstructures and emulsifying property of enzymatic modified quinoa starch (EMQS) and the effects of emulsion formulation on the EMQS based emulsions were investigated. The emulsifying capacity (EC) and stability (ES) of EMQS were positive correlated with enzyme amount (0-2.4 % w/wstarch). The particle sizes of EMQS decreased and its hydrophobicity increased with increasing enzyme amount (0-2.4 % w/wstarch), which were the main reasons for the increasing emulsifying performance of EMQS. With the increasing starch concentration, the EC of the EMQS increased, the oil droplet size of the emulsion decreased. With the oil/water ratios ranging from 1:9 to 6:4, the emulsification index (EI) and oil droplet size of the emulsion increased. EMQS based emulsion had a relatively good stability in the pH range of 2-10. This study lays the foundation for the application of EMQS as a stable clean-label Pickering emulsifier.

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The quinoa flour processing is mostly subject to the properties of starch. Starches from four colored quinoa varieties, including white quinoa (QS-W), yellow quinoa (QS-Y), red (QS-R), and black (QS-B), were compared with respect to their physicochemical properties and in vitro digestibility. Results indicated that QS-B exhibited the highest content of amylose (8.14%) (p < 0.05). All starch samples exhibited as irregular sphere with a particle size less than 3 µm. Results of the FT-IR and X-ray showed that the short-range order of the four quinoa starches exhibited no significant difference; all starches showed a typical A-type diffractrometric pattern and was not affected by seed color, and QS-Y had the highest relative crystallinity (34.3%) (p < 0.05). In addition, QS-W reflected the highest solubility (6.32%) and QS-Y showed the highest swelling power (19.45 g/g) (p < 0.05). QS-Y also presented a higher ΔH value (11.46 J/g) (p < 0.05), while QS-R peak temperature and peak G' were the lowest. Besides, QS-B had the highest slow-digestible starch (SDS) and resistant starch (RS) content, while the lowest estimated glycemic index (eGI) value (p < 0.05). Also, there was a negative correlation between hydrolysis rates and amylose content of quinoa starch. PRACTICAL APPLICATION: Due to the low gelatinization temperature of quinoa starch, it can be used to both produce and improve instant and fast food products. Quinoa starch particles are small, and Pickering emulsions and additives have potential application values. Red quinoa contains easily digestible starch, which can be a good food choice for infants and the elderly, while white quinoa starch has less swelling power and can be used in noodle products. The results of this study can help to underpin the study of quinoa nonstarch components versus starch component.

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BACKGROUND: Quinoa (Chenopodium quinoa Willd.) flour and processed traditional Peruvian quinoa breakfast foods were studied to evaluate the effect of extrusion and post-processing on protein properties, morphology and nutritional characteristics (amino acids and dietary fibers). RESULTS: The extrusion increased quinoa protein crosslinking and aggregation observed by size exclusion high-performance liquid chromatography and the amount of soluble fibers, as well as decreasing the amounts of insoluble fibers in the processed foods. The post-processing drying resulted in additional crosslinking of large protein fractions in the quinoa products. The microstructure of the extruded quinoa breakfast flakes and heat-post-processed samples studied by scanning electron microscopy and X-ray tomography differed greatly; post-drying induced formation of aerated protein microstructures in the heat-treated samples. Nanostructures revealed by small-angle and wide-angle X-ray scattering indicated that extrusion imparted morphological changes in the quinoa protein and starch (dominance of V-type). Overall, extrusion processing only reduced the content of most of the essential amino acids to a minor extent; the content of valine and methionine was reduced to a slightly greater extent, but the final products met the requirements of the Food and Drug Organization. CONCLUSION: This study presents innovative examples on how extrusion processing and post-processing heat treatment can be used to produce attractive future food alternatives, such as breakfast cereal flakes and porridge powder, from quinoa grains. Extrusion of quinoa flour into Peruvian foods was shown to be mostly impacted by the processing temperature and processing conditions used. Protein crosslinking increased due to extrusion and post-processing heating. Starch crystallinity decreased most when the product was dried after processing. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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Quinoa starch nanoparticles (QSNPs) prepared by nanoprecipitation method under the optimal condition was developed as a carrier for quercetin. The QSNPs prepared under the optimal condition (90 DMSO/H2O ratio, 10 ethanol/solvent ratio, and ultrasonic oscillation dispersion mode) had the smallest particle size and polymer dispersity index through full factorial design. Compared with maize starch nanoparticles (MSNPs), QSNPs exhibited a smaller particle size of 166.25 nm and a higher loading capacity of 26.62%. Starch nanoparticles (SNPs) interacted with quercetin through hydrogen bonding. V-type crystal structures of SNPs were disappeared and their crystallinity increased after loading with quercetin. QSNPs was more effective in protecting and prolonging quercetin bioactivity because of their small particle sizes and high loading capacities. This study will be useful for preparing starch-based carrier used to load sensitive bioactive compounds.

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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 ß-Sheet-1 and -2, random coil α elice and ß-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.

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Quinoa starch was developed as a new kind of Pickering emulsifier by enzymatic modification. The morphological structure, crystalline structure, lamellar structure, fractal structure, particle size distribution, contact angle, emulsion index (EI), and emulsion micromorphology were studied to explore the relationship between structure characteristics, hydrophilic property, and emulsifying properties of enzymatically modified (EM) quinoa starches. With the increasing enzymatic hydrolysis time in the test range of 0-9 h, particle size of EM quinoa starch decreased, and the broken starch and contact angle of EM quinoa starch increased; the EI value of emulsions with EM quinoa starch increased, and the oil droplet size of emulsions with EM quinoa starch decreased. It suggested that both the smallest particle size and the closest extent of the contact angle to 90° derived the best emulsifying property of EM-9. The EM quinoa starch had higher emulsifying capacity at higher oil volume fraction (Φ) (50%) than at lower Φ (20%), proving that the EM starch has potential to be used as Pickering emulsifiers in higher oil products, such as salad dressing.

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