Preparation and properties of phosphate starches from tuberous roots.

The diversification of raw materials in the starch industries is a current strategy. However, the production of native starches does not meet market demand, and it is essential to expand the knowledge about chemical modifications in the same production line for different sources of starch. Phosphate starches are one of the most abundantly produced and widely used chemically modified starches. However, the effects of this modification may vary with the starch source and the reaction conditions. In this study, arrowroot, cassava and sweet potato starches were modified with sodium trimetaphosphate (STMP)/sodium tripolyphosphate (STPP) mixture under same conditions. The reaction time ranged from 7.5 to 120 min. Unmodified and modified starches were analyzed for phosphorus, amylose, morphology, X-ray diffraction pattern, crystallinity, swelling power, solubility, pasting and thermal properties. Phosphorus content linked to the starches increased with the reaction time, which affected the physicochemical properties of the three starches. The changes were more significant in all reaction times for cassava starch, followed by arrowroot. Due to its intrinsic characteristics, longer reaction times were necessary for more significant changes in sweet potato starch. Regardless of the starch source, as the reaction time increased, the average starch granule diameter, swelling power, solubility and peak viscosity increased. There was a decrease in setback in the longer reaction times for cassava and arrowroot starches. The changes in the reaction times allowed obtaining phosphate tuberous starches with different properties which can meet the demands of the food and non-food industries.

Effect of amylolysis on the formation, the molecular, crystalline and thermal characteristics and the digestibility of retrograded starches.

This study evaluated the effect of amylases on the formation, and characteristics of retrograded starches using sweet potato (SPS), cassava (CAS) and high amylose maize (HAS) starches. The starches were gelatinized, hydrolyzed with fungal or maltogenic α-amylase, de-branched and retrograded. The modified starches were then analyzed for digestibility, chain size distribution, relative crystallinity and crystallite size, thermal properties and the proportion of double helices. CAS was the most susceptible and HAS the most resistant to the action of both enzymes. Amylolysis was efficient in forming resistant starch type 3 (RS3) and high levels (> 60%) were found for all starches. RS3 content was highly correlated with the proportion of chains with degrees of polymerization between 13 and 30 for all starches, especially for the root starches, while for HAS, the high amylose content and reduction in the size of amylose chains and very long amylopectin chains also deeply contributed for the RS3 formation. These sizes (DP 13-30) are best suited for the formation of a more crystalline, more perfect, and more strongly bonded structure, composed of larger crystallites, and with a higher concentration of double helices. High correlation coefficients were found between RS3, relative crystallinity, crystallites size, and enthalpy change.

Bambusa vulgaris starch: Characterization and technological properties.

The starch industry has grown quickly, and starch production has expanded around the world because it is a very versatile ingredient, despite limits in some foodstuffs. So, this study aimed to analyze morphology, physic and chemical characteristics of the starch extracted from three different parts (bottom, middle and top) of the young bamboo culm of B. vulgaris (SB, SM, and ST, respectively). The obtained data were evaluated by analysis of variance and Scott-Knot test (p < 0.05), and no significant difference was observed between SB, SM and ST samples. The starches presented yellowish coloration (L* > 88, a* > -0.2, and b* > 9), and SEM images showed compound granules with polyhedral shapes and average diameter of 6.55 µm; apparent amylose content of 37.45%, wherein SB and SM showed characteristics of resistant starch type 2, whereas ST was more similar to normal starch. Amylopectin presented high proportion of chains with DP 13-24 and lower proportion of long chains, corroborating with A-type crystalline pattern. The absence of a shoulder in the branch chain length distribution, suggest a perfect crystalline structure, similar to starches from D. asper and B. tuldoides. DSC shows gelatinization temperatures higher than 80 °C, lower transition temperatures and the percentage of retrogradation above 44%. The results are promising to obtain slow digesting starches, although it is necessary to evaluate the starch from other bamboo species, which may have different characteristics.

Gelatinized sweet potato starches obtained at different preheating temperatures in a spray dryer.

Native sweet potato starch was gelatinized at temperatures between 57 and 69 °C and then spray dried, to verify the changes caused by this process. The spray dried starch granules initially swelled with the increase in preheating temperature, displaying a larger diameter, but shrank upon colling. There was an increase in the gelatinization temperature and a decrease in the enthalpy change of the spray dried starches relative to those of native starch. Spray dried starch preheating at 69 °C showed highly reduced enthalpy change (80%) and relative crystallinity. Based on the parameters studied, the best preheating temperature was 67 °C. Under this condition, the starch can be applied in more viscous products that require a greater thickness, and with great process yield (65%). This study showed the feasibility of the application of this process to produce sweet potato starches with specific properties for different purposes in the food and non-food industries.

Relationship between the molecular structure of duckweed starch and its in vitro enzymatic degradation kinetics.

Starch molecular structural effects in duckweed (Lemna minor and Landoltia punctata) controlling in vitro enzymatic degradation kinetics was studied. The molecular size distributions of fully-branched starches and the chain length distributions (CLDs) of enzymatically debranched duckweed starches were obtained using size-exclusion-chromatography (SEC). The CLDs of both debranched amylose and amylopectin were fitted with models using biologically-meaningful parameters. While there were no significant correlations between amylose content and starch degradation rate, the total amounts of amylose with shorter chain length negatively correlated with undigested starch content, and the amount of amylopectin long chains negatively correlated with the degradation rate coefficient. This provides new knowledge for the utilization of duckweed starches in bioethanol production.

Characterization of young bamboo culm starch from Dendrocalamus asper.

The search for new and natural ingredients has been stimulated by the food and non-food industries, and the fresh young bamboo culm of Dendrocalamus asper emerges as promising for industrial production due to its composition with >10% of starch. So, this study aimed to characterize starch, extracted in aqueous solution, from three different parts (bottom, middle and top) of the young bamboo culm of D. asper (SB, SM and ST, respectively). Morphological and physicochemical characteristics of the young bamboo culm starches were evaluated, besides thermal properties, and the obtained data were evaluated by ANOVA and Scott-Knot test (p < 0.05). The starches presented pale yellow coloration, with high luminosity (L*  > 89), and lower index in the red region. SEM images showed compound granules, which under polarized light exhibit a Maltese cross. The starches presented polyhedral shape and small size with an average diameter of 5.4 µm. All the samples presented low moisture (7.0 g/100 g), protein (2.0 g/100 g), lipid (0.3 g/100 g) and ash (1.0 g/100 g) contents. ST and SB showed apparent amylose content similar to starches from cereals and isolated from bamboo seeds. This agress to molecular size distribution of starch chains, since the SB, SM and ST presented amylopectin levels higher than those of amylose, as well as normal starches. The chain length of amylopectin presented the main peak at DP 12-13 and the second on at DP 43, similar to cereals like wheat, rice and barley. Its chain has higher proportion of short chains, which corroborates with the A-type polymorph presented. Concerning about thermal properties, all the samples presented high gelatinization temperature (>78 °C) and low enthalpies values (<6.35 J·g-1), which indicates the greater molecular organization. The gelatinization temperatures of gelatinized starches were lower than the native ones. The physicochemical and thermal characteristics of the obtained starches corroborate with the success of the extraction, which keep the starch granule native, and were similar to those of other starches already used in food and non-food products.

Effect of spray-drying and extrusion on physicochemical characteristics of sweet potato starch.

This study aimed to understand the physicochemical characteristics of sweet potato starch following spray-drying and extrusion processes for desirable applications. Spray-dried starch showed formation of agglomerates and decreased in average granular size from 16.5 µm of the native starch granules to 14.1 µm. Spray-drying reduced the percentage crystallinity from 25.3 to 22.6% and showed a slight decrease in the molecular weight of amylopectin from 3.1 to 2.6 × 108 g mol-1. In addition, changes in the pasting and gelatinization properties, higher final viscosity (454.4 RVU), and less enthalpy change (8.73 J g-1) were reported after spray-drying. Thus, spray-drying resulted in partially gelatinized starch, which can be selected for making more viscous products. Extruded sweet potato starch displayed an amorphous structure, showed total loss of crystallinity, and significant reduction in molecular weight of amylopectin to 0.41 × 108 g mol-1, reflecting complete gelatinization of starch granules during extrusion. Extruded starch showed significant changes in pasting properties, including a display cold viscosity (9.4 RVU). Therefore, extruded starch was suitable for products that require quick solubility and a low final viscosity. Thus, the spray-drying and extrusion processes produce sweet potato starches with particular characteristics that can be used for different and potential applications in industries.

Structural, thermal, and morphological characteristics of cassava amylodextrins.

BACKGROUND: Amylodextrins from cassava starch were obtained by acid hydrolysis, and their structural, thermal and morphological characteristics were evaluated and compared to those from potato and corn amylodextrins. RESULTS: Cassava starch was the most susceptible to hydrolysis due to imperfections in its crystalline structure. The crystalline patterns of amylodextrins remained unchanged, and crystallinity and peak temperature increased with hydrolysis time, whereas thermal degradation temperature decreased, independent of treatment time and starch source. Cassava amylodextrins had similar structural and morphological characteristics to those from corn amylodextrins due to their A-type crystalline arrangements. A-amylodextrins were structurally and thermally more stable than potato amylodextrins (B-type). Starch nanocrystals (SNC) were observed by transmission electron microscopy from the third day of hydrolysis in cassava amylodextrins, whereas potato and corn amylodextrins displayed SNC only on the fifth day. A-SNC displayed platelet shapes, whereas B-SNC were rounded. The SNC shape was related to the packing form and geometry of unit cells of allomorphs A and B. CONCLUSION: Microstructures (agglomerated crystalline particles) and nanostructures (double helix organization) were observed for amylodextrins. Cassava starch was shown to be a promising material for SNC production, since it requires less hydrolysis time to obtaining more stable crystals. © 2017 Society of Chemical Industry.

Characterization of banana starches obtained from cultivars grown in Brazil.

The starch market is constantly evolving and studies that provide information about the physical and rheological properties of native starches to meet the diverse demands of the sector are increasingly necessary. In this study starches obtained from five cultivars of banana were analyzed for size and shape of granules, crystallinity, chemical composition, resistant starch, swelling power, solubility, thermal and paste properties. The granules of starch were large (36.58-47.24µm), oval, showed crystallinity pattern type B and the index of crystallinity ranged from 31.94 to 34.06%. The phosphorus content ranged from 0.003 to 0.011%, the amylose ranged from 25.13 to 29.01% and the resistant starch ranged from 65.70 to 80.28%. The starches showed high peak viscosity and breakdown, especially those obtained from 'Nanicão' and 'Grand Naine'. Peak temperature of gelatinization was around 71°C, the enthalpy change (ΔH) ranged from 9.45 to 14.73Jg(-1). The starch from 'Grand Naine' showed higher swelling power (15.19gg(-1)) and the starch from 'Prata-Anã' higher solubility (11.61%). The starches studied are highlighted by their physical and chemical characteristics and may be used in several applications.

Physicochemical and structural characteristics of rice starch modified by irradiation.

This work evaluated the physicochemical and structural properties of rice starch of the cultivars IAC 202 and IRGA 417 modified by irradiation. Starch samples were irradiated by (60)Co in doses 1, 2 and 5kGy, on a rate of 0.4kGy/h. A control not irradiated was used for comparison. The granule morphology and A-type X-ray diffraction pattern were not altered by irradiation. There was an increase in amylose content, carboxyl content and acidity with irradiation. Gamma radiation did not affect the thermal properties of IAC202, but increased gelatinization temperature of IRGA417, in the higher dose (5kGy). The number of long chains of amylopectin was reduced and short chains were increased for IAC202, whereas for IRGA 417, the opposite was observed, probably due to cross-linking of starch chains. Starches had their physicochemical and structural properties modified by irradiation differently.

Effect of lactic acid and UV irradiation on the cassava and corn starches

In this work, the effect of lactic acid and UV irradiation on the physicochemical and structural characteristics of cassava and corn starches was evaluated. Only the modified cassava starch presented baking expansion capacity. From RVA, reduction of viscosity values, greater internal stability and none set back for modified cassava starch were observed. Modified corn starch did not show any peak viscosity. There were no significant differences in DSC thermal properties of treated and native starches. Amylopectin and amylose molecules from both the modified starches displayed some degradation. Molecular weight of cassava amylopectin was mostly preserved, whereas corn amylopectin was evenly attacked through the granule. Nevertheless, the B long branched chains of cassava amylopectin, with DP~37, were degraded whereas they were unchanged for corn amylopectin.

Amido de mandioca modificado com ácido lático e radiação ultravioleta antes da secagem artificial têm mostrado boa capacidade de expansão, a exemplo da encontrada para o polvilho azedo. Neste trabalho, os efeitos do ácido lático e radiação UV sobre as características físico-químicas e estruturais de amidos de mandioca e milho foram investigados. Apenas o amido de mandioca modificado apresentou capacidade de expansão durante o forneamento. Do RVA, redução dos valores de viscosidade, boa estabilidade interna e nenhuma tendência a retrogradação para este amido modificado foi observado. O amido de milho não apresentou qualquer pico de viscosidade após modificação. Não foram observadas diferenças significativas nas propriedades térmicas, determinadas em DSC, entre os amidos nativos e modificados de ambas as fontes. As moléculas de amilopectina e amilose de ambos os amidos modificados mostraram alguma degradação. O peso molecular da amilopectina do amido de mandioca foi mais preservado, enquanto a amilopectina do amido de milho foi mais atacada em todo o grânulo. As cadeias ramificadas longas da amilopectina de mandioca, com DP~37, foram degradadas, enquanto as de milho mantiveram-se inalteradas.

Characterization of native and oxidized starches of two varieties of Peruvian carrot (Arracacia xanthorrhiza, B. ) from two production areas of Paraná state, Brazil

Two commercial varieties of Peruvian carrot ('Amarela de Carandaí' and 'Senador Amaral') were processed into flour, starch and bagasse and chemically evaluated. The starch was extracted, modified with H2O2 and characterized by the physicochemical methods. By using the methylene blue dyeing, the granules of the modified starches showed intense blue color. The carboxyl content, the reducing power and the amount of the water liberated from the pastes after the freeze-thawing were higher for the oxidized starches and their pastes were clearer than those of the native starches of the two varieties from the two production areas. The RVA viscoamylography showed that the modified starches had lower viscosities with differences between the varieties. In the thermal analysis, the temperatures of the pyrolysis were higher for the native (310.37, 299.08, 311.18 ºC) than for the modified starches (294.16, 296.65 e 293.29 ºC) for both the varieties. This difference could be related with the larger surface of the granules due to the partial degradation promoted by the chemical modification. In almost all results, the differences were evident between the varieties but not for the cultivation places.

No presente trabalho duas variedades comerciais de mandioquinha-salsa ('Amarela de Carandaí' e 'Senador Amaral') obtidas dos municípios de Castro e de Piraí do Sul (Paraná) foram processadas para a obtenção de farinha, farelo e amido e essas três frações foram caracterizadas quimicamente. O amido foi extraído, modificado com H2O2 e caracterizado por meio de análises físico-químicas. Na coloração com azul de metileno os grânulos dos amidos oxidados apresentaram coloração azul mais intensa. O teor de carboxilas, o poder redutor e a quantidade de água liberada das pastas foram maiores para as amostras de amidos modificados. As pastas dos amidos modificados foram mais claras que as dos nativos. Na análise viscoamilográfica (RVA) os amidos modificados apresentaram as menores viscosidades e houve diferenças entre as variedades, sendo que o amido modificado da variedade Senador Amaral de Piraí do Sul apresentou os menores valores de pico de viscosidade. Na análise térmica, as temperaturas de pirólise foram mais altas para os amidos nativos das variedades da mandioquinha-salsa (310,37, 299,08, 311,18 ºC) do que para os amidos modificados (294,16, 296,65 e 293,29 ºC) e esta diferença pode estar relacionada a maior superfície dos grânulos de amido parcialmente degradados pela modificação oxidativa. Os resultados revelaram diferenças entre os amidos das duas variedades, mas não entre os locais de cultivo.