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Normal corn starch (∼26% amylose content) was subjected to different degrees of extrusion-based pregelatinization (55, 75, and 95%) to improve the efficiency of octenyl succinic anhydride (OSA) esterification. The partial disruption of the native semi-crystalline structure was verified with X-ray diffraction and Fourier transform infrared analysis. It was found that partial gelatinization (pregelatinization) reduced the relative crystallinity, which is an effect that was magnified by OSA esterification. Polarized and scanning electron microscopies revealed gradual destruction of the starch granules, yielding a fraction of insoluble remnants for high gelatinization degrees. The emulsification index showed a marked increase of about 18% by single extrusion treatment. However, fully stable emulsions (emulsification index = 1.0) were obtained by dual extrusion-esterification treatment. The hardness of hydrogels was reduced by pregelatinization. Principal component analysis revealed that most starch characteristics were mutually interdependent and that the impact of gelatinization degree was independent of the impact of OSA esterification.

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The effects of gelatinization degree (GD) and octenyl succinic anhydride (OSA) esterification in the sorption-desorption characteristics of normal corn starch (NCS) were studied. NCS was subjected to different GD (53, 70, and 96%) with an extruder and lyophilized. FTIR analysis revealed that GD increased the hydrated (995/1022 ratio) and decreased the short-range ordered (1022/1047 ratio). The equilibrium sorption-desorption curve of starches was obtained for water activities up to 0.95 and fitted with the Guggenheim-Anderson-de Boer (GAB) model. Gelatinization of corn starch decreased its water sorption capacity, increased its sorption hysteresis and decreased its monolayer moisture content. OSA treatment of NCS reduced the water sorption capacity, hysteresis, and monolayer moisture content as reflected by slight variations of these parameters with the GD. A principal component analysis showed that GD and OSA esterification are mutually independent treatments, which can provide different effects on the water sorption characteristics of NCS.

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The influence of the pasta preparation stages on starch, proteins, and water structures of semolina and chickpea pasta was studied. The hydrated starch structures (995/1022 FTIR ratio) increased in semolina and reduced in chickpea pasta. The processing stages in semolina pasta led to a significant increase of ß-sheet structures (~50% to ~68%). The ß-sheet structures content in chickpea pasta was lower (~52%), and was most affected by sheeting and cooking. The water structure was assessed by the analysis of the OH fingerprint FTIR region (3700-2800 cm-1) and showing that water molecules (~90%) are strongly and moderately bound. The chickpea pasta displayed the highest content of strongly bonded water (about 55%) in contrast to the semolina pasta (~48%). A principal component analysis showed that the molecular organization of semolina pasta was mostly affected by dough formation and cooking; the molecular organization of chickpea pasta was determined by the cooking stage.

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In the last century, starch present in foods was considered to be completely digested. However, during the 1980s, studies on starch digestion started to show that besides digestible starch, which could be rapidly or slowly hydrolysed, there was a variable fraction that resisted hydrolysis by digestive enzymes. That fraction was named resistant starch (RS) and it encompasses those forms of starch that are not accessible to human digestive enzymes but can be fermented by the colonic microbiota, producing short-chain fatty acids. RS has been classified into five types, depending on the mechanism governing its resistance to enzymatic hydrolysis. Early research on RS was focused on the methods to determine its content in foods and its physiological effects, including fermentability in the large intestine. Later on, due to the interest of the food industry, methods to increase the RS content of isolated starches were developed. Nowadays, the influence of RS on the gut microbiota is a relevant research topic owing to its potential health-related benefits. This review summarizes over 30 years of investigation on starch digestibility, its relationship with human health, the methods to produce RS and its impact on the microbiome. © 2018 Society of Chemical Industry.

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The effect of amylose content in the in vitro digestibility of non-modified and OSA-modified corn starch was studied. Corn starches with different amylose content (waxy, normal and Hylon VII) were treated with 3% OSA solution. In vitro digestibility tests showed that OSA treatment reduced the fraction of fastly digestible starch, an effect that was more pronounced for cooked starch. The amylose content was negatively linked to the decrease of in vitro digestion. HPSEC analysis was conducted to gain insights on the effect of OSA-treatment on in vitro digestibility. The results showed an increase of the molecular weight of starch chains. Besides, the molecular weight increase was similar for amylose and amylopectin fractions. This suggests that OSA could be acting as a cross-linking agent between starch chains, reducing the susceptibility to amylolysis. Overall, OSA treatment induced the formation of more complex starch chains, offering more resistance for amylolytic reactions.

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ADP-glucose pyrophosphorylase (AGPase) is a key enzyme of starch synthesis in seeds, tubers and fruits. UDP-glucose pyrophosphorylase (UGPase) is an important enzyme of sucrose metabolism in the cytosol while alkaline phosphatase (ALP) is a marker enzyme of the amyloplast that keeps the production of ADPG by removing PPi. Unripe banana accumulates starch in the pulp during development, while ripe fruits are characterized by the accumulation of soluble sugars. The aim of the study was to compare starch granule structure, carbohydrate levels, subcellular location and activities of three enzymes: AGPase, UGPase and ALP. Protein extracts from the cytosolic and amyloplastidial fractions were obtained from the pulp of banana fruit at three developmental stages (11, 16 and 21 weeks after flowering) and analyzed by electrophoresis and immunodetection. Protein profiles were similar during ripening, showing a main electrophoretic band at 50-55 kDa. Higher protein content was found in the cytosolic than in the amyloplastidial fraction. Starch granules and ALP activity were enriched in the amyloplast, whereas AGPase showed a subcellular distribution similar to UGPase. Immunoblot analysis also confirmed the presence of AGPase in both cytosol and amyloplast. AGPase activity was higher in the cytosol than in the amyloplast. Both AGPase activity and western blot band intensity were highest at 16 weeks. UGPase activity was highest at 21 weeks. We conclude that cytosolic production of ADP-glucose is not an exclusive feature of cereal endosperms due to plant breeding, but it also occurs in fruits of non-domesticated plants such as tropical banana (Musa acuminata). This work increases our understanding about pyrophosphorylase activities in the pulp of banana fruit.

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The role of raw plantain flour (RPF) and its citric acid (CA)-esterified counterpart (EPF) on the carbohydrate nutritional properties of cookies was investigated. Cookies were elaborated with commercial wheat flour (CWF), RPF, EPF, or a CWF-EPF blend, and assessed for composition, starch digestibility, texture and sensory properties. EPF-cookie showed the lowest digestible starch (DS) content and estimated glycemic index (pGI) (25.0% and 59.3, respectively). Cookies made with CWF-EPF exhibited the highest indigestible fraction values attributed to the synergistic presence of the RS from EPF and the protein and non-starch polysaccharides from CWF. All RPF containing cookies exhibited lower hardness than CWF-cookie. Although the use of RPF decreased consumer's acceptability compared to CWF-cookie, the cookies with EPF showed sensory characteristics of 52-65% compared with the CWF-cookie (100%). This study shows CA esterification of plantain flour as a successful strategy to manufacture cookies with low DS and pGI.

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The development of starch granules of a banana cultivar (morado variety - Musa AAA subgroup Red dacca) from filamentous shape to semi-spherical and finally to oval shape, was studied. The purity of the extracted starch changed from 83.5% (6 weeks) to 95.4% (16 weeks). Impurities were ascribed to cellulosic and latex fractions responsible for the integrity of the pristine fruit. The amylose content was stabilized at about 29.6% after the 12th week. The thermal analysis showed that the gelatinization enthalpy increased from 5.0 to 11.2 J/g from the 6th to the 12th week, indicating an increased degree of internal molecular organization. The analysis of chain-length distribution and gel permeation chromatography, showing that the content of long chains (B1, B2, and B3+) increased with the development of the starch granule. Also, XRD analysis indicated that C- type X-ray diffraction pattern from early to later phases of development, although the relative crystallinity content increased from 19.3 to 23.5% after 16 weeks of development. FTIR revealed the formation of more ordered structures with the development time. In vitro digestion tests showed that the resistant starch fraction increased from 37.5% for week 6 to 55.5% for week 16.

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There is a growing interest in the development of functional ingredients, including those with high indigestible carbohydrate content. Unripe plantain flour (UPF) is a source of indigestible carbohydrates, type II resistant starch (RS) in particular. A major drawback of UPF, however, is that its RS content decreases sharply after wet heat treatment. Here, we explore the possibility of preparing an extruded UPF-based functional ingredient that retains limited starch digestibility features and high dietary fiber content. Both an unripe plantain pulp flour (UPFP) and a whole (pulp and peel) unripe plantain flour (UPFW) were prepared, extruded under identical conditions and evaluated for their gelatinization degree, total starch (TS), resistant starch (RS), and total dietary fiber (TDF) content; functional properties, such as pasting profile, water retention capacity, and solubility, and oil absorption index were also analyzed. The extruded functional ingredient was added to a yogurt and the rheological characteristics and in vitro starch digestibility of the product were evaluated. The extruded UPFW showed a lower gelatinization degree than the extruded UPFP, which may be due to the higher non-starch polysaccharide content of the former. A high TDF content was recorded in both extrudates (12.4% in UPFP and 18.5% in UPFW), including a significant RS fraction. The water retention capacity and solubility indices were higher in the extruded flours, particularly in UPFW, while only marginal differences in oil retention capacity were observed among the products. The addition of UPFP or UPFW (1.5 g TDF, w/v) to a yogurt did not alter the viscosity of the product, an important characteristic for the consumer's approval. Moreover, the composite yogurt showed a relatively low starch digestion rate. Extrusion of UPFs may be an alternative for the production of functional ingredients with important DF contents.

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Taro starch has the ability of producing spherical aggregates under spray-drying without the addition of binding agents. This property makes taro starch suitable for microencapsulation of dietary compounds. This study addressed the physical stability of hydrophilic and hydrophobic core materials microencapsulated by spray-drying into taro starch spherical aggregates determined from a thermodynamic standpoint via vapor adsorption isotherms. Ascorbic acid and almond oil were used as compound models. Encapsulation efficiency, GAB sorption parameters, differential and integral thermodynamic properties, Gibb's free energy, entropy-enthalpy compensation, spreading pressure, effective diffusion rate, activation energy and critical water activity were determined. The encapsulation efficiency of ascorbic acid and almond oil was 99% and 56%, respectively. Monolayer moisture content was relatively low for ascorbic acid microcapsules. The adsorption process was driven by entropic mechanisms. The physical stability of taro starch spherical aggregates microcapsules with different core material was guaranteed for a range of water activities and temperatures.

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The microstructure of cooked gluten-free pasta depends on the ingredients used, and this microstructure affects the starch hydrolysis (SH), the release of phenolic compounds (PC) and their antioxidant capacity (AC). The aim of this study was to evaluate the SD and bioaccessibility of PC during in vitro gastrointestinal digestion of gluten-free pasta and its relationship with the microstructure. The highest SH was during the intestinal phase (≈60%), but pasta with the highest content of unripe plantain and chickpea presented the lowest release of PC (≈60%). The insoluble dietary fibre could be responsible (≈12.5%) for these effects. The cooked pasta showed high AC in the intestinal phase. Regions with gelatinized starch granules in a less dense protein network and other regions with intact or swollen granules surrounded by a protein network were observed. The starch digestion and bioaccessibility of PC were related to the structure of the matrix.

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The phenolic compounds, color and antioxidant capacity of gluten-free pasta prepared with non-conventional flours such as chickpea (CHF), unripe plantain (UPF), white maize (WMF) and blue maize (BMF) were analyzed. Fifteen phenolic compounds (five anthocyanins, five hydroxybenzoic acids, three hydroxycinnamic acids, one hydroxyphenylacetic acid and one flavonol) were identified in pasta prepared with blue maize, and 10 compounds were identified for samples prepared with white maize. The principal component analysis (PCA) led to results describing 98% of the total variance establishing a clear separation for each pasta. Both the proportion (25, 50 and 75%) and type of maize flour (white and blue) affected the color parameters (L*, C ab *, h ab and ΔE* ab ) and antioxidant properties (DPPH, ABTS and FRAP methods) of samples, thus producing gluten-free products with potential health benefits intended for general consumers (including the population with celiac disease).

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Provitamin A (proVA) enhanced maize was developed to help alleviate vitamin A deficiency in maize-consuming populations. Nixtamalization (lime-cooking process) is the most commonly used maize-preparation method in Mexico and Central America. In this study, the effect of traditional nixtamalization (TN) and nixtamalized extrusion (NE) on proVA retention was evaluated. Kernel conversion to TN dough led to high proVA apparent retention (>100%), while kernel conversion to NE flour led to lower retention (85%). However, TN tortilla proVA carotenoid concentration was similar to the kernels' original concentration and slightly higher in NE tortillas. Genotypic variation has a strong effect on proVA retention in TN dough and NE flour, but no such variation in proVA retention was observed in tortillas. Tortillas prepared with proVA-enhanced maize, using either TN or NE, are a good source of proVA carotenoids. Also, dough made using TN and proVA-enhanced maize is a high proVA-content ingredient for other food products.

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The purpose of this study was to evaluate the effect of blue maize extracts obtained by acid-methanol treatment on the nutritional in vitro starch fractions such as: rapidly digestive starch (RDS), slowly digestive starch (SDS) and resistant starch (RS) of native and gelatinized commercial maize starch. Chromatographic analysis (HPLC-DAD/ESI-MS) of blue maize extracts showed the presence of seven anthocyanins, where cyanidin-3-(6″-malonylglucoside) was the main. Blue maize extracts modified nutritional in vitro starch fractions (decrease of RDS) while RS content increased (1.17 and 2.02 times for native and gelatinized commercial maize starch, respectively) when anthocyanins extracts were added to starch up to 75% (starch weight). This preliminary observation provides the basis for further suitability evaluation of blue maize extract as natural starch-modifier by the possible anthocyanins-starch interaction. Anthocyanin extracts can be a suitable to produce functional foods with higher RS content with potential human health benefits.

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Banana starch was chemically modified using single (esterification or cross-linking) and dual modification (esterification-cross-linking and cross-linking-esterification), with the objective to increase the slowly digestible starch (SDS) and resistant starch (RS) concentrations. Physicochemical properties and in vitro digestibility were analyzed. The degree of substitution of the esterified samples ranged from 0.006 to 0.020. The X-ray diffraction pattern of the modified samples did not show change; however, an increase in crystallinity level was determined (from 23.79 to 32.76%). The ungelatinized samples had low rapidly digestible starch (RDS) (4.23-9.19%), whereas the modified starches showed an increase in SDS (from 10.79 to 16.79%) and had high RS content (74.07-85.07%). In the cooked samples, the esterified starch increased the SDS content (21.32%), followed by cross-linked starch (15.13%). Dual modified starch (cross-linked-esterified) had the lowest SDS content, but the highest RS amount. The esterified and cross-linked-esterified samples had higher peak viscosity than cross-linked and esterified-cross-linked. This characteristic is due to the fact that in dual modification, the groups introduced in the first modification are replaced by the functional group of the second modification. Temperature and enthalpy of gelatinization decreased in modified starches (from 75.37 to 74.02 °C and from 10.42 to 8.68 J/g, respectively), compared with their unmodified starch (76.15 °C and 11.05 J/g). Cross-linked-esterified starch showed the lowest enthalpy of gelatinization (8.68 J/g). Retrogradation temperature decreased in modified starches compared with unmodified (59.04-57.47 °C), but no significant differences were found among the modified samples.

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The use of pigmented maize varieties has increased due to their high anthocyanins content, but very few studies are reported about the starch properties of these grains. The aim of this work was to isolate the starch granules from pigmented blue maize and carry out the morphological, physicochemical, and biochemical characterization studies. The proximate composition of starch granules showed high protein contents, after purification, the blue maize starch presented lower protein amount than starch from white maize (control). Although the purity of starch granules was increased, the damaged starch (determined for the Maltase cross absence) was also increased. Scanning electron microscopy showed the presence of some pores and channels in the blue maize starch. The electrophoretic protein profiles showed differences in the bands that correspond to the enzymes involved in the starch biosynthesis; these differences could explain the variation in morphological characteristics of blue maize starches against starch from white maize.

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Salted noodles were prepared with different contents of wheat grits and plantain starch (PS). The blends were hydrated with 2% NaCl (w/v), homogenized, and the resulting doughs were sheeted through a pasta machine, cut into strips ~30cm in length, cooked, and their composition and in vitro starch digestibility was assessed. Moisture (6.43-7.60%) and ash contents (2.08-3.12%) increased by the addition of PS. Fat level decreased from 0.41 to 0.31% as the substitution of wheat grits increased. Results showed a 7.39% lower total starch content in the control sample as compared to the noodle containing 30% PS. A similar pattern was observed for potentially available starch content, but the difference was greater (12.46%). Approximately 50% of total resistant starch (RS) in the noodles was resistant starch associated to fiber, showing that a part of RS is due to the physically inaccessible and retrograded starch fractions. Pure wheat (control) noodles presented a greater final a-amylolysis value, which is suggestive of potentially lower glycemic impact for the plantain/wheat products.

Se elaboraron tallarines salados con diferentes contenidos de sémola de trigo y almidón de plátano (AP). Las mezclas fueron hidratadas con solución NaCl 2% (p/v), homogenizadas y las masas laminadas en una máquina para elaborar pasta. Se cortaron en tiras de ~30cm de longitud, se cocinaron y se estudió su composición, así como la digestibilidad del almidón in vitro. El contenido de humedad (6,43-7,60%) y cenizas (2,08-3,12%) incrementaron con la adición del AP. El contenido de lípidos disminuyó de 0,41 a 0,31% conforme el nivel de sustitución de la semolina incrementó. El contenido de almidón total fue 7,39% menor en la muestra control comparado con el tallarín con 30% de AP. Un comportamiento similar se encontró en el almidón disponible, pero la diferencia fue mayor (12,46%). Aproximadamente 50% del almidón resistente total (AR) en los tallarines fue almidón resistente asociado a fibra, mostrando que una parte del AR es debido al almidón físicamente inaccesible y al almidón retrogradado. El valor final de la a-amilólisis fue mayor en el control de trigo puro, lo cual sugiere que los tallarines elaborados con la mezcla semolina/AP tienen menor impacto glucémico.

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BACKGROUND: Beans are rich and inexpensive sources of proteins and carbohydrates around the world, but particularly in developing countries. However, many legume varieties are still underutilized. In this study, physical characteristics of the seeds of three Phaseolus lunatus cultivars were characterized. Also, the chemical composition and starch digestibility in the cooked beans were assessed. RESULTS: 'Comba floja' variety exhibited the highest thousand-kernel weight whereas the lowest was found in 'comba violenta'. This agrees with seed dimensions: 'comba floja' had the Longest seeds (16.36 mm) and 'comba violenta' the shortest ones (13.98 mm). All samples exhibited high protein content, but levels in 'comba blanca' variety (216 g kg(-1)) were lower than the in other two cultivars. Total starch (370-380 g kg(-1)) and potentially available starch content (330-340 g kg(-1)) were similar in the three varieties. Resistant starch level in the cooked seeds ranged between 38 and 45 g kg(-1). Low enzymatic hydrolysis indices (HI) were recorded (30.2-35%), indicating a low digestion rate for Phaseolus lunatus starch. HI-based predicted glycemic indices ranged between 34% and 39%, which suggests a 'slow carbohydrate' feature for this legume. CONCLUSION: Phaseolus lunatus beans appear to be a good source of protein and slow-release carbohydrates with potential benefits for human health. Copyright © 2007 Society of Chemical Industry.

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Se estudió la composición química y la digestibilidad del almidón de cuatro variedades de frijol común (Phaseolus vulgaris L.). No se encontraron diferencias estadísticas (p£0,05) en el contenido de proteína y el contenido de lípidos fue bajo pero sin diferencias apreciables. Estos frijoles son buena fuente de minerales (3,67-5,15 por ciento cenizas). El valor de almidón total (AT) menor fue para la variedad Flor de Mayo (34,70 por ciento) y el mayor para Peruano (42,81 por ciento) y Mayocoba (40,24 por ciento). Los valores mayores de almidón disponible (AD) se determinaron en las variedades Flor de Mayo (32,27 por ciento) y Peruano (31,60 por ciento), y los menores en las variedades Mayocoba (22,87 por ciento) y Negro (21,7 por ciento). La variedad Flor de Mayo presentó el menor valor (2,43 por ciento) de almidón resistente (AR), y las variedades con el mayor valor de AT (40,24-42,81 por ciento) también tuvieron el valor más alto de AR (5,41-6,4 por ciento). Las variedades Flor de Mayo y Peruano mostraron los mayores porcentajes (p£0,05) de hidrólisis (34-37 por ciento), lo que coincidió con sus valores de AD. La predicción del índice glucémico (pIG) fue mayor en la variedad Peruano (68,69), y menor en Mayocoba (57,88) y Negro (58,40). Estos valores de pIG se consideran bajos

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Tortilla samples were elaborated by four small commercial factories in Mexico, employing masas prepared with the traditional nixtamalization process. Samples were stored at 4 degrees C for up to 72 hours and their chemical composition and in vitro starch digestibility features were evaluated. Chemical composition did not change with the storage time, but soluble carbohydrates decreased slightly during storage. A significant decrease in available starch content upon storage was observed, concomitant with increased resistant starch (RS) levels. These changes are possibly due to retrogradation. Retrograded resistant starch (RRS) values increased with storage time; in some samples, RRS represented more than 75% of total RS whereas in others it only accounted for 25%. The digestion rate (DR) in the freshly prepared tortillas was similar for the various samples, but after 72 h storage some differences among tortillas were found. Also, when a single tortilla sample was compared throughout the different storage times, lower DRs were determined in samples subjected to prolonged storage, which is related to the concomitant. increase in RRS. The differences found among the various tortilla samples may be due to minor variations in the commercial processing conditions and to the use of different corn varieties.

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