Ultrasonication followed by aqueous two-phase system for extraction, on-site modification and isolation of microalgal starch with reduced digestibility.

Microalgae are new and sustainable sources of starch with higher productivity and flexible production modes than conventional terrestrial crops, but the downstream processes need further development. Here, ultrasonication (with power of 200 W or 300 W and duration of 10, 15, 20, or 25 min) was applied to simultaneously extract and modify starch from a marine microalga Tetraselmis subcordiformis for reducing the digestibility, and an aqueous two-phase system (ATPS) of ethanol/NaH2PO4 was then used to isolate the starches with varied properties. Increasing ultrasonic duration facilitated the partition of starch into the bottom pellet, while enhancing the ultrasonic power was conducive to the allocation in the interphase of the ATPS. The overall starch recovery yield reached 73 âˆ¼ 87 % and showed no significant difference among the ultrasonic conditions tested. The sequential ultrasonication-ATPS process successfully enriched the starch with purities up to 65 % âˆ¼ 88 %, which was among the top levels reported in microalgal starch isolated. Ultrasonication produced more amylose which was mainly fractionated into the interface of the ATPS. The digestibility of the starch was altered under different ultrasonic conditions and varied from different ATPS phases as well, with the one under the ultrasonic power of 200 W for 15 min at the bottom pellet having the highest resistant starch content (RS, 39.7 %). The structural and compositional analysis evidenced that the ultrasonication-ATPS process could exert impacts on the digestibility through altering the surface roughness and fissures of the starch granules, modulating the impurity compositions (protein and lipid) that could interact with starch, and modifying the long- and short-range ordered structures. The developed ultrasonication-ATPS process provided novel insights into the mechanism and strategy for efficient production of functional starch from microalgae with a potential in industrial application.

Preparation and characterization of non-crystalline granular starch with low processing viscosity.

Non-crystalline granular starch (NCGS) has advantages in the deep processing of starch owing to its unique structure and function. In this study, NCGS was successfully prepared at a baking temperature of 210 °C, and the morphology, structure, pasting properties, and rheological properties of the NCGS were systematically studied. Compared with native starch, NCGS showed a lower processing viscosity and rapid reduction in the peak viscosity from 3795 to 147 cP. Furthermore, NCGS exhibited impaired short- and long-range ordered structures, as indicated by the lower ratio of absorbance at 1047/1015 cm-1 and decreased crystallinity compared to native starch. Additionally, amylose and amylopectin with long and medium chains in NCGS were degraded into short chains, resulting in an increase in amylose content and branch density. The analysis of the physicochemical properties of NCGS, especially the low processing viscosity, is of great importance for the industrial application of starch, particularly in terms of improving the yield, saving energy, and reducing environmental pollution.

Effect of atmospheric pressure non-thermal pin to plate plasma on the functional, rheological, thermal, and morphological properties of mango seed kernel starch.

This study aimed to investigate the effect of atmospheric pressure non-thermal pin-to-plate plasma on the functional, rheological, thermal, and morphological properties of mango seed kernel starch. As cold plasma contains highly reactive species and free radicals, it is expected to cause noticeable modifications in the attributes of starch treated. The isolated mango seed kernel starch was subjected to the plasma treatment of input voltages 170 and 230 V for 15 and 30 min of exposure. Water adsorption, swelling, and solubility at lower temperatures. There has been a significant reduction (p < 0.05) in pH values of starch from 7.09 to 6.16 and also the desirable reduction in turbidity values by 42.60%. However, there has been no significant change in the oil and water binding behavior of the starch. The FTIR spectra of MSKS demonstrate the formation of amines which contributes to the better hydrophilic nature of the starch. The structural modification has been adequately confirmed by SEM images. The maximum voltage and time combination, lead to depolymerization of starch which is supported by NMR spectra thus affecting thermal and rheological properties. The application of cold plasma-modified MSKS in food would facilitate stable and smooth textural development.

Optimization of ultrasonic-assisted enzymatic extraction of kiwi starch and evaluation of its structural, physicochemical, and functional characteristics.

A new ultrasound-assisted enzymatic extraction (UAEE) method of starch from kiwifruit was established and optimized using response surface methodology (RSM). Under optimal conditions (the pectinase-to-cellulase-to-papain ratio = 1:2:1 g/kg, solid/liquid ratio = 1:6.68, extraction pH = 5.23, ultrasound power = 300 W, and extraction temperature = 52 °C), the kiwi starch (KS) yield was about 4.25%, and the starch content of KS was 873.23 mg/g. Compared to other extraction methods, UAEE can obtain KS with high yield and purity with a shorter extraction time and less solvent and enzyme. The extracted KS has a low gelatinization enthalpy (8.02 J/g) and a high peak viscosity (7933 cP), with obvious particle properties and low adhesion. In addition, KS is rich in polyphenols, has strong antioxidant activity, and has higher contents of amylose starch (30.74%) and resistant starch (60.18%). This study established a novel and highly efficient method for KS extraction and suggest several possible applications for KS in the food industry.

Effects of Variety and Growing Location on Physicochemical Properties of Starch from Sweet Potato Root Tuber.

Three sweet potato varieties with purple-, yellow-, and white-fleshed root tubers were planted in four growing locations. Starches were isolated from their root tubers, their physicochemical properties (size, iodine absorption, amylose content, crystalline structure, ordered degree, lamellar thickness, swelling power, water solubility, and pasting, thermal and digestion properties) were determined to investigate the effects of variety and growing location on starch properties in sweet potato. The results showed that granule size (D[4,3]) ranged from 12.1 to 18.2 µm, the iodine absorption parameters varied from 0.260 to 0.361 for OD620, from 0.243 to 0.326 for OD680 and from 1.128 to 1.252 for OD620/550, and amylose content varied from 16.4% to 21.2% among starches from three varieties and four growing locations. Starches exhibited C-type X-ray diffraction patterns, and had ordered degrees from 0.634 to 0.726 and lamellar thicknesses from 9.72 to 10.21 nm. Starches had significantly different swelling powers, water solubilities, pasting viscosities, and thermal properties. Native starches had rapidly digestible starch (RDS) from 2.2% to 10.9% and resistant starch (RS) from 58.2% to 89.1%, and gelatinized starches had RDS from 70.5% to 81.4% and RS from 10.8% to 23.3%. Two-way ANOVA analysis showed that starch physicochemical properties were affected significantly by variety, growing location, and their interaction in sweet potato.

A novel route for identifying starch diagenetic products in the archaeological record.

This work introduces a novel analytical chemistry method potentially applicable to the study of archaeological starch residues. The investigation involved the laboratory synthesis of model Maillard reaction mixtures and their analysis through Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR-MS). Thus, starch from sixteen plant species were matured while reacting it with the amino acid glycine. The FTICR-MS analysis revealed > 5,300 molecular compounds, with numerous unique heteroatom rich compound classes, ranging from 20 (Zea mays) to 50 (Sorghum bicolor). These classes were investigated as repositories of chemical structure retaining source and process-specific character, linked back to botanical provenance. We discussed the Maillard reaction products thus generated, a possible pathway for the preservation of degraded starch, while also assessing diagenetic recalcitrance and adsorption potential to mineral surfaces. In some cases, hydrothermal experimentation on starches without glycine reveals that the chemical complexity of the starch itself is sufficient to produce some Maillard reaction products. The article concludes that FTICR-MS offers a new analytical window to characterize starchy residue and its diagenetic products, and is able to recognize taxonomic signals with the potential to persist in fossil contexts.

Enhancing the functional properties of rice starch through biopolymer blending for industrial applications: A review.

Rice starch has been used in various agri-food products due to its hypoallergenic properties. However, rice starch has poor solubility, lower resistant starch content with reduced retrogradation and poor functional properties. Hence, its industrial applications are rather limited. The lack of comprehensive information and a holistic understanding of the interaction between rice starch and endo/exogenous constituents to improve physico-chemical properties is a prerequisite in designing industrial products with enhanced functional attributes. In this comprehensive review, we highlight the potentials of physically mixing of biopolymers in upgrading the functional characteristics of rice starch as a raw material for industrial applications. Specifically, this review tackles rice starch modifications by adding natural/synthetic polymers and plasticizers, leading to functional blends or composites in developing sustainable packaging materials, pharma- and nutraceutical products. Moreover, a brief discussion on rice starch chemical and genetic modifications to alter starch quality for the deployment of rice starch industrial application is also highlighted.

Surface-charged starch nanocrystals from glutinous rice: Preparation, crystalline properties and cytotoxicity.

The high-amylopectin glutinous rice is used in this study for the preparation of starch nanocrystals (SNCs) with the acid hydrolysis and enzymatic treatment. The fabricated SNC is carried out the surface modifications by phosphorylation and cationization to produce the nanocrystals with the charged surface. Four kinds of SNCs are obtained with the different surface charges involving the varied negative charges, positive charge and no charge. The chemical structures, morphologies and crystalline properties of four SNCs were investigated, together with the effect of surface charges to their cytotoxicity for two cell lines RAW267.4 and CAL27 by the cell proliferation and cell migration assay. The sulfuric acid-hydrolyzed SNC and phosphorylated SNC have more ordered regions and therefore display the higher crystallinities than the enzymatic treated SNC. Four obtained SNCs all exhibited weak cytotoxicity, indicating their good biocompatibility in the potential biomedical application.

Isolation, characterization, modification and uses of taro starch: A review.

Taro is a major root crop utilized widely for diverse food and non-food applications. Taro corms are processed into various forms before consumption, which makes them digestible and palatable, extends the shelf life and reduces post-harvest losses. Taro corm contains starch as the major carbohydrate, accounting up to 70-80% of the whole dry matter. The starches obtained from different cultivars and sources significantly differ in physical, chemical, thermal, morphological, and functional properties, which can be explored for varied applications. Starch quality also controls the end-quality of food and industrial products. Several starch modification methods have been studied to improve its positive attributes and to eliminate deficiencies in its native characteristics. These modification methods, which can be categorised into physical, chemical and enzymatic, have proved to improve the characteristics and applications of starch. This review aims to compile the information about the chemical composition, characterization, isolation and modification methods, with an objective of its increased use in food or non-food industries. In addition, challenges and issues in the small-scale processing of taro are discussed. The information available in this review may help in a better understanding and utilization of taro starch.

Understanding Starch Metabolism in Pea Seeds towards Tailoring Functionality for Value-Added Utilization.

Starch is the most abundant storage carbohydrate and a major component in pea seeds, accounting for about 50% of dry seed weight. As a by-product of pea protein processing, current uses for pea starch are limited to low-value, commodity markets. The globally growing demand for pea protein poses a great challenge for the pea fractionation industry to develop new markets for starch valorization. However, there exist gaps in our understanding of the genetic mechanism underlying starch metabolism, and its relationship with physicochemical and functional properties, which is a prerequisite for targeted tailoring functionality and innovative applications of starch. This review outlines the understanding of starch metabolism with a particular focus on peas and highlights the knowledge of pea starch granule structure and its relationship with functional properties, and industrial applications. Using the currently available pea genetics and genomics knowledge and breakthroughs in omics technologies, we discuss the perspectives and possible avenues to advance our understanding of starch metabolism in peas at an unprecedented level, to ultimately enable the molecular design of multi-functional native pea starch and to create value-added utilization.

Composition, morphology and physicochemical properties of starches derived from indigenous Ethiopian tuber crops: A review.

Starch is a key food ingredient that can be extracted from roots, tubers, cereals, legumes and used in a variety of industrial applications. The issue of starch has received considerable critical attention. Most conventional sources of starch are being overexploited, it is necessary to investigate new botanical sources of starch to relieve pressure on traditional sources. Indigenous Ethiopian tuber crops can represent unexploited sources of starch with interesting characteristics in terms of potential uses as starch-based foods. It comes in a variety of shapes, sizes and properties allowing for a wide range of applications with high technological value in both the food and non-food industries. Compared to common starches, these starches have far fewer studies on their food and industrial applications. In the future, tubers grown Ethiopia could become another source of starch for the processor. This review summarizes current knowledge about the composition, structure, and physicochemical properties of Ethiopian tubers starches, intending to recommend future research to improve their use in the food industry. In the future, more in-depth work will be needed to reveal the mechanism of modification involved for structural change to use these starches for different purposes.

Structural changes in popped sorghum starch and their impact on the rheological behavior.

Sorghum has been used to expand snacks such as pop sorghum. However, it is still unknown how the structural changes during the popping affect its rheological and functional properties. This study evaluated the structural changes of popped sorghum starch (PS) and their impact on rheological behavior. Moisture sorghum was adjusted to 11, 15, and 20% before popped. Morphology, X-ray pattern (XRP), infrared spectra (IR), thermal properties, and rheological behavior before and after popping were evaluated. Micrographs showed a honeycomb-like structure in PS. XRP showed partial damage to the orthorhombic crystals of the sorghum starch after PS, while the growth of crystalline lamellae was also generated (13.08 and 20.01°). IR showed structural damage as the signal at 1045 cm-1 disappeared in PS. The IM increased to gelatinization of the starch. The rheological behavior of PS displayed better thermal stability, with the lowest breakdown (25 ± 3.5 cP), setback (253 ± 11.3 cP), and final (1337 ± 5.7 cP) viscosity. The consistency coefficient k and flow behavior index n increase, meaning a loss of the pseudoplastic character. Viscoelastic properties increased in PS, suggesting the formation of cross-links and a stable matrix. Correlation analysis showed a strong relationship between structural changes and the rheological behavior of PS.

Synthesis, characterization, and utilization of potato starch nanoparticles as a filler in nanocomposite films.

The nanoparticles for the preparation of nanocomposite starch films were synthesized from potato starch using the acid hydrolysis method. The films were prepared by incorporating starch nanoparticles into the film formulation at 0.5, 1, 2, 5, and 10% level of total starch. The control starch film was prepared without the incorporation of starch nanoparticles (SNPs) in film formulation. The starch and SNPs were analyzed for physicochemical and morphological properties. The absorption capacity of SNPs for water and oil was significantly (p < 0.05) lower as compared to native starch. Whereas, the swelling power and solubility of SNPs were significantly (p < 0.05) higher than the swelling power and solubility of starch, respectively. The starch granules were oval and spherical with regular surfaces whereas the SNPs had irregular cracked exteriors spaces. The water vapor transmission rate (WVTR) from nanocomposite starch films was significantly (p < 0.05) lower than the control starch film. The burst strength of films was increased significantly (p < 0.05) with an increased level of SNPs incorporation in film formulation. The incorporation of SNPs increased film thickness and biodegradability. Thus, the present study revealed that the incorporation of SNPs in film formulation resulted in improved film properties.

The assisting effects of ultrasound on the multiscale characteristics of heat-moisture treated starch from Agriophyllum squarrosum seeds.

Present study was aimed to characterize the effects of heat-moisture treatments supported by ultrasound on structural, physicochemical and digestive properties of the starch from Agriophyllum squarrosum seeds. The starch sample was subjected to heat-moisture (120°C, 25% moisture) for different durations with assisting by pre- or post-treatment of ultrasound (20 Hz, 300 W, 20 min). A. squarrosum starch exhibited the original A-type of crystalline structure after all treatments. All modified starches had lower amylose content, amylopectin molecular weight, swelling power and solubility, and higher resistant starch content than the native starch. Heat-moisture treatments and dual modifications of heat-moisture and ultrasound increased the gelatinization temperature of starch granules and significantly (p ≤ 0.05) reduced the viscosity of starch paste. Pretreatment of ultrasound enhanced the effects of heat-moisture on the viscosity properties while post-treatment of ultrasound weakened which on the gelatinization temperature, by regulating the changes of double helix structure and short-range ordered structure in starch granules tested by Fourier-transform infrared spectrometer. Scanning electron microscopy unveiled that A. squarrosum starch pretreated by ultrasound became more susceptible to heat moisture in morphology. This work was very important for the deep excavation of the characteristics of A. squarrosum starch and the effective application of ultrasound in starch modifications.

Molecular-structure evolution during in vitro fermentation of granular high-amylose wheat starch is different to in vitro digestion.

This study investigates the evolution of the distributions of whole molecular size and of chain length of granular wheat starches (37 ~ 93% amylose content), subjected to in vitro fermentation with a porcine faecal inoculum or digestion with pancreatic enzymes. The results showed that the molecular structures of high-amylose starch (HAS) unfermented residues largely remained unchanged during the fermentation process, while wild-type starch (37% amylose content) showed a preferential degradation of the amylopectin fraction. In contrast, under simulated digestion conditions, the undigested residues of HAS showed structural changes, including a decrease in amylose content, a shift of amylose peak position towards lower degrees of polymerisation, and an enzyme-resistant fraction. These changes of starch structure are likely to be dependent on the different starch-degrading enzyme activities present in pancreatic vs. microbial systems. Molecular changes in response to fermentation metabolism revealed by size-exclusion chromatography can help understand the microbial utilization of resistant starch.

Cassava starch-processing residue utilization for packaging development.

The starch-based film development has been extensively studied since, in general, it is possible to obtain transparent, non-toxic, odorless, good gas barrier, biodegradable, and tasteless samples. However, world hunger-related problems are a reality and the use of starches, a recognized carbohydrate source, in the packaging industry should be avoided. Thus, the use of different residual starchy can minimize the costs of production, promoting the development of innovative biomaterials, eliminating the competition with the food chain. The objective of the present work was to evaluate the impact of the cassava starch (CS) substitution by gelatinized starch (GS), a residue generated in the sieving step of starch processing, verifying possible changes in the final material characteristics. The raw materials characterization includes determination of amylose and moisture contents, centesimal composition, particle size distribution, and thermal analysis. After casting solution and drying processes, the samples were evaluated regarding the visual macroscopic and microscopic aspects showing continuous and homogeneous structure. The results were related to the physicochemical and mechanical properties. The GS addition promoted a decrease in the tensile strength (3.3 ± 0.1 MPa to 1.2 ± 0.3 MPa) and elastic modulus (52 ± 13 MPa to 10 ± 3 MPa) values, while the elongation percentage (160 ± 30% to 212 ± 14%) values seem to have not been so affected. It can be seen a high potential for the use of agro-industrial residues containing starch in bioplastic production.

Effects of vacuum packaging storage of minimally processed cassava roots at various temperatures on microflora, tissue structure, starch extraction by wet milling and granule quality.

BACKGROUND: Vacuum package storage is commonly applied to reduce postharvest deterioration in minimally processed cassava roots. However, the influence of vacuum packaging conditions on root end-use quality is poorly understood. Hence, the effects of vacuum packaged storage at ambient, refrigerated and freezing temperatures on microflora, cassava tissue structure and starch extraction by wet milling were studied. RESULTS: Vacuum packaged storage temperature strongly affected cassava root quality. Minimal adverse effects were obtained with frozen storage. With refrigerated storage, there was negligible microbial growth but some disruption of the parenchyma cell wall structure suggestive of chilling injury. With ambient temperature storage, there was considerable Lactobacilli dominated fermentation. This caused substantial cell degradation, probably due to the production of extracellular cellulolytic and other cell wall degrading enzymes. A benefit of this cell wall breakdown was that it substantially improved starch extraction with wet milling from the stored cassava pieces; by 18% with pieces that had been ambient vacuum packaged and wet milled using a 2000 µm opening screen. However, ambient temperature storage resulted in some starch granule pitting due to the action of extracellular amylases from the fermenting microorganisms. CONCLUSION: The best vacuum packaging storage conditions for minimally processed cassava depends on application and cost. For short-term storage, refrigeration would be best for vegetable-type products. For several months storage, freezing is best. For wet milling applications, this could be combined with subsequent short-term ambient temperature storage as it improves starch extraction efficiency and could reduce distribution energy costs. © 2021 Society of Chemical Industry.

Nopal cladode as a novel reinforcing and antioxidant agent for starch-based films: A comparison with lignin and propolis extract.

The potential use of nopal cladode flour (NC) as reinforcing/bioactive agent in cassava starch-based films was evaluated and compared with the use of propolis extract or lignin, which are commonly used for these purposes. Cassava starch-based films containing untreated NC (S-NC), NC treated at pH 12 (S-NC12), aqueous propolis extract at two different concentrations (SP1 or SP2), or lignin (S-L) were produced by the casting technique; glycerol was used as plasticizer. NC12 and NC affected the mechanical properties of the cassava starch-based film similarly as compared to propolis extract and lignin. Moreover, NC and NC12 had different performance as reinforcing and antioxidant agent in cassava starch-based film. Thus, S-NC12 film was more elongable (28.5 ± 6.5%), more hydrophobic (contact angle: 70.8° ± 0.1), less permeable to water vapor (0.8 ± 0.0 × 10-10 g·m-1·s-1·Pa-1) and had better antioxidant activity by ABTS•+ (44.70 ± 0.3 µM Trolox·g-1 of film) than the S-NC film. SEM and TGA analysis of films showed that NC12 was better incorporated into the cassava starch matrix than NC, lignin and propolis extract. Overall, nopal cladode flour has potential use in the production of active biodegradable packaging for the food preservation with high oxidation rate.

Mango seed starch: A sustainable and eco-friendly alternative to increasing industrial requirements.

During processing of mango (Mangifera indica) into beverages, squashes and jellies, by-products such as peel and kernel are generated. The higher generation volume of mango-seed makes it cheaper and readily available material for extraction of starch. The current article addresses the mango-seed as potential source of starch over the conventional sources. The starch isolation, its composition structural morphology along with the various physicochemical properties are well discussed. Various modifications for improving the functionality of mango-seed starch (MSS) are comprehensively investigated based on the previous findings. Digestibility profile and glycaemic index of MSS reflected the presence of more resistant starch compared to other conventional starches; making it suitable ingredient for managing diabetes. The structure of mango seed starch can be easily manipulated using biological, chemical and physical methods for improving its application in the foods. Possible utilization of the MSS at large scale will improve the economic viability of the mango processing industries.

Extraction and characterization of starch from Yard-long bean (Vigna unguiculata (L.) Walp. ssp. unguiculata cv.-gr. sesquipedalis).

Vigna unguiculata subsp. sesquipedalis is an important derivative cultivar of cowpea planted widely in China, and popularly known as "Yard-long bean". There is lack of research about the structural characterization and physicochemical aspects of carbohydrate content in Yard-long bean seeds. Thus, the present study aimed to evaluate structures, thermal and technological properties of Yard-long bean seeds starch (YSS). The starch contains little of ash, protein and total fiber meanwhile amylose content of 37.52%. The shapes of the starch granules obtained from field emission scanning electron microscopy (FESEM) were oval to semi-elliptical with little granules occurring in agglomerated structures clusters, and volume median diameter of granules ranged from 10.5 µm to 12.5 µm. The initial gelatinization temperature of YSS was 73.86 °C, peak temperature was 80.59 °C and final 88.53 °C. Solubility index (SI, 3.43% at 90 °C) and swelling power (SP, 6.62 g/g at 90 °C) were observed with low volume, which corroborated with the C-type structure shown by X-ray diffraction (XRD) and high crystallinity degree. The extraction of YSS can be feasible, and it has suitable properties for use in the food industry.