Freeze-drying changes the structure and digestibility of B-polymorphic starches

The impact of Cas9-mediated mutagenesis of genes encoding potato starch-branching enzymes on starch structural properties and in vitro digestibility

The digestibility of starch is affected by amylose content, and increasing amylopectin chain length which can be manipulated by alterations to genes encoding starch-branching enzymes (SBEs). We investigated the impact of Cas9-mediated mutagenesis of SBEs in potato on starch structural properties and digestibility. Four potato starches with edited SBE genes were tested. One lacked SBE1 and SBE2, two lacked SBE2 and had reduced SBE1, and one had reduced SBE2 only. Starch structure and thermal properties were characterised by DSC and XRD. The impact of different thermal treatments on digestibility was studied using an in vitro digestion protocol. All native potato starches were resistant to digestion, and all gelatinised starches were highly digestible. SBE modified starches had higher gelatinisation temperatures than wild type potatoes and retrograded more rapidly. Gelatinisation and 18 h of retrogradation, increased gelatinisation enthalpy, but this did not translate to differences in digestion. Following 7 days of retrogradation, starch from three modified SBE starch lines was less digestible than starch from wild-type potatoes, likely due to the recrystallisation of the long amylopectin chains. Our results indicate that reductions in SBE in potato may be beneficial to health by increasing the amount of fibre reaching the colon after retrogradation.

Effect of frozen storage on the quality of frozen instant soup rice noodles: From the moisture and starch characteristics

This study aimed to simulate frozen instant soup rice noodles (FISRN) and investigate the effects of long-term frozen storage (-18 °C, 180 days) on the quality characteristics, moisture status, and starch retrogradation of FISRN. The findings indicated that the extent of starch retrogradation gradually increased over 90 days, which elevated the RS rate and inhibited starch digestibility. However, recrystallization resulted in a gradual increase in ice crystal size after 90 days, which disrupted the ordered structure formed by starch retrogradation, reduced the degree of starch order, and accelerated the rate of starch digestion. Furthermore, a longer relaxation time (T24) was detected by NMR with increasing storage time. The weakly bound water in FISRN was gradually converted to free water. Texture results suggested that the hardness of FISRN experienced a general decrease. The cooking loss increased progressively from 3.66 % to 8.10 %. Scanning electron microscope demonstrated that the internal porous network structure of FISRN became inhomogeneous, and a significant number of apertures were formed on the surface. Overall, starch retrogradation and ice recrystallization significantly impact the quality of FISRN during long-term frozen storage. The findings may potentially influence the consumption and market circulation of FISRN positively.

Structural changes and degradation mechanism of type 3 resistant starch during in vitro fecal fermentation

The colonic fermentation metabolites of resistant starch (RS) are recognized to have various health benefits. However, the relationship between the structural variation of RS and the colonic fermentation properties, remains inadequately studied, especially for type 3 resistant starch. The in vitro fecal fermentation properties with multi-structure evolution of A- and B-type polymorphic resistant starch spherulites (RSS) were investigated. Both polymorphic types of RSS showed similar fermentation rate and total short-chain fatty acid profiles, while the butyrate concentration of the A-type RSS subjected to 24 h of fermentation was significantly higher compared to B-type RSS. In the case of recrystallized starch spherulites, irrespective of the polymorphic type, gut bacteria preferentially degraded the intermediate chains and crystalline regions, as the local molecule-ordered area potentially serves as suitable attachment sites or surfaces for microbial enzymes.

Short-range molecular order is the driving factor for starch digestibility and texture of alginate-encapsulated rice beads

BACKGROUND

Rice grain analogues with slow starch digestibility are commonly associated with an unsatisfactory texture, often leading to consumer dissatisfaction. Alginate encapsulation has been applied to reduce the digestibility of corn and potato starch. The fine molecular structures of rice starch can greatly determine its digestibility and texture. However, it remains unclear whether a combination of alginate encapsulation and varied starch molecular structures can be employed to create rice grain analogues that offer both slow starch digestibility and an appealing texture.

RESULTS

For the first time, the present study constructed alginate-encapsulated rice beads (as a rice grain analogue). A wide range of starch digestion rates were found among alginate-encapsulated rice beads prepared with different rice varieties, and only certain rice varieties (e.g. Subei and Nanjing) were able to result in rice beads with slower starch digestibility than their parental rice kernels. More importantly, all rice beads showed a relatively softer texture compared to their parental rice kernels. Correlation analysis showed that starch digestion rate, hardness and stickiness were all positively correlated with the ratio of short-range amorphous regions in rice bead samples, as obtained from Fourier transform-infrared spectroscopy, but not with the relative crystallinity.

CONCLUSION

Collectively, these results suggest that rice beads with slower starch digestion rate and softer texture could be obtained by choosing rice varieties that develop more short-range ordered structure after cooking. © 2024 Society of Chemical Industry.

Sonication-mediated modulation of macronutrient structure and digestibility in chickpea

Ultrasound processing is an emerging green technology that has the potential for wider application in the food processing industry. While the effects of ultrasonication on isolated macromolecules such as protein and starch have been reported, the effects of physical barriers on sonication on these macro-molecules, for example inside whole seed, tissue or cotyledon cells, have mostly been overlooked. Intact chickpea cells were subjected to sonication with different ultrasound processing times, and the effects of sonication on the starch and protein structure and digestibility were studied. The digestibility of these macronutrients significantly increased with the extension of processing time, which, however was not due to the molecular degradation of starch or protein but related to damage to cell wall macro-structure with increasing sonication time, leading to enhanced enzyme accessibility. Through this study, it is demonstrated that ultrasound processing has least effect on whole food structure, for example, whole seeds but can modulate the nutrient bioavailability without changing the properties of the macronutrients in seed fractions e.g. intact cells, offering new scientific knowledge on effect of ultrasound in whole foods at various length scales.

Effect of different drying methods on the structure and properties of porous starch

In order to investigate the effects of different drying methods on the properties of porous starch. The present study used four drying methods, namely hot air drying (HD), spray drying (SPD), vacuum freeze drying (FD) and supercritical carbon dioxide drying (SCD) to prepare maize and kudzu porous starch. Findings indicated that the physicochemical properties (e.g., morphology, crystallinity, enthalpy value, porosity, surface area and water absorption capacity as well as dye absorption capacity, particle size) of porous starch were significantly affected by the drying method. Compared with other samples, SCD-treated porous starch exhibited the highest surface areas of the starch (2.943 and 3.139 m2/g corresponding to kudzu and maize, respectively), amylose content (22.02 % and 16.85 % corresponding to kudzu and maize, respectively), MB and NR absorption capacity (90.63 %, 100.26 % and 90.63 %, 100.26 %, corresponding to kudzu ad maize, respectively), and thermal stability, whereas HD-treated porous starch showed the highest water-absorption capacity (123.8 % and 131.31 % corresponding to kudzu and maize, respectively). The dye absorption of the maize and kudzu porous starch was positively correlated with surface area, according to Pearson's correlation analysis. Therefore, in this study, our aim was to explore the effects of different drying methods on the Structure and properties of porous starch, and provide reference for selecting the best drying method for its application in different fields.

Physicochemical Characteristics of Porous Starch Obtained by Combined Physical and Enzymatic Methods, Part 1: Structure, Adsorption, and Functional Properties

Porous starch can be applied as an adsorbent and encapsulant for bioactive substances in the food and pharmaceutical industries. By using appropriate modification methods (chemical, physical, enzymatic, or mixed), it is possible to create pores on the surface of the starch granules without disturbing their integrity. This paper aimed to analyze the possibility of obtaining a porous structure for native corn, potato, and pea starches using a combination of ultrasound, enzymatic digestion, and freeze-drying methods. The starch suspensions (30%, w/w) were treated with ultrasound (20 kHz, 30 min, 20 °C), then dried and hydrolyzed with amyloglucosidase (1000 U/g starch, 50 °C, 24 h, 2% starch suspension). After enzyme digestion, the granules were freeze-dried for 72 h. The structure of the native and modified starches were examined using VIS spectroscopy, SEM, ATR-FTIR, and LTNA (low-temperature nitrogen adsorption). Based on the electrophoretic mobility measurements of the starch granules using a laser Doppler velocimeter, zeta potentials were calculated to determine the surface charge level. Additionally, the selected properties such as the water and oil holding capacities, least gelling concentration (LGC), and paste clarity were determined. The results showed that the corn starch was the most susceptible to the combined modification methods and was therefore best suited for the production of porous starch.

Effect of Heat-Moisture Treatment on the Structure and Digestibility of Sweet Potato Starch

The objective of this study was to investigate the effect of temperature changes during heat-moisture treatment (HMT) on the appearance, structure and digestibility of sweet potato starch (SPS). The results showed that after HMT, there were depressions, cavities and fragments on the surface of SPS particles. The polarized crosses of SPS were irregular and partially blurred. The relative crystallinity and short-range order of SPS decreased, while rearrangement and reorientation of the starch molecules occurred and the thermal stability increased. The resistant starch content of SPS reached the highest (24.77%) after 4 h treatment at 110 °C and 25% moisture. The obtained results can provide a reference for the modification of SPS.

Salt adopted in soaking solution controls the yield and starch digestion kinetics of intact pulse cotyledon cells

Intact cellular powders have gained attention as a functional ingredient due to their lower glycemic response and potential benefits in colon. The isolation of intact cells in the laboratory and pilot plant settings is mainly achieved through thermal treatment with or without the use of limited salts. However, the effects of salt type and concentration on cell porosity, and their impact on the enzymic hydrolysis of encapsulated macro-nutrients such as starch, have been overlooked. In this study, different salt-soaking solutions were used to isolate intact cotyledon cells from white kidney beans. The use of Na₂CO₃ and Na₃PO₄ soaking treatments, with high pH (11.5-12.7) and high amount of Na ion (0.1, 0.5 M), greatly improved the yield of cellular powder (49.6-55.5 %), due to the solubilization of pectin through β-elimination and ion exchange. Intact cell walls serve as a physical barrier, significantly reducing the susceptibility of cell to amylolysis when compared to white kidney bean flour and starch counterparts. However, the solubilization of pectin may facilitate enzyme access into the cells by enlarging cell wall permeability. These findings provide new insights into the processing optimization to improve the yield and nutritional value of intact pulse cotyledon cells as a functional food ingredient.

Genotype specific starch characteristics in relation to resistant starch formation in table potatoes

Table potatoes are important staple foods with a higher satiety index than rice or pasta, but also reach a higher glycemic index (GI), leading to contradictory dietary recommendations. Previous studies identified resistant starch (RS) content as primary criterium for the GI. Hence, the relevance of starch molecular properties for genotype specific RS formation was investigated. Six common table potato varieties were used to investigate the starch pasting and digestibility in whole tubers and their isolated starches. A Micro-Visco Amylograph was used to simulate the cooking process for isolated starches and determine their pasting curves. In vitro starch digestibility was determined for raw freeze-dried cooked tubers kept at 4 °C for up to 72 h and for isolated starches. Moreover, important molecular starch properties, including granule size distribution, molar mass distribution, amylose content and inter- and intra-molecular structures were determined. The results show substantial differences in starch digestibility and pasting characteristics among genotypes. Soraya starch showed small and low-branched amylopectin and small granule size as characteristics for rapid RS formation in isolated starch, which was not evident in the whole tuber. In contrast, Huckleberry Gold formed RS in the tuber already shortly after cooking, whereas slow RS formation was evident in the isolated starch. The results suggest, that starch structural characteristics play a role in RS formation, but non-starch constituents of the tuber have to be considered as well. The results help to identify breeding goals for varieties with low GI and high nutritional value.

Variation in structural and in vitro starch digestion of pulse cotyledon cells imposed by temperature-pressure-moisture combinations

Starch digestibility in whole pulses is affected by food structural characteristics, which in turn can be modulated by processing methods. In present study, high-pressure steam (HPS) and hydrothermal treatment (HT) with different moisture content were applied to clarify the mechanisms of processing variables affecting in vitro starch digestibility in pulse cells. Based on thermal and X-ray results, the relative crystallinity of cells decreased after HPS and HT treatments. However, HPS-treated cells under higher (>50%) moisture content showed insignificant discrepancies in crystallinity than HT samples. Starch digestion in HPS-treated cells increased with higher moisture content but was still lower than in HT samples. Results of FITC-dextran diffusion and methyl esterification of cell walls indicated that cells with higher wall permeability exhibited relatively higher starch digestibility. This study suggests that the enzyme susceptibility to starch in cells is dominantly influenced by cell wall structure, which could be optimized through processing variables.

Characteristics of physically modified starches

Starch is an abundant natural, non-toxic, biodegradable polymer. Due to its low price, it is used for various purposes in various fields such as the cosmetic, paper, and construction industries as well as the food industry. Due to recent consumer interest in clean label materials, physically modified starch is attracting attention. Manufacturing methods of physically modified starch include pregelatinization, hydrothermal treatment such as heat moisture treatment and annealing, hydrostatic pressure treatment, ultrasonic treatment, milling, and freezing. In this study, toward development of clean label materials, manufacturing methods and characteristics of physically modified starches were discussed.

Encapsulated starch characteristics and its shell matrix mechanisms controlling starch digestion

Encapsulated starch can be classified as physically inaccessible starch or type 1 resistant starch (RS1), which is produced by encapsulating starch granules within food matrices using various encapsulation techniques. Encapsulated starch has the potential to be used as a functional ingredient in low-/medium-glycemic index (GI) foods as it can help control glycemic and insulin responses. Despite its remarkable benefits, the relevant information related to entrapped starch and its application is still insufficient and needs further elucidation. The objective of this work is to present a comprehensive overview of the current techniques utilized for the preparation of encapsulated starch and its characteristics, thereby extending the fundamental knowledge. Furthermore, this review delves into the mechanisms governing starch hydrolysis regulated by shell matrices and provides the prospective utilization of encapsulated starch in food production.

Comparative study on the structural and in vitro digestion properties of starch within potato parenchyma cells under different cooking methods

To study the effects of cooking methods on the structure and digestion changes of starch encapsulated by cellular structure, intact potato parenchyma cells were successfully isolated and then subjected to different domestic cooking methods, including baking, frying, boiling, and autoclaving. The morphology, crystalline structure, thermal properties, and in vitro starch digestibility of cooked cell samples were investigated. Our results indicated that potato cell walls remained intact and performed as physical barriers preventing the diffusion/absorption of α-amylase to intracellular starch substrates after baking or frying treatment. However, boiling or autoclaving treatment destroyed cell wall structure, and the disrupted cellular structure reduced the digestion rate, likely by inhibiting diffusion of amylase through a weakened cell wall barrier, but could not lower the final digestion extent when compared to the pure starch. These findings suggested that potato products with lower glycemic index can be obtained by baking or frying treatment.

The Effects of Starch Molecular Fine Structure on Thermal and Digestion Properties of Rice Starch

Whole white rice is a major staple food for human consumption, with its starch digestion rate and location in the gastrointestinal tract having a critical role for human health. Starch has a multi-scale structure, which undergoes order-disorder transitions during rice cooking, and this structure is a major determinant of its digestibility. The length distributions of amylose and amylopectin chains are important determinants of rice starch gelatinization properties. Starch chain-length and molecular-size distributions are important determinants of nucleation and crystal growth rates, as well as of intra- and intermolecular interactions during retrogradation. A number of first-order kinetics models have been developed to fit starch digestograms, producing new information on the structural basis for starch digestive characteristics of cooked whole rice. Different starch digestible fractions with distinct digestion patterns have been found for the digestion of rice starch in fully gelatinized and retrograded states, the digestion kinetics of which are largely determined by starch fine molecular structures. Current insights and future directions to better understand digestibility of starch in whole cooked rice are summarized, pointing to ways of developing whole rice into a healthier food by way of having slower starch digestibility.

Multi-Scale Structures and Functional Properties of Quinoa Starch Extracted by Alkali, Wet-Milling, and Enzymatic Methods

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 (2.39%), larger size of aggregated granules (44.1 μm), higher relative crystallinity (29.6%), 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 (2.1), 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 (6.7 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 (15.5% 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.

Legume Seed Protein Digestibility as Influenced by Traditional and Emerging Physical Processing Technologies

The increased consumption of legume seeds as a strategy for enhancing food security, reducing malnutrition, and improving health outcomes on a global scale remains an ongoing subject of profound research interest. Legume seed proteins are rich in their dietary protein contents. However, coexisting with these proteins in the seed matrix are other components that inhibit protein digestibility. Thus, improving access to legume proteins often depends on the neutralisation of these inhibitors, which are collectively described as antinutrients or antinutritional factors. The determination of protein quality, which typically involves evaluating protein digestibility and essential amino acid content, is assessed using various methods, such as in vitro simulated gastrointestinal digestibility, protein digestibility-corrected amino acid score (IV-PDCAAS), and digestible indispensable amino acid score (DIAAS). Since most edible legumes are mainly available in their processed forms, an interrogation of these processing methods, which could be traditional (e.g., cooking, milling, extrusion, germination, and fermentation) or based on emerging technologies (e.g., high-pressure processing (HPP), ultrasound, irradiation, pulsed electric field (PEF), and microwave), is not only critical but also necessary given the capacity of processing methods to influence protein digestibility. Therefore, this timely and important review discusses how each of these processing methods affects legume seed digestibility, examines the potential for improvements, highlights the challenges posed by antinutritional factors, and suggests areas of focus for future research.

Characteristics of catechin loading rice porous starch/chitosan functional microsphere and its adsorption towards Pb2+

In this paper, we explore the adsorption potential of catechin (CT) loaded composite microspheres and provide a new micron scale carrier of functional factor. Chitosan (CS) modified rice porous starch (RPS/CS) was used as a CT adsorption carrier to prepare bioactive CT-loaded composite microspheres (CT@RPS/CS). The adsorption kinetics, storage characteristics, and biological activity maintenance of CT@RPS/CS were studied in an aqueous solution, and the sustained-release characteristics of CT@RPS/CS were studied in vitro during simulated gastrointestinal digestion. An aqueous solution further studied the removal characteristics of adsorbed heavy metal ion Pb²⁺. RPS/CS can significantly improve the ability to adsorb CT. RPS/CS can also significantly improve CT's storage stability, antioxidant stress, and slow-release characteristics, and the sustained release effect in gastric and intestinal juice. CT@RPS/CS can be removed Pb²⁺ by adsorbing in the solution, and their adsorption was physical adsorption and chemisorption, but the primary interaction is chemisorption. CT@RPS/CS can be used as a micron carrier of new food functional factors, which has potential space for improving and expanding the functional characteristics of its loaded functional factors and the endowing of new functions.

Starch structure and nutritional functionality - Past revelations and future prospects

Starch exists naturally as insoluble semi-crystalline granules assembled by amylose and amylopectin. Acknowledging the pioneers, we have reviewed the major accomplishments in the area of starch structure from the early 18th century and further established the relation of starch structure to nutritional functionality. Although a huge array of work is reported in the area, the review identified that some features of starch are still not fully understood and needs further elucidation. With the rise of diet-related diseases, it has never been more important to understand starch structure and use that knowledge to improve the nutritional value of the world's principal energy source.

Simple thermal and freezing treatments to improve absorption capacity and alter digestibility of canna starch granules

Swollen canna starches (SCS) were prepared by controlled heating of unmodified and heat-moisture treated (HMT) starch suspensions at sub-gelatinization temperatures; subsequently, freezing was conducted to stabilize the structure of the SCS. Sizes of both unmodified and HMT swollen granules increased with increasing heating temperatures (up to 2.5 times), and freezing resulted in a significant reduction of granular size. The absorption capacities of the swollen starches increased up to 6 times for water and 3 times for tributyrin and palm oil compared to unmodified starch. The differences in absorption capacities of the unmodified and HMT swollen starches were small. Freezing the swollen starches tended to decrease oil and water absorptions, except for unmodified starch swollen at 70 °C, where freezing increased water absorption. Freezing significantly decreased the susceptibility of the swollen unmodified starches to amylase digestion and slowed down the digestion of the swollen HMT starches.

Structural modification and dynamic in vitro fermentation profiles of precooked pea starch as affected by different drying methods

Pea starch was pre-cooked before being subjected to different drying treatments including oven-drying, infrared-drying, microwave-drying and freeze-drying. Different dried pea starch samples were then anaerobically fermented by human gut microbiota. Their structural features, morphological changes, the synthesis of short-chain fatty acids, as well as the microbiological responses during the 24 h in vitro human fecal fermentation were determined. Oven-dried pea starch (ODPS) displayed relatively stronger fluorescence intensity on the confocal laser scanning microscopic images, which was in qualitative agreement with its significantly highest crystallinities obtained from X-ray diffractogram (XRD) and 13C cross-polarization magic angle spinning (13C CP/MAS) NMR. The obtained results demonstrated that the significant differences in structural and morphological features observed for these four dried starch samples originate from different evaporation patterns of water molecules. Changes in R1047/1022 and R995/1022 during in vitro colonic fermentation corresponded well with the transition in relative crystallinity obtained from XRD and 13C CP/MAS NMR measurements, suggesting an increase in the molecular order upon starch utilization by the gut bacteria. The correlation analysis indicated that the dried starch with higher degree of short-range ordered structure was beneficial for the growth of Firmicutes, whereas starch substrate with a relatively loose granular structure would be beneficial for the growth of Bacteroides. The significantly highest operational taxonomic unit level of Bifidobacterium species after the fermentation of ODPS corresponded well with its highest propionate and butyrate concentration. The results obtained are expected to help food processors to tailor the drying method during the manufacture of processed starch samples with desirable structural features and prebiotic properties.

Effects of anthocyanins on bread microstructure, and their combined impact on starch digestibility

Several studies have confirmed the reduction of starch digestibility with anthocyanins in food systems via mechanisms of enzyme inhibition. However, starch-polyphenol interactions may also contribute to this reduction, by modifying food microstructures and physicochemical properties of starch. The interactions among anthocyanins, starch digestibility, and food microstructures are significant to clarify the digestion processes of fortified food systems, but its interrelationship lacks clarity. Hence, we aim to evaluate the effects of black rice anthocyanin extract (BRAE) incorporation on the microstructural changes of wheat bread, in relation to overall digestibility. Overall, BRAE incorporation demonstrated a dose-dependent reduction in starch digestibility. Physicochemical analyses reflected that BRAE incorporation decreased starch gelatinisation and increased crystallinity. Microscopic imaging revealed differentiating microstructural characteristics of starch and gluten with BRAE incorporation, supporting the reduction in digestibility. Our results conclusively demonstrate that BRAE incorporation in bread suppresses starch digestibility not only through enzyme inhibition, but also food microstructural modifications.

Starch granule size: Does it matter?

Nature has developed starch granules varying in size from less than 1 μm to more than 100 μm. The granule size is an important factor affecting the functional properties and the applicability of starch for food and non-food applications. Within the same botanical species, the range of starch granule size can be up to sevenfold. This review critically evaluated the biological and environmental factors affecting the size of starch granules, the methods for the separation of starch granules and the measurement of size distribution. Further, the structure at different length scales and properties of starch-based on the granule size is elucidated by specifying the typical applications of granules with varying sizes. An amylopectin cluster model showing the arrangement of amylopectin from inside toward the granule surface is proposed with the hypothesis that the steric hindrance for the growth of lamellar structure may limit the size of starch granules.

Process characterization and optimization of cold brew coffee: effect of pressure, temperature, time and solvent volume on yield, caffeine and phenol content

BACKGROUND

Cold brew coffee, based on cold extraction, is rapidly attracting consumers' preference worldwide. Low total solids yield and long extraction times (up to 24 h) are the main drawbacks of this process. Five different treatments were investigated: the traditional cold extraction method, freezing, lyophilization of coffee beans, use of chaotropic salt and reduced pressure extraction. The latter was optimized by applying a Box-Behnken design. Pressure, vacuum cycles, duration of each cycle and mass of ground coffee to water ratio were the optimization parameters. Yield, caffeine and phenol concentration were the response variables.

RESULTS

Caffeine concentration and yield were significantly affected by vacuum cycles and by the combination of vacuum cycles and duration of each cycle. Validation of the derived quadratic models for each response variable was performed. Optimum values for highest extraction yield (22%) and phenol concentration as well as mass transfer coefficients of phenol and caffeine were also determined.

CONCLUSIONS

Extraction under reduced pressure might be the best treatment for the acceleration of cold brew coffee extraction. © 2021 Society of Chemical Industry.

Effects of Different Processing Methods and Internal Components on Physicochemical Properties and Glycemic Index of Adzuki Bean Powder

The estimated glycemic index (eGI) value of adzuki bean powder prepared by steamed cooking (SC), extruded cooking (EC) and roller cooking (RC) was studied comparatively. Results showed that RC had the highest eGI, with 80.1, and both EC and SC resulted in a lower eGI value of 70.0 and 49.7, respectively. Compared with the EC and RC methods, the SC method provided a more intact physical barrier for starch digestion, resulting in a less destroyed cell structure. As the essential components that form the cell wall, the study further investigated the effects of protein and fiber on physicochemical properties, in vitro starch digestibility and the eGI of adzuki bean powder processed with the SC method. Viscozyme and Protamax were used to obtain the deprotein and defiber samples. Results showed that the SC treatment with Viscozyme and Protamax, respectively, had significant effects on in vitro starch digestibility. The eGI of different samples were given as follows: steamed cooking adzuki bean powder (49.7) < deproteined adzuki bean powder (60.5) < defibered adzuki bean powder (83.1), which indicates that fiber may have a greater influence on the eGI than protein.

Pea cell wall integrity controls the starch and protein digestion properties in the INFOGEST in vitro simulation

The cell wall microstructure has been recognized to modulate the digestibility and bioaccessibility of nutrients in whole pulse foods, while the role of cell wall integrity is unclarified in the hydrolysis of intracellular nutrients during human gastrointestinal transit. Intact pea cells were isolated to prepare a series of cell wall integrity subjected to cooking and followed by the in vitro hydrolysis of starch and protein properties using the INFOGEST 2.0 in vitro simulation. Thermal properties showed that cell samples either in raw or cooked form with different wall integrity exhibited similar and higher starch gelatinization temperatures compared to the isolated starch counterpart. It was found that intact pea cells showed the limited hydrolysis extent of the maltose (16.2%) and NH2 (6.7%) compared to the damaged cells. In addition, intact cells also withheld the cell wall integrity throughout gastrointestinal digestion with minor rupture, and presented the higher protein molecular weight (70 kDa) in the SDS-PAGE profiles. Results suggested that the in vitro starch and protein digestion properties are modulated by the cell wall integrity, which may lead to lower glycemic response and open up the possibilities of designing health food products.

Removal of starch granule associated proteins alters the physicochemical properties of annealed rice starches

The effect of removal of starch granule associated proteins (SGAPs), annealing and dual-treatment on physicochemical properties of three rice starches with different amylose content (AC) was investigated. SGAPs removal reduced stability of starch granules, thus increasing amylose leaching, swelling power, solubility, and pseudoplasticity of Qiuguang (15.6% AC) and Luhui (22.1% AC) rice starches, decreasing pseudoplasticity of Yangfunuo (1.56% AC) starch, and decreasing T_o, T_p, and T_c, pasting viscosity and storage modulus of all three rice starches. Annealing decreased amylose leaching of the three starches, and pasting properties, pseudoplastic and storage modulus of Yangfunuo starch, but increased swelling power of the three starches, ΔH and T_o of Qiuguang starch, and pasting properties and pseudoplasticity of Qiuguang and Luhui starches. The effect of dual-treatment was generally the sum of effect of SGAPs removal and annealing treatment. But an interaction effect of the dual-treatment was observed for some parameters. The effect of annealing was closely related to the variety and composition of the starch.

Determination of starch crystallinity with the Fourier-transform terahertz spectrometer

We measured the terahertz (THz) spectra of native, amorphous, and dried starches derived from corn and potato using the Fourier-transform (FT) system and compared these spectra to the X-ray diffraction (XRD) patterns. Both native corn and potato starches had seven absorption peaks in the terahertz regions, but five peaks were observed in the amorphous states. While spectral changes slightly occurred in corn starch even after drying, increase and decrease in the terahertz peak intensities were obtained in potato starch during drying. Similar changes in both starches during amorphization and drying were obtained in the X-ray diffraction patterns, and the correlations were found between terahertz peaks and the X-ray signals. Since the intensity of the peak at 9.0 THz was correlated with crystallinity obtained using an X-ray diffraction (r² = 0.98), our data indicate that the Fourier-transform terahertz spectrometer can be a new analytical device to measure the starch crystallinity.

Effect of Drying Methods on Properties of Potato Flour and Noodles Made with Potato Flour

This work investigated the impact of three drying methods on structural and functional properties of potato flour (PF), as well as the quality characteristics of fresh noodles made from wheat-potato flours. The results indicated that ethanol drying (ED) and oven drying (OD) had small effects on the properties of starch in potato flour, however, freeze drying (FD) caused some pores and channels on the starch granules and disruption of the long- and short-range ordered structure of starch. The maximum addition of potato flour in fresh noodles was 40% for FD-PF and 50% for both ED-PF and OD-PF. With increasing addition of potato flour in noodles, the L* (lightness) values of noodles decreased gradually, while the a* (redness) and the b* (yellowness) values, as well as the hardness and springiness values of fresh potato noodles increased. This study clearly showed that drying methods have different effects on the properties of potato flour, and in turn the quality of fresh noodles made with potato flour.

Side-by-side and exo-pitting degradation mechanism revealed from in vitro human fecal fermentation of granular starches

The in vitro fecal fermentation characteristics and microbiota responses to A- and B-type polymorphic starches as model (whole) foods enriched with resistant starch was investigated. Marked difference in fermentation rate as well as microbial genera was observed during fermentation, the degradation pattern as well as structural evolution during fermentation was almost similar. The final butyrate concentrations of both HAMS and PS (ca. 38 mM) were significantly higher than that of WMS (23 mM) and NMS (33 mM), which was associated with the increase of the relative abundance of Roseburia, Blautia, and Lachnospiraceae. A-type polymorphic starches, on the other hand had remarkably faster fermentation rate and promoted Megamonas. X-ray diffraction and size-exclusion chromatography of residual starch during the fermentation course demonstrated the "side-by-side" fermentation pattern. Based on the structural changes observed, we conclude that in vitro fecal fermentation of starch granules predominantly controlled by the surface features rather than the molecular and supra-molecular structure.

Structural characterization and physicochemical properties of starch from four aquatic vegetable varieties in China

Nelumbo nucifera Gaertn., Eleocharis dulcis, Sagittaria sagittifolia L., and Trapa bispinosa Roxb. are common aquatic vegetables that are rich in starch. Starches from these four aquatic vegetables and their applications in edible films were studied to facilitate full use of starch resources. Significant differences in transparency, freeze-thaw stability, water solubility index, swelling power, water and oil absorption capacities, starch particle morphology, and rheology were observed among the starches from these four aquatic vegetables. All starches exhibited a typical "A" type diffraction pattern. N. nucifera, E. dulcis, and S. sagittifolia starches have similar thermal properties, while T. bispinosa starch has a higher gelatinization temperature. S. sagittifolia starch film has the highest transparency and lower WVP and water solubility. These results will promote the development of products based on starch obtained from aquatic vegetables.

Physical and chemical characteristics of Asian sea bass bio-calcium powders as affected by ultrasonication treatment and drying method

The effects of ultrasonication and drying method on particle size and other product characteristics of bio-calcium powder from Asian sea bass (Lates calcarifer) backbone were investigated. Ultrasonication was performed at different amplitudes (60%, 70%, and 80%) for varying periods (15 and 30 min). Ultrasonication at higher amplitudes for a longer time reduced the powder particle size more effectively (p < .05), but had no impact on zeta potential (p > .05). The bio-calcium powder ultrasonicated at 70% amplitude for 15 min had the smallest particle size (3.38 µm) when compared to the control (28.85 µm). When the ultrasonicated bio-calcium was subjected to drying, freeze-drying produced powders with higher calcium solubility but lower whiteness than hot air (tray) drying. The results suggest that the ultrasonication is a potential suitable method to reduce the size of bio-calcium powders, while the drying method slightly affected the product characteristics. The bio-calcium powder could serve as a suitable functional ingredient for food fortification aimed at improving the calcium bioavailability. Particle size of bio-calcium powder from fishbone could affect the mouth feel and calcium solubility when used for food product fortification. This work showed that ultrasonication could be used to obtain up to 10-fold reduction in the particle size of fishbone bio-calcium powders, which promotes increased calcium solubility when subjected to simulated gastrointestinal tract digestion. Few differences in characteristics of the bio-calcium powder were observed for freeze-dried and hot air-dried samples. Thus, an economical, safe, and fast process can be implemented for the production of small particle size bio-calcium powder from fishbone.