Effect of twin-screw extrusion pretreatment on starch structure, rheological properties and 3D printing accuracy of whole potato flour and its application in dysphagia diets.

Twin-screw extrusion pretreatment has great potential for the development of three-dimensional (3D) printed food as dysphagia diets. This study aimed to investigate the effect of twin-screw extrusion pretreatment on starch structure, rheological properties and 3D printing accuracy of whole potato flour and its application in dysphagia diets. The results indicated that twin-screw extrusion pretreatment was found to change chain length distributions, short-range ordered structure and relative crystallinity of whole potato flour (WPF), thereby improving its 3D printing performance. With the increasing proportion of long linear chains (DP > 12), the intensity of hydrogen bonds, linear viscoelastic region, storage modulus (G'), loss modulus (G″), viscosity and n of whole potato flour paste were increased, enhancing high printing accuracy and shape retention of 3D printed samples with a denser microstructure and smaller pore diameter distribution. The whole potato flour paste extruded with a peristaltic pump speed at 5.25 mL/min (WPF-4) displayed the highest printing accuracy with excellent rheological properties, good water distribution state and dense network structure, which classified as class 5 level dysphagia diets. This research provides an effective guidance for the modification of whole potato flour using twin-screw extrusion pretreatment as 3D printed food inks for dysphagia patients.

Investigating potato flour processing methods and ratios for noodle production.

A partial substitution of wheat flour with potato flour processed by various procedures was used to determine an optimal potato pretreatment method for noodle processing. Wheat flour was substituted with 10%, 30%, and 50% potato flour. Potato flour (PF) was processed using two different methods, including freeze-drying (FD) and low-temperature blanching, then oven drying (LTB_OD). The results showed that substituting wheat flour with freeze-dried (FD) flour (44.29 µm) significantly decreased the mean particle size of the blended flour, while LTB_OD flour (223.09 µm) increased the mean particle size. The pasting properties of wheat flour significantly improved when potato flour was added, with FD flour blends having the highest results. The highest dough development time (14.46 min) was attained when LTB_OD potato flour was substituted up to 50%. The microstructure images showed a poor and discontinuous gluten framework when potato flour content reached 50%. Adding potato flour decreased noodles' brightness (L*) while increasing their yellowness (b*). Noodles made from wheat and LTB_OD flour blends resulted in the highest cooking loss. The texture properties of noodles deteriorated when potato flour content reached 30%. Substituting up to 30% with freeze-dried flour and 10% LTB_OD resulted in noodles with the highest overall liking scores. The study suggests that for optimal noodle processing, substituting wheat flour with FD potato flour is more favorable than using LTB_OD, as it improves particle size, pasting properties, and overall liking scores while minimizing adverse effects on texture and cooking loss.

Physicochemical characterization of a composite flour: Blending purple sweet potato and rice flours.

In this study, the physicochemical characterization of different ratios of purple sweet potato flour (PSPF) and rice flour was investigated to improve the nutritional value and enrich the variety of rice-based staple food. The results showed that adding PSPF increased total dietary fiber and anthocyanin content whereas decreased amylose content of the composite flours. Additionally, the composite flours exhibited lower thermodynamic parameters and displayed darker, redder, and bluer colors. There were no noticeable changes in the functional group structure of the composite flours. The addition of PSPF decreased the crystallinity and water-holding capacity of the composite flours, whereas increased the average particle size and iodine blue value. PSPF increased the pasting temperature of the flours whereas decreased the breakdown and setback values. Overall, the addition of PSPF significantly affects the nutrition, color and physicochemical properties of the composite flours.

Interactions between partially gelatinized starch and nonstarch components in potato flour and their performance in emulsification.

To develop natural complex materials as starch-dominated emulsifiers, pregelatinization was conducted on potato flour. The effects of gelatinization degrees (GDs, 0 %-50 %) on the structural characteristics, physicochemical properties, and emulsifying potentials of potato flour were investigated. Increasing GD of potato flour promoted protein aggregation on starch granules surfaces and transformed starch semicrystalline structures into melted networks. The emulsion stabilized with 50 % GD potato flour exhibited excellent storage stability (7 d) and gel-like behavior. With increasing GD from 0 to 50 %, the respective apparent viscosities and elastic moduli of emulsion increased from 21.4 Pa to 1126.7 Pa, and from 0.133 Pa·s to 1176.6 Pa·s, promoting the formation of a stable network structure in the emulsion. Fourier transform infrared spectra from emulsions with a continuous phase of >20 % GD displayed a new peak around 1740 cm-1, suggesting improved covalent interactions between droplets, thereby facilitating emulsion stability. Confocal laser scanning microscopy images indicated that droplets could be anchored in the melted networks and broken starch granules, inhibiting droplets coalescence. These results suggest that pregelatinization is a viable strategy for customizing natural starch-dominated emulsions.

Changes in the structural and physicochemical characteristics of sonicated potato flour.

Ultrasound has been widely used for physical modifications of starch because of its effectiveness and environment friendliness; however, only a few reports have focused on the effect of varying ultrasonic treatments on the physicochemical properties of potato flour. In the present study, ultrasound at varying power levels (200, 300, 400, 500, and 600 W) and time intervals (20, 40, 60, 80, and 100 min) were used to obtain sonicated flour. Sonicated potato flour exhibited a significant (P < 0.05) decrease in blue value and oil holding capacity but an increase in swelling power, water solubility, syneresis rate, and transparency. Moreover, ultrasound decreased the RDS content while increasing RS and SDS contents. Thermal properties demonstrated significant (P < 0.05) increases in T0 (64.39℃-83.52℃) and TC (144.29℃-146.87℃) but a decrease in ΔH of the sonicated flour. SEM revealed wrinkles, less debris, and larger particle size at the surface of the sonicated flour. FTIR profiles of all samples exhibited similar characteristics peaks, but the sonicated flour had a higher R1047/1022 value. Additionally, ultrasound did not affect crystalline patterns, but it increased the crystallinity of the sonicated flour. Our study contributes to the understanding of physicochemical property changes of sonicated potato flour, which could have industrial applications.

Preparation and Product Characterization of Microwaveable Food Using Lentinus edodes Protein through 3D Printing.

The Lentinus edodes protein (LP) is a high-quality protein known for its well-balanced amino acid composition. In this study, we developed three-dimensional (3D)-printed microwaveable food using a combination of LP and potato flour, and optimized the formulation to achieve a ratio of LP: potato flour: xanthan gum: water = 2:8:1:23. The 3D-printed samples exhibited better shape, weight, and size compared to the molded samples after microwave treatment, with the most favorable microwave effect observed at a 90% filling ratio. The LP content affected the viscosity and retrogradation value of the LP-potato starch mixture. Microwave duration affected the surface hardness, interior softness, and moisture content of the product. The highest overall score of 8.295 points was obtained with a microwave processing duration of 2 min. This study lays a foundation for the development of LP-based 3D-printed food.

Immunomodulatory and Antioxidant Properties of Ipomoea batatas Flour and Extracts Obtained by Green Extraction.

Sweet potato (SP), Ipomoea batatas Lam, belongs to the Convolvulaceae family. It produces edible storage roots. Currently, orange varieties contribute to improving food systems and managing vitamin A deficiency. Processing of this food crop into flour allows better conservation. However, nutrition health data regarding SP flour obtained by green extraction remains scarce. In this study, we therefore explored its phytochemistry and its associated bioactivity potential for human health. We analyzed the nutritional composition of orange flesh sweet potato (OFSP) flour and assessed the antioxidant (free radical scavenging) and immunomodulatory (on inflammatory murine macrophages) properties of the extract. More specifically, we measured the impact of OFSP flour extract on mediators such as Nitric Oxide (NO) and the production of pro-inflammatory cytokines such as Interleukin-6 (IL-6), Tumor Necrosis Factor alpha (TNF-alpha), Monocyte Chemoattractant Protein-1 (MCP-1), and Prostaglandin-E2 (PGE-2). Our results indicated significant fiber, mineral, beta-carotene, and polyphenols content in the extracts, and antioxidant and immunomodulatory bioactivities were also demonstrated with a concentration-dependent inhibition of cytokine production. Taken together, our results suggest that Ipomoea batatas flour could, in addition to being a good source of energy and beta-carotene provitamin A, constitute a food of interest for the prophylaxis of metabolic diseases associated with an underlying low-grade inflammatory state.

Interaction of starch and non-starch polysaccharides in raw potato flour and their effects on thickening stability.

The present study sought to explore the potential of raw potato flour prepared from two common potato varieties (Atlantic and Favorita) as a thickener and the underlying mechanisms of its thickening stability based on the chemical component content, chemical group, starch, pectin, cell wall integrity, and the cell wall strength of raw potato flour. The raw potato flour prepared from Favorita potato (FRPF) showed great potential as a thickener with a valley viscosity/peak viscosity of 97.24 %. Additionally, the viscosity of FRPF after heat treatment, acid treatment and shear treatment was maintained at 70.73 %, 65.99 % and 78.89 % of the original viscosity, respectively, which is better than that of ARPF (44.98 %, 47.03 % and 61.57 %, respectively). The results also revealed that high pectin content, cell wall integrity and strength contributed significantly to the thickening stability of potato meal, which was achieved by limiting the swelling and disintegration of starch. Finally, the correctness of the principle was verified using the raw potato flour prepared from four types of potatoes (Heijingang, Innovator, Qingshu No. 9, and Guinongshu No. 1). Overall, the development of thickener from raw potato flour has broadened the variety of clean label additives in the food industry.

Studying the Role of Potato Powder on the Physicochemical Properties and Dough Characteristics of Wheat Flour.

Potato flour (PF) is rich in health-promoting compounds that can improve the nutritional benefits of food products after blending with wheat flour. However, the incorporation of PF may influence the processing characteristics of mixed powders and the quality properties of products. In this study, the physicochemical properties, processing characteristics, and structures of mixed powders and their corresponding doughs with different PF content (0%, 10%, 20%, 30%, 40%, 60%, 80%, and 100%) were investigated. The addition of PF dramatically increased the fiber content from 0.09 to 1.10 g·kg-1 but diluted the protein in wheat flour. The peak and final viscosity of mixed powders decreased (from 5111.00 to 1806.33 cP and 5195.33 to 2135.33 cP, respectively) with an increase in PF fraction. The incorporation of PF significantly increased gelatinization temperature. The rapidly digestible starch decreased from 30.48% to 19.67%, and resistant starch increased from 16.93% to 41.84% when the PF content increased from 0% to 100%. The water absorption, stability time, and development time decreased with an increase in PF levels. The G' and G″ of the dough decreased as the addition amount of PF increased, while tan δ presented a complex change tendency. Due to the decrease in protein content in the mixed powders, the addition of PF in wheat flour notably decreased the Hm values of doughs and total carbon dioxide volume produced during fermentation. Additionally, the SH and S-S contents decreased with an increase in PF fraction. Scanning electron microscopy results showed that when the PF content reached up to 80%, a poor and discontinuous gluten framework was formed in the dough. Results showed that PF affected the processing characteristics and gluten structures of wheat dough and was related to the interaction or competition for water molecules between protein and starch, as well as potato starch and wheat starch. Thus, the results of the present study can provide insights into the optimal level of addition of PF during the development of potato-based food products.

Hot air-assisted radio frequency drying of grated potato (Solanum tuberosum L.): Drying behavior and the associated effect on characteristics of potato flour.

In this study, drying of grated potato in a hot air-assisted radio frequency system (HA-RF) and the associated effects on the final potato flour quality were studied. The drying behavior of the grated potatoes at different electrode distances (70-90 mm) and sample thickness (2-4 cm) was investigated. The safe drying (without burning tendency) of the maximum amount of sample (1000 g) in a reasonable drying time was carried out at 80 mm of electrode gap and 4 cm of sample thickness. HA-RF drying kinetics were studied and compared with hot air (HA) and radio frequency (RF) (without hot air) drying methods. HA-RF drying increased drying rate and shortened drying time by about 58% and 70% compared to HA and RF drying, respectively. The properties of the final potato flour obtained after HA-RF drying were also compared with those produced by RF, HA, and freeze drying. The flour obtained by HA-RF was superior to RF and HA dried samples with better retention of cellular microstructure and color. The drying method significantly affected the functional properties, thermal characteristics, pasting properties, and other characteristics of potato flours. PRACTICAL APPLICATION: HA-RF as an alternative drying technology was used for the first time to produce potato flour. The functional, thermal, and structural properties of the HA-RF dried product were compared with those dried by HA, RF, and freeze drying. The results of this study ensured very useful information for the use of potato flour obtained by different drying methods in the development of products with specific functional and rheological properties.

Effect of Pretreatments and Drying Methods on Physical and Microstructural Properties of Potato Flour.

This study evaluated the effects of pretreatments (blanching (60 and 95 °C) and boiling) and drying methods (freeze-drying and oven drying) on the quality characteristics of potato flour derived from three potato varieties, namely, Shangi, Unica, and Dutch Robjin. The percentage flour yield, color, particle size distribution, flow characteristics, microstructural and functional properties of the potato flour were determined. Unica recorded the least peeling loss, while the Dutch Robjin variety had the highest. Color parameters were significantly affected (p < 0.05) by the pretreatments and drying methods. Freeze drying produced lighter potato flour (L* = 92.86) compared to the other methods. Boiling and blanching at 95 °C followed by oven drying recorded a low angle of repose and compressibility index, indicating better flow characteristics. The smallest particle size (56.5 µm) was recorded for the freeze-drying treatment, while boiling followed by oven drying had the largest particle size (307.5 µm). Microstructural results indicate that boiling and blanching at 95 °C, followed by oven drying resulted in damaged starch granules, while freeze-drying and low-temperature blanching (60 °C) maintained the native starch granule. Particle size and the solubility index of potato flour showed strong positive correlation. This study revealed that the pretreatments and drying methods affected potato flour's physical and microstructural parameters differently, resulting in changes in their functionality.

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.

Effects of intermittent radio frequency drying on structure and gelatinization properties of native potato flour.

Radio frequency (RF) treatment technology has now been studied and used for kinds of food products as its rapid and volumetric heating effects. It is meaningful to study the characteristics of potato drying with a new RF treatment method. In this study, intermitted RF combined treatments were used to get high-efficiency dehydration effects for potato drying, but the impact and mechanism of RF radiation on drying efficiency or quality is still unknown. To explore the drying characteristics, the effects of different RF radiation and the associated intermittent periods on the characterization of color, crystalline, thermal, pasting, rheology, and structural properties of potato flour were systematically studied. Longer RF radiation period (7 min) has a positive effect on drying efficiency and quality. The effect of intermittent period was not as significant as that of RF radiation, but a slightly increasing trend of the quality properties with intermittent period also indicated the tempering effect. The combined action of RF intermittent treatment on potato drying was found and investigated in this study, which may support RF drying processing improvement.

The functionality of laccase- or peroxidase-treated potato flour: Role of interactions between protein and protein/starch.

Potato flour is used in bakery products, extruded products and snacks. However, it displays weaker gel strengths and thus the wholesome utility is curtailed significantly. To improve viscoelastic properties and stability of potato gels, herein potato flour was treated with laccase and peroxidase to create a protein network structure leading to stable gels. The results revealed that the secondary structure of potato proteins altered upon the enzyme treatment. The gels of peroxidase-treated potato flour (PPF) and laccase-treated potato flour (LPF) displayed larger anti-shear ability, thermal stability and stronger three-dimensional network structure compared to the native potato gel. The PPF and LPF gels exhibited stronger viscoelastic properties and structural stability compared to peroxidase-treated potato protein and laccase-treated potato protein gels. The outcome serves as a theoretical basis to improve the properties of potato gels and to promote the designing and the development of novel potato flour based functional food.

Effect of potato flour on quality and staling properties of wheat-potato flour bread.

To elucidate the impact of potato flour (PF) on quality changes and staling characteristics of the composite bread from wheat-potato flour (WPF), the physicochemical (specific volume, colority, sensory value, texture, and viscosity) properties, and staling (X-ray diffraction and water migration) properties of bread were investigated. The quality of composite bread was comparable to wheat bread when addition level of PF at 20%, but decreased when the addition level increased to 30% or more, and became unacceptable at 50%. A chewy mouthfeel and an elastic and none-crumbly texture were observed on composite bread, which had higher hardness than wheat bread, and could keep on both longer linear distance and higher linear force during compression test. It indicated that such new parameters other than hardness should be introduced to coordinate with the texture quality of composite bread. During storage, the higher addition level of PF significantly decreased crystallinity of composite bread and slowed water migration rate from the crumb to crust, suggesting that PF had antistaling effect on composite bread, which was further emphasized by the fact that the setback value of the WPF decreased with the increase of PF addition.

Preparation and quality evaluation of potato steamed bread with wheat gluten.

The present study aimed to study the preparation and quality evaluation of potato steamed bread by using potato flour, wheat flour, and gluten at the presence of yeast and inorganic additives. As the rheological properties of the potato-wheat formulated flour negatively related to the potato flour, the potato-wheat formulated flour with 35% potato flour was set as the basic flour (100%). The effects of wheat gluten on the rheological properties of the dough were also evaluated, and gluten addition amount was set at 6.5%. The effects of yeast, sodium bicarbonate, citric acid, and monocalcium phosphate addition on steamed bread properties have been studied and optimized by orthogonal test. The obtained potato steamed bread formula was 100% basic flour (potato/wheat mass ratio of 35:65), 6.5% wheat gluten, 1.1% yeast, 1.4% NaHCO3, 0.75% citric acid, and 0.50% Ca(H2PO4)2. The prepared potato steamed bread has good sensory and texture properties, with natural potato flavor.

Effects of temperature and shear on the structural, thermal and pasting properties of different potato flour.

BACKGROUND: The properties of potato flour will be different due to different processing parameters, which will affect their processing adaptability. In this paper, different potato flour were investigated to determine viscoelastic properties and structural transformation using thermodynamics, rheological and spectrum methods. Potato flour was prepared by drying at different temperature after soaking in citric acid, microwave and steamed respectively. The treated samples were dried by hot air and then compared with the freeze-dried potato flour. Four kinds of potato flour showed different properties after shearing at high temperature. RESULTS: Differential scanning calorimetry (DSC) results revealed that potato flour with low gelatinization had lower enthalpy and faster melting process than freeze-dried potato powder. RVA and texture results showed that potato flour with low gelatinization had the best retrogradation property and the stable gel. X-ray diffraction (XRD) patterns revealed that the crystalline properties of different potato flour after shearing at high temperature were the same. In addition, low gelatinization potato flour presented a crystalline structure or strong internal order. Fourier-transform infrared spectroscopy (FTIR) spectra showed that high temperature and shearing mainly caused δ-deformation of O-H in intact potato granules. CONCLUSION: Freeze drying and hot air drying at low temperature made potato flour had better gel stability than microwave and steamed treatment. Hot air drying at low temperature made potato flour had good retrogradation after hot shearing, which was more conducive to the formation of hot-processed products.

Isolation and physicochemical property of individual parenchyma cells from mealy sweet potato.

This study prepared the dehydrated sweet potato parenchyma cell (SPPC) by isolating intact, individual parenchyma cells (PC) from sweet potato (SP) flesh using pectinase, and compared its chemical compositions, solubility and swelling power, gelatinization, and pasting viscosity to sweet potato starch (SPST) and flour (SPFL). The highest yield of SPPC was achieved when frozen SP whole-tissues were treated with pectin lyase. The majority constituting SPPC was intact, individual PCs fully filled with SPST granules. SPPC possessed lower crude protein and ash contents than SPFL. SPPC revealed lower solubility and swelling power, higher gelatinization temperatures, and lower pasting viscosity than SPST, while it showed lower solubility, higher swelling power, lower gelatinization temperatures, and higher pasting viscosity than SPFL. Overall, SPPC characteristics may result from intact PC walls surrounding clusters of SPPC granules, and SPPC could be considered an alternative to SPFL and SPST for expanding industrial applications of SP.

Dynamic changes of proton populations in potato flours during fermentation and their relationship with digestibility and functional properties.

The effects of fermentation on the dynamic state of proton populations, digestibility, and functional properties of potato flours prepared from Atlantic and Kexin No. 1 were investigated. Depending on the changes in moisture content and digestibility of potato flours during fermentation, three proton populations were distinguished. Populations P21 and P22 of fermented potato flours gradually increased during fermentation, resistant starch content, swelling power, and pasting properties also increased, whereas moisture content, digestible starch content, and water solubility index gradually decreased. Correlation analyses showed that populations P21 and P22 had significantly positive correlations with resistant starch content, swelling power, peak viscosity, and breakdown viscosity of fermented potato flours (p < 0.05), while population P23 had significantly positive correlations with moisture content, digestible starch content, and water solubility index (p < 0.001). The results implied that the proton population was an important factor influencing the digestibility and functional properties of fermented potato flours.

Effects of high hydrostatic pressure and soaking solution on proximate composition, polyphenols, anthocyanins, ß-carotene, and antioxidant activity of white, orange, and purple fleshed sweet potato flour.

Effects of high hydrostatic pressure (100, 200, and 400 MPa) and soaking solution (citric acid, calcium chloride, ascorbic acid, and distilled water) on proximate composition, polyphenols, anthocyanins, ß-carotene, and antioxidant activity of white, orange, and purple fleshed sweet potato flour were investigated. Total polyphenol content was increased in sweet potato flour of Jishu 98 (white) at 200 MPa with ascorbic acid and Pushu 32 (orange) at 0.1 MPa with ascorbic acid treatment (0.51 and 0.83 mg gallic acid equivalent/g dry weight, respectively), but was decreased in Xuzishu No. 3 (purple) in both high hydrostatic pressure and soaking solution treatments. Total anthocyanin content was declined in all treated sweet potato flour. Nevertheless, high hydrostatic pressure with citric acid, calcium chloride, and distilled water significantly increased the ß-carotene content in Pushu 32. Correlation analysis between total polyphenol content, total anthocyanin content, and antioxidant activity suggested that polyphenols are the most pivotal antioxidant in sweet potato flour. High hydrostatic pressure and soaking solution treated sweet potato flour could be potentially utilized in food with acceptable nutritional values.