Extraction of water-soluble polysaccharides from kidney beans and examination of their protein dispersion and stabilization properties under acidic conditions

Pea soluble polysaccharide interactions with plant albumins

Interactions occurring in foods at acidic pH are important for improving the colloidal stability of protein suspensions. This study evaluated the binding between pea albumins (PA) and anionic soluble pea polysaccharides, comparing them to β-lactoglobulin (β-lg) and high methoxyl pectin (HMP). High-/low methoxyl soluble pea polysaccharides (HM-/LM-PPS) and HMP were first analyzed by size exclusion chromatography coupled with multi-angle light scattering to determine molar mass distribution. Then, the interactions with albumins were quantified using isothermal titration calorimetry (ITC) at pH 4. In all cases, complex formation was exothermic with Gibbs free energy between -6.5 to -8.8 kcal/mol. Enthalpy was found to be the main driving force for complexation of HMP and LM-PPS, while both entropy and enthalpy contributions were important for the HM-PPS-protein complexation. β-lg showed a higher binding affinity compared to PA to the polysaccharides. This research highlights the potential of pea soluble polysaccharides as a functional food ingredient.

A high molecular mass emulsifier derived from lentil seeds: The role of polysaccharide and protein in its stabilization behavior

A water-soluble lentil polysaccharide (SLPS) extract was obtained from lentil fiber, at pH 10, after heating at 120 °C for 90 min, with a recovery as high as 16.5 %. SLPS had a weight average molecular mass of 1975 kg/mol, and contained 47 % glucose, 42 % arabinose, and 7 % uronic acid. Objective of this work was to evaluate the potential of SLPS to be employed as a natural emulsifier, by measuring its interfacial properties, as well as emulsifying capacity on a model emulsion system. Acidic emulsions were prepared with 5 % oil and 5 % SLPS and their particle size distribution was evaluated by light scattering and complementary microscopy, to determine their stability. SLPS showed the ability to reduce interfacial tension at oil/water interfaces, and the emulsions were stable under acidic conditions. Two different molecular weight fractions (SLPS-H and -L were investigated), and while the high molecular weight fraction (SLPS-H; 1567 kg/mol) was effective at stabilizing interfaces, emulsions prepared with low molecular weight fraction (SLPS-L; 2.3 kg/mol) showed aggregation and coalescence of oil droplets. Addition of pectinase caused aggregation of the droplets as measured by dynamic light scattering, demonstrating that adsorbs on the surface of oil droplets, and prevents aggregation of the oil droplets.

Simultaneous extraction and purification of polysaccharides and proteins from Pleurotus ostreatus using an aqueous two-phase system

Pleurotus ostreatus is a nutrient-dense edible fungus renowned for its delicate texture, appealing flavor, and numerous potential health benefits. Simultaneous extraction within the framework of food resource processing facilitates the concurrent isolation and analysis of multiple target compounds. In this study, an ethanol/salt aqueous two-phase system (ATPS) was employed to extract polysaccharides (PS) and proteins from P. ostreatus. The impacts of pH, inorganic salts, and temperature on ATPS phase formation were systematically evaluated. The ethanol/K₂HPO₄ system demonstrated superior selective extraction performance under optimal conditions: 25.16% ethanol (w/w), 15.91% K₂HPO₄ (w/w), and 24.11% crude extract (w/w) without pH adjustment. The highest recovery efficiency of PS and proteins were 90.29% ± 0.24% and 76.35% ± 0.15%, respectively. The simultaneous extraction efficiency of PS and proteins was 12.49% ± 0.14% and 20.34% ± 0.09%, respectively. As a comparison, hot water extraction and alkali extraction methods were performed to assess the impact of ATPS on the physicochemical properties of PS and proteins. SDS-PAGE and HPLC analyses confirmed that the protein subunit distribution was consistent across different extraction methods, whereas the ATPS-extracted PS exhibited characteristics of homogeneous heteropolysaccharides with a molecular weight of 28.8 × 10⁶ Da. Monosaccharides such as mannose, glucuronic acid, and glucose were identified in the PS hydrolysate. The results demonstrate that ATPS preserves the physicochemical integrity of the extracted substances. This method holds promise for unlocking new possibilities and has the potential to become an effective method for large-scale extraction and purification of polysaccharides and proteins from edible fungi. PRACTICAL APPLICATION: This work describes an efficient and straightforward aqueous two-phase system (ATPS) method for simultaneously extracting polysaccharides and proteins from Pleurotus ostreatus. This approach offers advantages such as reduced operational time, lower toxicity solvents, and minimized byproduct waste for the extraction of bioactive substances from edible fungi. Additionally, the reduced residue levels help to shorten subsequent purification steps. This promising method has potential applications in the food, pharmaceutical, and health product industries.

Extraction of water-soluble polysaccharides from lupin beans and their function of protein dispersion and stabilization under acidic conditions

In the current environment whereby new sources of proteins are extracted from plant material, it is also important to study the potential use of the resulting side streams. Although a number of studies have been conducted on various polysaccharides extracted from plant raw material, a polysaccharide fraction extracted from lupin bean is yet to be explored, in spite of the emerging interest in this crop as a source of food ingredients. In this work lupin soluble polysaccharide (LuPS) was obtained with a recovery as high as 46 % by extraction at pH 8, 120 °C, for 90 min. This fraction, named LuPS-8, was composed of a mostly linear pectic polysaccharide with a weight average molecular mass of 6608 kg/mol, and containing 71.0 % galactose, with minor amounts of arabinose (16.0 %), glucuronic acid 4.6 %, and galacturonic acid 4.1 %. When added to an acid milk dispersion, LuPS-8 improved its dispersibility, providing storage stability against sedimentation over a wider pH range than a HM-pectin reference, between 3.6-4.4. This research demonstrated the potential for upcycling of a side stream of lupin protein production, by the creation of value-added novel functional polysaccharide.

Non-starch polysaccharides from kidney beans: comprehensive insight into their extraction, structure and physicochemical and nutritional properties

Kidney beans (Phaseolus vulgaris L.) are an important legume source of carbohydrates, proteins, and bioactive molecules and thus have attracted increasing attention for their high nutritional value and sustainability. Non-starch polysaccharides (NSPs) in kidney beans account for a high proportion and have a significant impact on their biological functions. Herein, we critically update the information on kidney bean varieties and factors that influence the physicochemical properties of carbohydrates, proteins, and phenolic compounds. Furthermore, their extraction methods, structural characteristics, and health regulatory effects, such as the regulation of intestinal health and anti-obesity and anti-diabetic effects, are also summarized. This review will provide suggestions for further investigation of the structure of kidney bean NSPs, their relationships with biological functions, and the development of NSPs as novel plant carbohydrate resources.

Molecular structures of high- and low-methoxy water-soluble polysaccharides derived from peas and their functions for stabilizing milk proteins under acidic conditions

The structural and functional properties of two different pea water-soluble polysaccharides, a high methyl-esterified (HM-SPPS; degree of methyl esterification (DMe): 71.0 %) and low methyl-esterified SPPS (LM-SPPS; DMe: 25.2 %) were investigated. The two extracts did not vary in composition and showed a weight average molecular mass of about 1,000 kDa, as measured by size exclusion chromatography equipped with a multi-angle light scattering detector. Both HM-SPPS and LM-SPPS had similar sugar compositions, with arabinose 42.2-47.1 %, glucose 26.6-31.0 %, and galacturonic acid 17.5-18.0 %, as their main sugars. Their charge varied as a function of pH. The molecular structure was observed by a scanning probe microscope and showed a straight chain structure with small branches. The structure was similar to that already reported for polysaccharides from kidney bean. SPPS molecules interact with acidified milk protein particles at pH < 4.4. There were differences between the two SPPS. LM-SPPS could stabilize a model acidified milk dispersion with minimal aggregation between pH 3.6-4.4, while HM-SPPS showed the presence of bridging flocculation caused by polysaccharide's entanglements. It was concluded that SPPS stabilizes acidified protein by steric and electrostatic repulsion.

Physicochemical Characteristics and Antidiabetic Properties of the Polysaccharides from Pseudostellaria heterophylla

This study aimed to investigate the Pseudostellaria heterophylla polysaccharides (PF40) physicochemical and antidiabetic characteristics. The ultraviolet–visible (UV) spectra, Fourier transform infrared radiation (FT-IR) spectra, nuclear magnetic resonance (NMR) spectra, zeta potential, surface characteristics, and conformational and thermal stability properties of PF40 were characterized. X-ray diffraction (XRD) and scanning electron microscopy (SEM), combined with Congo red test, revealed that PF40 powder has mainly existed in amorphous form with triple-helix conformation. The single-molecular structure of PF40 exhibited a multi-branched structure extending from the center to the periphery by scanning probe microscopy (SPM) scanning. The monosaccharide residue of PF40 was an α-pyranoid ring and exhibits good stability below 168 °C. Experimental studies on antidiabetic characteristics found that PF40 could significantly improve STZ-induced intestinal mucosal damage and reduce the apoptosis of villus epithelial cells. PF40 combined with metformin could significantly improve the symptoms of insulin resistance in type 2 diabetes mellitus (T2DM) rats, the molecular mechanism might be through inhibiting the expression of RORγ protein and increasing Foxp3 protein in the jejunum of T2DM rats, and then restoring the STZ-induced imbalance of T helper 17(Th17)/ regulatory T cells (Treg) cells, thereby maintaining intestinal immune homeostasis. Results identified in this study provided important information regarding the structure and antidiabetic characteristics of Pseudostellaria heterophylla polysaccharides, which can contribute to the development of Pseudostellaria heterophylla polysaccharides for industrial purposes in the future.

Interaction between Gelatin and Mulberry Leaf Polysaccharides in Miscible System: Physicochemical Characteristics and Rheological Behavior

In this study, the miscible system was formed by mixing gelatin (G) with mulberry leaf polysaccharides (MLPs) continuously extracted with a hot buffer (HBSS), a chelating agent (CHSS), a dilute alkali (DASS), and a concentrated alkali (CASS), and the zeta potential, turbidity, particle size, distribution, and rheological properties of the miscible systems were evaluated. Under acidic conditions, the miscible systems of four polysaccharides and gelatin were in a clear state; under alkaline conditions, G-HBSS and G-CHSS were clarified, and G-DASS and G-CASS changed from clarification to turbidity. The zeta potential changed from positive to negative with the increase in pH. When the pH was at 7, it increased with the increase in polysaccharide concentration but was still negative. The four miscible systems all showed polydispersity. The particle sizes of G-HBSS and G-CHSS decreased with the increase in pH, while the particle sizes of G-DASS and G-CASS were increased. The four miscible systems showed “shear thinning” behavior, and the addition of gelatin reduced the apparent viscosity of the four polysaccharide solutions. G-CHSS was highly stable, and G-CASS was more suitable as a stabilizer in the freezing process.

Structural characteristics of three pectins isolated from white kidney bean

Three water-soluble pectic polysaccharides (WKBP-P2, P3 and P4) were isolated from white kidney bean by ion exchange combined with size-exclusion methods. The structural features were characterized by GC-MS, NMR spectroscopy and HPSEC-MALLS-RI. It was found that three pectic polysaccharides were the major water-extracted polysaccharides in white kidney bean. All the WKBP-P2, P3 and P4 were probably composed of various structural regions including homogalacturonan (HG), xylogalacturonan (XGA), rhamnogalacturonan I (RG-I) regions in backbone, and arabinan region mainly as side chain. However, these pectic polysaccharides were significantly different in molar ratios of these structural regions and molecular size. WKBP-P2 was HG-predominant pectin (partially methyl-esterified) with weight-average molecular weight (M_w) of 1.2 × 10⁴ g/mol, and contained minor RG-I, arabinan and probable XGA regions. WKBP-P3 (M_w of 4.0 × 10⁴ g/mol) primarily embraced XGA, HG, arabinan regions and minor RG-I region. WKBP-4 with highest M_w (4.5 × 10⁵ g/mol) had the most arabinan region (51.3%), which was probably the side chain linked to the backbone composed of RG-I, HG and slight XGA regions. These findings provided a structural basis for study on polysaccharides from white kidney bean, which was benefit for development of functional food.