Influences of Ultrasonic Treatments on the Structure and Antioxidant Properties of Sugar Beet Pectin

Modulation of protein glutaminase α-helix and disulfide bonds in a sunflower pollen microgel microenvironment: A strategy to enhance enzyme activity and stability

Protein glutaminase (PGase) can improve plant protein solubility, but its activity tends to decline under the influence of external factors. Here, we developed a novel PGase-stabilizing agent (sunflower pollen microgel, SPMG) and investigated the mechanism for its stabilizing effect on PGase. Alkali treatment could regulate the physicochemical microenvironment of SPMG, and its ability to stabilize PGase declined with prolonged treatment time. SPMG increased PGase activity by a maximum of 49.24 %, while enhanced its storage stability by 30.61 %, 21.64 %, and 26.00 % at 4 °C, 25 °C, and 37 °C, respectively. SPMG improved PGase properties through hydrophobic interaction, resulting in the burying of inner hydrophobic groups and enhancement of intermolecular hydrogen bonding, which promoted the α-helix content from 23.28 % to 26.19 %. Additionally, these interactions facilitated the sulfhydryl-disulfide bond exchange reaction between PGase molecules, significantly increasing the disulfide bond content by nearly 80 %. This compact structure ultimately enhanced the activity and stability of PGase.

Effects of Maillard Reaction Durations on the Physicochemical and Emulsifying Properties of Chickpea Protein Isolate

This study investigated the physicochemical and emulsifying properties of chickpea protein isolate (CPI)-citrus pectin (CP) conjugates formed via the Maillard reaction across varying reaction durations. CPI and CP were conjugated under controlled dry-heating conditions, and the resulting conjugates were characterized by measuring their particle size, zeta potential, solubility, thermal stability, surface hydrophobicity, and emulsifying properties. The results showed that as reaction duration increased, the particle size and zeta potential of the CPI-CP conjugates increased significantly, reaching a maximum particle size of 1311.33 nm and a zeta potential of -35.67 mV at 12 h. Moreover, the Maillard reaction improved the solubility, thermal stability, and hydrophobicity of the CPI. Glycosylation increased the emulsifying activity index (EAI) and emulsifying stability index (ESI) of the CPI to 145.33 m2/g and 174.51 min, respectively. Optimal emulsions were achieved at a protein concentration of 1.5 wt% and a 10% volume fraction of the oil phase. The Maillard reaction promoted the interfacial protein content and the thickness of the interfacial layer while decreasing the droplet size and zeta potential of the emulsion. Additionally, the emulsion prepared with CPI-CP-12 h showed outstanding long-term stability. These results demonstrate that a moderate Maillard reaction with CP effectively enhances the physicochemical and emulsifying characteristics of CPI.

Impact of green techniques on intricate cell wall structure of bee pollen to enhance functional characteristics and improve its in vitro digestibility

Bee pollen is a nutrient-rich super food, but its rigid dual-layered structure limits nutrient release and absorption. The outer exine, composed of stress-resistant sporopollenin, and the inner intine, consisting of cellulose and pectin, form a barrier to digestive breakdown. This study investigates the potential of green techniques, specifically supercritical fluid extraction and ultrasonication, to disaggregate pollen cell walls, enhancing its bioavailability and maximizing nutrient utilization. Ultrasonication treated pollen (USTP) and supercritical fluid extraction-treated pollen (STP) demonstrated disruption, as evidenced by scanning electron microscopy imaging. In relation to scanning electron microscopy, techno-functional, antioxidant, and compositional analysis displayed a positive outcome, with crude lipid, protein, antioxidant activity (2,2-diphenyl-1-picrylhydrazyl activity and 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid assay) and total phenolic content increased by 34.80%, 32.58%, 10.80%, 11.37%, and 83.94%, respectively. Based on the above properties, USTP for 4 h and STP at 400 bar for 40 min were identified as the optimal conditions for disintegration. Furthermore, optimized samples analyzed for amino acid and mineral release revealed a notable increase in composition of essential amino acid and minerals (Ca, Cu, Fe, etc.) by ∼1.5 and 1.2 times, respectively. Along with significant changes in composition, fractured pollen exhibited 1.4 folds increase in protein digestibility with minor differences in thermal stability, and crystallinity as established by differential scanning calorimetry, and X-ray diffraction analysis. The study confirms that nutrient release and absorption remain restricted without pre-treatment, highlighting the necessity of specific treatment to disintegrate bee pollen before its use as a functional food ingredient. PRACTICAL APPLICATION: Bee pollen is a rich source of all the essential nutrients required by the humans and recognised as a complete food. However, its tough cellular structure restricts its utilisation in numerous food applications. Therefore, to disintegrate bee pollen and release its nutrients, ultrasonication and super critical fluid extraction processes were employed to improve its utilization for human purposes. Both the treatment techniques, enhanced bee pollen's bioavailability and functional properties, making it more suitable for use in nutraceuticals and functional foods.These treatments proved to increase the antioxidant capacity, digestibility, and create high-value ingredient for supplements, beverages, and fortified foods.

Sequential extraction of hawthorn pectin: An attempt to reveal their original mode of being in plants and functional properties

Hawthorn is rich in pectin, which is much higher than most cultivated fruits, but conventional extraction methods do not meet the requirements of low energy consumption and green production. Pectin in hawthorn is divided into soluble and insoluble parts, and with the ripening of hawthorn, the original pectin is converted into soluble pectin and pectic acid under the action of enzymes. Therefore, based on the characteristics of hawthorn pectin, this study sequentially extracted hawthorn pectin using water-soluble pectin (WSP) and hot acid-soluble pectin (HAP) method, verifying the feasibility of extracting hawthorn pectin with pure water at room temperature, and systematically analyzing and comparing the physicochemical properties and functional characteristics of the two methods. The combination of texture analysis and gel rheology revealed that WSP formed a more uniform and dense network structure during the gelation process. Additionally, microscopic observations and emulsification index results indicated that the emulsion prepared with WSP (WSE) had a smaller particle size and better stability. This indicates that hawthorn pectin is suitable for extraction with pure water at room temperature, which can maintain its good physical properties while reducing energy consumption, providing a new approach for the large-scale extraction of pectin in the food 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.

Structural, chemical and technofunctional properties pectin modification by green and novel intermediate frequency ultrasound procedure

The impact of intermediate frequency ultrasound (IFUS, 582, 864 and 1144 kHz), mode of operation (continue and pulsed) and ascorbic acid (Aa) addition on the structural, chemical and technofunctional properties of commercial citrus high methoxyl-grade pectin (HMP) was investigated. The chemical dosimetry of IFUS, monitored by the triiodide formation rate (I3-), demonstrated that the pulsed ratio (1900 ms on/100 ms off) at the three frequencies was similar to that of continue mode but IFUS1144 kHz produced more acoustic streaming demonstrated by the height liquid measured using image analysis. In presence of Aa, HMP presented higher fragmentation than in its absence. IFUS did not give rise any changes in the main functional groups of the HMP. In general, a reduction in molecular weight was observed, being the presence of Aa the most influencing factor. Regarding monosaccharides, IFUS modified the structure of homogalacturonan and rhamnogalacturonan-I and increased of GalA contents of the HMP in presence of Aa at the above three frequencies. A reducing of the consistency index (k) and increasing of the flow index (n) of HMP were showed by IFUS frequency and Aa addition. The emulsifying activity and stability index were increased for HMP treated by IFUS in continue mode at all frequencies and in presence of Aa. The results presented in this research shown the effectiveness of IFUS as tool to modify pectin into different structures with different functionalities.