Microstructure change in whole egg protein aggregates upon freezing: Effects of freezing time and sucrose addition

The influence of pH and calcium ions on the gelation of low methoxy pectin from potato

In this study, pectin was extracted from potato with the hydrolysis of cellulose, as well as its acid-induced and Ca2+-induced gelation behavior was investigated, too. The gelation process of unhydrolyzed pectin might be used as a model for studying the gelation behavior and characteristic of pectin within the cell wall. The results showed that potato pectin solution (3%) could form a gel state at a minimal concentration of 0.25% CaCl2 or a maximum pH value of 4.60. Furthermore, acetic acid-induced and CaCl2-induced gels were both concentration-independent. Specifically, the gel strength increased with decreasing levels of pH and increasing concentrations of CaCl2. Moreover, CaCl2-induced gels exhibited superior gelation characteristics with a higher storage modulus (7.2 Pa), larger fractal dimension (2.58), smaller porosity (12.11%), shorter relaxation time T2, and a denser gel network structure. This disparity stemmed from different mechanism: acetic acid provided H+ to combine with free carboxyl groups on the pectin chains, reducing the repulsion between pectin molecules, narrowing chain spacing, and fostering hydrogen bond formation; whereas CaCl2 promoted gelation primarily via the information of the "egg box" structure involving non-covalent bonded calcium bridges. This research could provide a theoretical basis for acid-induced and Ca2+-induced gelation of unhydrolyzed pectin extracted from the cell wall.

Impact of cold plasma-assisted Non-thermal deamidation and glycosylation on the construction of sugar derivative-zein conjugates for enhancing pickering foam stability: Technical principles and molecular interactions

There is an urgent need for stable, plant-based Pickering foams to address the growing consumer demand for sustainable, low-calorie, aerated sweet foods. This study employed a cold plasma-assisted deamidation and glycosylation (CPDG) approach to promote hydrophilic reassembly of zein, resulting in the formation of sugar derivative-zein conjugates. This was accomplished by coupling deamidated zein with polyhydroxy sugars including sucralose (Suc), maltitol (Mal), mannitol (Man), and stevioside (Ste). The research focused on elucidating the technical mechanisms of conjugate formation and the molecular interactions that enhance foam performance. The CPDG-treated conjugates demonstrated substantially increased foamability (140.00-223.33 %) and foam stability (28.57-105.07 %). Furthermore, microscopy (100 × magnification) revealed enhanced bubble counts (+13-15 bubbles) and interface layer thickness (+1.85-4.60 nm), along with a decrease in the drainage area (+8.47-20.52 %) for all conjugates, except Suc/ZN-CP. Particularly, the amphiphilic nature of Ste, characterized by multiple chiral centers, various hydroxyl groups, and a distinct carbonyl group, resulted in the highest covalent grafting degree (38.82 %), water solubility (0.28 mg/mL), foaming capacity (223.33 %), and foam stability (105.07 %) of ZN/Ste-CP after CPDG treatment. Regarding interaction forces, CPDG treatment enhanced both hydrogen bonding and covalent interactions in zein while diminishing electrostatic and hydrophobic forces. Confocal laser scanning microscopy validated that these changes resulted in a hydrophilic conformational shift of the conjugates, allowing Ste to coat micelle surfaces and form chain-like aggregates through viscous stretching, thereby facilitating favorable adsorption and unfolding at the air/water interface. The CPDG technology proved to be an effective and eco-friendly method for modifying the interface of zein, offering a valuable strategy for its application in highly flexible, stabilized Pickering foamed foods.

High-moisture extrusion of curdlan: Texture and structure

High-moisture extrusion is a promising thermomechanical technology extensively employed in manufacturing fibrous meat analogues from plant-based proteins, garnering considerable research attention. However, polysaccharide-based extrusion has been rarely explored. The present study investigates the effects of varying extruder barrel temperatures (130 °C-200 °C) on the texture and structure of curdlan extrudates, and highlights the formation mechanism. Results showed that the single chain of curdlan aggregates to form triple-helix chains upon extrusion, consequently enhancing the crystallinity, particularly at 170 °C. The hardness, chewiness, and mechanical properties improved with increasing barrel temperature. Moreover, barrel temperatures affected the macrostructure, the extrudates maintained intact morphologies except at 160 °C due to the melting of curdlan gel as confirmed by the differential scanning calorimetry thermogram. Microstructural analysis revealed that curdlan extrudates transited through three phases: original gel (130 °C, 140 °C, and 150 °C), transition state (160 °C), and regenerated gel (170 °C, 180 °C, 190 °C, and 200 °C). The steady state of regenerated gel (170 °C) exhibited higher crystallinity and smaller fractal dimension, resulting in a more compact and crosslinked gel network. This study elucidates the structure transition of curdlan gel at extremely high temperatures, offering valuable technical insights for developing theories and methods with respect to polysaccharide-based extrusion that may find applications in food-related fields.

Application of Formulation Principles to Stability Issues Encountered During Processing, Manufacturing, and Storage of Drug Substance and Drug Product Protein Therapeutics

The field of formulation and stabilization of protein therapeutics has become rather extensive. However, most of the focus has been on stabilization of the final drug product. Yet, proteins experience stress and degradation through the manufacturing process, starting with fermentaition. This review describes how formulation principles can be applied to stabilize biopharmaceutical proteins during bioprocessing and manufacturing, considering each unit operation involved in prepration of the drug substance. In addition, the impact of the container on stabilty is discussed as well.

The regulation of carbon dioxide on food microorganisms: A review

This review presents a survey of two extremely important technologies about CO2 with the effectiveness of controlling microorganisms - atmospheric pressure CO2-based modified atmosphere packaging (MAP) and high pressure CO2 non-thermal pasteurization (HPCD). CO2-based MAP is effectively in delaying the lag and logarithmic phases of microorganisms by replacing the surrounding air, while HPCD achieved sterilization by subjecting food to either subcritical or supercritical CO2 for some time in a continuous, batch or semi-batch way. In addition to the advantages of healthy, eco-friendly, quality-preserving, effective characteristic, some challenges such as the high drip loss and packaging collapse associated with higher concentration of CO2, the fuzzy mechanisms of oxidative stress, the unproven specific metabolic pathways and biomarkers, etc., in CO2-based MAP, and the unavoidable extraction of bioactive compounds, the challenging application in solid foods with higher efficiency, the difficult balance between optimal sterilization and optimal food quality, etc., in HPCD still need more efforts to overcome. The action mechanism of CO2 on microorganisms, researches in recent years, problems and future perspectives are summarized. When dissolved in solution medium or cellular fluids, CO2 can form carbonic acid (H2CO3), and H2CO3 can further dissociate into bicarbonate ions (HCO3-), carbonate (CO32-) and hydrogen cations (H+) ionic species following series equilibria. The action mode of CO2 on microorganisms may be relevant to changes in intracellular pH, alteration of proteins, enzyme structure and function, alteration of cell membrane function and fluidity, and so on. Nevertheless, the effects of CO2 on microbial biofilms, energy metabolism, protein and gene expression also need to be explored more extensively and deeply to further understand the action mechanism of CO2 on microorganisms.

Potential of Good's buffers to inhibit denaturation of myofibrillar protein upon freezing

The current systematic study sought to examine the potential use of three Good's buffers (MES, MOPS and HEPES) in inhibiting myofibrillar protein (MFP) denaturation induced by acidity changes. The highest degree of acidity variation was found in the center and bottom of large bottles due to the freeze-concentration effect. Good's buffer tended to basify during freezing, and it could prevent the crystallization of sodium phosphate (Na-P) buffer. Acidification upon freezing Na-P disrupted the natural conformation of MFP and induced the formation of large proteins aggregates with tight packing. The 15 mM MES, 20 mM MOPS, and 30 mM HEPES were respectively added to neutralize the strong acidity drop induced by freezing 20 mM Na-P, and all of them significantly improved the stability of the MFP conformation (P < 0.05). This work is not only critical to meet the growing demand for protein, but also groundbreaking for broadening the applicability of Good's buffers in the food industry.