Ice recrystallization inhibition effect of cellulose nanocrystals: Influence of sucrose concentration

Enhancing Antimicrobial Activity of Thyme Essential Oil Through Cellulose Nano Crystals-Stabilized Pickering Emulsions

Essential oils (EOs), such as thyme essential oil (TEO), are widely known for their antimicrobial properties; however, their direct application in food systems is limited due to their poor stability, which affects their efficacy. This study aims to improve the stability and antimicrobial efficacy of TEO by encapsulating it in Pickering emulsions stabilized with cellulose nanocrystals (CNC). Two formulations of Pickering emulsions with 5% and 10% TEO were prepared and compared to traditional surfactant-based emulsions. The stability of the emulsions was assessed over 21 days, and particle size, zeta potential, Raman spectroscopy, and FTIR were used for characterization. The antimicrobial activity was tested against several foodborne pathogens, with minimum inhibitory concentration (MIC) values determined. The 10% TEO Pickering emulsion showed antimicrobial activity, with MIC50 values of 4096 µg/mL against Staphylococcus aureus and Escherichia coli, while the 5% TEO formulation had no effect at MIC50 > 8192 µg/mL. The CNC-stabilized Pickering emulsions exhibited superior stability, showing no phase separation over 21 days. The findings suggest that CNC-stabilized Pickering emulsions are effective at improving the stability and antimicrobial performance of TEO, making them a promising natural preservative for food packaging and safety. Further research is recommended to optimize the formulation and broaden TEO's application in food preservation.

Effect of different freezing conditions on ice crystal formation behavior and ice-growth inhibition by cryoprotectants

BACKGROUND

The formation of ice crystals will have adverse effects on aquatic products, and the key to ensure the long-term preservation and better quality preservations of the product is to evaluate the intercellular ice crystal formation to find suitable refrigeration conditions and cryoprotectants.

RESULTS

The ice crystal formation was successfully captured by using an inverted microscope cryomicroscopic system equipped with a low-temperature stage, the ice crystals formed under different freezing methods between tuna muscle cells were observed directly, the deformation degree of muscle tissue pores during crystallization was evaluated, and the effect of freeze-thaw times on tuna samples was analyzed. The effects of the use of cryoprotectant such as cellobiose and carboxylated cellulose nanofibers on ice-growth inhibition were investigated, and the reliability of the ice crystal observation results was further verified by the determination of physical properties. The results showed that carboxylated cellulose nanofibers had the best ice-growth inhibition effect, they prevented about 50% cell deformation compared with the control group, and also reduced the minimum size of ice crystal formation. In addition, the addition of cellobiose and sodium tripolyphosphate gave the ice crystals a more uniform size and roundness.

CONCLUSION

The experiment proposed a stable and clear observation method for the process of intercellular ice crystal formation, and the accuracy of the observation method was further verified by some physical indicators. This may help in the selection of suitable measurement methods to directly observe ice crystal formation behavior and screen cryoprotectants. © 2024 Society of Chemical Industry.

Effects of Flammulina velutipes polysaccharide with ice recrystallization inhibition activity on the quality of beef patties during freeze-thaw cycles: An emphasis on water status and distribution

The antifreeze activity of Flammulina velutipes polysaccharide (FVP) autoclave-extracted with dilute alkaline and effects of FVP on moisture status, size of ice crystals, physical and chemical characteristics of beef patties during repeated freeze-thaw (F-T) cycles were investigated. Results showed that FVP exhibited ice recrystallization inhibition activity and was able to alter the onset freezing/melting temperature of beef patties. 0.01% FVP significantly alleviated (P < 0.05) the decrement in water holding capacity by inhibiting water migration, restraining the mobility of water, and reducing the size of ice crystals of beef patties during the repeated F-T cycles. In addition, FVP could effectively inhibited oxidation reaction and protein aggregation of beef patties with significant decreases in TBARS value, protein turbidity, contents of total sulfhydryl and carbonyl of myofibrillar protein, and an increase in protein solubility during the repeated cycles. These results suggest FVP could be developed to be a promising cryoprotectant in frozen patties.

Inulin Can Improve Red Blood Cell Cryopreservation by Promoting Vitrification, Stabilizing Cell Membranes, and Inhibiting Ice Recrystallization

In transfusion medicine, the cryopreservation of red blood cells (RBCs) is of major importance. The organic solvent glycerol (Gly) is considered the current gold-standard cryoprotectant (CPA) for RBC cryopreservation, but the deglycerolization procedure is complex and time-consuming, resulting in severe hemolysis. Therefore, it remains a research hotspot to find biocompatible and effective novel CPAs. Herein, the natural and biocompatible inulin, a polysaccharide, was first employed as a CPA for RBC cryopreservation. The presence of inulin could improve the thawed RBC recovery from 11.83 ± 1.40 to 81.86 ± 0.37%. It was found that inulin could promote vitrification because of its relatively high viscosity and glass transition temperature (Tg'), thus reducing the damage during cryopreservation. Inulin possessed membrane stability, which also had beneficial effects on RBC recovery. Moreover, inulin could inhibit the mechanical damage induced by ice recrystallization during thawing. After cryopreservation, the RBC properties were maintained normally. Mathematical modeling analysis was adopted to compare the performance of inulin, Gly, and hydroxyethyl starch (HES) in cryopreservation, and inulin presented the best efficiency. This work provides a promising CPA for RBC cryopreservation and may be beneficial for transfusion therapy in the clinic.

Self-assembly of tamarind seed polysaccharide via enzymatic depolymerization and degalactosylation enhanced ice recrystallization inhibition activity

Polysaccharides are becoming potential candidates for developing food-grade cryoprotectants due to their extensive accessibility and health-promoting effects. However, unremarkable ice recrystallization inhibition (IRI) activity and high viscosity limit their practical applications in some systems. Our previous study found a galactoxyloglucan polysaccharide from tamarind seed (TSP) showing moderate IRI activity. Herein, the enhancement of the IRI performance of TSP via enzymatic depolymerization and degalactosylation-induced self-assembly was reported. TSP was depolymerized and subsequently removed ∼40 % Gal, which induced the formation of supramolecular rod-like fiber self-assembles and exhibited a severalfold enhancement of IRI. Ice shaping assay did not show obvious faceting of ice crystals, indicating that both depolymerized and self-assembled TSP showed very weak binding to ice. Molecular dynamics simulation confirmed the absence of molecular complementarity with ice. Further, it highlighted that degalactosylation did not cause significant changes in local hydration properties of TSP from the view of a single oligomer. The inconsistency between molecular simulation and macroscopic IRI effect proposed that the formation of unique supramolecular self-assemblies may be a key requirement for enhancing IRI activity. The findings of this study provided a new opportunity to enhance the applied potential of natural polysaccharides in food cryoprotection.

Corn cob hemicelluloses as stabilizer for ice recrystallization inhibition in ice cream

Food stabilizers, such as guar gum and locust bean gum (LBG), are often added to ice cream to improve its texture and to combat its main shelf-life concern - ice recrystallization. Recently these gums have become increasingly expensive due to the limited supplies. In this study, holocellulose nanocrystals (holoCNCs) and hemicelluloses (hemiCs) were prepared from readily available corn cobs and tested for ice recrystallization inhibition (IRI) activities in the 25.0 % sucrose solution and ice cream mixes (ICMs). In the sucrose solution, holoCNCs were not IRI active at a concentration of 0.5 %, but hemiCs demonstrated a good IRI activity, even at 0.1 %. In the ICMs, the IRI activity of hemiCs was better than those of guar gum and LBG at a concentration of 0.2 %. Adding 0.2-0.5 % hemiCs had no negative influences on the physicochemical properties of ICMs and ice cream, including viscosity profile, particle size distribution, overrun, hardness, and meltdown rate. These research findings demonstrated corn cob hemiCs' potential as a more sustainable ice cream stabilizer.

Shelf-Stability of Kiln- and Liquid-Smoked Inulin-Fortified Emulsion-Type Pangasius Mince Sausage at Refrigerated Temperature

The objective of this study was to investigate the effects of the kiln (SK-S) and liquid smoking (LS-S) processes on the quality of inulin-fortified emulsion-type Pangasius mince sausages. The moisture content during the storage significantly (p < 0.05) decreased in C-S (control) sausages and increased (p < 0.05) in SK-S and LS-S sausages. The protein content decreased (p < 0.05) in C-S, SK-S, and LS-S throughout the storage period. Initially, among the three processed sausages, LS-S showed a lower pH value, and as the days of storage progressed, all the treatments exhibited a declining trend (p < 0.05). A significant (p < 0.05) increase in the PV was observed in all the sausages during the storage days at 5 ± 1 °C, but the intensity of the increase was lower in SK-S and LS-S. The total viable count of C-S and SK-S sausages reached the limit of acceptability (6 log10cfu g-1) on the 20th day and on the 24th day of storage. The electrophoretic protein pattern of LS-S samples exhibited retention of all bands, indicating the lower proteolysis of MHC, actin, and troponin T in comparison with other treatments. The hardness (p < 0.05) and cohesiveness (p > 0.05) values of both SK-S and LS-S reduced as the storage days progressed. The present study indicates that the emulsion-type Pangasius sausages incorporated with inulin powder (2%) exposed to kiln smoking and commercial liquid smoking retained good-to-better sensory attributes up to day 16 (C-S) and day 20 (SK-S and LS-S) under refrigerated storage at 5 ± 1 °C in low-density vacuum polyethylene (LDPE) pouches.

Ice recrystallization inhibition effect of cellulose nanocrystals at constant and cycling temperatures

Understanding the effects of ice recrystallization inhibitors at varying temperatures is critical for evaluating their applications. We studied the ice recrystallization inhibition (IRI) effects of cellulose nanocrystals (CNCs) at constant and cycling temperatures. A splat assay using a 3.0 % sucrose solution showed that the IRI effect of 0.2 % CNCs decreased with increasing temperatures from -10 °C to -2 °C; the IRI effects of 0.5 % and 1.0 % CNCs remained unchanged for an increase in temperature from -10 °C to -4 °C but decreased at the temperature of -2 °C. A sandwich assay using a 25.0 % sucrose solution revealed that IRI effects increased with increasing temperatures, except in the presence of 0.2 % and 0.5 % CNCs at -5 °C and - 4 °C. A sandwich assay using a 35.0 % sucrose solution revealed that better IRI effects were observed at higher temperatures at all CNCs concentrations. At cycling temperatures, CNCs were inactive for storage times for ≤2 h, regardless of the rate, holding time, and amplitude of temperature fluctuation, but were active for storage times of 2 and 10 days. The IRI effects of CNCs at different temperatures may be related to the coverage of CNCs on ice surface, diffusion rate of CNCs to ice surface, and types of ice recrystallization.

Physicochemical and Sensory Properties Colored Whey Protein-Cellulose Nanocrystal Edible Films after Freeze-Thaw Treatment

Balancing physicochemical properties and sensory properties is one of the key points in expanding edible packaging applications. The work consisted of two parts, one was to investigate the effects of cellulose nanocrystals (CNC) on the packaging-related properties of whey protein isolate films with natural colorants (curcumin, phycocyanin, and lycopene) under freeze-thaw (FT) conditions; the other was to test oral tactility and visual sensory properties of the edible films and their overall acceptability in packed ice cream. FT treatment reduced the mechanical strength and moisture content and increased the water vapor permeability of the films, as water-phase transformation not only disrupted hydrogen bonds but also the film network structure through physical stress. The oral tactility produced by CNC and the visual effect produced by colorants could affect participants' preference for edible films. This study provides a good reference for the consumer-driven product development of packaged low-temperature products.

The quality properties of frozen large yellow croaker fillets during temperature fluctuation cycles: improvement by cellobiose and carboxylated cellulose nanofibers

Frozen aquatic products undergo unavoidable quality changes owing to temperature fluctuations during frozen storage and distribution. This study investigated the effects of 1% cellobiose (CB), and 0.5 and 1% carboxylated cellulose nanofibers (CNF) on ice crystal growth and recrystallization of frozen large yellow croaker fillets exposed to temperature fluctuations. Denser and more uniformly distributed ice crystals were observed in the CB- and CNF-treated samples than in the water-treated samples. Furthermore, the addition of CB and CNF suppressed the conversion of bound water to frozen water in the samples during temperature fluctuation cycles, played a positive role in fixing the ionic and hydrogen bonds that stabilize the protein structure, limited the conformational transition from α-helix to β-sheet, and improved protein thermal stability. Based on turbidity, zeta potential, and confocal laser scanning microscopy (CLSM) analyses, the presence of CB and CNF restricted the protein aggregation. Compared with CB, CNF molecules with abundant carboxyl functional groups and longer morphology exhibited better cryoprotective effects. Moreover, the fillets were more improved protected from mechanical damage induced by large ice crystals at a higher CNF concentration. This study reveals the potential of CB and CNF as novel cryoprotectants.

Potent Time-Dependent Ice Recrystallization Inhibition Activity of Cellulose Nanocrystals in Sucrose Solutions

Exploring novel materials with ice recrystallization inhibition (IRI) activity in several fields often starts with a quantitative analysis of ice crystal size change by a splat assay or sandwich assay on a short time scale from 0.5 to 1 h. This study found that this time scale was insufficient to evaluate the IRI activity of cellulose nanocrystals (CNCs) in a model ice cream system-25.0% sucrose solution. No IRI activity was observed in CNCs incubated with ice crystals on a short time scale of 0.5-2.0 h. However, over longer time scales, the growth of ice crystals was entirely inhibited by 1.0% CNCs (between 2 and 24 h) and 0.5% CNCs (between 24 and 72 h) with corresponding final crystal sizes of 25 and 40 μm, respectively. Additionally, ice shaping was observed on a long exposure time, but not on a short exposure time. The findings presented here can be explained by a time-dependent surface coverage of CNCs on ice crystals. The data here indicate the importance of choosing a suitable exposure time for evaluating the IRI activity of new materials and prompt a better understanding of IRI mechanisms involving CNCs.