Impact of sugar and sugar alcohol on the pasting and retrogradation properties of starch with distinct molecular structures.

The molecular structures of starch and sugar/sugar alcohol are recognized as critical determinants of starch pasting and retrogradation properties. However, their combined effects on these properties remain elusive. This study for the first time examined the pasting and retrogradation properties of nine starches with diverse molecular structures, both with and without the addition of glucose, sucrose, isomaltose, isomalt, and sorbitol. The presence of sugar/sugar alcohol significantly enhanced starch pasting viscosity. In particular, the variations of the peak viscosity of wheat starch were more pronounced than other starches, possibly due to its distinct molecular structures. The changes in melting temperatures and enthalpy of retrograded starches were complex, varying depending on the type of starch and sugar/sugar alcohol used. For example, the melting peak temperature ranged from 56.45 °C (TS) to 61.9 °C (WMS), and the melting enthalpy ranged from 0.16 J/g (TS) to 5.6 J/g (PES). The micromorphology of retrograded starch revealed agglomeration and needle-like structures, instead of a network structure, after the addition of glucose and sorbitol, respectively. Correlations between starch molecular structure and pasting properties remained largely unchanged, while the relationship between starch molecular structure and retrogradation properties exhibited notable variations after the addition of sugars or sugar alcohols. These findings help a better understanding of the effects of starch molecular structure and the presence of sugar/sugar alcohol on starch pasting and retrogradation properties.

ATR-FTIR spectroscopy and machine/deep learning models for detecting adulteration in coconut water with sugars, sugar alcohols, and artificial sweeteners.

Packaged coconut water offers various options, from pure to those with added sugars and other additives. While the purity of coconut water is esteemed for its health benefits, its popularity also exposes it to potential adulteration and misrepresentation. To address this concern, our study combines Fourier transform infrared spectroscopy (FTIR) and machine learning techniques to detect potential adulterants in coconut water through classification models. The dataset comprises infrared spectra from coconut water samples spiked with 15 different types of potential sugar substitutes, including: sugars, artificial sweeteners, and sugar alcohols. The interaction of infrared light with molecular bonds generates unique molecular fingerprints, forming the basis of our analysis. Departing from previous research predominantly reliant on linear-based chemometrics for adulterant detection, our study explored linear, non-linear, and combined feature extraction models. By developing an interactive application utilizing principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE), non-targeted sugar adulterant detection was streamlined through enhanced visualization and pattern recognition. Targeted analysis using ensemble learning random forest (RF) and deep learning 1-dimensional convolutional neural network (1D CNN) achieved higher classification accuracies (95% and 96%, respectively) compared to sparse partial least squares discriminant analysis (sPLS-DA) at 77% and support vector machine (SVM) at 88% on the same dataset. The CNN's demonstrated classification accuracy is complemented by exceptional efficiency through its ability to train and test on raw data.

Material Composition Characteristics of Aspergillus cristatus under High Salt Stress through LC-MS Metabolomics.

Aspergillus cristatus is a crucial edible fungus used in tea fermentation. In the industrial fermentation process, the fungus experiences a low to high osmotic pressure environment. To explore the law of material metabolism changes during osmotic pressure changes, NaCl was used here to construct different osmotic pressure environments. Liquid chromatography-mass spectrometry (LC-MS) combined with multivariate analysis was performed to analyze the distribution and composition of A. cristatus under different salt concentrations. At the same time, the in vitro antioxidant activity was evaluated. The LC-MS metabolomics analysis revealed significant differences between three A. cristatus mycelium samples grown on media with and without NaCl concentrations of 8% and 18%. The contents of gibberellin A3, A124, and prostaglandin A2 related to mycelial growth and those of arabitol and fructose-1,6-diphosphate related to osmotic pressure regulation were significantly reduced at high NaCl concentrations. The biosynthesis of energy-related pantothenol and pantothenic acid and antagonism-related fluvastatin, aflatoxin, and alternariol significantly increased at high NaCl concentrations. Several antioxidant capacities of A. cristatus mycelia were directly related to osmotic pressure and exhibited a significant downward trend with an increase in environmental osmotic pressure. The aforementioned results indicate that A. cristatus adapts to changes in salt concentration by adjusting their metabolite synthesis. At the same time, a unique set of strategies was developed to cope with high salt stress, including growth restriction, osmotic pressure balance, oxidative stress response, antioxidant defense, and survival competition.

Tailoring silk fibroin hydrophilicity and physicochemical properties using sugar alcohols for medical device coatings.

This study explores the modification of silk fibroin films for hydrophilic coating applications using various sugar alcohols. Films, prepared via solvent casting, incorporated glycerol, sorbitol, and maltitol, revealing distinctive transparency and UV absorption characteristics based on sugar alcohol chemical structures. X-ray diffraction confirmed a silk I to silk II transition influenced by sugar alcohols. Glycerol proved most effective in enhancing the ß-sheet structure. The study also elucidated a conformational shift towards a ß-sheet structure induced by sugar alcohols. Silk fibroin-sugar alcohol blind docking and sugar alcohol-sugar alcohol blind docking investigations were conducted utilizing the HDOCK Server. The computer simulation unveiled the significance of size and hydrogen bonding characteristics inherent in sugar alcohols, emphasizing their pivotal role in influencing interactions within silk fibroin matrices. Hydrophilicity of ozonized silicone surfaces improved through successful coating with silk fibroin films, particularly glycerol-containing ones, resulting in reduced contact angles. Strong adhesion between silk fibroin films and ozonized silicone surfaces was evident, indicating robust hydrogen bonding interactions. This comprehensive research provides crucial insights into sugar alcohols' potential to modify silk fibroin film crystalline structures, offering valuable guidance for optimizing their design and functionality, especially in silicone coating applications.

d-Arabitol production by a high arabitol-producing yeast, Zygosaccharomyces sp. Gz-5 isolated from miso.

d-Arabitol, an alternative sweetener to sugar, has low calorie content, high sweetness, low glycemic index, and insulin resistance-improving ability. In this study, d-arabitol-producing yeast strains were isolated from various commercial types of miso, and strain Gz-5 was selected among these strains. Phylogenetic tree analysis of the internal transcribed spacer sequence revealed that strain Gz-5 was distinct from Zygosaccharomyces rouxii, a major fermenting yeast of miso. The strain, identified as Zygosaccharomyces sp. Gz-5, grew better than other Z. rouxii in 150 g/L NaCl and produced 114 g/L d-arabitol from 295 g/L glucose in a batch culture for 8 days (0.386 g/g-consumed glucose). In a fed-batch culture, the yeast produced 133 g/L d-arabitol for 14 days, and the total d-arabitol amount increased by 1.75-fold. These results indicated that Zygosaccharomyces sp. Gz-5, a non-genetically modified strain, has excellent potential for the industrial production of d-arabitol.

Isolation, screening, and characterization of the newly isolated osmotolerant yeast Wickerhamomyces anomalus BKK11-4 for the coproduction of glycerol and arabitol.

This study explored the isolation and screening of an osmotolerant yeast, Wickerhamomyces anomalus BKK11-4, which is proficient in utilizing renewable feedstocks for sugar alcohol production. In batch fermentation with high initial glucose concentrations, W. anomalus BKK11-4 exhibited notable production of glycerol and arabitol. The results of the medium optimization experiments revealed that trace elements, such as H3BO3, CuSO4, FeCl3, MnSO4, KI, H4MoNa2O4, and ZnSO4, did not increase glucose consumption or sugar alcohol production but substantially increased cell biomass. Osmotic stress, which was manipulated by varying initial glucose concentrations, influenced metabolic outcomes. Elevated glucose levels promoted glycerol and arabitol production while decreasing citric acid production. Agitation rates significantly impacted the kinetics, enhancing glucose utilization and metabolite production rates, particularly for glycerol, arabitol, and citric acid. The operational pH dictated the distribution of the end metabolites, with glycerol production slightly reduced at pH 6, while arabitol production remained unaffected. Citric acid production was observed at pH 6 and 7, and acetic acid production was observed at pH 7. Metabolomic analysis using GC/MS identified 29 metabolites, emphasizing the abundance of sugar/sugar alcohols. Heatmaps were generated to depict the variations in metabolite levels under different osmotic stress conditions, highlighting the intricate metabolic dynamics occurring post-glucose uptake, affecting pathways such as the pentose phosphate pathway and glycerolipid metabolism. These insights contribute to the optimization of W. anomalus BKK11-4 as a whole-cell factory for desirable products, demonstrating its potential applicability in sustainable sugar alcohol production from renewable feedstocks.

Clinical Effects of Sugar Substitutes on Cariogenic Bacteria: A Systematic Review and Meta-Analysis.

BACKGROUND: The use of sugar substitutes in food products has recently increased. Limited information regarding the role of various sugar substitutes in caries prevention was found. This systematic review and meta-analysis was conducted to investigate the effects of sugar substitute consumption on reducing cariogenic bacteria in dental plaque and saliva. METHODS: We systematically searched PubMed, EMBASE, and Web of Science (inception to July 2023) for prospective controlled trials published in English and investigated the effects of sugar substitute consumption on cariogenic bacteria in dental plaque and saliva. The primary outcome was the changes in cariogenic bacteria. Two independent reviewers screened the papers. Quality was assessed using the Cochrane risk-of-bias tools. RESULTS: From 977 studies identified, 32 trials were included. Almost half (14/32, 44%) of the included studies had a high risk of bias. Almost all (31/32, 96.88%) were investigations of xylitol and other sugar alcohols (low-intensity sweeteners), such as sorbitol, erythritol, and maltitol. Only one trial investigated stevia, a high-intensity sweetener, whereas no studies on other high-intensity sweeteners, such as sucralose, saccharin, or aspartame, were found. Almost all studies (30/32, 93.75%) showed the consumption of low-intensity sweeteners led to a significant reduction of different types of cariogenic bacteria. The results of the meta-analysis showed that consumption of low-intensity sweeteners led to a significant reduction of cariogenic bacteria in both dental plaque and saliva compared to no treatment. CONCLUSION: The consumption of low-intensity sweeteners helps reduce cariogenic bacteria in dental plaque and saliva. There is limited clinical evidence regarding the role of high-intensity sweeteners in reducing cariogenic bacteria.

Random mutagenesis and transcriptomics-guided rational engineering in Zygosaccharomyces rouxii for elevating D-arabitol biosynthesis.

D-arabitol, a versatile compound with applications in food, pharmaceutical, and biochemical industries, faces challenges in biomanufacturing due to poor chassis performance and unclear synthesis mechanisms. This study aimed to enhance the performance of Zygosaccharomyces rouxii to improve D-arabitol production. Firstly, a mutant strain Z. rouxii M075 obtained via atmospheric and room temperature plasma-mediated mutagenesis yielded 42.0 g/L of D-arabitol at 96 h, with about 50 % increase. Transcriptome-guided metabolic engineering of pathway key enzymes co-expression produced strain ZR-M3, reaching 48.9 g/L D-arabitol after 96 h fermentation. Finally, under optimized conditions, fed-batch fermentation of ZR-M3 in a 5 L bioreactor yielded an impressive D-arabitol titer of 152.8 g/L at 192 h, with a productivity of 0.8 g/L/h. This study highlights promising advancements in enhancing D-arabitol production, offering potential for more efficient biomanufacturing processes and wider industrial applications.

Membrane Lipids and Osmolytes in the Response of the Acidophilic Basidiomycete Phlebiopsis gigantea to Heat, Cold, and Osmotic Shocks.

Previously, we found for the first time the participation of osmolytes in adaptation to acidic conditions in three acidophilic fungi. Because trehalose can protect membranes, we hypothesized a relationship between osmolyte and membrane systems in adaptation to stressors. In the mycelium of Phlebiopsis gigantea, the level of osmolytes reaches 8% of the dry mass, while trehalose and arabitol make up 60% and 33% of the sum, respectively. Cold shock does not change the composition of osmolytes, heat shock causes a twofold increase in the trehalose level, and osmotic shock leads to a marked increase in the amount of trehalose and arabitol. Predominance of phospholipids (89% of the sum) and low proportions of sterols and sphingolipids are characteristic features of the membrane lipids' composition. Phosphatidic acids, along with phosphatidylethanolamines and phosphatidylcholines, are the main membrane lipids. The composition of the membrane lipids remains constant under all shocks. The predominance of linoleic (75% of the sum) and palmitic (20%) acids in phospholipids results in a high degree of unsaturation (1.5). Minor fluctuations in the fatty acid composition are observed under all shocks. The results demonstrate that maintaining or increasing the trehalose level provides stability in the membrane lipid composition during adaptation.

Sequential Co-Immobilization of Enzymes on Magnetic Nanoparticles for Efficient l-Xylulose Production.

Multi-enzymatic strategies have shown improvement in bioconversion during cofactor regeneration. In this study, purified l-arabinitol 4-dehydrogenase (LAD) and nicotinamide adenine dinucleotide oxidase (Nox) were immobilized via individual, mixed, and sequential co-immobilization approaches on magnetic nanoparticles, and were evaluated to enhance the conversion of l-arabinitol to l-xylulose. Initially, the immobilization of LAD or Nox on the nanoparticles resulted in a maximum immobilization yield and relative activity of 91.4% and 98.8%, respectively. The immobilized enzymes showed better pH and temperature profiles than the corresponding free enzymes. Furthermore, co-immobilization of these enzymes via mixed and sequential methods resulted in high loadings of 114 and 122 mg/g of support, respectively. Sequential co-immobilization of these enzymes proved more beneficial for higher conversion than mixed co-immobilization because of better retaining Nox residual activity. Sequentially co-immobilized enzymes showed a high relative conversion yield with broader pH, temperature, and storage stability profiles than the controls, along with high reusability. To the best of our knowledge, this is the first report on the mixed or sequential co-immobilization of LAD and Nox on magnetic nanoparticles for l-xylulose production. This finding suggests that selecting a sequential co-immobilization strategy is more beneficial than using individual or mixed co-immobilized enzymes on magnetic nanoparticles for enhancing conversion applications.

Comparative Conformational Analysis of Acyclic Sugar Alcohols Ribitol, Xylitol and d-Arabitol by Solution NMR and Molecular Dynamics Simulations.

Ribitol (C5H12O5) is an acyclic sugar alcohol that was recently identified in O-mannose glycan on mammalian α-dystroglycan. The conformation and dynamics of acyclic sugar alcohols such as ribitol are dependent on the stereochemistry of the hydroxyl groups; however, the dynamics are not fully understood. To gain insights into the conformation and dynamics of sugar alcohols, we carried out comparative analyses of ribitol, d-arabitol and xylitol by a crystal structure database search, solution NMR analysis and molecular dynamics (MD) simulations. The crystal structures of the sugar alcohols showed a limited number of conformations, suggesting that only certain stable conformations are prevalent among all possible conformations. The three-bond scholar coupling constants and exchange rates of hydroxyl protons were measured to obtain information on the backbone torsion angle and possible hydrogen bonding of each hydroxyl group. The 100 ns MD simulations indicate that the ribitol backbone has frequent conformational transitions with torsion angles between 180∘ and ±60∘, while d-arabitol and xylitol showed fewer conformational transitions. Taking our experimental and computational data together, it can be concluded that ribitol is more flexible than d-arabitol or xylitol, and the flexibility is at least in part defined by the configuration of the OH groups, which may form intramolecular hydrogen bonds.

Nanopore analysis of cis-diols in fruits.

Natural fruits contain a large variety of cis-diols. However, due to the lack of a high-resolution sensor that can simultaneously identify all cis-diols without a need of complex sample pretreatment, direct and rapid analysis of fruits in a hand-held device has never been previously reported. Nanopore, a versatile single molecule sensor, can be specially engineered to perform this task. A hetero-octameric Mycobacterium smegmatis porin A (MspA) nanopore modified with a sole phenylboronic acid (PBA) adapter is prepared. This engineered MspA accurately recognizes 1,2-diphenols, alditols, α-hydroxy acids and saccharides in prune, grape, lemon, different varieties of kiwifruits and commercial juice products. Assisted with a custom machine learning program, an accuracy of 99.3% is reported and the sample pretreatment is significantly simplified. Enantiomers such as DL-malic acids can also be directly identified, enabling sensing of synthetic food additives. Though demonstrated with fruits, these results suggest wide applications of nanopore in food and drug administration uses.

Structural Elucidation of Sialylated O-Glycan Alditols Obtained from Mucins by Mass Spectrometry.

Acidic O-glycans having sialic acid and/or sulfate residue are abundantly expressed in intestinal mucins. However, structural elucidation of acidic O-glycans is a laborious and time-consuming task due to their large structural variations. Here, we describe a methodology of structural elucidation for sialylated O-glycan alditols from intestinal mucins using tandem mass spectroscopy. Methylesterification and mild periodate oxidation of sialylated O-glycan alditols assist mass analysis. This description includes the purification process of O-glycan alditols for structural analysis.

The important role of starch fine molecular structures in starch gelatinization property with addition of sugars/sugar alcohols.

The relationship between the fine structure of starch and its gelatinization properties is not well studied, particularly in relation to the influence of sugar or sugar alcohol. In this study, seven starches with distinct molecular structures were investigated to determine how different sugars and sugar alcohols affect their gelatinization properties. The inclusion of sugars and sugar alcohols resulted in a significant elevation of starch gelatinization temperatures (∼ 8 °C), especially with sucrose, isomaltose and isomalt. Nevertheless, the influence of these sugars/ sugar alcohols on the gelatinization temperature range and enthalpy change varied depending on the particular starch varieties. According to the correlation analysis, sugars and sugar alcohols mainly exert their impact on the starch gelatinization temperature range and enthalpy change by possibly interacting with amylose chains possessing a degree of polymerization ranging from 100 to 1000 (p < 0.05) and inhibiting the amylose leaching during gelatinization. These findings help a better understanding of the complex relationship between starch fine structure and gelatinization properties under the influence of sugars and sugar alcohols.

Discovery and biochemical characterization of thermostable glycerol oxidases.

Alditol oxidases are promising tools for the biocatalytic oxidation of glycerol to more valuable chemicals. By integrating in silico bioprospecting with cell-free protein synthesis and activity screening, an effective pipeline was developed to rapidly identify enzymes that are active on glycerol. Three thermostable alditol oxidases from Actinobacteria Bacterium, Streptomyces thermoviolaceus, and Thermostaphylospora chromogena active on glycerol were discovered. The characterization of these three flavoenzymes demonstrated their glycerol oxidation activities, preference for alkaline conditions, and excellent thermostabilities with melting temperatures higher than 75 °C. Structural elucidation of the alditol oxidase from Actinobacteria Bacterium highlighted a constellation of side chains that engage the substrate through several hydrogen bonds, a histidine residue covalently bound to the FAD prosthetic group, and a tunnel leading to the active site. Upon computational simulations of substrate binding, a double mutant targeting a residue pair at the tunnel entrance was created and found to display an improved thermal stability and catalytic efficiency for glycerol oxidation. The hereby described alditol oxidases form a valuable panel of oxidative biocatalysts that can perform regioselective oxidation of glycerol and other polyols. KEY POINTS: • Rapid pipeline designed to identify putative oxidases • Biochemical and structural characterization of alditol oxidases • Glycerol oxidation to more valuable derivatives.

Synergistic Cytotoxicity of Extracts of Chaga Mushroom and Microalgae against Mammalian Cancer Cells In Vitro.

Chaga mushroom (Inonotus obliquus) contains bioactive metabolites and has been used to treat various ailments, including cancer. Similarly, marine microalgae are considered a sustainable food supplement with anticancer and antioxidant properties. This study investigated the cytotoxicity of different extracts prepared from I. obliquus and microalgae using cultured human and canine cancer cell lines (MCF-7, HepG2, HOS, D-17, and DH-82). MTS cell viability assay was used to study the cytotoxicity of I. obliquus and microalgae extracts, and a synergy matrix effect was used to study the combined effect of the extracts. Isobologram analysis and the highest single agent synergy model were applied to study and validate the synergy between the extracts from I. obliquus and microalgae. Ethanol-based extraction and supercritical water extract significantly inhibited the growth of various mammalian cancer cells compared to aqueous extracts. Osteosarcoma cells were more susceptible to the supercritical extracts of I. obliquus and chlorophyll-free and sugar-free ethanol extracts of microalgae. A combination of ethanol-based I. obliquus extract and chlorophyll-free microalgae extract resulted in a synergistic interaction with various tested cancer cells. This study provides experimental evidence supporting the potential therapeutic application of I. obliquus and microalgae extracts with a synergistic effect to inhibit the growth of various mammalian cancer cells. Additional in vivo studies are required to fully explore possible therapeutic applications of these unique mixtures to be used in treating cancers.

Synthesis, structural study and antitumor activity of novel alditol-based imidazophenanthrolines (aldo-IPs).

A series of 1H-imidazo [4,5-f][1,10] phenanthroline derivatives functionalized at 2-position with chiral, and conformationally flexible polyhydroxy alkyl chains derived from carbohydrates (alditol-based imidazophenanthrolines, aldo-IPs) is presented herein. These novel glycomimetics showed relevant and differential cytotoxic activity against several cultured tumor cell lines (PC3, HeLa and HT-29), dependent on the nature and stereochemistry of the polyhydroxy alkyl chain. The mannose-based aldo-IP demonstrated the higher cytotoxicity in the series, substantially better than cisplatin metallo-drug in all cell lines tested, and better than G-quadruplex ligand 360A in HeLa and HT29 cells. Cell cycle experiments and Annexin V-PI assays revealed that aldo-IPs induce apoptosis in HeLa cells. Initial study of DNA interactions by DNA FRET melting assays proved that the aldo-IPs produce only a slight thermal stabilization of DNA secondary structures, more pronounced in the case of quadruplex DNA. Viscosity titrations with CT dsDNA suggest that the compounds behave as DNA groove binders, whereas equilibrium dialysis assays showed that the compounds bind CT with Ka values in the range 104-105 M-1. The aldo-IP derivatives were obtained with synthetically useful yields through a feasible one-pot multistep process, by aerobic oxidative cyclization of 1,10-phenanthroline-5,6-diamine with a selection of unprotected aldoses using (NH4)2SO4 as promoter.

Effect of black wolfberry anthocyanin and maltitol on the gelation and microstructural properties of curdlan/gellan gum hybrid gels.

BACKGROUND: Laboratory scale experiments have shown that curdlan and gellan gum gelled together as curdlan/gellan gum (CG) hybrid gels showed better gel properties than the individual curdlan and gellan gum. In this study, CG and black wolfberry anthocyanin (BWA), CG and maltitol (ML) hybrid gels were constructed using CG hybrid gel as matrix. The effects of BWA or ML on the gel properties and microstructure of CG hybrid gels were investigated and a confectionery gel was developed. RESULTS: The presence of BWA increased the storage modulus (G') value of CG at 0.1 Hz, whereas ML had little effect on the G' value of CG. The addition of BWA (5 g L-1 ) and ML (0.3 mol L-1 ) increased the melting and gelling temperatures of CG hybrid gels to 42.4 °C and 34.1 °C and 44.2 °C and 33.2 °C, respectively. Meanwhile, the relaxation time T22 in CG-ML and CG-BWA hybrid gels was reduced to 91.96 and 410.27 ms, indicating the strong binding between BWA and CG, ML and CG. The hydrogen bond interaction between BWA or ML and CG was confirmed by the shift in the hydroxyl stretching vibration peak. Moreover, the microstructures of CG-ML and CG-BWA hybrid gels were denser than that of CG. In addition, confectionery gel containing CG-BWA-ML has good chewing properties. CONCLUSION: These results indicated that the incorporation of BWA or ML could improve the structure of CG hybrid gels and assign a sustainability potential for the development of confectionery gels based on CG complex. © 2024 Society of Chemical Industry.

Sustainable bio-manufacturing of D-arabitol through combinatorial engineering of Zygosaccharomyces rouxii, bioprocess optimization and downstream separation.

Biosynthesis of D-arabitol, a high value-added platform chemical, from renewable carbon sources provides a sustainable and eco-friendly alternative to the chemical industry. Here, a robust brewing yeast, Zygosaccharomyces rouxii, capable of naturally producing D-arabitol was rewired through genome sequencing-based metabolic engineering. The recombinant Z. rouxii obtained by reinforcing the native D-xylulose pathway, improving reductive power of the rate-limiting step, and inhibiting the shunt pathway, produced 73.61% higher D-arabitol than the parent strain. Subsequently, optimization of the fermentation medium composition for the engineered strain provided 137.36 g/L D-arabitol, with a productivity of 0.64 g/L/h in a fed-batch experiment. Finally, the downstream separation of D-arabitol from the complex fermentation broth using an ethanol precipitation method provided a purity of 96.53%. This study highlights the importance of D-xylulose pathway modification in D-arabitol biosynthesis, and pave a complete and efficient way for the sustainable manufacturing of this value-added compound from biosynthesis to preparation.

Tailoring the optical and mechanical properties of cellulose nanocrystal film by sugar alcohols and its pH/humidity-responsive behavior.

Cellulose nanocrystals (CNC) have gained widespread attention in intelligent food packaging because of their iridescent optical properties. Here, we report a CNC composite film employing CNC, sugar alcohols (e.g., maltol, erythritol, mannitol, sorbitol, and xylitol) and natural pigment anthocyanins, which has a special iridescent color that can be used as a pH and humidity sensor. The effects of five sugar alcohols with different addition ratios on the structural, optical, and mechanical properties of the CNC films were investigated. The results demonstrated that the addition of sugar alcohol made composite films exhibiting a red-shift of λmax, a more uniform color in visual observation, and a larger pitch. Among them, the CNC-mannitol composite film with a ratio of 10:1 exhibited the best mechanical properties, possessing a tensile stress strength of 57 MPa and toughness of 137 J/m3. Subsequently, anthocyanins were incorporated to this composite film, which showed a marked color change along with the pH from 2 to 12 and exhibited a reversible color change from red to transparent upon a relative humidity change from 35 % to 85 %. Overall, such multi-environment-responsive iridescent films with excellent mechanical properties have a great potential for use in intelligent food packaging applications.