A multi-platform approach for the comprehensive analysis of per- and polyfluoroalkyl substances (PFAS) and fluorine mass balance in commercial ski wax products.

The unique properties of per- and polyfluoroalkyl substances (PFAS) have led to their extensive use in consumer products, including ski wax. Based on the risks associated with PFAS, and to align with PFAS regulations, the international ski federation (FIS) implemented a ban on products containing "C8 fluorocarbons/perfluorooctanoate (PFOA)" at all FIS events from the 2021/2022 season, leading manufactures to shift their formulations towards short-chain PFAS chemistries. To date, most studies characterising PFAS in ski waxes have measured a suite of individual substances using targeted analytical approaches. However, the fraction of total fluorine (TF) in the wax accounted for by these substances remains unclear. In this study, we sought to address this question by applying a multi-platform, fluorine mass balance approach to a total of 10 commercially available ski wax products. Analysis of TF by combustion ion chromatography (CIC) revealed concentrations of 1040-51700 µg F g-1 for the different fluorinated waxes. In comparison, extractable organic fluorine (EOF) determined in methanol extracts by CIC (and later confirmed by inductively-coupled plasma-mass spectrometry and 19F- nuclear magnetic resonance spectroscopy) ranged from 92 to 3160 µg g-1, accounting for only 3-8.8 % of total fluorine (TF). Further characterisation of extracts by cyclic ion mobility-mass spectrometry (IMS) revealed 15 individual PFAS with perfluoroalkyl carboxylic acid concentrations up to 33 µg F g-1, and 3 products exceeding the regulatory limit for PFOA (0.025 µg g-1) by a factor of up to 100. The sum of all PFAS accounted for only 0.01-1.0 % of EOF, implying a high percentage of unidentified PFAS, thus, pyrolysis gas chromatography-mass spectrometry was used to provide evidence of the nature of the non-extractable fluorine present in the ski wax products.

Mechanical properties of wax-oleogels: Assessing their potential to mimic commercial margarine functionality under small and large deformations.

Utilizing waxes to gel oils presents a viable approach for diminishing trans and saturated fat levels in commercial fats such as margarines. This technique ensures that oleogels mimic traditional fats in terms of rheological properties, oil-binding capacity, and overall structure. Our study employed cooling-shear rates to finely adjust physical characteristics, evaluating rheology via SAOS-LAOS, oil retention, and crystal structure of wax oleogels, compared against commercial margarines as benchmarks. Findings indicate that wax oleogels, under specific cooling/shear conditions, exhibit softer yet more ductile-like behavior, akin to margarine, while retaining oil effectively. This similarity is evidenced through Lissajous curves and plastic dissipation ratio during yielding, reflecting a ductile yielding response characterized by square-like Lissajous curves and a plastic dissipation ratio index approximating one. Although these crystallization conditions influence the mechanical properties of wax oleogels, they do not alter oil losses or wax characteristics.

Chitosan-based nanocomposite films with carnauba wax, rosin resin, and zinc oxide nanoparticles.

This work aimed to develop edible emulsion-based barriers in the form of chitosan composite films, with a focus on assessing the impacts of carnauba wax, rosin resin, and zinc oxide nanoparticles on their properties. Six films were produced by casting using chitosan as polymer base and glycerol as plasticizer. Acetic acid and polysorbate 80 were also used to facilitate the dissolution and mixing of the components. The six filmogenic solutions contained chitosan at 1.2% w/v, wax or resin content with 0 or 0.6% m/v and ZnO with 0 or 0.05% m/v. The dried films were characterized according to their chemical, barrier, mechanical, thermal and optical properties. All treatments resulted in flexible films. Chitosan films appeared smoother and more uniform under SEM imaging, while carnauba wax films displayed roughness due to their hydrophobic nature. Wax and resin films were less transparent and water soluble than the chitosan-only films. On the other hand, the addition of ZnO in the formulations increased the solubility of the films. The sorption degree was in line with the solubility results, i.e., films with ZnO presented higher sorption degree and solubility values. All treatments showed low or non-light UV transmission, indicating that the films provide good barrier to UV light. In the visible light region, films of resin with ZnO showed the lowest transmittance values, hence offering a good barrier to visible light. Among the evaluated films, chitosan, and resin films with ZnO nanoparticles were more rigid and resistant to deformation. Overall, films produced with rosin resin and ZnO nanoparticles showed potential improvements in barrier, mechanical, thermal, and optical properties, mainly due to their low water solubility, good UV protection and low permeability to water vapor and oxygen, which are suitable for using in formulations, intended to produce edible films and coatings.

Preparation and application of hydroxypropyl methylcellulose blended with beeswax and essential oil edible coating to enhance the shelf life of sweet cherries.

The study involved preparing and applying edible nano-emulsion coatings containing hydroxypropyl methylcellulose (HPMC), beeswax (BW), and essential oils (thyme, cinnamon, clove, and peppermint) onto sweet cherries. The application was conducted at 4 °C, and the coated cherries were stored for 36 days. This research examines synthesized nano-emulsions physicochemical properties and antibacterial and antifungal activities (C1, C2, and C3). Additionally, it evaluates the quality parameters of control and coated sweet cherry samples. The features of the three edible coatings were assessed, and the findings from the zeta sizer, zeta potential, FTIR, and SEM analyses were deemed satisfactory. It was observed that the application of nano-emulsion coating C1 yielded positive results in maintaining quality attributes such as total suspended solids (TSS), total solids (TS), color, weight loss, respiration rate, firmness, total phenolic contents, and sensory evaluations. Nano-emulsion coating C1 demonstrated efficacy as an antibacterial and antifungal agent against foodborne pathogens E. coli and A. niger, respectively. The current research results are promising and applicable in food industries. The implications suggest that composite nano-emulsion, specifically nano-emulsion edible coatings, can be extensively and effectively used to preserve the quality and shelf life of fruits and vegetables. Furthermore, the environmental waste from conventional food packaging will be minimized using edible packaging applications.

A cost-effective and facile technique for realizing fabric based microfluidic channels using beeswax and PVC stencils.

Microfluidic channels fabricated over fabrics or papers have the potential to find substantial application in the next generation of wearable healthcare monitoring systems. The present work focuses on the fabrication procedures that can be used to obtain practically realizable fabric-based microfluidic channels (µFADs) utilizing patterning masks and wax, unlike conventional printing techniques. In this study, comparative analysis was used to differentiate channels obtained using different masking tools for channel patterning as well as different wax materials as hydrophobic barriers. Drawbacks of the conventional tape and candle wax technique were noted and a novel approach was used to create microfluidic channels through a facile and simple masking technique using PVC clear sheets as channel stencils and beeswax as the channel barriers. The resulting fabric based microfluidic channels with varying widths as well as complex microchannel, microwell, and micromixer designs were investigated and a minimum channel width resolution of 500 µm was successfully obtained over cotton based fabrics. Thereafter, the PVC clear sheet-beeswax based microwells were successfully tested to confine various organic and inorganic samples indicating vivid applicability of the technique. Finally, the microwells were used to make a simple and facile colorimetric assay for glucose detection and demonstrated effective detection of glucose levels from 10 mM to 50 mM with significant color variation using potassium iodide as the coloring agent. The above findings clearly suggest the potential of this alternative technique for making low-cost and practically realizable fabric based diagnostic devices (µFADs) in contrast to the other approaches that are currently in use.

Hydrophobic polyethylene film prepared by film blowing process for preservation of fried shrimp rolls.

Hydrophobic coatings have wide applications, but face challenges in food flexible packaging in terms of poor adhesion and inadequate wear resistance. Health hazards and poor adhesion drive the search for novel hydrophobic coatings substitutes. Here, we introduced rationally synthesized carnauba wax-SiO2 microspheres as a component to composite polyethylene (PE) film construction, and created a wear-resistant hydrophobic composite PE film via the blown film technique. The resultant hydrophobic composite film demonstrated an enhanced water contact angle from 86° to above 100°, coupled with favorable mechanical properties such as wear resistance, tensile strength and effective barrier performance against water vapor and oxygen. Upon implementation in the preservation of a Cantonese delicacy, Chaoshan fried shrimp rolls, it was observed that at 25 °C, the carnauba wax-SiO2-PE composite packaging film extended the shelf life of the product by 3 days compared to pure PE film.

BrBCAT1 mutation resulted in deficiency of epicuticular wax crystal in Chinese cabbage.

KEY MESSAGE: BrBCAT1 encoding a branched-chain amino acid aminotransferase was responsible for the glossy trait, which was verified by allelic mutants in Chinese cabbage. The glossy characteristic, thanks to the epicuticular wax crystal deficiency, is an excellent commodity character for leafy vegetables. Herein, two allelic glossy green mutants, wdm11 and wdm12, were isolated from an ethyl methane sulfonate (EMS)-mutagenized population of Chinese cabbage, and the mutant phenotype was recessive inherited. Cryo-SEM detected that epicuticular wax crystal in the mutant leaves was virtually absent. MutMap and Kompetitive allele-specific PCR analyses demonstrated that BraA06g006950.3C (BrBCAT1), homologous to AtBCAT1, encoding a branched-chain amino acid aminotransferase was the candidate gene. A SNP (G to A) on the fourth exon of BrBCAT1 in wdm11 caused the 233rd amino acid to change from glycine (G) to aspartic acid (D). A SNP (G to A) on the second exon of BrBCAT1 in wdm12 led to the 112th amino acid change from glycine (G) to arginine (R). Both of the allelic mutants had genetic structural variation in the candidate gene, which indicated that the mutant phenotype was triggered by the BrBCAT1 mutation. The expression levels of BrBCAT1 and genes related to fatty acid chain extension were decreased significantly in the mutant compared to the wild-type, which might result in epicuticular wax crystal deficiency in the mutants. Our findings proved that the mutation of BrBCAT1 induced the glossy phenotype and provided a valuable gene resource for commodity character improvement in Chinese cabbage.

Novel pH- and thermal-responsive oleogel capsules: Featuring an oleogel core and ultrathin calcium-alginate shell.

Oleogels have been explored as a new lipid-based delivery system, however, their insolubility and unsuitable shape severely limit their application in food systems. Herein, core-shell oleogel capsules with high monodispersity (coefficient variation (CV) < 5%)) were prepared via gravity-assisted co-flowing microfluidic device and simply air-drying. The oleogel capsules with oleogel core and ultrathin calcium-alginate shell were prepared. Oleogel capsules maintained their original shape at pH = 2.0 but swelled rapidly at pH = 6.8 and 7.4. The swelling ratio of shell can be adjusted by inner fluid flow rate (Qin). Notably, the core with beeswax (BW) crystal network, effectively improved the stability performances and also could provide thermal response. Finally, the oleogel capsules demonstrated excellent sustained release and UV protection of lipophilic bioactives. This work sheds light on development of novel oleogel capsules, making them ideal candidates for smart food encapsulation applications.

The gelation characteristics of Torreya grandis wax in diacylglycerol and its preparation of oleogel substitution for shortening.

Torreya grandis wax (TGW), a new nut wax and by-product of refined Torreya grandis oil, lacks sufficient research and application. In this study, the gelling behavior in diacylglycerol (DAG) and chemical compositions of TGW were investigated. Compared with four typical natural waxes, TGW exhibited the lowest critical gelling concentration (Cg, 1 %wt) in DAG. The results performed that TGW-DAG oleogels at Cg possessed the highest G'LVR and G″, highest critical stress, good thermal stability, moderate viscosity recovery, and osc. yields stress, indicating strong gel. The microstructure and correlation analysis revealed that excellent gelling behaviors of TGW-DAG oleogels were due to the solid three-dimensional network formed by rod-like TGW crystal, and the higher hydrocarbon compound (HC) content and HC/wax ester in TGW. Formulation optimization suggested that oleogel containing 3.2 % TGW and 1.0 % diosgenin (DSG) better mimicked the characteristics of shortening in terms of hardness, adhesiveness, spreadability. The bread prepared with TGW/DSG-DAG oleogel owned uniform and dense pores, the best moisture retention capability, and soft and firm taste, demonstrating that TGW/DSG-DAG oleogel was a good shortening substitute. Therefore, this study provides the systematically fundamental knowledge of TGW and develops DSG-TGW-DAG oleogels as promising shortening substitutions.

The cuticular wax composition and crystal coverage of leaves and petals differ in a consistent manner between plant species.

Both leaves and petals are covered in a cuticle, which itself contains and is covered by cuticular waxes. The waxes perform various roles in plants' lives, and the cuticular composition of leaves has received much attention. To date, the cuticular composition of petals has been largely ignored. Being the outermost boundary between the plant and the environment, the cuticle is the first point of contact between a flower and a pollinator, yet we know little about how plant-pollinator interactions shape its chemical composition. Here, we investigate the general structure and composition of floral cuticular waxes by analysing the cuticular composition of leaves and petals of 49 plant species, representing 19 orders and 27 families. We show that the flowers of plants from across the phylogenetic range are nearly devoid of wax crystals and that the total wax load of leaves in 90% of the species is higher than that of petals. The proportion of alkanes is higher, and the chain lengths of the aliphatic compounds are shorter in petals than in leaves. We argue these differences are a result of adaptation to the different roles leaves and petals play in plant biology.

Fungicidal Activity of New Pyrrolo[2,3-d]thiazoles and Their Potential Action on the Tryptophan Metabolic Pathway and Wax Biosynthesis.

The main challenge in the development of agrochemicals is the lack of new leads and/or targets. It is critical to discover new molecular targets and their corresponding ligands. YZK-C22, which contains a 1,2,3-thiadiazol-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole skeleton, is a fungicide lead compound with broad-spectrum fungicidal activity. Previous studies suggested that the [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole scaffold exhibited good antifungal activity. Inspired by this, a series of pyrrolo[2,3-d]thiazole derivatives were designed and synthesized through a bioisosteric strategy. Compounds C1, C9, and C20 were found to be more active against Rhizoctonia solani than the positive control YZK-C22. More than half of the target compounds provided favorable activity against Botrytis cinerea, where the EC50 values of compounds C4, C6, C8, C10, and C20 varied from 1.17 to 1.77 µg/mL. Surface plasmon resonance and molecular docking suggested that in vitro potent compounds C9 and C20 have a new mode of action instead of acting as pyruvate kinase inhibitors. Transcriptome analysis revealed that compound C20 can impact the tryptophan metabolic pathway, cutin, suberin, and wax biosynthesis of B. cinerea. Overall, pyrrolo[2,3-d]thiazole is discovered as a new fungicidal lead structure with a potential new mode of action for further exploration.

Relationship between skin greasiness and cuticular wax in harvested "Hongro" apples.

We investigated the ripening and skin greasiness of "Hongro" apples during storage at 20 °C. Postharvest treatment using 100 µLL-1 ethylene accelerated ripening and increased greasiness, whereas treatment using 1 µLL-1 1-methylcyclopropene delayed ripening and reduced greasiness. Scanning electron microscopy showed changes in cuticular wax structure linked to greasiness. Metabolic analysis identified specific metabolites related to greasiness, which varied upon postharvest treatment. Greasiness was positively associated with ethylene production and butyl-9,12-octadecadienoate content. Random forest modeling predicted greasiness levels with high accuracy, with root mean square error values of 0.322 and 0.362 for training and validation datasets, respectively. These findings illuminate the complex interplay between postharvest treatment, apple ripening, wax composition, and skin greasiness. The application of predictive models exemplifies the potential for technology-driven approaches in agriculture and aids in the development of postharvest strategies to control greasiness and maintain fruit quality.

Microstructural and physicochemical quality maintenance in green bell pepper infected with Botrytis cinerea and treated with thyme essential oil combined with carnauba wax.

Bell pepper presents rapid weight loss and is highly susceptible to gray mold caused by the fungus Botrytis cinerea. The most employed method to control this disease is the application of synthetic fungicides such as thiabendazole (TBZ); however, its continued use causes resistance in fungi as well as environmental problems. For these reasons, natural alternatives arise as a more striking option. Currently, bell pepper fruits are coated with carnauba wax (CW) to prevent weight loss and improve appearance. Moreover, CW can be used as a carrier to incorporate essential oils, and previous studies have shown that thyme essential oil (TEO) is highly effective against B. cinerea. Therefore, this study aimed to evaluate the effect of CW combined with TEO on the development of gray mold and maintenance of microestructural and postharvest quality in bell pepper stored at 13°C. The minimal inhibitory concentration of TEO was 0.5%. TEO and TBZ provoked the leakage of intracellular components. TEO and CW + TEO treatments were equally effective to inhibit the development of gray mold. On the quality parameters, firmness and weight loss were ameliorated with CW and CW + TEO treatments; whereas lightness increased in these treatments. The structural analysis showed that CW + TEO treatment maintained the cell structure reducing the apparition of deformities. The results suggest that CW + TEO treatment could be used as a natural and effective antifungal retarding the appearance of gray mold and maintaining the postharvest quality of bell pepper. PRACTICAL APPLICATION: CW and TEO are classified as generally recognized as safe (GRAS) by the US Food and Drug Administration (FDA). This combination can be employed on the bell pepper packaging system to extend shelf life and oppose gray mold developments. Bell pepper fruits are normally coated with lipid-base coatings such as CW before commercialization; therefore, TEO addition would represent a small investment without any changes on the packaging system infrastructure.

Cuticle properties, wax composition, and crystal morphology of Hami melon cultivars (Cucumis melo L.) with differential resistance to fruit softening.

Cuticle wax chemicals are cultivar-dependent and contribute to storage quality. Few research reported on wax analysis between melting flesh-type (MF; 'Jinhuami 25') and nonmelting flesh-type (NMF; 'Xizhoumi 17' and 'Chougua') Hami melons. Chemicals and crystal structures of Hami melon cuticular wax, cell wall metabolism related to fruit melting, and fruit physiology were analyzed to observe wax functions. Results showed that Hami melon cuticle wax predominantly consists of esters, alkanes, alcohols, aldehydes, and terpenoids. MF-type has a lower alkane/terpenoid ratio, concomitant to its higher weight loss and cuticle permeability. Micromorphology of wax crystals appears as numerous platelets with irregular crystals, and the transformation of wax structure in NMF Hami melon is delayed. Waxy components affect cell wall metabolism and physiological quality, which results in the pulp texture difference between MF-type and NMF-type during storage. Results provide a reference for the regulation of wax synthesis in both types of melons.

Effect of mango butter on the physicochemical properties of beeswax-Moringa seed oil-based oleogels for topical application.

OBJECTIVE: The purpose of this research was to determine any connections between the characteristics of oleogels made of beeswax and the impact of mango butter. METHODS: Oleogel was prepared through inverted tube methods, and optimized through oil binding capacity. Other evaluations like bright field and polarized microscopy, Fourier-transform infrared (FTIR) spectroscopy, crystallization kinetics, mechanical study, and X-ray diffractometry (XRD). The drug release kinetic studies and in vitro antibacterial studies were performed. RESULTS: FTIR study reveals that the gelation process does not significantly alter the chemical composition of the individual components. Prepared gel exhibiting fluid-like behavior or composed of brittle networks is particularly vulnerable to disruptions in their network design. The incorporation of mango butter increases the drug permeation. In-vitro microbial efficacy study was found to be excellent. CONCLUSION: The studies revealed that mango butter can be used to modify the physico-chemical properties of the oleogels.

Impact of binary mixtures of natural waxes in mechanical properties and microstructure of oleogels.

BACKGROUND: Solid fats are critical to obtaining a wide range of food texture and quality characteristics, but their consumption is strongly associated with higher cardiovascular disease risks. Structuring unsaturated oils with natural waxes into oleogels (OG) is an innovative solution to develop fat mimics with a healthier profile. RESULTS: Soy wax (SW), beeswax (BW) and carnauba wax (CW), have been used in binary mixtures of waxes, aiming to understand their interactions and influence on OG quality properties and microstructural characteristics. In the present study, OGs were produced using binary wax mixtures and analyzed for texture, color, smoke point, microstructure, Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Wax combinations led to antagonistic (mixtures with SW) and synergistic interactions (BW/CW) based on their mechanical properties. At the microstructural level BW/CW blends showed a reduction in crystal size and with a more compact structure. XRD and FTIR spectra revealed a packing of orthorhombic perpendicular subcell for most OGs, whereas SW produced samples with an arrangement with ß' crystals, characteristic of edible solid fats. Additionally, when compared to commercial beef fat, BW/CW mixtures showed similar quality attributes indicating that they could act as fat mimic. CONCLUSION: The combined analysis of microstructure, spectroscopic and mechanical properties enhanced the understanding of how the nature of the interactions between waxes and lipid phases impact in the final quality of the structured oils. The study's insights indicate that binary wax combinations can efficiently replace solid fats, offering healthier alternatives at the same time as preserving desired sensory characteristics. © 2024 Society of Chemical Industry.

Feasibility of replacing waxy rice with waxy or sweet-waxy corn viewed from the structure and physicochemical properties of starches.

To explore the feasibility of substituting waxy rice with waxy or sweet-waxy corn, eight varieties of waxy and sweet-waxy corns were selected, including three self-cultivated varieties (Feng nuo 168, Feng nuo 211, and Feng nuo 10). Their starches were isolated and used as research objects, and commercially available waxy rice starch (CAWR) and waxy corn starch (CAWC) were used as controls. X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, rapid viscosity analyzer, and rotational rheometer were used to analyze their physicochemical and structural characteristics. The morphologies of all corn starch granules were generally oval or round, with significant differences in particle size distributions. All ten starches exhibited a typical A-type crystal structure; however, their relative crystallinity varied from 20.08% to 31.43%. Chain length distribution analysis showed that the A/B ratio of Jing cai tian nuo 18 and Feng nuo 168 was similar to that of CAWR. Peak viscosities of corn starches were higher than that of CAWR, except for Feng nuo 10, while their setback values were lower than that of CAWR. Except for Feng nuo 10, the paste transparency of corn starches was higher than that of CAWR (10.77%), especially for Jing cai tian nuo 18 (up to 24%). In summary, Jing cai tian nuo 18 and Feng nuo 168 are promising candidates to replace CAWR in developing various rice-based products.

Another Brick in the Wall of Tear Film Insights Added Through the Total Synthesis and Biophysical Profiling of anteiso-Branched Wax and Cholesteryl Esters.

The tear film lipid layer (TFLL) plays a vital part in maintenance of ocular health and represents a unique biological barrier comprising unusual and specialized lipid classes and species. The wax and cholesteryl esters (WEs and CEs) constitute roughly 80-90% of the TFLL. The majority of species in these lipid classes are branched and it is therefore surprising that the synthesis and properties of the second largest category of species, i.e., the anteiso-branched species, remain poorly characterized. In this study, we have developed a total synthesis route and completed a detailed NMR spectroscopic characterization of two common anteiso-branched species, namely: (22S)-22-methyltetracosanyl oleate and cholesteryl (22'S)-22'-methyltetracosanoate. In addition, we have studied their structural properties in the bulk state by wide-angle and small-angle X-ray scattering and their behavior at the aqueous interface using Langmuir monolayer techniques. A comparison to the properties displayed by iso-branched and straight-chain analogues indicate that branching patterns lead to distinct properties in the CE and WE lipid classes. Overall, this study complements the previous work in the field and adds another important brick in the tear film insights wall.

Contaminant dynamics in honey bees and hive products of apiaries from environmentally contrasting Argentinean regions.

Argentina is a leading honey producer and honey bees are also critical for pollination services and wild plants. At the same time, it is a major crop producer with significant use of insecticides, posing risks to bees. Therefore, the presence of the highly toxic insecticide chlorpyrifos, and forbidden contaminants (organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs)) was investigated in honey bee, beebread, wax and honey samples in apiaries from three contrasting regions of Argentina. Chlorpyrifos was detected in all samples with higher levels during period 1 (spring) in contrast to period 2 (fall), agreeing with its season-wise use in different crops, reaching 3.05 ng/g in honey bees. A subsequent first-tier pesticide hazard analysis revealed that it was relevant to honey bee health, mainly due to the high concentrations found in wax samples from two sites, reaching 132.4 ng/g. In addition, wax was found to be the most contaminated matrix with a prevalence of OCPs (∑OCPs 58.23-172.99 ng/g). Beebread samples showed the highest concentrations and diversity of pesticide residues during period 1 (higher temperatures). A predominance of the endosulfan group was registered in most samples, consistent with its intensive past use, especially in Central Patagonia before its prohibition. Among the industrial compounds, lighter PCB congeners dominated, suggesting the importance of atmospheric transport. The spatio-temporal distribution of pesticides shows a congruence with the environmental characteristics of the areas where the fields are located (i.e., land use, type of productive activities and climatic conditions). Sustained monitoring of different pollutants in beekeeping matrices is recommended to characterize chemical risks, assess the health status of honey bee hives and the pollution levels of different agroecosystems. This knowledge will set a precedent for South America and be helpful for actions focused on the conservation of pollination services, apiculture and ecosystems in Argentina.

Effects of exogenous salicylic acid on starch physicochemical properties and in vitro digestion under heat stress during the grain-filling stage in waxy maize.

Waxy maize starch serves as a pivotal component in global food processing and industrial applications, while high temperature (HT) during the grain-filling stage seriously affects its quality. Salicylic acid (SA) has been recognized for its role in enhancing plant heat resistance. Nonetheless, its regulatory effect on the quality of waxy maize starch under HT conditions remains unclear. In this study, two waxy maize varieties, JKN2000 (heat-tolerant) and SYN5 (heat-sensitive) were treated with SA after pollination and then subjected to HT during the grain-filling stage to explore the effect of SA on grain yield and starch quality. The results indicate that exogenous SA under HT treatment led to an increase in kernel weight and starch content in both varieties. Moreover, SA reduced the HT-induced holes on the surfaces of starch granules, enlarged the starch granule size, elevated the amylopectin branching degree, and reduced amylopectin average chain length. Consequently, improvements of pasting viscosity and the decrease of retrogradation percentage of starch were observed with SA under HT. Exogenous SA reduced HT-induced rapidly digestible starch content in SYN5, but had no significant effect on that in JKN2000. In summary, SA pretreatment effectively alleviated the detrimental effects of HT on starch pasting and thermal properties of waxy maize.