Sanitization of hydroponic farming facilities in Singapore: what, why, and how.

This study performed microbial analysis of nutrient film technique (NFT) hydroponic systems on three indoor farms in Singapore (the "what"). To justify the necessity of sanitizing hydroponic systems, strong biofilm-forming bacteria were isolated from the facility and investigated for their influence on Salmonella colonization on polyvinyl chloride (PVC) coupons in hydroponic nutrient solutions (the "why"). Finally, sanitization solutions were evaluated with both laboratory-scale and field-scale tests (the "how"). As a result, the microbiome composition in NFT systems was found to be highly farm specific. The strong biofilm formers Corynebacterium tuberculostearicum C2 and Pseudoxanthomonas mexicana C3 were found to facilitate the attachment and colonization of Salmonella on PVC coupons. When forming dual-species biofilms, the presence of C2 and C3 also significantly promoted the growth of Salmonella (P < 0.05). Compared with hydrogen peroxide (H2O2) and sodium percarbonate (SPC), sodium hypochlorite (NaOCl) exhibited superior efficacy in biofilm removal. At 50 ppm, NaOCl reduced the Salmonella Typhimurium, C2, and C3 counts to <1 log CFU/cm2 within 12 h, whereas neither 3% H2O2 nor 1% SPC achieved this effect. In operational hydroponic systems, the concentration of NaOCl needed to achieve biofilm elimination increased to 500 ppm, likely due to the presence of organic matter accumulated during crop cultivation and the greater persistence of naturally formed multispecies biofilms. Sanitization using 500 ppm NaOCl for 12 h did not impede subsequent plant growth, but chlorination byproduct chlorate was detected at high levels in the hydroponic solution and in plants in the sanitized systems without rinsing. IMPORTANCE: This study's significance lies first in its elucidation of the necessity of sanitizing hydroponic farming systems. The microbiome in hydroponic systems, although mostly nonpathogenic, might serve as a hotbed for pathogen colonization and thus pose a risk for food safety. We thus explored sanitization solutions with both laboratory-scale and field-scale tests. Of the three tested sanitizers, NaOCl was the most effective and economical option, whereas one must note the vital importance of rinsing the hydroponic systems after sanitization with NaOCl.

Acid adaptation increased the resistance of Escherichia coli O157:H7 in bok choy (Brassica rapa subsp. chinensis) juice to high-pressure processing.

IMPORTANCE: Based on the U.S. Food and Drug Administration regulations, E. coli O157:H7 is a pertinent pathogen in high acid juices that needs to be inactivated during the pasteurization process. The results of this study suggest that the effect of acid adaptation should be considered in the selection of HPP parameters for E. coli O157:H7 inactivation to ensure that pasteurization objectives are achieved.

The differences in main components, enzyme activity, and microbial composition between substandard and normal jiuyao.

BACKGROUND: Jiuyao is a critical fermenting agent in traditional huangjiu brewing and it affects the quality of huangjiu. To assess and monitor the quality of jiuyao effectively we determined the differences between two common types of substandard jiuyao and normal jiuyao, with emphasis on the comparison of the main components, enzymatic activity, volatile substances, and microbial community structure. RESULTS: The water and starch content, acid protease activity, and esterification capability of type I substandard jiuyao were significantly lower than those of the normal jiuyao, and the protein contents, liquefaction capability, glycation capability, and neutral protease activity were substantially higher than those of the normal jiuyao. Type II substandard jiuyao had significantly lower indices than the normal group except for the starch and free amino acid content, which were significantly higher than those of the normal jiuyao. Significant differences were observed between substandard and normal jiuyao in the content of 21 volatile compounds. 2-Pentylfuran could be used as a marker of substandard jiuyao. Type I substandard jiuyao contained a higher abundance of aerobic Pediococcus and Marivita in comparison with the normal jiuyao. Type II substandard jiuyao consisted of a greater abundance of anaerobic Mucor and Staphylococcus. CONCLUSION: The quality of jiuyao was significantly affected by the water content. Due to the different abundances of aerobic and anaerobic bacteria in jiuyao, oxygen may also be an important parameter affecting the quality of jiuyao. We believe that the present study offers a theoretical basis for the evaluation and control of the quality of jiuyao. © 2023 Society of Chemical Industry.

Alleviation of loperamide-induced constipation with sticky rice fermented huangjiu by the regulation of serum neurotransmitters and gut microbiota.

BACKGROUND: Huangjiu is an important component of traditional fermented food. It is produced by cereal fermentation. Sticky rice fermented huangjiu is an abundant source of polysaccharides, oligosaccharides, proteins, amino acids, and flavor compounds (POPAF), and it has been used as a dietary supplement and pharmaceutical ingredient. The purpose of this study is to explore the alleviation of constipation using sticky rice fermented huangjiu, with the aim of providing a basis for the nutritional treatment of constipation. RESULTS: Sticky rice fermented huangjiu was more effective in the alleviation of constipation than same concentration of ethanol treatment on serum neurotransmitters, gut microbiota, and intestinal metabolites in this 17 days constipation mouse model. Compared with ethanol treatment, the administration of sticky rice fermented huangjiu to constipated mice increased gastrointestinal motility. It alleviated the decrease in motilin (27.94%), substance P (13.85%), gastrin (63.46%), 5-hydroxytryptamine (4.55%), and short-chain fatty acid (19.80%) levels, and alleviated the increase in somatostatin levels (9.54%). Furthermore, the administration of sticky rice fermented huangjiu regulated the microbiota-mediated gut ecology through alterations in the characteristic taxa. CONCLUSION: The results reveal that sticky rice fermented huangjiu may alleviate loperamide-induced constipation by the regulation of serum neurotransmitters and gut microbiota. These findings reveal that huangjiu is endowed with many functional components by cereal fermentation, and the bioactive substances in huangjiu can be separated and applied for medical treatment or diet therapy in the future. © 2022 Society of Chemical Industry.

Low-energy X-ray inactivation of Listeria monocytogenes in mono-/co-culture biofilms with Pseudomonas fluorescens on food contact surfaces.

This study assessed the inactivation kinetics of 150 keV low-energy X-ray on mono-/co-culture biofilms of Listeria monocytogenes and Pseudomonas fluorescens on three different food-contact-surfaces (polyethylene, acrylic, and stainless steel). The results indicated that the level of biofilm formation of mono-/co-cultures of L. monocytogenes and P. fluorescens was the highest on acrylic. The mono-culture L. monocytogenes biofilm cells exhibited higher resistance to the low-energy X-rays than the corresponding mono-culture P. fluorescens biofilm cells, regardless of surface types. Furthermore, co-culture had enhanced the resistance of both P. fluorescens and L. monocytogenes biofilm cells to the low-energy X-ray. Two kinetic models for the inactivation process were investigated, including (i) Linear model and (ii) Weibull model. Based on R2, RMSE and AIC analysis, the Weibull model was superior in fitting the inactivation curves of low-energy X-ray on L. monocytogenes in mono-/co-culture biofilms with P. fluorescens. For mono-culture biofilms, the irradiation achieved the tR1 value (derived from the Weibull model, i.e., the dose required for the first 1-log reduction) of 46.36-50.81 Gy for L. monocytogenes and the tR1 value of 25.61-31.33 Gy for P. fluorescens. For co-culture biofilms, higher tR1 values for L. monocytogenes (59.54-70.77 Gy) and P. fluorescens (32.73-45.13 Gy) were yielded than those for their individual counterparts in mono-culture biofilm.

Perspectives and Trends in the Application of Photodynamic Inactivation for Microbiological Food Safety.

Photodynamic inactivation is a phenomenon that has the potential to cause microbial inactivation using visible light. It works on the principle that photosensitizers within the microbial cell can be activated using specific wavelengths to trigger a series of cytotoxic reactions. In the last few years, efforts to apply this intervention technology for food safety have been on the rise. This review article offers a detailed commentary on this research. The mechanism of photodynamic inactivation has been discussed as have the factors that influence its efficacy in food. Efforts to inactivate bacteria, fungi, and viruses have been analyzed in dedicated sections and so has the application of this technology to specific product classes such as fresh produce, dry fruits, seafood, and poultry. The challenges and opportunities facing the application of this technology to food systems have been evaluated and future research directions proposed. Thus, this review will provide insights for researchers and industry personnel looking for a novel solution to combat microbial contamination and resistance.

Effect of LED irradiation on the ripening and nutritional quality of postharvest banana fruit.

BACKGROUND: With the ability to tailor wavelengths necessary to the photosynthetically active radiation spectrum of plant pigments, light-emitting diodes (LEDs) offer vast possibilities in horticultural lighting. The influence of LED light irradiation on major postharvest features of banana was investigated. Mature green bananas were treated daily with selected blue (464-474 nm), green (515-525 nm) and red (617-627 nm) LED lights for 8 days, and compared with non-illuminated control. RESULTS: The positive effect of LED lighting on the acceleration of ripening in bananas was greatest for blue, followed by red and green. Under the irradiation of LED lights, faster peel de-greening and flesh softening, and increased ethylene production and respiration rate in bananas were observed during storage. Furthermore, the accumulations of ascorbic acid, total phenols, and total sugars in banana fruit were enhanced by LED light exposure. CONCLUSION: LED light treatment can induce the ripening of bananas and improve their quality and nutrition potential. These findings might provide new chemical-free strategies to shorten the time to ripen banana after harvest by using LED light source. © 2018 Society of Chemical Industry.

Inactivation and changes in metabolic profile of selected foodborne bacteria by 460 nm LED illumination.

The objective of this study was to investigate the effect of 460 nm light-emitting diode (LED) on the inactivation of foodborne bacteria. Additionally, the change in the endogenous metabolic profile of LED illuminated cells was analyzed to understand the bacterial response to the LED illumination. Six different species of bacteria (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7, Pseudomonas aeruginosa and Salmonella Typhimurium) were illuminated with 460 nm LED to a maximum dose of 4080 J/cm2 at 4, 10 and 25 °C. Inactivation curves were modeled using Hom model. Metabolic profiling of the non-illuminated and illuminated cells was performed using a Liquid chromatography-mass spectrometry system. Results indicate that the 460 nm LED significantly (p < 0.05) reduced the populations of all six bacterial species. For example, the population of S. aureus reached below detection limit within 7 h. B. cereus was most resistant to photo-inactivation and exhibited about 3-log reduction in 9 h. Metabolic profiling of the illuminated cells indicated that several metabolites e.g. 11-deoxycortisol, actinonin, coformycin, tyramine, chitobiose etc. were regulated during LED illumination. These results elucidate the effectiveness of 460 nm LED against foodborne bacteria and hence, its suitability as a novel antimicrobial control method to ensure food safety.

Effect of fat type in baked bread on amylose-lipid complex formation and glycaemic response.

The formation of amylose-lipid complexes (ALC) had been associated with reduced starch digestibility. A few studies have directly characterised the extent of ALC formation with glycaemic response. The objectives of this study were to investigate the effect of using fats with varying degree of saturation and chain length on ALC formation as well as glycaemic and insulinaemic responses after consumption of bread. Healthy men consumed five test breads in a random order: control bread without any added fats (CTR) and breads baked with butter (BTR), coconut oil (COC), grapeseed oil (GRP) or olive oil (OLV). There was a significant difference in glycaemic response between the different test breads (P=0·002), primarily due to COC having a lower response than CTR (P=0·016), but no significant differences between fat types were observed. Insulinaemic response was not altered by the addition of fats/oils. Although BTR was more insulinotropic than GRP (P<0·05), postprandial ß-cell function did not differ significantly. The complexing index (CI), a measure of ALC formation, was significantly higher for COC and OLV compared with BTR and GRP (P<0·05). CI was significantly negatively correlated with incremental AUC (IAUC) of change in blood glucose concentrations over time (IAUCglucose) (r -0·365, P=0·001). Linear regression analysis showed that CI explained 13·3 % of the variance and was a significant predictor of IAUCglucose (ß=-1·265, P=0·001), but IAUCinsulin did not predict IAUCglucose. Our study indicated that a simple way to modulate glycaemic response in bread could lie in the choice of fats/oils, with coconut oil showing the greatest attenuation of glycaemic response.

Enhancing the antibacterial effect of 461 and 521 nm light emitting diodes on selected foodborne pathogens in trypticase soy broth by acidic and alkaline pH conditions.

Light emitting diodes (LEDs) with their antibacterial effect present a novel method for food preservation. This effect may be influenced by environmental conditions such as the pH of the food contaminated by the pathogen. Thus, it is necessary to investigate the influence of pH on the antibacterial effect of LEDs before their application to real food matrices. Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in trypticase soy broth were illuminated using 10-W 461 (22.1 mW/cm(2)) and 521 nm (16 mW/cm(2)) LEDs at pH values of 4.5, 6.0, 7.3, 8.0 and 9.5 for 7.5 h at 15 °C. Using the 461 nm LEDs, the populations of E. coli O157:H7 decreased by 2.1 ± 0.02, 1.2 ± 0.08 and 4.1 ± 0.42 log CFU/ml at pH 4.5, 7.3 and 9.5 respectively, after a dosage of 596.7 J/cm(2). For L. monocytogenes, approximately a 5.8 ± 0.03 log reduction was observed after 238.7 J/cm(2) at pH 4.5 using the 461 nm LEDs, while the bacterial concentration was reduced by 1.8 ± 0.01 log at pH 9.5 after 596.7 J/cm(2). Bacterial inactivation using the 521 nm LEDs showed similar trends to the 461 nm LEDs at both acidic and alkaline pH conditions but with lower (1-2 log CFU/ml) reductions after 432 J/cm(2). Lower D-values were observed for L. monocytogenes when exposed to LEDs at acidic pH values, while the sensitivity of E. coli O157:H7 and S. Typhimurium to LED was markedly increased at an alkaline pH. Regardless of the pH at which the cultures were illuminated, the percentage of sublethal injury increased with the treatment time. These results highlight the enhanced antibacterial effect of the 461 nm LED under acidic and alkaline pH conditions, proving its potential to preserve foods as well as to have synergistic effect with acidic and alkaline antimicrobials.

Second order kinetic modeling of headspace solid phase microextraction of flavors released from selected food model systems.

The application of headspace-solid phase microextraction (HS-SPME) has been widely used in various fields as a simple and versatile method, yet challenging in quantification. In order to improve the reproducibility in quantification, a mathematical model with its root in psychological modeling and chemical reactor modeling was developed, describing the kinetic behavior of aroma active compounds extracted by SPME from two different food model systems, i.e., a semi-solid food and a liquid food. The model accounted for both adsorption and release of the analytes from SPME fiber, which occurred simultaneously but were counter-directed. The model had four parameters and their estimated values were found to be more reproducible than the direct measurement of the compounds themselves by instrumental analysis. With the relative standard deviations (RSD) of each parameter less than 5% and root mean square error (RMSE) less than 0.15, the model was proved to be a robust one in estimating the release of a wide range of low molecular weight acetates at three environmental temperatures i.e., 30, 40 and 60 °C. More insights of SPME behavior regarding the small molecule analytes were also obtained through the kinetic parameters and the model itself.

Deciphering the inhibitory mechanisms of betanin and phyllocactin from Hylocereus polyrhizus peel on protein glycation, with insights into their application in bread.

Protein glycation closely intertwines with the pathogenesis of various diseases, sparking a growing interest in exploring natural antiglycation agents. Herein, high-purity betacyanins (betanin and phyllocactin) derived from Hylocereus polyrhizus peel were studied for their antiglycation potential using an in vitro bovine serum albumin (BSA)-glucose model. Notably, betacyanins outperformed aminoguanidine, a recognized antiglycation agent, in inhibiting glycation product formation across different stages, especially advanced glycation end-products (AGEs). Interestingly, phyllocactin displayed stronger antiglycation activity than betanin. Subsequent mechanistic studies employing molecular docking analysis and fluorescence quenching assay unveiled that betacyanins interact with BSA endothermically and spontaneously, with hydrophobic forces playing a dominant role. Remarkably, phyllocactin demonstrated higher binding affinity and stability to BSA than betanin. Furthermore, the incorporation of betacyanins into bread dose-dependently suppressed AGEs formation during baking and shows promise for inhibiting in vivo glycation process post-consumption. Overall, this study highlights the substantial potential of betacyanins as natural antiglycation agents.

Purification and characterization of betacyanin monomers from Hylocereus polyrhizus peel: A comparative study of their antioxidant and antidiabetic activities with mechanistic insights.

Betacyanins have garnered escalating research interest for their promising bioactivities. However, substantial challenges in purification and separation have impeded a holistic comprehension of the distinct bioactivities of individual betacyanins and their underlying mechanisms. Herein, betanin and phyllocactin monomers with purity exceeding 95% were successfully obtained from Hylocereus polyrhizus peel using a feasible protocol. These monomers were subsequently employed for comparative bioactivity assessments to uncover underlying mechanisms and illuminate structure-activity relationships. Interestingly, phyllocactin exhibited superior antioxidant activities and 36.1% stronger inhibitory activity on α-glucosidase compared to betanin. Mechanistic studies have revealed that they function as mixed-type inhibitors of α-amylase and competitive inhibitors of α-glucosidase, with interactions predominantly driven by hydrogen bonding. Notably, phyllocactin demonstrated a greater binding affinity with enzymes than betanin, thereby substantiating its heightened inhibitory activity. Overall, our results highlight novel bioactivities of betacyanin monomers and provide profound insights into the intricate interplay between structures and properties.

3D printing of prawn mimics with faba proteins: The effects of transglutaminase and curdlan gum on texture.

With its capability for automated production of high-resolution structures, 3D printing can develop plant-based seafood mimics with comparable protein content. However, the challenge lies in solidifying 3D printed products to achieve the firmness of seafood. Targeting prawn, texturisation of its 3D printed mimic by curdlan gum was compared against incubation with a protein cross-linking enzyme, microbial transglutaminase. Faba bean protein extract (FBP) was selected for its lightest colour. To confer structural stability to the FBP-based ink without hindering extrudability, adding 1 % xanthan gum was optimal. Printed curdlan-containing mimics were steamed for 9 min, while printed transglutaminase-containing mimics were incubated at 55 °C before steaming. Either adding 0.0625 % or 0.125 % w/w curdlan or, incubating the transglutaminase-containing mimics for an hour achieved chewiness of 818.8-940.6 g, comparable to that of steamed prawn (953.13 g). Curdlan hydrogel penetrated and reinforced the FBP network as observed under confocal imaging. Whereas incubation of transglutaminase-containing mimics enhanced microstructural connectivity, attributable to transglutaminase-catalysed isopeptide cross-linkages, and the consequent increase in disulfide bonding and ß-sheet. Ultimately, transglutaminase treatment appeared more suitable than curdlan, as it yielded mimics with cutting strength comparable to steamed prawn. Both demonstrated promising potential to broaden the variety of 3D printed seafood mimics.

Towards sustainable upcycling of side streams of purple bread wheat using dry fractionation: Enhancing bioactive compounds and reducing harmful elements.

Side streams from milling result in significant food wastage. While highly nutritious, their harmful elements raise concerns. To repurpose these side streams safely, this study designed a dry fractionation technique for anthocyanin-rich purple bread wheat. Four fractions - from inner to outer layers: flour, middlings, shorts and bran - alongside whole-wheat flour were obtained and examined by microstructure, antioxidant activity, anthocyanin profiles, and essential and harmful minerals. Across the four investigated cultivars, both anthocyanin content and antioxidant capacity increased from inner to outer layers. In comparison to flour, cyanidin-3-glucoside concentrations in middlings, shorts and bran were 2-5 times, 3-9 times, and 6-19 times, respectively. Concentrations of Cr, Ni, Sr and Ba progressively increased from inner to outer layers, Pb and Se exhibited uniform distribution, while Al was more concentrated in inner layers. These findings indicate that the fractionation technique is effective in deriving valuable ingredients from underexploited side streams, especially bran.

Effect of heat treatment on the structural and emulsifying properties of copra meal protein: Improving interfacial properties to enhance performance of its Pickering emulsion.

This study investigated the impact of different temperatures and durations on the structural and emulsifying properties of copra meal protein. Additionally, the stability of copra meal protein Pickering emulsions was assessed through rheological and interfacial characteristics. Findings revealed a positive correlation between emulsification properties and heating temperature and duration. Thermal aggregates, facilitated by hydrogen bonds, hydrophobic interactions, and disulfide bonds, significantly enhanced surface hydrophobicity. Heat-treated copra meal protein-based Pickering emulsions demonstrate enhanced adsorption at the oil-water interface and resistance to diffusion. The three-phase contact angle increases from 57.7° to 79.8° following heating at 95 °C for 30 min. The addition of NaCl and heating treatment did not affect emulsion particle size or interface adsorption ability. But it improved the rheological properties to varying degrees. These results offer valuable insights for optimizing the physicochemical and functional attributes of copra meal protein in the food industry.

Decellularised plant scaffolds facilitate porcine skeletal muscle tissue engineering for cultivated meat biomanufacturing.

Cultivated meat (CM) offers a sustainable and ethical alternative to conventional animal agriculture, involving cell maturation in a controlled environment. To emulate the structural complexity of traditional meat, the development of animal-free and edible scaffolds is crucial, providing vital physical and biological support during tissue development. The aligned vascular bundles of the decellularised asparagus scaffold were selected to facilitate the attachment and alignment of murine myoblasts (C2C12) and porcine adipose-derived mesenchymal stem cells (pADMSCs). Muscle differentiation was assessed through immunofluorescence staining with muscle markers, including Myosin heavy chain (MHC), Myogenin (MYOG), and Desmin. The metabolic activity of Creatine Kinase in C2C12 differentiated cells significantly increased compared to proliferated cells. Quantitative PCR analysis revealed a significant increase in Myosin Heavy Polypeptide 1 (MYH1) and MYOG expression compared to Day 0. These results highlight the application of decellularised plant scaffold (DPS) as a promising, edible material conducive to cell attachment, proliferation, and differentiation into muscle tissue. To create a CM prototype with biological mimicry, pADMSC-derived muscle and fat cells were also co-cultured on the same scaffold. The co-culture was confirmed through immunofluorescence staining of muscle markers and LipidTOX staining, revealing distinct muscle fibres and adipocytes containing lipid droplets respectively. Texture profile analysis conducted on uncooked CM prototypes and pork loin showed no significant differences in textural values. However, the pan-fried CM prototype differed significantly in hardness and chewiness compared to pork loin. Understanding the scaffolds' textural profile enhances our insight into the potential sensory attributes of CM products. DPS shows potential for advancing CM biomanufacturing.

Improved in vitro bioaccessibility of quercetin by nanocomplexation with high-intensity ultrasound treated soy protein isolate.

The health benefits of quercetin are limited by its low bioaccessibility. This could be improved by developing plant-based protein delivery systems. Encapsulating quercetin using untreated and high-intensity ultrasound treated (20 kHz at 139 W for 10, 15 and 20 min) soy protein isolate (SPI) produced composite nanoparticles at around 127-136 nm. Ultrasound treatments on SPI caused structural changes of proteins (e.g. around 6-fold increase of surface hydrophobicity and protein solubility) favorable to encapsulation. The encapsulation efficiency for quercetin complexed with 15 min ultrasound treated SPI (76.5 %) was around 10-fold of that with the native SPI (7.2 %). Quercetin was significantly more in vitro bioaccessible when complexed with the treated SPI (61.1 %-64.5 %), as compared to the free quercetin (10.5 %-13.0 %). Ultrasound treated SPI seems to be a promising nanocarrier to encapsulate hydrophobic bioactive ingredients with higher solubility, stability, and bioaccessibility.

Ultrasound-assisted formation of chitosan-glucose Maillard reaction products to fabricate nanoparticles with enhanced antioxidant activity.

The influence of ultrasonic processing parameters including reaction temperature (60, 70 and 80 °C), time (0, 15, 30, 45 and 60 min) and amplitude (70, 85 and 100%) on the formation and antioxidant activity of Maillard reaction products (MRPs) in a solution of chitosan and glucose (1.5 wt% at mass ratio of 1:1) was investigated. Selected chitosan-glucose MRPs were further studied to determine the effects of solution pH on the fabrication of antioxidative nanoparticles by ionic crosslinking with sodium tripolyphosphate. Results from FT-IR analysis, zeta-potential determination and color measurement indicated that chitosan-glucose MRPs with improved antioxidant activity were successfully produced using an ultrasound-assisted process. The highest antioxidant activity of MRPs was observed at the reaction temperature, time and amplitude of 80 °C, 60 min and 70%, respectively, with âˆ¼ 34.5 and ∼20.2 µg Trolox mL-1 for DPPH scavenging activity and reducing power, respectively. The pH of both MRPs and tripolyphosphate solutions significantly influenced the fabrication and characteristics of the nanoparticles. Using chitosan-glucose MRPs and tripolyphosphate solution at pH 4.0 generated nanoparticles with enhanced antioxidant activity (∼1.6 and âˆ¼ 1.2 µg Trolox mg-1 for reducing power and DPPH scavenging activity, respectively) with the highest percentage yield (∼59%), intermediate particle size (∼447 nm) and zeta-potential âˆ¼ 19.6 mV. These results present innovative findings for the fabrication of chitosan-based nanoparticles with enhanced antioxidant activity by pre-conjugation with glucose via the Maillard reaction aided by ultrasonic processing.

Atmospheric solids analysis probe-mass spectrometry (ASAP-MS) as a rapid fingerprinting technique to differentiate the harvest seasons of Tieguanyin oolong teas.

Atmospheric solids analysis probe-mass spectrometry (ASAP-MS), an ambient mass spectrometry technique, was used to differentiate spring and autumn Tieguanyin teas. Two configurations were used to obtain their chemical fingerprints - ASAP attached to a high-resolution quadrupole time-of-flight mass spectrometer (i.e., ASAP-QTOF) and to a single-quadrupole mass spectrometer (i.e., Radian™ ASAP™ mass spectrometer). Then, orthogonal projections to latent structures-discriminant analysis was conducted to identify features that held promise in differentiating harvest seasons. Four machine learning models - decision tree, linear discriminant analysis, support vector machine, and k-nearest neighbour - were built using these features, and high classification accuracy of up to 100% was achieved. The markers were putatively identified using their accurate masses and MS/MS fragmentation patterns from ASAP-QTOF. This approach was successfully transferred to the Radian ASAP MS, which is more deployable in the field. Overall, this study demonstrated the potential of ASAP-MS as a rapid fingerprinting tool for differentiating spring and autumn Tieguanyin.