Functional characterization and reclassification of an enzyme previously proposed to be a limonoid UDP-glucosyltransferase

BACKGROUND

A major problem in the orange industry is 'delayed' bitterness, which is caused by limonin, a bitter compound developing from its non-bitter precursor limonoate A-ring lactone (LARL) during and after extraction of orange juice. The glucosidation of LARL by limonoid UDP-glucosyltransferase (LGT) to form non-bitter glycosyl-limonin during orange maturation has been demonstrated as a natural way to debitter by preventing the formation of limonin.

RESULT

Here, the debittering potential of heterogeneously expressed glucosyltransferase, maltose-binding protein (MBP) fused to cuGT from Citrus unishiu Marc (MBP-cuGT), which was previously regarded as LGT, was evaluated. A liquid chromatography - mass spectrometry (LC-MS) method was established to determine the concentration of limonin and its derivatives. The protocols to obtain its potential substrates, LARL and limonoate (limonin with both A and D ring open), were also developed. Surprisingly, MBP-cuGT did not exhibit any detectable effect on limonin degradation when Navel orange juice was used as the substrate; MBP-cuGT was unable to biotransform either LARL or limonoate as purified substrates. However, it was found that MBP-cuGT displayed a broad activity spectrum towards flavonoids, confirming that the enzyme produced was active under the conditions evaluated in vitro.

CONCLUSION

Our results based on LC-MS demonstrated that cuGT functionality was incorrectly identified. Its active substrates, including various flavonoids but not limonoids, highlight the need for further efforts to identify the enzyme responsible for LGT activity to develop biotechnology-based approaches for producing orange juice from varietals that traditionally have a delayed bitterness. © 2020 Society of Chemical Industry.

Probabilistic risk assessment of patulin in imported apple juice and apple-containing beverages in Taiwan

BACKGROUND

In Taiwan, nearly 90% of apples and raw ingredients for apple-based products are imported. Apple juices (137 samples) and apple-containing beverages (35 samples) were collected in Taiwan from imported food and analyzed for patulin content.

RESULTS

The results revealed that the incidence levels of patulin for apple juice and apple-containing beverages are 5.84% and 5.71%. The mean contamination levels were 1.7 and 1.4 μg kg^-1 for apple juice and apple-containing beverages. One sample exceeded 50 μg kg^-1 , the maximum permissible limit according to the Taiwan Sanitation Standard for the Tolerance of Mycotoxins in Foods. The estimated intake of patulin for consumers ranged from 5.4 to 18.0 ng kg^-1 body weight per day for apple juice and between 6.1 and 11.2 ng kg^-1 body weight for apple-containing beverages. The highest average patulin intake was observed among infants aged 0-3 years, followed by children aged 4-12 years old. Finally, the hazard index (HI) for the 50th, 90th, and 95th percentiles are 0.0186, 0.1201, and 0.2048, respectively, for infants aged 0-3 years.

CONCLUSION

The dietary intake of patulin from imported apple juices and apple-containing beverages is well below the safety levels and does not present a risk for adult and children consumers. However, it is important to point out that we only analyzed imported apple juices and apple-containing beverages. More studies are necessary to establish if the HI for patulin will still remain below 1 when other foods and beverages are included in the risk calculations. © 2020 Society of Chemical Industry.

Affinity Crystallography Reveals Binding of Pomegranate Juice Anthocyanins at the Inhibitor Site of Glycogen Phosphorylase: The Contribution of a Sugar Moiety to Potency and Its Implications to the Binding Mode

Anthocyanins (ACNs) are dietary phytochemicals with an acknowledged therapeutic significance. Pomegranate juice (PJ) is a rich source of ACNs with potential applications in nutraceutical development. Glycogen phosphorylase (GP) catalyzes the first step of glycogenolysis and is a molecular target for the development of antihyperglycemics. The inhibitory potential of the ACN fraction of PJ is assessed through a combination of in vitro assays, ex vivo investigation in hepatic cells, and X-ray crystallography studies. The ACN extract potently inhibits muscle and liver isoforms of GP. Affinity crystallography reveals the structural basis of inhibition through the binding of pelargonidin-3-O-glucoside at the GP inhibitor site. The glucopyranose moiety is revealed as a major determinant of potency as it promotes a structural binding mode different from that observed for other flavonoids. This inhibitory effect of the ACN scaffold and its binding mode at the GP inhibitor binding site may have significant implications for future structure-based drug design endeavors.

Impacts of operating conditions on efficiency of electrokinetically enhanced filtration for de-watering of orange juice and malt extract

The effects of operational factors an on an electrokinetic-enhanced filtration (EKEF) application to dewater orange juice (OJ) and malt extract (ME) was investigated. EKEF improved dewatering of both foodstuffs and resulted in net dewatering efficiencies of 7.4% and 4.9% for OJ and 10.7% and 6.3% for ME after 5.5 h processing under 30 V and 15 V, respectively. Dry matter content was increased by 19.2% and 15.6% for OJ after 5.5 h and 14.8% and 12.8% for ME after 3.5 h under 30 V and 15 V, respectively, compared with 14.9% and 10.3% under the control conditions for OJ and ME, respectively. The EKEF process effectively improved dewatering of high moisture-content foods with positive impacts on process efficiency by increased voltage, pressure, and the pore size of filters. The initial distance between electrodes had a negative impact as the distance increased. EKEF is a useful adjunct to improve high pressure filtration of foodstuffs.

Smartphone assisted colorimetric and fluorescent triple-channel signal sensor for ascorbic acid assay based on oxidase-like CoOOH nanoflakes

Ascorbic acid (AA) is an important diet-derived antioxidant to human body. Thus, efficient and accurate detection of AA is of considerable significance in food analysis. Herein, smartphone assisted colorimetric and fluorescent triple-channel signal sensor has been developed for AA monitoring based on oxidase-like CoOOH nanoflakes. CoOOH nanoflakes can efficiently catalyze the oxidation of p-phenylenediamine (p-PD) into reddish brown p-PDox. The carbon dots (C-dots) are further introduced, of which the fluorescence can be quenched by p-PDox. However, in the presence of AA, the CoOOH nanoflakes is reduced and thus collapsed. As a result, the oxidation of p-PD is restrained, and thus the fluorescence of C-dots keeps strong. Based on AA induced light color, low absorbance, and strong fluorescence, triple-channel signal sensor has been proposed for AA determination. The AA assay shows a dynamic response range from 0.5 to 10 μM with a detection limit of 0.09 μM. The method assay allows detection of AA in real samples such as fruit juices. Combination with portable smartphone, the developed sensor is potential for AA determination in resource-poor settings.

Grape juice attenuates left ventricular hypertrophy in dyslipidemic mice

OBJECTIVE

We evaluated the effects of grape juice (Vitis labrusca L.) on dyslipidemia, resistance to insulin, and left ventricular hypertrophy (LVH) in mice homozygous for the absence of the LDL receptor gene (LDLr -/-) under a hyperlipidemic diet.

METHODOLOGY

We divided 30 male mice (3 months old) into three groups (n = 10); the HL group was fed a high-fat diet, the HLU group received a high-fat diet and 2 g/kg/day of grape juice, and the HLS group was fed a high-fat diet and simvastatin (20 mg/kg/day). We assessed the blood pressure profile of the mice. We also determined the levels of C-reactive protein (CRP) and lipid profile, glycemic and insulinemic profiles, and calculated the HOMA-IR. Cardiomyocyte hypertrophy, interstitial collagen deposit, and the expression of CD40 ligand (CD40L) and metalloproteinases 2 and 9 were assessed immunohistologically.

RESULTS

After 60 days, the mice treated with grape juice showed similar results as those of the group treated with simvastatin. The use of grape fruit attenuated dyslipidemia and insulin resistance and significantly increased the levels of high cholesterol density lipoproteins (HDLc). The antioxidant potential of phenolic compounds associated with the increase in HDLc levels in the mice of the HLU group prevented the development of LVH and arterial hypertension since it inhibited the inflammatory response induced by the CD40 pathway and its ligand CD40L. Consequently, there was a lower expression of MMP-2 and MMP-9 and lower serum levels of CRP.

CONCLUSION

Grape juice has a hypolipidemic and cardiac protective potential, presenting a similar effect as that of simvastatin through a direct antioxidant action of phenolic compounds, or indirectly, via antioxidant action and anti-inflammatory activity of the HDLc. These results suggest that grape juice is a functional food possessing a high potential to prevent cardiovascular diseases.

Formulation of Orange Juice with Dietary Fibers Enhances Bioaccessibility of Orange Flavonoids in Juice but Limits Their Ability to Inhibit In Vitro Glucose Transport

The effect of formulating orange juice (OJ) with dietary fibers (DFs) on in vitro bioaccessibility of flavonoids and their ability to inhibit glucose transport in Caco-2 cells were investigated on Valencia orange fruit (OF), OJ, and OJ formulated with 1 and 2.8% DFs. DFs were either orange pomace (P) or commercial pulverized citrus pulp fiber (CF). Juice extraction and formulation with CF led to minimal loss of flavonoids compared to formulation with P (474 μmol/100 g for OF vs 315-368 μmol/100 g for OJ and OJ with CF, and 266-280 μmol/100 g for OJ with P). Addition of DFs led to similar or improved flavonoid bioaccessibility compared to OJ (9.5% in OJ vs 7.9-33.4% with DFs) but higher glucose transport in Caco-2 cells (0.45 μmol/min in OJ alone vs 0.64-0.94 μmol/min with DFs). This paradoxical effect was attributed to potential complexation of flavonoids and DFs, preventing flavonoids from interfering with glucose transport.

Impact of processing on the nutritional and functional value of mandarin juice

BACKGROUND

Although phenolic compounds have a role in the health benefits of fruit juice consumption, little is known about the effect of processing on their bioaccessibility. The release of phenolic compounds from the food matrix during digestion is an important pre-requisite for their effectiveness within the human body, and so it is fundamental to identify technological treatments able to preserve not only the concentration of phytochemicals, but also their bioaccessibility. In the present study, we investigated the impact of high-pressure homogenization (HPH), alone and in the presence of 100 g kg^-1 trehalose or Lactobacillus salivarius, on the bioaccessibility of flavonoids in mandarin juice. In addition, digested mandarin juices were supplemented to liver cultured cells in basal and stressed conditions to evaluate their protective effect in a biological system.

RESULTS

HPH reduced the concentration of total phenolics and main flavonoids but increased their bioaccessibility after in vitro digestion (P < 0.001). In the basal condition, supplementation with all digested juices significantly reduced intracellular reactive oxygen species (ROS) concentration (P < 0.001). Thiobarbituric acid reactive substances concentration in the medium was also reduced by supplementation with HPH-treated juices. Although pre-treatment with juices did not completely counteract the applied oxidative stress, it preserved cell viability, and cells pre-treated with juices submitted to HPH in the presence of probiotics showed the lowest ROS concentration.

CONCLUSION

The present study represents an important step ahead in the evaluation of the impact of processing on the nutritional and functional value of food, which cannot simply be assessed based on chemical composition. © 2020 Society of Chemical Industry.

Combination of magnetic solid-phase extraction and HPLC-UV for simultaneous determination of four phthalate esters in plastic bottled juice

A magnetic o-hydroxyazobenzene (M-HAzo) porous organic polymer was facilely prepared by a green azo coupling reaction in aqueous solution. The prepared M-HAzo was applied as a new adsorbent for the first time to pre-concentrate phthalate esters (PAEs) from plastic bottled juice, followed by their determination with high performance liquid chromatography-ultraviolet detection. The effects of various parameters, i.e., the mass ratio of the Fe₃O₄@SiO₂ to HAzo, extraction time, ionic strength, pH of the sample, desorption conditions were optimized. Under the optimized conditions, the M-HAzo based method exhibited good performance in terms of linear range (0.3-50.0 μg L^-1), detection limit (0.08-0.50 μg L^-1), accuracy (recovery of 78.0-115.0%) and repeatability (relative standard deviation of 2.9-7.8%). This work provides a sensitive method for analysis of PAEs at trace levels in drinks, which is featured with high sensitivity, simple operation and environmentally-friendly merit and will have a promising potential in analysis of other organic pollutants.

Effects of Storage Time and Temperature on Antioxidants in Juice from Momordica charantia L. and Momordica charantia L. var. abbreviata Ser

This study determined the antioxidant activities of juice from Momordica charantia L. (MC) and MC var. abbreviata Ser. (MCVAS) by analyzing 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging ability, ferric reducing power (FRP), and total phenolic content (TPC). The effects of storage time and storage temperature on these antioxidant activities were investigated. Liquid chromatography-mass spectrometry was conducted to identify the major components of MC and MCVAS. The results revealed that the antioxidant activity of MCVAS was better than that of MC, possibly because of richer components of MCVAS. For MC and MCVAS, the scavenging concentrations of 50% DPPH were 3.33 and 1.19 mg/mL, respectively; moreover, the FRP values were 68.93 and 118.14 mg ascorbic acid equivalent/g dry weight, respectively; and the TPC values were 8.15 and 11.47 mg gallic acid equivalent/g dry weight, respectively. The antioxidant activities of MC and MCVAS decreased with storage time. High storage temperature decreased antioxidant activity more quickly than a low temperature. In addition, MC had exhibited a faster decline in DPPH scavenging ability and FRP than MCVAS during 24-day storage, but no difference was observed in TPC.

Inhibitory Effect of Azamacrocyclic Ligands on Polyphenol Oxidase in Model and Food Systems

Enzymatic browning is one of the main problems faced by the food industry due to the enzyme polyphenol oxidase (PPO) provoking an undesirable color change in the presence of oxygen. Here, we report the evaluation of 10 different azamacrocyclic compounds with diverse morphologies as potential inhibitors against the activity of PPO, both in model and real systems. An initial screening of 10 ligands shows that all azamacrocyclic compounds inhibit to some extent the enzymatic browning, but the molecular structure plays a crucial role on the power of inhibition. Kinetic studies of the most active ligand (L2) reveal a S-parabolic I-parabolic noncompetitive inhibition mechanism and a remarkable inhibition at micromolar concentration (IC₅₀ = 10 μM). Furthermore, L2 action has been proven on apple juice to significantly reduce the enzymatic browning.

Application of cold atmospheric pressure plasmas for high-throughput production of safe-to-consume beetroot juice with improved nutritional quality

A one-step, highly-efficiency, and low-cost cold atmospheric pressure plasma (CAPP)-based method for obtaining safe-to-consume beetroot juice (BRJ) with enhanced nutritional quality is presented. Three reaction-discharge systems with different CAPPs were studied to check how the composition and physicochemical properties changed during CAPP treatment of BRJ. To identify reactive species occur in gas phase of applied CAPP for BRJ treatment, optical emission spectrometry was used. Finally, the cytotoxicity of so-obtained BRJ to human epithelial colorectal adenocarcinoma (Caco-2) and human non-malignant intestine microvascular endothelial cells (HIMEC) was assessed. Based on the performed analyses it was found that controlled CAPP treatment of BRJ changes the fraction pattern of elements in addition to increase the content of phenolic compound presents in BRJ. Furthermore, the defined CAPP treatment of BRJ inhibits proliferation of Caco-2 cell lines, exhibiting non-cytotoxic effect for HIMEC non-malignant endothelial cells. As a result, safe-to-consume BRJ of improved nutritional quality was produced.

Gastrointestinal digestion of dietary advanced glycation endproducts using an in vitro model of the gastrointestinal tract (TIM-1)

Protein- and sugar-rich food products processed at high temperatures contain large amounts of dietary advanced glycation endproducts (dAGEs). Our earlier studies have shown that specifically protein-bound dAGEs induce a pro-inflammatory reaction in human macrophage-like cells. To what extent these protein-bound dAGEs survive the human gastrointestinal (GI) tract is still unclear. In this study we analysed gastric and small intestinal digestion of dAGEs using the validated, standardised TNO in vitro gastroIntestinal digestion model (TIM-1), a dynamic in vitro model which mimics the upper human GI tract. This model takes multiple parameters into account, such as: dynamic pH curves, peristaltic mixing, addition of bile and pancreatic digestive enzymes, and passive absorption. Samples of different digested food products were collected at different time points after (i) only gastric digestion and (ii) after both gastric plus small intestinal digestion. Samples were analysed for dAGEs using UPLC-MS/MS for the lysine derived Nε-carboxymethyllysine (CML) and Nε-carboxyethyllysine (CEL), and the arginine derived methylglyoxal-derived hydroimidazolone-1 (MG-H1), and glyoxal-derived hydroimidazolone-1 (G-H1). All AGEs were quantified in their protein-bound and free form. The results of this in vitro study show that protein-bound dAGEs survive gastrointestinal digestion and are additionally formed during small intestinal digestion. In ginger biscuits, the presence MG-H1 in the GI tract increased with more than 400%. This also indicates that dAGEs enter the human GI tract with potential pro-inflammatory characteristics.

Characterization and Quantification of Nonanthocyanin Phenolic Compounds in White and Blue Bilberry (Vaccinium myrtillus) Juices and Wines Using UHPLC-DAD-ESI-QTOF-MS and UHPLC-DAD

The nonanthocyanin phenolic compounds in juice and wine produced from fruits of white bilberry, a nonpigmented mutant of Vaccinium myrtillus, and blue bilberry (pigmented variety) were analyzed using liquid chromatography with a diode array detector (LC-DAD) and LC-DAD-electrospray ionization-quadrapole/time of flight hybrid mass spectrometry (ESI-QTOF-MS). On the basis of elution order, UV-vis spectra, accurate mass data, and fragmentation pattern and standards, 42 compounds including 22 phenolic acids, 15 flavonols, and 5 flavan-3-ols, were identified in juices and wines prepared from the two bilberry varieties. The levels of most individual nonanthocyanin phenolic compounds in white bilberry products were significantly lower than those in pigmented ones. In bilberry juices, phenolic acids were the most predominant, accounting for approximately 80% of total phenolic content, with p-coumaroyl monotropeins and caffeic acid hexoside being the major phenolic acids. After fermentation, the total contents of phenolic acids, flavonols, and nonanthocyanin phenolic compounds significantly increased, while the content of total flavan-3-ols decreased significantly. p-Coumaroyl monotropeins still dominated in the wine products, while caffeic acid content showed dramatic elevation with the significant drop of caffeic acid hexoside.

Rolling circle amplification promoted magneto-controlled photoelectrochemical biosensor for organophosphorus pesticides based on dissolution of core-shell MnO2 nanoflower@CdS mediated by butyrylcholinesterase

A photoelectrochemical (PEC) aptasensing platform is devised for sensitive detection of an organophosphorus pesticide based on dissolution of core-shell MnO₂ nanoflower@CdS (MnO₂ NF@CdS) by thiocholine (TCh). TCH is produced from the butyrylcholinesterase-acetylthiocholine system, accompanied by target-triggered rolling circle amplification (RCA). The core-shell MnO₂ NF@CdS with excellent PEC performance was synthesized and employed as a photo-sensing platform. The target was detected on a functionalized magnetic probe with the corresponding aptamer. Upon malathion introduction, the aptamer was detached from the magnetic beads, while capture DNA (cDNA, with primer fragment) remained on the beads. The primer fragment in cDNA can trigger the RCA reaction to form a long single-stranded DNA (ssDNA). Furthermore, a large number of butyrylcholinesterase (BChE) were assembled on the long ssDNA strands through the hybridization with the S₂-Au-BChE probe. Thereafter, TCh generated from hydrolysis of ATCh by BChE can reduce MnO₂ NF (core) to Mn²⁺ and release the CdS nanoparticles (shell) from the platform electrode, significantly enhancing the PEC signal. Under optimal conditions, the proposed aptasensor exhibited high sensitivity for malathion with a low detection limit of 0.68 pg mL^-1. Meanwhile, it also presents outstanding specificity, reproducibility, and stability. Importantly, the sensing platform provides a new concept for detection of pesticide. Graphical abstract Herein, this work devised a photoelectrochemical (PEC) aptasensing platform for sensitive detection of organophosphorus pesticide based on dissolution of core-shell MnO₂ nanoflower@CdS (MnO₂ NF@CdS) by the as-produced thiocholine (TCh) from the butyrylcholinesterase-acetylthiocholine system, accompanying with the target-triggered rolling circle amplification (RCA).

Stable isotope analysis of non-exchangeable hydrogen in carbohydrates derivatised with N-methyl-bis-trifluoroacetamide by gas chromatography - Chromium silver reduction/High temperature Conversion-isotope ratio mass spectrometry (GC-CrAg/HTC-IRMS)

A novel procedure for the rapid isotope analysis of the carbon-bound non-exchangeable (CBNE) hydrogen in mono and disaccharides has been developed to demonstrate the feasibility of detecting undeclared addition of exogenous sugar products in foods and beverages susceptible to economically motivated adulteration. The procedure utilizes a simple one-step reaction, with the derivatising agent N-methyl-bis-trifluoroacetamide, to substitute the exchangeable hydroxyl-hydrogens with trifluoroacetate derivatives that are sufficiently volatile to be separated and measured by a gas chromatograph coupled to an isotope ratio mass spectrometer. The conversion of the derivatised sugars into the measuring gas is achieved using a high temperature chromium-silver reactor that retains carbon, oxygen and fluorine whilst releasing hydrogen gas for stable isotope measurement. The new procedure has advantages over existing methods in terms of ease of use, analysis time and compound-specific information. Sugars from fruit juice and honey have been measured to demonstrate the feasibility of using this technique.

Viburnum opulus L. Juice Phenolic Compounds Influence Osteogenic Differentiation in Human Osteosarcoma Saos-2 Cells

Bone mass loss occurs with a decrease in osteoblast proliferation and differentiation, or the enhancement of bone resorption, which further leads to the impairment of bone mineral density and increase in bone fracture. Recent studies suggest that some phenolic compounds found in food play positive role in bone metabolism. High content of phenolic compounds with potential beneficial effects on bone metabolism have been identified in the Viburnum opulus fruit. The aim of the study was to determine the influence of V. opulus fresh juice (FJ) and juice purified by solid phase extraction (PJ) on osteogenesis processes with osteosarcoma Saos-2 cell lines. V. opulus purified juice revealed stronger potential as an inducer of Saos-2 osteogenic differentiation. Saos-2 cells matrix mineralization was evaluated with alkaline phosphatase (ALP) activity measurement and alizarin red S staining. Gene expression analysis showed the elevation of the mRNA levels of Runt-related transcription factor 2 (RUNX2), ALP, collagen type 1 and osteonectin, whereas the nuclear factor-κB ligand and osteoprotegerin ratio (RANKL/OPG) decreased. Furthermore, V. opulus was able to diminish the secretion of pro-inflammatory cytokines Il6 and TNFα, however had no effect on vascular endothelial growth factor (VEGF). It decreased intracellular oxidative stress and induced DNA repair, but had no effect on the growth inhibition of lactic acid beneficial microorganisms.

Use of information dependent acquisition mass spectra and sequential window acquisition of all theoretical fragment-ion mass spectra for fruit juices metabolomics and authentication

INTRODUCTION

LC-MS based untargeted metabolomics are the main untargeted methods used for juice metabolomics to solve the authentication problem faced in fruit juice industry.

OBJECTIVES

To evaluate the performances of different untargeted metabolomics methods on fruit juices metabolomics and authentication, orange and apple fruit juices were selected for this study.

METHODS

IDA-MS and SWATH-MS based on UHPLC-QTOF were used for the metabolomics and authenticity determination of apple and orange juices, including the lab-made samples of oranges (Citrus sinensis Osb.) from Jiangxi Province, apples (Malus domestica Borkh) from Shandong Province, and different brands of commercial orange and apple juice samples from markets.

RESULTS

IDA-MS and SWATH-MS could both acquire numerous MS1 features and MS2 information of juice components, while SWATH-MS excels at the acquisition rate of MS2. Distinctive separation between authentic orange juice and not authentic orange juice could be seen from principal component analysis and hierarchical clustering analysis based on both IDA-MS and SWATH-MS. After analysis of variance, fold change analysis and orthogonal projection to latent structures discriminant mode, 53 and 46 potential markers were defined by IDA-MS and SWATH-MS (with 77.4% and 100% MS2 acquisition rate) separately. Subsequently, these potential markers were putatively annotated using general chemical databases with 6 more annotated by SWATH-MS. Furthermore, 7 of the potential markers, l-asparagine, umbelliferone, glucosamine, phlorin, epicatechin, phytosphingosine and chlorogenic acid, were identified with standards. For the consideration of model simplicity, two determined makers (umbelliferone and chlorogenic acid) were selected to construct the DD-SIMCA model in commercial samples because of their good correlation with apple adulteration proportion, and the sensitivity and specificity of the model were 100% and 95%.

CONCLUSION

SWATH-MS excels at the MS2 acquisition of juice components and potential markers. This study provides an overall performance comparison between IDA-MS and SWATH-MS, and guidance for the method selection on fruit juice metabolomics and juice authenticity determination. Two of the potential markers determined, umbelliferone and chlorogenic acid, could be used as apple juice indicators in orange juice.

Viburnum opulus L. Juice Phenolics Inhibit Mouse 3T3-L1 Cells Adipogenesis and Pancreatic Lipase Activity

Viburnum opulus L. fruit is a rich source of phenolic compounds that may be involved in the prevention of metabolic diseases. The purpose of this study was to determine the effects of Viburnum opulus fresh juice (FJ) and juice purified by solid-phase extraction (PJ) on the adipogenesis process with murine 3T3-L1 preadipocyte cell line and pancreatic lipase activity in triolein emulsion, as well as their phenolic profiles by UPLC/Q-TOF-MS. Decrease of lipids and triacylglycerol accumulation in differentiated 3T3-L1 cells were in concordance with downregulation of the expression of peroxisome proliferator-activated receptor-gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPβ/α), and sterol regulatory element-binding protein 1c (SREBP-1c). Furthermore, regulation of PPARγ-mediated β-lactamase expression by V. opulus components in reporter gene assay, as well as their binding affinity to ligand-binding domain of PPARγ, were tested. In addition, the levels of enzymes involved in lipid metabolism, like fatty acid synthase (FAS) or acetyl-CoA carboxylase (ACC), were decreased, along with inflammatory cytokines, like tumor necrosis factorα (TNFα), interleukin-6 (Il-6) and leptin. Moreover, FJ and PJ were able to inhibit pancreatic lipase, which potentially could reduce the fat absorption from the intestinal lumen and the storage of body fat in the adipose tissues. Thirty-two phenolic compounds with chlorogenic acid as the dominant compound were identified in PJ which revealed significant biological activity. These data contribute to elucidate V. opulus juice phenolic compounds’ molecular mechanism in adipogenesis regulation in 3T3-L1 cells and dietary fat lipolysis.

Insight into non-enzymatic browning of shelf-stable orange juice during storage: A fractionation and kinetic approach

BACKGROUND

Non-enzymatic browning (NEB) is the main quality defect in shelf-stable orange juice and other fruit juices during storage. Previous studies on NEB focused solely on the soluble fraction of orange juice, regardless of the fact that both soluble and insoluble fractions turn brown during extended storage. Clear evidence of the relative contribution of both fractions to NEB is currently lacking in the literature. This study investigated the contribution of the soluble and insoluble fractions of orange juice, which were obtained by centrifugation and ethanol precipitation, to NEB during storage. Changes in different NEB-related attributes, such as ascorbic acid (AA) degradation, and the browning index (BI), were quantified and kinetically modeled.

RESULTS

Evaluation of color during storage showed that the orange juice and the soluble compound-containing fractions turned brown whereas the insoluble fractions did not. The soluble compound-containing fractions showed exactly the same browning behavior with storage as the plain orange juice. Based on the kinetic parameters obtained, the degradation of AA, the hydrolysis of sucrose, the increase in the glucose and fructose content, and the formation of furfural and 5-hydroxymethylfurfural during storage were similar for the plain orange juice and the soluble compound-containing fractions.

CONCLUSION

This work provided evidence that the soluble fraction of orange juice plays the major role in NEB, unlike the insoluble fraction, which seems to make no contribution. Results from this work also demonstrate the potential use of the soluble fraction as an orange-juice-based model system of reduced complexity that can be used for the further investigation of NEB processes. © 2020 Society of Chemical Industry.

Detect, remove and re-use: Sensing and degradation pesticides via 3D tilted ZMRs/Ag arrays

The objective of this study was to design a versatile and reusable pesticide detection surface-enhanced Raman scattering (SERS) substrate in combination with SERS enhancement and self-cleaning properties. In this paper, we present an inexpensive way to synthesize three-dimensional tilted ZnO micron rods with an Ag hierarchical structure (ZMRs/Ag arrays). Although expensive materials and complex methods were not used, the detection limit of thiram residue was 10^-11 M, with a quantitative relationship (R² = 0.9929) between the thiram concentration and the intensity of the SERS peaks. Additionally, the substrates exhibited fast and efficient photocatalytic activity for the degradation of adsorbed thiram, and the degradation rate in 30 min was close 100 % under visible-light irradiation. The enhancement and photocatalytic mechanism of this substrate were meticulously analyzed in detail. Furthermore, the residues of several mixed pesticides (e.g., thiram and methamidophos compounds) in various juices (such as grape, pear, orange, apple, and cherry juices) were quickly detected using ZMRs/Ag substrates. The main advantages of this substrate are recyclability, stability, selectivity, handiness, and cost-eff ;ectiveness. The substrate can prevent single-use problems associated with conventional SERS substrates and can be applied in pesticide residue and food security.

Storage effects on the quality quartet of orange juice submitted to moderate thermosonication: Predictive modeling and odor fingerprinting approach

The effects of moderate thermosonication (MTS) on the quality quartet: physico-chemical, microbial, nutritional and sensory qualities of orange juice (OJ) inoculated with Alicyclobacillus acidoterrestris (AAT) were studied during 24 days of storage at ambient and refrigerated temperatures. The bioactive compounds and antioxidant activity of OJ decreased with storage, while the pectin methyl esterase (PME) increased. Nonetheless, noticeable changes were observed from the 12th day of storage. There was no obvious (p > 0.05) variation in pH and total soluble solids. To determine the nutritional and microbial quality characteristics of OJ during storage, non-linear kinetic curves were successfully fitted with least square fitting polynomial and four-parameter log-logistic distribution models. The E-nose sensors succeeded in discriminating between the aroma of non-treated and treated OJ based on linear discriminant analysis (LDA). Furthermore, terpenes, alcohol and partially aromatic compounds were the main spoilage indicators of OJ during storage based on E-nose analysis and confirmed by HS-SPME-GC/MS analysis. Thus, MTS significantly extended the shelf life of the quality quartet of natural OJ at 4 °C. E-nose-GC/MS fusion offered odor fingerprints to AAT microorganisms that can be used as spoilage index without using traditional food analysis techniques. The proposed approach can be used as an alternative tool for rapid detection of spoilage microorganisms in OJ.

Effect of ultrasound combined with ultraviolet treatment on microbial inactivation and quality properties of mango juice

This work explored the effect of ultraviolet-assisted ultrasound (US-UV) as an emerging non-thermal sterilization technology on mango juice in aspects of microbial growth and quality changes. The juice in the ice bath was subjected to US-UV treatment at different US powers (0-600 W) and times (0-40 min), and no pathogen bacteria could be detected after treatment, while the physicochemical features (particle size, suspension stability, color, content of total polyphenols, carotenoids, sugar, reducing sugar and protein) and antioxidant ability of treated juice was preserved or improved to some extent. Based on these results, we further validated its positive effects on the nutritional value (content of ascorbic acid and soluble dietary fiber, antioxidant ability) and quality parameters (titratable acid, sugar acidity, total soluble solids, rheological behavior, metal elements) of mango juice treated at the optimal US parameter (10 min, 600 W); Not only the inactivation of polyphenol oxidation enzyme, peroxidase and pectin methylesterase was achieved but also the treated juice has a significant different volatile profile compared with the fresh juice, which might offer the better color, texture, and smell. Importantly, through the HPLC-MSD-Trap-XCT (phenols) and UPLC-Q Exactive Orbitrap-MS (carotenoids) study, the US-UV treatment will not cause difference on compounds composition, but it was responsible for changes in content of individual compounds, especially the all-trans-β-carotene, became the main component of carotenoids in processed mango juice (increased from 43.72% to 75.15%, relative content), and the oxygenated carotenoids (xanthophylls) are highly sensitive to the US (reduced from 50.96% to 4.85%) while the carotenes show a strong resistance to the US (increased 49.04% to 95.15%). Thus, the overall safety and quality of mango juice were enhanced while the sensory characteristics remained stable, suggesting that this non-thermal combination sterilization processing may successfully be implemented in the commercial processing of mango juice.

Application of a Krypton-Chlorine Excilamp To Control Alicyclobacillus acidoterrestris Spores in Apple Juice and Identification of Its Sporicidal Mechanism

The aim of this study was to investigate the sporicidal effect of a krypton-chlorine (KrCl) excilamp against Alicyclobacillus acidoterrestris spores and to compare its inactivation mechanism to that of a conventional UV lamp containing mercury (Hg). The inactivation effect of the KrCl excilamp was not significantly different from that of the Hg UV lamp for A. acidoterrestris spores in apple juice despite the 222-nm wavelength of the KrCl excilamp having a higher absorption coefficient in apple juice than the 254-nm wavelength of the Hg UV lamp; this is because KrCl excilamps have a fundamentally greater inactivation effect than Hg UV lamps, which is confirmed under ideal conditions (phosphate-buffered saline). The inactivation mechanism analysis revealed that the DNA damage induced by the KrCl excilamp was not significantly different (P > 0.05) from that induced by the Hg UV lamp, while the KrCl excilamp caused significantly higher (P < 0.05) lipid peroxidation incidence and permeability change in the inner membrane of A. acidoterrestris spores than did the Hg UV lamp. Meanwhile, the KrCl excilamp did not generate significant (P > 0.05) intracellular reactive oxygen species, indicating that the KrCl excilamp causes damage only through the direct absorption of UV light. In addition, after KrCl excilamp treatment with a dose of 2,011 mJ/cm2 to reduce A. acidoterrestris spores in apple juice by 5 logs, there were no significant (P > 0.05) changes in quality parameters such as color (L*, a*, and b*), total phenolic compounds, and DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging activity.IMPORTANCEAlicyclobacillus acidoterrestris spores, which have high resistance to thermal treatment and can germinate even at low pH, are very troublesome in the juice industry. UV technology, a nonthermal treatment, can be an excellent means to control heat-resistant A. acidoterrestris spores in place of thermal treatment. However, the traditionally applied UV sources are lamps that contain mercury (Hg), which is harmful to humans and the environment; thus, there is a need to apply novel UV technology without the use of Hg. In response to this issue, excilamps, an Hg-free UV source, have been actively studied. However, no studies have been conducted applying this technique to control A. acidoterrestris spores. Therefore, the results of this study, which applied a KrCl excilamp for the control of A. acidoterrestris spores and elucidated the inactivation principle, are expected to be utilized as important basic data for application to actual industry or conducting further studies.

Influence of pH and Composition on Nonenzymatic Browning of Shelf-Stable Orange Juice during Storage

Nonenzymatic browning during storage of pasteurized shelf-stable orange juice causes a major color deterioration, which negatively affects consumer acceptance of the juice. This study, for the first time, investigated on a kinetic basis the effect of pH and suspected nonenzymatic browning reaction precursors such as ascorbic acid, fructose, and arginine on nonenzymatic browning during accelerated storage (42 °C) using an orange-juice-based model system. The results showed that lowering the pH of the model juice system from 3.8 to 1.5 significantly increased the rate of ascorbic acid degradation, the rate changes (increases and decreases) in different sugars, and the rates of furfural and 5-hydroxymethylfurfural formation. These changes coincided with a higher browning intensity, which became more pronounced toward the end of storage of the juice model system. Similarly, adding more ascorbic acid and fructose largely increased the formation of furfural and 5-hydroxymethylfurfural, respectively, and resulted in a higher browning intensity. In conclusion, lowering the pH of the orange juice or addition of ascorbic acid or fructose will enhance its browning during prolonged storage.