Vegetable Matrices Research Articles

Rapid screening and confirmation of 415 pesticide residues in red cabbages by liquid chromatography-quadrupole-time of flight-mass spectrometry

应用液相色谱-四极杆-飞行时间质谱(LC-QTOF/MS)建立了一次进样可同时对紫甘蓝中415种农药残留进行快速筛查和准确确证的分析方法。实验采用1%(v/v)醋酸乙腈溶液提取,无水硫酸镁和氯化钠进行盐析,ZORBAX SB-C18色谱柱(100 mm×2.1 mm, 3.5 μm)分离,以0.1%(v/v)甲酸水溶液(含5 mmol/L乙酸铵)-乙腈为二元流动相进行梯度洗脱,应用LC-QTOF/MS在电喷雾电离、全离子MS/MS(All Ions MS/MS)扫描正模式下进行检测,基质匹配外标法定量分析。通过优化全自动MS/MS采集模式(Auto MS/MS)和全离子MS/MS采集模式下的不同参数,得到每种采集模式下的最佳条件。然后在2种不同采集模式的最佳条件下对比,最终选取All Ions MS/MS采集模式。实验结果表明,采用所建立的分析方法可以准确定性和定量筛查紫甘蓝中415种农药残留,所有415种农药在各自的范围内线性相关系数(r2)均大于0.990,其中411种农药的筛查限(SDL)≤5 μg/kg, 413种农药的定量限(LOQ)≤10 μg/kg。在1倍、2倍和10倍LOQ添加水平下,农药的回收率分别为65.7%~118.4%、72.0%~118.8%和70.2%~111.2%,相对标准偏差分别为0.9%~19.7%、0.2%~19.9%和0.6%~19.9%。将该方法应用于2019年欧盟能力验证项目的紫甘蓝样品中未知农药残留筛查方法和定量方法考核样的检测,所有添加农药均被准确定性筛查和定量检测,没有假阳性和假阴性。结果表明,该方法快速、准确、可靠,适用于对紫甘蓝中多种农药残留的高通量定性筛查和准确定量,可以扩展到其他果蔬基质中多农残的高通量筛查。

Measurement and PC-SAFT Modeling of the Solubility of Gallic Acid in Aqueous Mixtures of Deep Eutectic Solvents

Deep eutectic solvents have appeared as potential solvents for improving the extraction of polyphenols from vegetable or fruit matrixes. Since gallic acid is abundant in these sources, it is considered as a typical standard for quantifying their total polyphenol content after extraction with solvents. However, there are no extensive studies on the solubility behavior of gallic acid in different solvents or deep eutectic solvents. Thus, in this work, the solubility of gallic acid is measured in pure water; aqueous solutions of different hydrogen bond donors such as ethylene glycol, levulinic acid, and glycerol; and aqueous mixtures of deep eutectic solvents using choline chloride as the hydrogen bond acceptor and ethylene glycol, levulinic acid, and glycerol as the hydrogen bond donors. All of the measurements were performed at 293.15, 303.15, and 313.15 K and at 101.3 kPa and were validated by comparing the solubility of gallic acid in water from the literature. Results suggest that a 50 wt % aqueous solution of deep eutectic solvent based on ethylene glycol or glycerol improves the gallic acid solubility compared with a 50 wt % aqueous solution of its corresponding hydrogen bond donor. The deep eutectic solvent containing levulinic acid acts as the best aqueous mixture for gallic acid dissolution. Nondissolved gallic acid was measured after equilibrium using powder X-ray diffraction, showing that its structure does not change upon mixing with all of the liquid mixtures. All of the solid–liquid equilibrium results were accurately modeled with perturbed-chain statistical associating fluid theory (PC-SAFT).

Method Development and Determination of Chlorinated Polycyclic Aromatic Hydrocarbons in Different Matrices

The aim of this study was to develop an analytical method, which separates selected chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) from fat, and fat-free or vegetable matrices. The method contains extraction-, cleanup-, and quantification steps. Integration of automated analysis actions, as in extraction and cleanup, should enhance the reproducibility, precision, and efficiency of the method. This was confirmed by validation of the overall analytical process. In the end, as a performance check, the developed method was applied on different matrices, e.g., tea, rice, grilled pork, and eel and predator eggs, as a non-food example. An inter-laboratory check was initiated as replacement for the lack of proficiency tests. Due to the high level of automation, both personnel and time effort are very low. In addition, the method is very robust with regard to the variability of the solvent selection and the loss of analytes by evaporation to dryness. It could be demonstrated that the developed method is applicable to different matrices with reproducible and precise results. This applies also to low-fat food and feed.

Determination of selected water-soluble vitamins (thiamine, riboflavin, nicotinamide and pyridoxine) from a food matrix using hydrophilic interaction liquid chromatography coupled with mass spectroscopy

Water-soluble vitamins are essential dietary components with a multitude of important functions that require quantification from food sources to characterise the nutritional status of food. In this study, we have developed a hydrophilic interaction chromatography (HILIC) based method coupled to single-quadrupole mass spectrometry (MS) for the analysis of selected water-soluble vitamins. Due to their involvement in energy release from macronutrients, the quantification of thiamine (B1), riboflavin (B2), nicotinamide (B3) and pyridoxine (B6) offers significant value in food analysis.A commercially available vegetable soup was selected as the food matrix for this study and utilised to develop an efficient extraction procedure for the vitamins of interest. Vitamins were extracted using meta-phosphoric acid coupled with a reducing agent, DL-dithiothreitol (DTT) to produce the parent compound. The extracted vitamins were then analysed using an LC-MS system with electrospray – atmospheric pressure ionization (ES-API) source, operated in positive single ion monitoring (SIM) mode. The MS provided good linearity within the investigated range from 5 to 400 ng/mL with coefficient of determination (r2) ranging from 0.98 to 0.99. Retention times (0.65–9.04 min) were reproducible and no coelution between vitamins was observed. Limit of detection (LOD) varied from 2.4 to 9.0 ng/mL and limit of quantification (LOQ) was from 8 to 30 ng/mL, comparable to previously published studies. The extraction method provided good intra-day (%CV 1.56–6.56) and inter-day precision (%CV 8.07–10.97). Standard injections were used as part of quality control measures and provided excellent reproducibility (%CV 0.9–3.4). The overall runtime of this method was 19 min, including column reconditioning. Using this method, the quantity of thiamine (67 ± 7 ng/g), riboflavin (423 ± 39 ng/g), nicotinamide (856 ± 77 ng/g) and pyridoxine (133 ± 11 ng/g) was determined from a complex food matrix.In conclusion, we have developed a rapid and reliable, HILIC-single quad MS method utilising SIM for the low-level quantification of four B vitamins in a vegetable soup matrix in under 20 min. This method has shown excellent linearity, intra- and inter-day reproducibility and is directly applicable to other plant-based food matrices.

Vegan probiotic products: A modern tendency or the newest challenge in functional foods

Vegan consumers represent an attractive economic target for the food industry with demand of products with health benefits, such as probiotic products. This review aimed to explore the so called vegan probiotic products by providing an overview of the commercial and studied products and their associated in vitro/in vivo health-promoting effects, and discuss the effect of probiotics on the technological and sensory properties in a range of products. The factors that impact on the probiotic survival, the main challenges and the trends of this market niche are presented. Vegan probiotic products may improve the lipid profile and the immune system, manage the diabetes, reduce Helicobacter pylori-associated diseases, have anticarcinogenic properties, and improve the general well-being. Fermented and non-fermented beverages are the main vegan probiotic products. The survival of probiotic cultures is dependent on the processing steps, food matrix, probiotic strain and the form of incorporation into the matrix, storage conditions, and addition of prebiotic components. Probiotics may alter the chemical composition, acidity, color, and acceptance of vegan foods and beverages but products with suitable probiotic survival, physicochemical characteristics, technological properties, and sensory acceptance can be obtained. However, the source of the strain may compromise the vegan status since most of those currently available are not isolated from vegetable matrices. Therefore, short-term marketing strategies should focus not only on the vegan public but also on those consumers that want to reduce the consumption of animal-derived products, besides seeking new non-animal derived strains.

Immunomodulatory Properties of a γ-Aminobutyric Acid-Enriched Strawberry Juice Produced by Levilactobacillus brevis CRL 2013.

Gamma-aminobutyric acid (GABA) plays a key role in mammals as the major inhibitory neurotransmitter of the central nervous system. Although GABA may not be able to cross the human blood-brain barrier, it was approved as a food ingredient because of its benefits to the host after oral administration including anti-hypertensive, anti-depressant and anti-inflammatory activities. Considering the current trend toward the development of new functional and natural products and that microbial fermentation is one of the most promising methods to produce this non-protein amino acid, the in situ production of GABA through fermentation of strawberry and blueberry juices by the efficient GABA producer strain, Levilactobacillus brevis (formerly known as Lactobacillus brevis) CRL 2013, was evaluated. A high GABA production (262 mM GABA) was obtained after fermenting strawberry juice supplemented with yeast extract for 168 h, being GABA yield significantly higher in strawberry juices than in the blueberry ones. Thus, GABA-enriched fermented strawberry juice (FSJ) was selected to carry out in vivo and in vitro studies. The in vitro functional analysis of the GABA-enriched FSJ demonstrated its ability to significantly decrease the expression of cox-2 gene in LPS stimulated RAW 264.7 macrophages. In addition, in vivo studies in mice demonstrated that both, L. brevis CRL 2013 and the GABA-enriched FSJ were capable of reducing the levels of peritoneal, intestinal and serum TNF-α, IL-6, and CXCL1, and increasing IL-10 and IFN-γ in mice exposed to an intraperitoneal challenge of LPS. Of note, the GABA-enriched FSJ was more efficient than the CRL 2013 strain to reduce the pro-inflammatory factors and enhance IL-10 production. These results indicated that the CRL 2013 strain exerts anti-inflammatory effects in the context of LPS stimulation and that this effect is potentiated by fermentation. Our results support the potential use of L. brevis CRL 2013 as an immunomodulatory starter culture and strawberry juice as a remarkable vegetable matrix for the manufacture of GABA-enriched fermented functional foods capable of differentially modulating the inflammatory response triggered by TLR4 activation.

Dispersive solid-phase extraction using microporous metal-organic framework UiO-66: Improving the matrix compounds removal for assaying pesticide residues in organic and conventional vegetables

An efficient dispersive solid-phase extraction method was developed to trace pesticide residues in commonly consumed vegetables. In this method, UiO-66 with uniform micropores was used as sorbent, and gas chromatography-mass spectrometry was applied to detect the pesticides. Thanks to the size sieving action of uniform micropores, UiO-66 directly extracted the target pesticides from vegetable matrices and excluded the relatively large matrix compounds. This well eliminated the matrix effect. The important experimental conditions were evaluated by orthogonal array experimental design. In optimized conditions, good linearity (R2 ≥ 0.99), detection limits (0.4–2.0 ng/g), recoveries (60.9–117.5%) and precision (relativestandarddeviations < 14.6%) were achieved. Moreover, the sorbent UiO-66 can be reused more than 20 times. These demonstrate a simple, reliable and robust method to screen the pesticide residues in vegetables. Furthermore, the validated method was applied to detect the pesticides in various organic and conventional vegetables.

Calcium ions hyaluronan/gellan gum protective shell for delivery of oleuropein in the knee

Oleuropein has several beneficial properties. Strong evidences of its role in preventing osteoarthritis and playing analgesic and sedative effects are gaining. Starting from that, we entrapped a vegetal bioactive matrix rich in oleuropein into calcium ions crosslinked gellan gum and hyaluronan formulations. Infrared spectroscopy and thermal analysis confirmed the absence of significant interactions between the polysaccharide shells and the bioactive matrix, thus guaranteeing a burst release of oleuropein. The adequate mechanical performance of the systems for the foreseen application as viscosupplement was also verified. Cytocompatibility of developed systems toward fibroblasts and human chondrocytes was assessed.

Simultaneous determination of 49 amino acids, B vitamins, flavonoids, and phenolic acids in commonly consumed vegetables by ultra-performance liquid chromatography–tandem mass spectrometry

A sensitive and reliable method was developed and validated for the simultaneous determination of 49 amino acids, B vitamins, flavonoids, and phenolic acids based on a rapid metabolomic extraction procedure combined with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC–MS/MS) in a single chromatographic run and applied in analysis of 26 commonly consumed vegetables. The chromatographic and sample preparation conditions were optimized, given the high diversity of the target analytes. Eight isotope-labeled standards were applied to validate the method in terms of recovery, linearity, matrix effects, precision, and sensitivity. Most recoveries in four vegetable matrices ranged from 65.0% to 105.3% with associated RSDs < 20%. Low LOQs ranged from 0.06 to 17 µg/kg. Linear calibration curves with different ranges were established with R2 > 0.993. Among the 26 vegetables, purple cabbage, broccoli, and red lettuce were found to contain the highest concentrations of free amino acids, B vitamins, and phenolic compounds.

Green technologies for the extraction of proteins from jackfruit leaves (Artocarpus heterophyllus Lam).

The application of emerging technologies such as ultrasound, microwaves and high hydrostatic pressure, allows the extraction of compounds in a sustainable manner from a vegetable matrix with a high value such as jackfruit leaf proteins (Artocarpus heterophyllus Lam). Currently, the main method of protein extraction is based on the precipitation with the use of an aggressive solvent, therefore it is necessary to optimize extraction methods with a minimum waste production. In the protein extraction of jackfruit leaves, we obtained a content of 84.1mg/g using solvents. On the other hand, emergent extractions such as ultrasound, microwaves, and high hydrostatic pressure showed concentrations of 96.3, 95.6 and 147.3mg/g, respectively. In addition, we found that the best extraction agent was 0.5M NaCl, offering a range of possibilities that support green technologies as an imperative change in the food industry.

Vegetable-Oil-Based Intelligent Ink for Oxygen Sensing.

An oil-based composite is employed to monitor the exposure to oxygen inside food packaging, aiming at evaluating the package integrity and the freshness of food. The composite is an oxygen-sensitive printable ink consisting of electrically conductive silver microflakes, embedded in a vegetable oil matrix. The sensitivity of the oil to oxygen is driven by its high content of unsaturated fatty acids that polymerize and shrink upon exposure to atmospheric oxygen. Shrinkage increases the silver concentration and induces percolation, manifested by a steep increase in the electrical conductivity of the composite. We found that the electrical conductivity of the composite is related to its exposure time to air. Employing linseed oil as a matrix demonstrates an increase in electrical conductivity from 10-11 to 10-3 S/cm after only 6 days of exposure to air. We also show that this time span could be modified by changing the oil type to fit various expiration periods of food products.

Home range of the mouse Phyllotis osilae in forest fragments of Polylepis subtusalbida with different habitat matrix

Home range is an aspect of ecology that allows us to understand the mechanisms and spatial relationships that underlie habitat choice and animal responses to environmental change. However, studies on this subject have been focused mainly on medium and large mammals, while those on small mammals are scarce. Small mammals play important roles in maintaining ecological processes, such as the survival of several plant species. Phyllotis osilae is a phyllotine rodent, which functions as a potential seed disperser for Polylepis subtusalbida , a tree that is endemic and categorized as Vulnerable (VU) for Bolivia. The forests of P. subtusalbida are highly fragmented, with reforestation with introduced species such as Pinus radiata and Eucalyptus globulus . The question we pose for this study is: how does the home range of P. osilae vary between fragments of P. subtusalbida with different types of matrix (natural grassland and exotic tree plantations)? The study was carried out on four fragments of P. subtusalbida in Tunari National Park in the city of Cochabamba, Bolivia: two fragments in the exotic tree plantation matrix (Pajcha locality) and two in the natural grassland matrix (San Miguel locality). For telemetry purposes, radio collars were installed on 16 individuals. The home ranges were calculated using the Minimun Convex Polygon (MCP) at 95 %, in the same way the Kernel density (KDE) was estimated at 95 %. The percentage of presence of P. subtusalbida and matrix trees within each home range was determined, with an area interval between 50.5 m 2 and 3,010 m 2 . No significant differences were found between both matrices regard to the area of activity; however, in the comparison of the percentages of presence of P. subtusalbida trees and matrix, significant differences were found. Our results for home ranges show that the matrix would not have an effect on the area, but on its mobility; this is evidenced by the absence of movements of P. osilae from the fragments to the exotic matrix. In this case, the exotic tree matrix is operating as a barrier and is reflected in the almost total absence of this vegetation matrix in the home range. P. osilae may be playing an important role in the recovery and conservation of these ecosystems, so knowing aspects of their natural history as well as their responses to fragmentation is of great importance in understanding the fate of the Polylepis forests.

Effect of experimental wet and dry cycles on bamboo fibre reinforced acrylic polymer modified cement composites

Abstract This study experimentally evaluated the effect of accelerated wet/dry cycles on the dimensional stability and some selected mechanical properties of polymer modified vegetable fibre cement composites. The bamboo fibres were pre-treated with 10% conc. of sodium hydroxide and varied from 0 – 2.0% while acrylic polymer admixture of 10% w/w of cement was added to improve the properties. The modified fibre-cement composites were subjected to 50 cycles of wet/dry processes to simulate natural weathering process of the environment. The samples were subjected to water absorption, thickness swelling, modulus of rupture (MOR) and modulus of elasticity (MOE) after 28 days of curing and aging cycles respectively using 5 replicates. One way ANOVA at p&lt;0.05 was used to analyse the results. Scanning electron microscope (SEM) and Fourier Transformer Infrared Spectroscopy (FTIR) analyses were conducted on the samples. The results showed improvement of 33.3, 64, 71 and 57% in MOR and 135, 85, 101 and 188% in MOE for samples with 0.5, 1, 1.5 and 2% fibre inclusion after ageing tests. Significantly improved dimensional stability values were observed in this study in comparison with data from similar ageing tests conducted on unmodified vegetable fibre-cement matrix. SEM micrographs showed marginal increase in the size of the pores before and after ageing tests. FTIR analysis indicated increase in intensities during the ageing tests especially for spectra bands located at 3384 – 3520cm−1 which are denoted for OH vibration stretching as well as 1676, 1726 and 1794 cm−1 which depict the presence of carbonyl groups because of absorption of polymers to the fibre surface during the ageing cycles. The study has shown thatwet/dry ageing cycles showed less harmful effect on vegetable fibre cement composites provided the cement matrix is modified with polymer admixtures.

Antibacterial Activity of Essential Oils and Trametes versicolor Extract against Clavibacter michiganensis subsp. michiganensis and Ralstonia solanacearum for Seed Treatment and Development of a Rapid In Vivo Assay.

Clavibacter michiganensis subsp. michiganensis (Smith) Davis et al. (Cmm) and Ralstonia solanacearum Yabuuchi et al. (Smith) (Rs) are important seed-borne bacterial pathogens of tomato (Solanum lycopersicum) listed as A2 pests in the EPPO (European and Mediterranean Plant Protection Organization) region. At present, there are few strategies to control these pathogens, and seed control with eco-compatible approaches is widely encouraged. In this work, the essential oils (EOs) of oregano (Origanum vulgare), garlic (Allium sativum), basil (Ocimum basilicum), cinnamon (Cinnamomum zeylanicum), clove buds (Syzygium aromaticum), thyme (Thymus vulgaris), and Trametes versicolor extract (Tve) were tested in vitro for their antimicrobial activity against Cmm and Rs (broth microdilution method). The tested EOs and the Tve extract caused a significant inhibition of bacterial growth, with very promising MBC (minimum bactericidal concentration) and MIC90 (minimum inhibitory concentration causing a 90% growth inhibition) values. Moreover, an in vivo germination test showed no major reduction in seed germination when the substances were applied as seed treatment. A rapid molecular screening method has been developed, through real-time PCR, for the specific quantification of Cmm in the presence of a vegetable matrix to test in vivo the antimicrobial efficacy of oregano and cinnamon oil on seed treatment without resorting to whole plant essays, which are time- and space-consuming.

A hard-to-keep promise: Vegetation use and aboveground carbon storage in silvopastures of the Dry Chaco

In dry woodland regions, silvopastures have emerged as a promising option to balance cattle production, carbon storage and biodiversity. However, one of the major challenges in these systems, particularly when implemented in a matrix of natural vegetation, is the preservation of tree populations in the face of management actions implemented by ranchers to control woody encroachment. Here, we investigate the extent of that tradeoff by analyzing the impact of woody encroachment control practices on carbon storage in silvopastures of the Argentine Dry Chaco. First, we analyze tree density and carbon storage in aboveground woody biomass for silvopastures and woodlands at 24 sites in five properties across the Argentine Dry Chaco. Then, we characterize vegetation management goals and actions of ranchers who have adopted silvopastures in that same region, combining field assessments, high-resolution imagery analysis, characterization of site history, and surveys. We find that woody biomass in silvopastures retains an average of 64 % of the carbon present in aboveground biomass in intact woodlands (28.8 Mg C ha−1). However, we also find that this storage capacity decreases by 12 % with each woody encroachment control intervention, due to these interventions’ negative effects on tree density. Ranchers expressed concern about tree mortality, but also indicated low profitability of wood products and highlighted woody encroachment as a major issue for livestock production. Therefore, ranchers feel they have no choice but to continue preventing woody encroachment, even if this implies the gradual depletion of tree populations. Understanding how ranchers manage silvopastures, and how that management affects the provision of ecosystem services, is essential and will require more careful long-term monitoring and evaluation. This is particularly true in agricultural frontiers such as the Argentine Dry Chaco, where silvopastoral systems have the potential to mitigate the seemingly irremediable conflict between commodity production and nature conservation.

Genetic Characterization of a Listeria monocytogenes Serotype IVb Variant 1 Strain Isolated from Vegetal Matrix in Italy.

We report the chromosome and plasmid sequences of a strain of Listeria monocytogenes IVb variant 1, a recently emerging serotype, isolated in Italy from ready-to-eat vegetables.

Genetic Characterization of a Listeria monocytogenes Serotype IVb Variant 1 Strain Isolated from Vegetal Matrix in Italy

Genetic Characterization of a Listeria monocytogenes Serotype IVb Variant 1 Strain Isolated from Vegetal Matrix in Italy

Evaluation of Dyeing and UV Protective Properties on Hemp Fabric of Aqueous Extracts from Vegetal Matrices of Different Origin

Clothes are one of the most effective measures to minimize health hazards due to the current levels of UV radiation on the earth’s surface. Fabrics made of natural fibers and dyed with natural pigments are an excellent means to reduce UV exposure. In this study, the UV protection properties were tested on a vegetal fiber fabric (hemp) dyed with water extracts from madder, chestnut, onion, inula, and logwood, at three increasing concentrations. Dyeing extracts were obtained from different sources: agro-food industry residues (chestnut and onion), spontaneous (inula), and commercial dyeing plants (madder and logwood). The quantitative characterization of water dye extracts was performed to evaluate the amount of dye in pre- and post-dyeing solutions as well as the dye fastened to the fabric. The percentage values of dye fastened to the fabric, in relation to the plant dry weight, were relatively low for all the considered species. The fabric Ultraviolet Protection Factor (UPF) was evaluated using both a laboratory spectrophotometer and a spectroradiometer in outdoor conditions. A progressive increase in UPF with the increase of the dye-bath concentration was shown. Chestnut and onion, reaching the minimum protection level (UPF=15) at the highest dye-bath concentration, can be considered the most effective. The UPF persistence of the fabrics was also evaluated after sun exposure and repeated washing. Colors and UV protective properties obtained by the dyeing procedure tested in this research can provide added value to hemp fabric and meet the demands of an expanding “eco-friendly” market.

Electrochemical and Spectrophotometric Methods for Polyphenol and Ascorbic Acid Determination in Fruit and Vegetable Extracts.

SUMMARYResearch backgroundFresh-cut fruits and vegetables are considered sources of antioxidant compounds. However, their shelf life is limited due to nutritional, quality and safety deterioration. Therefore, in recent decades, various methods have been reported for food processing and preservation, as well as for the determination of antioxidant compounds, due to their many benefits when consumed. The aim of the present work is to compare the performance of electrochemical and spectrophotometric methods in the analysis of the content of polyphenolic compounds and ascorbic acid in extracts from fruits (eggplant), edible roots (carrot) and leaves (rocket, lettuce and chard), and evaluate their capability to detect small changes in the antioxidant content in the eggplant extracts previously irradiated with different UV-C light intensities.Experimental approachPolyphenolic compounds and ascorbic acid were determined by electrochemical and spectrophotometric methods. An enzymatic biosensor and a nanocomposite sensor were used for polyphenolic compounds and ascorbic acid, respectively, in electrochemical measurements, while Folin-Ciocalteu and Kampfenkel methods were used for spectrophotometric measurements.Results and conclusionResults obtained through the different methodologies were comparable and consistent with each other. Both methods allowed determining the content of ascorbic acid and polyphenolic compounds in the fruit and vegetable extracts. Moreover, both techniques enable the detection of the analyte concentration changes in samples exposed to different UV-C intensities and storage days. Finally, it was observed that the antioxidant capacity depends on the type of food, treatment and storage period.Novelty and scientific contributionBoth methodologies were suitable for the quantification of analytes; however, the electrochemical sensors provided higher specificity and selectivity, applicable to different fruit and vegetable matrices, obtaining results with higher precision, in shorter time and with a smaller sample volume, minimizing the economic costs because of the lower consumption of reagents.

Three Types of Beetroot Products Enriched with Lactic Acid Bacteria.

Beetroot (Beta vulgaris L.) represents a very rich source of bioactive compounds such as phenolic compounds and carotenoids, among which the most important being betalains, mainly betacyanins and betaxanthins. The beetroot matrix was used in a fresh or dried form or as lyophilized powder. A 1012 CFU/g inoculum of Lactobacillus plantarum MIUG BL3 culture was sprayed on the vegetal tissue. The lactic acid bacteria (LAB) viability for all the products was evaluated over 21 days, by microbiological culture methods. The antioxidant activity of the obtained food products was correlated to the betalains content and the viability of LAB. The content of polyphenolic compounds varied between 225.7 and 1314.7 mg L−1, hence revealing a high content of bioactive compounds. Through the confocal laser scanning microscopy analysis, a large number of viable probiotic cells were observed in all the variants but especially in the fresh red beet cubes. After 21 days of refrigeration, the high content of Lb. plantarum (CFU per gram) of the food products was attributed to the biocompounds and the nutrients of the vegetal matrix that somehow protected the bacterial cells, and thus maintained their viability. The obtained food products enriched with probiotic LAB can be regarded as new functional food products due to the beneficial properties they possessed throughout the undertaken experiments.