Novel Zinc/Silver Ions-Loaded Alginate/Chitosan Microparticles Antifungal Activity against Botrytis cinerea.

Addressing the growing need for environmentally friendly fungicides in agriculture, this study explored the potential of biopolymer microparticles loaded with metal ions as a novel approach to combat fungal pathogens. Novel alginate microspheres and chitosan/alginate microcapsules loaded with zinc or with zinc and silver ions were prepared and characterized (microparticle size, morphology, topography, encapsulation efficiency, loading capacity, and swelling behavior). Investigation of molecular interactions in microparticles using FTIR-ATR spectroscopy exhibited complex interactions between all constituents. Fitting to the simple Korsmeyer-Peppas empirical model revealed the rate-controlling mechanism of metal ions release from microparticles is Fickian diffusion. Lower values of the release constant k imply a slower release rate of Zn2+ or Ag+ ions from microcapsules compared to that of microspheres. The antimicrobial potential of the new formulations against the fungus Botrytis cinerea was evaluated. When subjected to tests against the fungus, microspheres exhibited superior antifungal activity especially those loaded with both zinc and silver ions, reducing fungal growth up to 98.9% and altering the hyphal structures. Due to the slower release of metal ions, the microcapsule formulations seem suitable for plant protection throughout the growing season. The results showed the potential of these novel microparticles as powerful fungicides in agriculture.

Encapsulation of Rosemary Extracts using High Voltage Electrical Discharge in Calcium Alginate/Zein/Hydroxypropyl Methylcellulose Microparticles.

The increased demand for functional food with added health benefits is directing industrial procedures toward more sustainable production of naturally added bioactive compounds. The objective of this research was to investigate the potential of bioactive compounds from rosemary extract obtained using high-voltage electrical discharge as a green extraction method, for microencapsulation as a protective method for future application in functional food. Four types of microparticles were made via the ionic gelation method using alginate (Alg), zein (Z), and hydroxypropyl methylcellulose (HPMC) biopolymers and were analyzed considering the physicochemical properties. The diameter of dry microparticles ranged from 651.29 to 1087.37 µm. The shape and morphology analysis of microparticles showed that the obtained microparticles were quite spherical with a granular surface. The high encapsulation efficiency was obtained with a loading capacity of polyphenols up to 11.31 ± 1.47 mg GAE/g (Alg/Z microparticles). The microencapsulation method showed protective effects for rosemary polyphenols against pH changes during digestion. Specifically, the addition of both zein and HPMC to calcium-alginate resulted in microparticles with a prolonged release for better availability of polyphenols in the intestine. This research background indicates that the release of rosemary extract is highly dependent on the initial biopolymer composition with high potential for further functional food applications.

Chitosan-based layer-by-layer edible coatings application for the preservation of mandarin fruit bioactive compounds and organic acids.

The layer-by-layer application of biopolymeric coatings to mandarin fruits as a postharvest treatment to improve fruit coating efficacy has been reported. A single 1 % (w/v) chitosan application was evaluated, and polyelectrolyte complexes such as 1.5 % (w/v) alginate/chitosan, 1 % (w/v) hydroxypropyl methylcellulose/chitosan, and 0.2 % (w/v) locust bean gum/chitosan were applied to mandarin fruits. The quality of coated mandarin fruits was observed at temperatures: 20 ± 2 °C (up to 10 days) and 5 °C (up to 28 days). Changes in the fruit metabolism were observed by evaluating bioactive compounds (polyphenolic compounds and flavonoids), antioxidant activity, and organic acids during the preservation of mandarin fruits. All of the tested combinations of layer-by-layer coatings significantly impacted the quality of mandarin fruits throughout storage, both at room temperature and cold storage, respectively. The overall best performance was observed for a layer-by-layer hydroxypropyl methylcellulose/chitosan coating in terms of visual aspects, bioactive compounds, antioxidant activity, and organic acids content.

Development and Characterization of a Novel Soil Amendment Based on Biomass Fly Ash Encapsulated in Calcium Alginate Microspheres.

Biomass fly ash (BFA) from a biomass cogeneration plant was encapsulated into calcium alginate microspheres (ALG/Ca) and characterized. An FTIR analysis indicated that BFA loading weakened molecular interactions between ALG/Ca constituents (mainly hydrogen bonding and electrostatic interactions), thus changing the crosslinking density. SEM and AFM analyses revealed a wrinkled and rough surface with elongated and distorted granules. The in vitro release of BFA's main components (K, Ca, and Mg) was controlled by diffusion through the gel-like matrix, but the kinetics and released amounts differed significantly. The smaller released amounts and slower release rates of Ca and Mg compared to K resulted from the differences in the solubility of their minerals as well as from the interactions of divalent cations with alginate chains. The physicochemical properties of the novel microsphere formulation reveal significant potential for the prolonged delivery of nutrients to crops in a safe manner.

Increasing the lycopene content and bioactive potential of tomato fruits by application of encapsulated biological and chemical agents.

Plant secondary metabolites play an important part in the human diet. This research investigated the effect of alginate microspheres loaded with chemical (calcium or copper ions) or chemical and biological (Trichoderma viride) agents on plant secondary metabolites synthesis of two tomato varieties ('Vasanta' and 'Abellus') in two types of greenhouse cultivation, hydroponic and soil. Targeted and controlled release of active agents facilitates the root of plants to respond to the encapsulated agents and stimulate the synthesis of investigated plant metabolites both in hydroponic and soil types of cultivation. A significant increase in lycopene (up to 230%), total polyphenols content (up to 61%), and the overall antioxidant activity (up to 77%) of the tomato fruits was found for all of the treatments, respectively. Encapsulated chemical and biological agents remarkably stimulate the synthesis of plant secondary metabolites in tomato fruits indicating its great potential in the production of value-added foods.

ICP-MS Determination of Antimicrobial Metals in Microcapsules.

Silver (Ag) and zinc (Zn) are very powerful antimicrobial metals. Therefore, in this research, a high-throughput, sensitive, and rapid method was developed for the determination of Ag and Zn in microcapsules using inductively coupled plasma mass spectrometry (ICP-MS). The sample preparation procedure employed simple microwave digestion of the microcapsules with 55.55% v/v HNO3 and 44.45% v/v H2O2. The method was applied to determine Ag and Zn in microcapsule samples of different sizes (120 and 450 µm) after their preparation with and without chitosan. Prepared microcapsules, after characterization, were bonded to a polymer carrier by sol-gel procedure and the materials were characterized by FTIR spectroscopy and high-resolution optical microscopy. Significant differences were found in Ag and Zn levels between microcapsules samples prepared with and without chitosan. The results have shown that samples with chitosan had up to 20% higher levels of Zn than Ag: 120 µm microcapsules contained 351.50 µg/g of Ag and 85.51 µg/g of Zn, respectively. In contrast, samples prepared without chitosan showed larger overall variability: In microcapsules with a diameter of 120 µm, the amounts of antimicrobial metals were 98.32 µg/g of Ag and 106.75 µg of Zn, respectively. Moreover, 450 µm microcapsules contained 190.98 µg/g of Ag and 121.35 µg/g of Zn. Those quantities are high enough for efficient antimicrobial activity of newly prepared microcapsules, enabling the application of microcapsules in different antimicrobial coatings.

Functionalization of Polymer Surface with Antimicrobial Microcapsules.

The development of antimicrobial polymers is a priority for engineers fighting microbial resistant strains. Silver ions and silver nanoparticles can assist in enhancing the antimicrobial properties of microcapsules that release such substances in time which prolongs the efficiency of antimicrobial effects. Therefore, this study aimed to functionalize different polymer surfaces with antimicrobial core/shell microcapsules. Microcapsules were made of sodium alginate in shell and filled with antimicrobial silver in their core prior to application on the surface of polymer materials by dip-coating methodology. Characterization of polymers after functionalization was performed by several spectroscopic and microscopic techniques. After the characterization of polymers before and after the functionalization, the release of the active substances was monitored in time. The obtained test results can help with the calculation on the minimal concentration of antimicrobial silver that is encapsulated to achieve the desired amounts of release over time.

Chemical Profiling and Antimicrobial Properties of Honey Bee (Apis mellifera L.) Venom.

The incidence of antibiotic resistance in pathogenic bacteria has become an alarming clinical and social problem. Therefore, the demand for alternative antimicrobial compounds has increased. In this study, a chemical profile of honey bee (Apis mellifera L.) venom (HBV) has been determined by HPLC and FTIR-ATR spectroscopy, and tested for antibacterial activity, as well as efficiency with regard to conventional antibiotics. The investigated HBV was of high quality with melittin and total protein contents of 70.10 ± 7.01%, and 84.44 ± 3.12 g/100 g, respectively. The purity of HBV was confirmed by FTIR-ATR spectral profiling, which revealed a unique pattern of absorption bands that are characteristic of its major fractions. In addition, HBV showed a broad spectrum of activity against all three tested biomasses of potentially pathogenic Gram-positive and Gram-negative bacteria with MIC values ranging between 12.5 and 200 µg/mL, and MBC between 12.5 and 400 µg/mL. When compared to conventional antibiotics, HBV (400 µg) showed up to 27.8% efficiency of tetracycline (30 µg), 52.2% erythromycin (15 µg), 21.2% ciprofloxacin (5 µg), and 34.6% of ampicillin-sulbactam (20 µg). The overall results demonstrate the therapeutic potential of the analyzed HBV.

Encapsulation of Synthesized Plant Growth Regulator Based on Copper(II) Complex in Chitosan/Alginate Microcapsules.

A new copper complex, trans-diaqua-trans-bis [1-hydroxy-1,2-di (methoxycarbonyl) ethenato] copper (abbreviation Cu(II) complex), was synthesized and its plant growth regulation properties were investigated. The results show a sharp dependence of growth regulation activity of the Cu(II) complex on the type of culture and its concentration. New plant growth regulator accelerated the development of the corn root system (the increase in both length and weight) but showed a smaller effect on the development of the wheat and barley root systems. Stimulation of corn growth decreased with increasing Cu(II) complex concentration from 0.0001% to 0.01% (inhibition at high concentrations-0.01%). The development of corn stems was also accelerated but to a lesser extent. Chitosan-coated calcium alginate microcapsules suitable for delivery of Cu(II) complex to plants were prepared and characterized. Analysis of the FTIR spectrum showed that complex molecular interactions between functional groups of microcapsule constituents include mainly electrostatic interactions and hydrogen bonds. Microcapsules surface exhibits a soft granular surface structure with substructures consisting of abundant smaller particles with reduced surface roughness. Release profile analysis showed Fickian diffusion is the rate-controlling mechanism of Cu(II) complex releasing. The obtained results give new insights into the complexity of the interaction between the Cu(II) complex and microcapsule formulation constituents, which can be of great help in accelerating product development for the application in agriculture.

Synthesis, Characterization, and Encapsulation of Novel Plant Growth Regulators (PGRs) in Biopolymer Matrices.

Novel plant growth regulators (PGRs) based on the derivatives of dehydroamino acids 2,3-dehydroaspartic acid dimethyl ester (PGR1), Z-isomer of the potassium salt of 2-amino-3-methoxycarbonylacrylic acid (PGR2) and 1-methyl-3-methylamino-maleimide (PGR3) have been synthesized and their growth-regulating properties investigated. Laboratory testing revealed their plant growth-regulating activity. PGR1 showing the most stimulating activity on all laboratory tested cultures were used in field experiments. Results showed that PGR1 is a highly effective environmentally friendly plant growth regulator with effects on different crops. Biopolymeric microcapsule formulations (chitosan/alginate microcapsule loaded with PGR) suitable for application in agriculture were prepared and characterized. Physicochemical properties and release profiles of PGRs from microcapsule formulations depend on the molecular interactions between microcapsule constituents including mainly electrostatic interactions and hydrogen bonds. The differences in the microcapsule formulations structure did not affect the mechanism of PGRs release which was identified as diffusion through microcapsules. The obtained results opened a perspective for the future use of microcapsule formulations as new promising agroformulations with a sustained and target release for plant growth regulation.

The survival rate and efficiency of non-encapsulated and encapsulated native starter cultures to improve the quality of artisanal game meat sausages.

This study addresses the application of native, multiple strain starter cultures for standardization of game meat sausages production. The designed starter cultures consisting of two indigenous Lactobacillus sakei and one Leuconostoc mesenteroides strains. These strains were used in both, the encapsulated and non-encapsulated form, in the game meat dough, individually or in combination, with eight treatments in total. Microbiological and physicochemical characteristics of the sausages were monitored throughout the manufacturing process, while sensory properties, biogenic amine content, and volatile compounds were evaluated in the final products. As revealed by rep-PCR, native starter cultures, encapsulated or non-encapsulated, had survived the whole sausage production process; however, to varying degrees. The application of indigenous decarboxylase negative Lb. sakei strains significantly (P < 0.05) reduced tyramine content, rapidly decreased pH and promoted the number reduction of Enterobacteriaceae and elimination of E. coli, L. monocytogenes and coliforms in ready-to-eat products. A total of 84 volatile compounds were identified by SPME-GC-MS in the eight treatment batches of game meat sausages, with only minor differences between the treatments. No significant differences in sensory traits (P > 0.05) between tested treatments were found, although treatment with the Lb. sakei strains received the highest scores for the sensory traits including cross-section, odour, hardness, aroma, and overall acceptability. Combination of multi-strain Lb. sakei starter cultures resulted in growth prevention of undesirable microbiota, reduction of tyramine content and increased the acceptability parameters of full-ripened sausages, which make them good candidates for industrial as well as artisanal application.

Encapsulation of two fermentation agents, Lactobacillus sakei and calcium ions in microspheres.

Alginate microspheres loaded with two fermentation active agents, calcium cations and strain LS0296 identified as Lactobacillus sakei, have been prepared and characterized. The role of calcium cation is twofold, it acts as gelling cation and as fermentation active agent. Encapsulation and the presence of calcium ions in the same compartment do not inhibit the activity of LS0296. Molecular interactions in microspheres are complex, including mainly hydrogen bonds and electrostatic interactions. In vitro calcium cations and strain LS0296 release profiles were fitted to the Korsmeyer-Peppas empirical model. The calcium cation release process is driven at first by Fickian diffusion through microspheres and then by anomalous transport kinetics. The in vitro LS0296 release process is driven by Fickian diffusion through microspheres showing a much slower releasing rate than calcium cations. The release of LS0296 strain is followed by a decrease in the pH value. Results obtained give us a new insight into complex interactions between bacterial cultures and microsphere constituents. Prepared formulations of calcium alginate microspheres loaded with LS0296 could be used as a new promising tool and a model for different starter cultures encapsulation and use in the production of fermented foods.

The enhancement of plant secondary metabolites content in Lactuca sativa L. by encapsulated bioactive agents.

Encapsulated bioactive agents applied to the Lactuca sativa L. present an innovative approach to stimulate the production of plant secondary metabolites increasing its nutritive value. Calcium and copper ions were encapsulated in biopolymeric microparticles (microspheres and microcapsules) either as single agents or in combination with biocontrol agents, Trichoderma viride spores, a fungal plant growth mediator. Both, calcium and copper ions are directly involved in the synthesis of plant secondary metabolites and alongside, Trichoderma viride can provide indirect stimulation and higher uptake of nutrients. All treatments with microparticles had a positive effect on the enhancement of plant secondary metabolites content in Lactuca sativa L. The highest increase of chlorophylls, antioxidant activity and phenolic was obtained by calcium-based microparticles in both, conventionally and hydroponically grown lettuces. Non-encapsulated fungus Trichoderma viride enhanced the synthesis of plant secondary metabolites only in hydroponics cultivation signifying the importance of its encapsulation. Encapsulation proved to be simple, sustainable and environmentally favorable for the production of lettuce with increased nutritional quality, which is lettuce fortified with important bioactive compounds.

Influence of surface morphology and structure of alginate microparticles on the bioactive agents release behavior.

The structure-property relationship in alginate microparticles (microspheres and microcapsules prepared with or without Trichoderma viride spores (Tv) was investigated. Surface morphology, structure and release behavior from alginate microparticles strongly depend on calcium concentration and presence of Tv and chitosan layer. All microparticles exhibited a granular surface structure with substructures consisting of abundant smaller particles. In vitro active agents release study revealed that the increase in calcium cation concentration reduced the release rate of Tv (˜84% for microspheres; ˜57% for microcapsules) and calcium cations (˜20% for microspheres; ˜23% for microcapsules). The average decrease in k values due to chitosan layer addition is 41% for Tv and 93% for calcium ions, respectively. The underlying Tv release mechanism from microspheres is anomalous transport kinetics, whereas from microcapsules is controlled by Type II transport. The differences in microparticle surface properties did not affect the mechanism controlling calcium ions release detected as diffusion through microparticles.

Kinetics and Mechanisms of Chemical and Biological Agents Release from Biopolymeric Microcapsules.

Kinetics and mechanisms of copper cations and Trichoderma viride spores release from uncoated and chitosan coated alginate microcapsules were investigated. The gelation of a fixed amount of sodium alginate at different concentrations of copper ion solutions resulted in distinct kinetics and release mechanisms. The increase in copper cation concentration promoted, but the presence of the chitosan layer on the microcapsule surface and the increase in microcapsule size reduced the rate of active agent release. Fitting to simple Korsmeyer-Peppas empirical model revealed that the underlying release mechanism (Fickian diffusion or a combination of the diffusion and erosion mechanisms) depends on the copper cation concentration and presence of T. viride spores. The investigation pointed out that the proper selection of formulation variables helps in designing microcapsules with the desirable release of copper ions and T. viride for plant protection and nutrition.

The effects of postharvest application of lecithin to improve storage potential and quality of fresh goji (Lycium barbarum L.) berries.

To enhance storage life and post-storage quality of fresh goji berries, three treatments with lecithin (1, 5, 10g·L-1) and two storage times (8, 16days) were evaluated. The significant effects on the physiological and biochemical parameters were varied. 1g·L-1 lecithin showed its main effects after 8days of storage by reduction in total weight loss and decay, SSC/TA ratio (also at 16days), and chlorophyll content and with highest scores of sensory attributes (also at 16days). 5g·L-1 lecithin showed its main effects after 16days of storage: highest SSC, highest TA (also at 8days), highest TPC, only significant reduction in DPPH antioxidant activity, and highest total flavonoid content. 10g·L-1 lecithin showed its main effects after 8days of storage with highest SSC, chlorophyll content, total flavonoid, DPPH, and ABTS antioxidant activity (also at 16days), but with least scores of sensory attributes.

Encapsulation of Biological and Chemical Agents for Plant Nutrition and Protection: Chitosan/Alginate Microcapsules Loaded with Copper Cations and Trichoderma viride.

Novel chitosan/alginate microcapsules simultaneously loaded with copper cations and Trichoderma viride have been prepared and characterized. Information about the intermolecular interactions between biopolymers and bioactive agents was obtained by Fourier transform infrared spectroscopy. Encapsulation of T. viride spores and the presence of copper cations in the same compartment does not inhibit their activity. Microcapsule loading capacity and efficiency as well as swelling behavior and release depend on both the size of the microcapsule and bioactive agents. The in vitro copper cation release profile was fitted to a Korsmeyer-Peppas empirical model. Fickian diffusion was found to be a rate-controlling mechanism of release from smaller microcapsules, whereas anomalous transport kinetics controlled release from larger microcapsules. The T. viride spore release profile exhibited exponential release over the initial lag time. The results obtained opened perspectives for the future use of chitosan/alginate microcapsules simultaneously loaded with biological and chemical agents in plant nutrition and protection.

Consumer acceptability of liquorice root (Glycyrrhiza glabra L.) as an alternative sweetener and correlation with its bioactive content and biological activity.

Consumer acceptability and sensory properties of liquorice root (Glycyrrhiza glabra L.) were evaluated. Quantitation of total polyphenolics and glycyrrhizic acid (GA), as well as the antioxidant capacity of liquorice extracts, was conducted and their biological effects (cytotoxic, antioxidative/pro-oxidative activity, lipid peroxidation on human laryngeal carcinoma cell line) compared to the ones of their predominant bioactive compound - GA. Conducted consumer survey revealed poor familiarity with liquorice (12.37% of correspondents), but willingness towards its use as an alternative sweetener (77.32% of consumers). Polyphenolic content of evaluated extracts ranged from 1018.18 to 1277.27 mg gallic acid equivalents (GAE)/l while GA content varied between 2179.53 and 2944.13 mg/l. The most pronounced cytotoxic effect (60%) and lipid peroxidation were exerted by treatment with the highest applied extract concentrations (10 mg/ml). Pure GA exhibited cytotoxic and pro-oxidative effects at concentrations of 0.12-0.6 mg/ml. Due to high GA content, coupled with its pronounced cytotoxic activity, the intake of liquorice root should be limited.