Nanoparticle applications in food - a review.

The use of nanotechnology in the food industry raises uncertainty in many respects. For years, achievements of nanotechnology have been applied mainly in biomedicine and computer science, but recently it has also been used in the food industry. Due to the extremely small (nano) scale, the properties and behavior of nanomaterials may differ from their macroscopic counterparts. They can be used as biosensors to detect reagents or microorganisms, monitor bacterial growth conditions, increase food durability e.g. when placed in food packaging, reducing the amount of certain ingredients without changing the consistency of the product (research on fat substitutes is underway), improve the taste of food, make some nutrients get better absorbed by the body, etc. There are companies on the market that are already introducing nanoparticles into the economy to improve their functionality, e.g. baby feeding bottles. This review focuses on the use of nanoparticles in the food industry, both organic (chitosan, cellulose, proteins) and inorganic (silver, iron, zinc oxide, titanium oxide, etc.). The use of nanomaterials in food production requires compliance with all legal requirements regarding the safety and quantity of nano-processed food products described in this review. In the future, new methods of testing nanoparticles should be developed that would ensure the effectiveness of compounds subjected to, for example, nano-encapsulation, i.e. whether the encapsulation process had a positive impact on the specific properties of these compounds. Nanotechnology has revolutionized our approach towards food engineering (from production to processing), food storage and the creation of new materials and products, and the search for new product applications.

Physico-chemical properties and antimicrobial activity of silver nanoparticles fabricated by green synthesis.

A proper understanding of silver (Ag) nanoparticles properties is fundamental for developing new antimicrobial agents. In this study, Ag nanoparticles were obtained by green synthesis methods using natural reducing agents present in extracts of apples, oranges, potatoes, red pepper, white onion, garlic and radish. The antimicrobial properties of respective nanoparticles, expressed as the minimum inhibitory concentration, were assessed against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Candida krusei. Characterization of Ag nanoparticles was done with the application of transmission electron microscopy, X-ray diffraction and UV-vis spectroscopy. The obtained results led to the conclusions that in each extract (pH from 2.1 to 6.2) were obtained specific particles (size from 9 to 30 ± 2 nm) with different antimicrobial activity. Our study indicates that plant extracts gives the Ag nanoparticles specific properties, yet the best antimicrobial properties show nanoparticles obtained in the presence of potato extract.

Determination of hyperfine fields orientation in nuclear probe techniques.

One of the most popular nuclear probes, 57Fe is used for the investigation of orientations of hyperfine fields and also for the determination of other important properties. In particular, the orientation of iron magnetic moments can be unambiguously determined, including its signs. Experiments with polarized radiation are presented with regard to selected systems. Orientation of electric field gradient is used for acquiring information about the shape of the texture-free spectra. Applications on the analysis of iron-based superconductors are presented.

Stability of core-shell magnetite nanoparticles.

In the paper, we present three different types of magnetite nanoparticles which were prepared from co-percipitation of iron (II) and (III) chlorides in aqueous solution with and without SiO2 and from thermal decomposition of iron (III) acetylacetonate in nonaqeous solutions. The obtained core-shell nanoparticles were tested in respect of their stability in distilled water, 10% acetic acid, 0.01 M citric acid, 0.9% NaCl and commercial white wine (12% of alcohol). Changes of the nanoparticles were examined by infrared spectroscopy, atomic absorption spectroscopy, transmission electron microscopy, X-ray diffraction and differential scanning calorimetry methods. Modification of magnetic properties was measured by Mössbauer spectroscopy.

Organophosphorous functionalization of magnetite nanoparticles.

In this work magnetite nanoparticles covered by gold and silver shell were obtained. Analyzed particles were modified by two kinds of organophosphorous compounds: 3-phosphonopropionic acid and 16-phosphonohexadecanoic acid. Enzyme immobilization on particles modified in such a way was tested. The crystal structure of obtained nanoparticles was characterized by transmission electron microscopy and X-ray diffraction. Possible changes on the surfaces were analyzed by the use of infrared spectroscopy. Magnetic properties were studied by Mössbauer spectroscopy.

Organophosphorous modifications of multifunctional magnetic nanowires.

In the presented study, efforts have been undertaken to obtain the magnetic nanowires of multisegmental internal structure by AC and DC electrodeposition methods. The core-shell nanowires were obtained by wetting chemical deposition followed by thermal crystallization and electrodeposition. Such nanowires were tested to obtain functionalization by organophosphorous compounds and finally immobilize enzymes like trypsin. All obtained nanostructures were tested by X-ray diffraction, infrared spectroscopy and transmission electron microscopy.

Preparation of magnetite-fullerene nanocomposite with enzyme immobilization.

This study presents modification of magnetite nanoparticles and fullerene for biocompatibility. It show also specific fabrication of magnetite-carbon nanocomposite with immobilized biomolecule. The composites were created by joining individual components step-by-step manner (fullerene to magnetite and glucose oxidase or glucose oxidase to magnetite and fullerene). The resulting nanocomposites were characterized by infrared spectroscopy (IR) and transmission electron microscopy (TEM).

Structure and serological analysis of the Hafnia alvei 481-L O-specific polysaccharide containing phosphate in the backbone chain.

The lipopolysaccharide was extracted from cells of Hafnia alvei 481-L bacterial strain and, after mild acid hydrolysis, the O-specific polysaccharide was isolated and characterised. On the basis of chemical analyses and NMR spectroscopic studies of the polysaccharide and oligosaccharides obtained after Smith degradation, or hydrogen fluoride treatment, it was found that the repeating unit of the O-specific polysaccharide is a phosphorylated hexasaccharide: [see text]. The biological repeating unit of the H. alvei 481-L O-antigen has galactose phosphate at the nonreducing terminus. Serological tests indicate that this strain represents an individual serotype in the H. alvei genus.

Structure of the O-specific polysaccharide isolated from the lipopolysaccharide of Citrobacter gillenii serotype O12a, 12b strain PCM 1544.

A neutral O-specific polysaccharide was isolated from the lipopolysaccharide of Citrobacter gillenii strain PCM 1544, representing serotype O12a,12b. The polysaccharide was studied by sugar and methylation analyses and Smith degradation along with 1H and 13C NMR spectroscopy, including a ROESY experiment. The following structure of the tetrasaccharide repeating unit was established, in which substitution with terminal GlcNAc is approximately 60%. [structure: see text]