Innovative analytical tools to characterize prebiotic carbohydrates of functional food interest

Functional foods are one of the most interesting areas of research and innovation in the food industry. A functional food or functional ingredient is considered to be any food or food component that provides health benefits beyond basic nutrition. Recently, consumers have shown interest in natural bioactive compounds as functional ingredients in the diet owing to their various beneficial effects for health. Water-soluble fibers and nondigestible oligosaccharides and polysaccharides can be defined as functional food ingredients. Fructooligosaccharides (FOS) and inulin are resistant to direct metabolism by the host and reach the caecocolon, where they are used by selected groups of beneficial bacteria. Furthermore, they are able to improve physical and structural properties of food, such as hydration, oil-holding capacity, viscosity, texture, sensory characteristics, and shelf-life. This article reviews major innovative analytical developments to screen and identify FOS, inulins, and the most employed nonstarch carbohydrates added or naturally present in functional food formulations. Highperformance anion-exchange chromatography with pulsed electrochemical detection (HPAEC-PED) is one of the most employed analytical techniques for the characterization of those molecules. Mass spectrometry is also of great help, in particularly matrix-assisted laser desorption/ionization timeof- flight mass spectrometry (MALDI-TOF-MS), which is able to provide extensive information regarding the molecular weight and length profiles of oligosaccharides and polysaccharides. Moreover, MALDI-TOF-MS in combination with HPAEC-PED has been shown to be of great value for the complementary information it can provide. Some other techniques, such as NMR spectroscopy, are also discussed, with relevant examples of recent applications. A number of articles have appeared in the literature in recent years regarding the analysis of inulin, FOS, and other carbohydrates of interest in the field and they are critically reviewed

Antimicrobial films containing lysozyme for active packaging obtained by sol-gel technique

Antimicrobial packaging is a promising form of active packaging that refers to the incorporation of antimicrobial agents into packaging systems with the aim to extend the product shelf life maintaining its quality and safety. In our work an antimicrobial active packaging based on poly(ethylene terephthalate) (PET) was prepared by sol–gel route, incorporating as antimicrobial agent lysozyme with the aim to obtain packaging films with controlled release properties. The fine tuning of the sol concentration and viscosity as well as the dip-coating extraction rate, allowed to deposit on the external surface of the PET support uniform coatings with controllable thickness at the sub-micron scale. FTIR microspectroscopic and tapping mode-Atomic Force Microscopy (TM-AFM) measurements were used to characterize the prepared coatings. The antimicrobial activity of the obtained surface modified films was tested on agar plates against Micrococcus lysodeikticus. Furthermore, the stability of the coating was evaluated in order to verify a possible migration of lysozyme to a liquid media (buffered solution at pH 6.2), due to a possible release from the plastic substrate. The quantitative determination of the released lysozyme in the buffered solution was performed by HPLC UV-DAD. Results show that the incorporation of lysozyme into the sol–gel modified PET do not lead to a loss of activity of the enzyme, and suggest a significant potential for the use of these packaging materials

Natamycin based sol-gel antimicrobial coatings on polylactic acid films for food packaging

In this work a comprehensive study on a new active packaging obtained by a hybrid organic–inorganic coating with antimicrobial properties was carried out. The packaging system based on polylactic acid was realised by sol–gel processing, employing tetraethoxysilane as a precursor of the inorganic phase and polyvinyl alcohol as the organic component, and incorporating natamycin as the active agent. Films with different organic–inorganic ratios (in a range between 1:19 and 1:4) were prepared, and the amount of antimycotic entrapped was found to be modulated by the sol composition, and was between 0.18 and 0.25 mg/dm2. FTIR microspectroscopic measurements were used to characterise the prepared coatings. The antifungal properties of the films were investigated against mould growth on the surface of commercial semi-soft cheese. The release of natamycin from the films to ethanol 50% (v/v) was studied by means of HPLC UV-DAD. The maximal level released was about 0.105 mg/dm2, which is far below the value allowed by legislation

Classification of extra virgin olive oils according to their geographical origin using phenolic compound profiles obtained by capillary electrochromatography

A simple and reliable method for the evaluation of the phenolic fraction of extra virgin olive oils (EVOO) by capillary electrochromatography (CEC) with UV–Vis detection, using lauryl acrylate (LA) ester-based monolithic columns, has been developed. The percentages of the porogenic solvents in the polymerization mixture, and the mobile phase composition, were optimized. The optimum monolith was obtained with a monomers/porogens ratio of 40:60% (wt/wt) using a LA/1,3-butanediol diacrylate ratio of 70:30% (wt/wt) and a 1,4-butanediol/1-propanol ratio of 25:75% (wt/wt). A satisfactory resolution between the phenolic compounds was achieved in less than 25 min with a 15:85 (v/v) ACN–water buffer containing 5 mM formic acid at pH 3.0. The method was applied to the analysis of the phenolic fraction of EVOO samples. Using linear discriminant analysis of the CEC phenolic profiles, the EVOO samples belonging to three different geographical origins (Croatia, Italy and Spain) were correctly classified with an excellent resolution among all the categories

DNA recognition by peptide nucleic acid-modified PCFs: from models to real samples

The increased concern, emerged in the last few years, on food products safety has stimulated the research on new techniques for traceability of raw food materials. DNA analysis is one of the most powerful tools for the certification of food quality, and it is presently performed through the polymerase chain reaction technique. Photonic crystal fibers, due to the presence of an array of air holes running along their length, can be exploited for performing DNA recognition by derivatizing hole surfaces and checking hybridization of complementary nucledotide chains in the sample. In this paper the application of a suspended core photonic crystal fiber in the recognition of DNA sequences is discussed. The fiber is characterized in terms of electromagnetic properties by means of a full-vector modal solver based on the finite element method. Then, the performances of the fiber in the recognition of mall synthetic oligonucleotides are discussed, together with a test of the possibility to extend this recognition to samples of DNA of applicative interest, such as olive leaves