Giuliana Vinci

Biogenic amines: quality index of freshness in red and white meat

Abstract Biogenic amine (BA) content in meat can be considered as a freshness marker or as a bad conservation marker. In particular the study of BA quantities in meat as a function of conservation time, could be a useful tool to control meat spoilage. In fact, the formation of some amines and concentration increase of those already existing in meat, are due to degrading processes in food, which are promoted by enzymatic reactions caused by external microbial activity or by endogenous tissue activities. The amines considered are: tryptamine, putrescine, cadaverine, serotonin, tyramine, spermidine, spermine. Their quantitative determination was carried out by means of HPLC, with spectrophotometric-UV detection, on pre-treated meat samples, both “red” (adult bovine) and “white” (chicken). The amines were extracted in acid aqueous solution (HClO4) and then derivatised by dansylchloride. The trend of BA concentrations as a function of time was also investigated, in a period of 36 days, at the conservation temperature of 4±1 ° C . The proposed method is linear in the range of concentrations between 0.01 and 5.0 μg/ml. For all the amines considered recoveries were ⩾93%. The CV values for all the measures ranged between 1.47% and 2.94%. The results show that in red meat the BA levels are still low until 9 days of storage (⩽30 mg/kg) and that over 36 days only cadaverine and tyramine concentrations become very high (⩾120 mg/kg). In white meat all the BA levels remain quite low (⩽40 mg/kg) all over the 36 days, instead of the cadaverine content which gains 50 mg/kg at the seventh day of storage.

Ascorbic acid in exotic fruits: a liquid chromatographic investigation

Abstract The levels of ascorbic acid (AA) have been measured by means of an HPLC method in 11 different exotic fruits (avocado pear, babaco, feijoa, grapefruit, kiwi, kumquat, litchi, mango, papaya, passion fruit, pineapple) and, for comparative purposes, in two citrus fruits (lemon and orange). They were measured in the exotic fruits at two different stages of ripening: (i) immediately after purchasing from a local fresh fruit market, and (ii) after a one-week period of artificial ripening. The results show that all tropical fruits contain relatively high levels of AA (varying between 20 and 90 mg/100g), with the exceptions of avocado pear and feijoa (whose AA levels are markedly affected by oxidation processes). Moreover, the results show that there is a remarkable loss of AA content (usually 30–40%) after the one-week period of artificial ripening, in all the different tropical fruits considered. They seem to indicate that the process of artificial ripening, which is usually carried out during the short-term storage of exotic fruits, can affect the nutritional value of this kind of food as far as the concentration of the reduced form of vitamin C is concerned.

Bioremediation of Food Industry Effluents: Recent Applications of Free and Immobilised Polyphenoloxidases

Enzymes are specific biological catalysts able to react under mild conditions of temperature and pH and their use in food industry for bioremediation is well known. Research in recent years has been intense, much of it elicited by the great number of different exploitable enzymes. Employment of enzymes in many bioremediation processes is made in order to protect the environment from damage caused by industrial polluting effluents. In particular, the food industry is one of the most important sectors among the manufacturing industries as far as production values are concerned; indeed, food industry processes involve large amounts of water and contribute to pollution loads discharged into water resources. In particular the presence of phenols in agroindustrial effluents has attracted interest for laccases and tyrosinases use in wastewater treatment and bioremediation. The presence of phenolic compounds in drinking and irrigation water or in cultivated land represents a significant health and/or environmental hazard and, therefore, the development of methods for their removal and transformation have received increased attention in recent years. The main purpose of this paper was to present the most recent results dealing with the fundamental and applied aspects of free and immobilised polyphenoloxidases for food industry wastewater processing.

Authenticity and quality of animal origin food investigated by stable-isotope ratio analysis.

Authentication of a food product is the procedure by which it is verified that the product matches the statements on the label, and that it conforms to what is established by regulations. This testing process includes analysis of the ingredients, determination of the geographical origin, and examination of the production methods. In particular, the use of rapid, effective and reliable analytical methods, when correctly applied to verify the authenticity and the traceability of the product, represents a valuable and irreplaceable tool for the authorities to carry out control functions. Tools and methodologies from scientific innovation and technological evolution can help to quickly locate particularly sophisticated frauds and adulterations. The feeding regime of livestock is a fundamental issue for the properties and safety of animal origin food, but this regime is often hidden from the consumer, making the zootechnical sector more prone to fraudulent practices. This review reports the results recently obtained in authentication of animal origin food by the application of stable-isotope ratio analysis, the most promising analytical technique in this field.

Fast determination of biogenic amines in beverages by a core–shell particle column

A fast and reliable HPLC method for the determination of 11 biogenic amines in beverages has been performed. After pre-column derivatization with dansyl-chloride a Kinetex C18 core-shell particle column (100 mm × 4.6 mm, 2.6 μm particle size) has been employed and the biogenic amines were identified and quantified in a total run time of 13 min with ultraviolet (UV) or fluorescence detection (FLD). Chromatographic conditions such as column temperature (kept at 50 °C), gradient elution and flow rate have been optimized and the method has been tested on red wine and fruit nectar. The proposed method is enhanced in terms of reduced analysis time and eluent consumption with respect of classical HPLC method as to be comparable to UHPLC methods. Green and cost-effective, this method can be used as a quality-control tool for routine quantitative analysis of biogenic amines in beverages for the average laboratory.

Rapid and direct determination of fructose in food: A new osmium-polymer mediated biosensor

This paper describes the development and performance of a new rapid amperometric biosensor for fructose monitoring in food analysis. The biosensor is based on the activity of fructose dehydrogenase (FDH) immobilised into a carbon nanotube paste electrode according to two different procedures. The direct wiring of the FDH in a highly original osmium-polymer hydrogel was found to offer a better enzyme entrapment compared to the immobilisation of the enzyme in an albumin hydrogel. The optimised biosensor required only 5U of FDH and kept the 80% of its initial sensitivity after 4months. During this time, the biosensor showed a detection limit for fructose of 1μM, a large linear range between 0.1 and 5mM, a high sensitivity (1.95μAcm(-2)mM), good reproducibility (RSD=2.1%) and a fast response time (4s). Finally, the biosensor was applied for specific determination of fructose in honey, fruit juices, soft and energy drinks. The results indicated a very good agreement with those obtained with a commercial reference kit. No significant interference was observed with the proposed biosensor.

Determination of Phospholipids in Food Samples

Phospholipids (PLs), the most important class of polar lipids in foods, are ubiquitous compounds because they are the major components of animal and plant cell membranes. Their technological and biological properties therefore make them important in human nutrition. The efficient separation and accurate quantification of PLs can be achieved with high-performance liquid chromatography–evaporative light scattering detection (HPLC-ELSD) because ELSD is a quasi-universal detector for liquid, countercurrent, and supercritical fluid chromatography and can detect any analyte less volatile than the mobile phase. In this article, the principles of ELSD operation (i.e., nebulization of the chromatographic effluent, evaporation of the mobile phase, and measurement of the scattered light) as well as the application of LC-ELSD to determine the amount of PLs in different food matrices are reviewed. Food matrices containing PLs include milk and dairy products, meat, fish, eggs, cereals, and oils. Both the technological aspects and analytical parameters affecting the concentration and quantitative determination of PLs in food matrices are evaluated. In particular, different extraction, purification, and chromatographic conditions were extensively investigated; moreover, wherever possible, the results obtained are reported and compared with other detection methods.

Determination of free fatty acids and lipase activity in milk: quality and storage markers

The free fatty acid (FFA) content together with the lipase activity control can be considered as useful indexes of good quality and correct storage of food, especially for milk. The quantitative analysis of FFA in different kinds of milk has been performed by a potentiometric method, using a new extractive methodology outlined herein. The lipase activity has been controlled by a sensitive calorimetric method, previously validated by us, based on the direct measure of the heat quantity involved in the enzymatic reaction. In order to verify the milk quality after the healing treatments and/or during the shelf life, the behaviours of FFA content and of lipase activity have been outlined in function of storage time and pH variations on different typologies of milk. The FFA content in sample of fresh pasteurised milk was found to be quite high after the 5th/6th day of storage at +4 degrees C, meanwhile the pH values were always constant and only after the 9th day begun to decrease. At the same time the lipase activity, directly measured, was found to be appreciable after the 6th day of storage, giving an exothermic answer at the calorimeter, similar to that of a milk sample where only three international units of standard lipase were added.

Rapid determination of polycyclic aromatic hydrocarbons in rainwater by liquid–liquid microextraction and LC with core‐shell particles column and fluorescence detection

Liquid-liquid microextraction coupled to LC with fluorescence detection for the determination of Environmental Protection Agencys 16 priority pollutant polycyclic aromatic hydrocarbons in rainwater has been developed. The optimization of the extraction method has involved several parameters, including the comparison between an ultrasonic bath and a magnetic stirrer as extractant apparatus, the choice of the extractant solvent, and the optimization of the extraction time. Liquid-liquid microextraction gave good results in terms of recoveries (from 73.6 to 102.8% in rainwater) and repeatability, with a very simple procedure and low solvent consumption. The reported chromatographic method uses a Core-Shell technology column, with particle size <3 μm instead of classical 5-μm particles column. The resulting backpressure was below 300 bar, allowing the use of a conventional HPLC system rather than the more expensive ultrahigh performance LC (UHPLC). An average decrease of 59% in run time and 75% in eluent consumption has been obtained, compared to classical HPLC methods, keeping good separation, sensitivity, and repeatability. The proposed conditions were successfully applied to the determinations of polycyclic aromatic hydrocarbons in genuine rainwater samples.

Determination of the urease activity and the relative inhibition in the presence of some metal ions: a microcalorimetric study

Abstract Batch microcalorimetry has been employed to obtain a calibration curve for the enzymatic activity of urease in solution. This method is simplier, more reliable and easier to handle than the more common techniques (spectrophotometry and potentiometry), because it is based on direct investigation of the enzymatic reaction. By comparison with calorimetric studies employing the thermistor combined with the immobilized, enzyme, this method also allows the catalytic activity to be measured. Variations in the urease activity in the presence of nine metal ions [Hg(II), Ag(I), Cu(II),Zn(II), Cd(II), Ni(II), Co(II), Mn(II) and Mg(II)] are also described. A graphic method has been devised for immediate identification of the minimum inhibitor concentration,determining the start, 50% and complete inhibition of ureasic activity.