1,720,980 research outputs found
Metodo Analitico per la determinazione del contenuto in ferro totale nella carne fresca
No full textLipid oxidation is one of the primary mechanisms of quality deterioration in foods and especially in meat and meat products and actually how this occurs still has not been resolved. It’s generally believed that the presence of transition metals, notably iron, is pivotal in facilitating the generation of species capable of abstracting a proton from an unsaturated fatty acid and in starting the oxidative process. The changes in quality are manifested by negative changes in flavour, colour, texture and nutritive value, and the possible production of toxic compounds. A simple and cheap method for the determination of total iron in fresh meat has been developed. Total iron was determined by using 1-10 Phenanthroline to detect the iron in wet ash digests. Sulphuric acid and hydrogen peroxide was employed for wet ashing. The method, validated in the range 3,8 – 34,3 μg Fe/g, showed average recovery (value ± standard deviation) of 99,2% ± 1,5%. The limit of quantification (LOQ) and limit of detection (LOD) were respectively 3,8 μg Fe/g e 1,0 μg Fe/g. The method was finally tested on raw beef meat, breast broiler and turkey meat sample
Experimental and mechanistic study of the bromomalonic acid/bromate oscillating system catalyzed by [Fe(phen)3]2+
No full textThe oscillatory behavior of a [Fe(phen)3]2+ -catalyzed/bromomalonic acid/acidic bromate Belousov–Zhabotinsky system in aerated batch conditions has been reinvestigated. An 18-step skeleton mechanism is proposed. Reactions involving oxygen in the aqueous phase as well as reactions involving organic radicals are included in the skeleton mechanism. The numerical treatment of the corresponding differential equations leads to simulated behaviors in satisfactory agreement with the experimental ones. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 291–300, 1998
The BZ Reaction: Experimental and Model Studies in the Physical Chemistry Laboratory
No full textThe paper illustrates integrated physical chemistry-computational lab experiments at the tertiary level on the "classic" Belousov-Zhabotinsky (BZ) oscillating reaction. The complete work was designed for studying the behavior of the Ce4+/Ce3+- and Fe(phen)32+/Fe(phen)33+-catalyzed BZ systems and developing a kinetic model to interpret the experimental data. The students prepared the appropriate reactant mixtures and followed spectrophotometrically the absorbance of Ce4+ and Fe(phen)32+ ions. Then they plot the period of oscillation as a function of the initial concentration of any one of the mixture components observing in particular the difference in the dependence of the oscillation period on the [Ce4+]o and [Fe(phen)32+]o respectively. These differences suggest that the two redox couples catalyze the BZ reaction by different mechanisms. A kinetic mathematical model based on the FKN mechanism for the cerium-catalyzed reaction is presented and discussed. The numerical intergration solutions of the resulting rate equations show that the model accounts satsfactorily for the oscillations of the Ce4+/Ce3+-catalyzed system but fails to reproduce the experimental behavior of the system catalyzed by the couple Fe(phen)32+/Fe(phen)33+. It has been proved that these integrated chemistry-computational lab experiments are a powerful tool in stimulating student interest in physical chemistry and in showing the importance of chemical kinetics in the elucidation of reaction mechanism
Indagine conoscitiva in un macello della Toscana nei confronti della prevenzione della BSE
No full textThe European Common Market represents an important milestone for the
realisation of an European agri-food policy. Yet, it implies several troubles often related to the
abolition of the boundary veterinary controls, modifying interventions and responsibilities of
the N.S.S. In this work, we examined the outcomes of BSE tests performed on 291 bovines
older than 24 months, in a slaughterhouse of Tuscany along a period of 17 months. No
positive cases have been found. Furthermore, the percentage of animals with problems related
to clinic systemic pathologies was very low (9,62%)
Alterazioni cromatiche del tessuto muscolare di tacchino: indagine preliminare
No full textIn this work we performed a preliminary investigation on a localised darkening process in deboned turkey's thigh muscle. A qualitative analysis on the myoglobin's spectral properties together with TVB-N and a,e-aminogroups assays were fulfilled in order to understand the physical-chemical events associated to the aforesaid instance
Technical aspects about measuring phosphorus in food
No full textPhosphorus is an essential nutrient present in food from either vegetable or animal sources, which could be part of the inorganic salts or bound to organic compounds. Organic phosphates are present in foods as phosphoproteins and phospholipids, phytate or starch phosphate monoester in vegetables, as well as several enzymes involved in many different metabolic pathways, namely phosphocreatine, nucleotides, nucleoproteins, and nucleic acids. In addition to the above mentioned compounds, which are naturally present in foods, phosphorus can be added as preservative. These additives can be either organic (like lecithin) or inorganic (like polyphosphate) compounds
Extra-phosphate load from food additives in commonly eaten foods: a real and insidious danger for renal patients
No full textBACKGROUND: Restriction of dietary phosphorus is a major aspect of patient care in those with renal disease. Restriction of dietary phosphorus is necessary to control for phosphate balance during both conservative therapy and dialysis treatment. The extra amount of phosphorus which is consumed as a result of phosphate-containing food additives is a real challenge for patients with renal disease and for dieticians because it represents a "hidden" phosphate load. The objective of this study was to measure phosphorus content in foods, common protein sources in particular, and comprised both those which included a listing of phosphate additives and those which did not.
METHODS: Determinations of dry matter, nitrogen, total and soluble phosphate ions were carried out in 60 samples of foods, namely cooked ham, roast breast turkey, and roast breast chicken, of which, 30 were with declared phosphate additives and the other 30 similar items were without additives.
RESULTS: Total phosphorus (290 ± 40 mg/100 g vs. 185 ± 23 mg/100 g, P < .001) and soluble phosphorus (164 ± 25 mg/100 g vs. 100 ± 19 mg/100 g, P < .001) content were higher in products containing additives than in foods without additives. No difference was detected between the 2 groups regarding dry matter (27.2 ± 2.0 g/100 g vs. 26.7 ± 1.9 g/100 g) or total nitrogen (3.15 ± 0.40 g/100 g vs. 3.19 ± 0.40 g/100 g). Consequently, phosphorus intake per gram of protein was much greater in the foods containing phosphorus additives (15.0 ± 3.1 mg/g vs. 9.3 ± 0.7 mg/g, P < .001).
CONCLUSIONS: Our results show that those foods which contain phosphate additives have a phosphorus content nearly 70% higher than the samples which did not contain additives. This creates a special concern because this extra amount of phosphorus is almost completely absorbed by the intestinal tract. These hidden phosphates worsen phosphate balance control and increase the need for phosphate binders and related costs. Information and educational programs are essential to make patients with renal disease aware of the existence of foods with phosphate additives. Moreover, these facts highlight the need for national and international authorities to devote more attention to food labels which should clearly report the amount of natural or added phosphorus
BIOCHEMICAL SURVEY ON EPISODIC LOCALIZED DARKENING IN TURKEY DEBONED THIGH MEAT PACKAGED IN MODIFIED ATMOSPHERE.
No full textThe color of food, especially meat and meat products, is a parameter that strongly influences consumer choice. In Italy, repeated cases of darkening in deboned thigh meat of male turkeys packaged in modified atmosphere (MAP; 80% O2, 20% CO2) have been reported. The pH, lipid oxidation (TBARS), heme proteins, and iron content were investigated in MAP samples of turkey males, females, and in oxygen-permeable filmpackaged males. Furthermore, the absorbance spectrum (400 to 700 nm) of the meat extracts was analyzed to better delineate the evolution and characteristics of the darkening process. Results showed that darkening occurred only in males with higher content of total iron, independently of the content of heme proteins, which differs only between males and females. Furthermore, pH was higher in muscles taken as controls, with respect to muscles involved in the darkening, as well as in females.
Finally, TBARS values were found to be higher in darkened regions than in not darkened ones, as well as in MAP samples with respect to oxygen-permeable filmpackaged samples. These findings suggest that darkening occurrence might depend on kind of muscle, sex, and individual characteristics of the animals raised under the same breeding conditions
- …
