Comparison of meat quality characteristics and oxidative stability between conventional and free-range chickens

The aim of this research was to evaluate quality traits and oxidative stability of meat products from free range (FR) and conventionally (C) raised chickens as they actually reach consumers in the Italian retail market. FR female and male chickens (n=1500 + 1500), medium growing Isa strain, were raised under commercial conditions for 56 (1.8 kg of live wt.) and 70 d (3.1 kg of live wt.), respectively; C female and male birds (n=5000 + 5000) were a fast growing hybrid (Ross 708) and were separately raised for 39 (1.9 kg of live wt.) and 50 d (3.1 kg of live wt.), respectively. A total of 96 chickens (equally divided by production system and sex) were slaughtered into 2 separate sessions, to obtain the main two commercial categories (rotisserie and cut-up, respectively). After slaughtering, 12 carcasses of each treatment group were randomly selected and used to assess quality properties, chemical composition and oxidation stability of breast and leg meat. C birds had dramatic higher carcass and breast meat yield, whereas FR had higher wing and leg yields. FR birds exhibited higher water holding capacity in both breast and leg meat. Although shear force did not differ in breast meat, legs from FR birds were tougher. Fatty acid composition of FR breast and thigh meat of both categories were characterized by a higher PUFA n-6-/n-3 ratio. In general, a low lipid oxidation level (peroxide value (PV) < 1.3 meq O2/kg of lipid and thiobarbituric acid reactive substances (TBARs) < 0.2 mg MDA/kg of sample) was found in breast and legs, regardless of the commercial category. However, the C system significantly increased PV in rotisserie thigh meat, whereas FR led to a significantly higher TBARs in breast meat. Our results demonstrated that free range can modify the properties of chicken meat and also highlighted the importance of the animal genetic background to select nutritional strategies to improve meat quality traits and oxidative stability in poultry

I bisogni espressi dai docenti in formazione

Analisi dei bisogni formativi espressi attraverso la partecipazione a forum on- line (piattaforma moodle) dai docenti-allievi in formazione che hanno frequentato il TFA (tirocinio Formativo Attivo) organizzato dalla Sapienza nell'a.a. 2012-1

Stability of flavoured phytosterol-enriched drinking yogurts during storage as affected by different packaging materials

The aim of this study was to investigate the influence of different packaging materials on storage stability of flavoured phytosterol-enriched drinking yogurts. White vanilla (WV) and blood orange (BO) phytosterol-enriched drinking yogurts conditioned in mono-layer and triple-layer co-extruded plastic bottles were stored at +6\ub11 18C for 35 days (under alternating 12 hlight and 12 hdarkness) to simulate shelf-life conditions. Sampleswere collected at three different storage times and subjected to determination of total sterol content (TSC), peroxide value (PV) and thiobarbituric acid reactive substances (TBARs). TSC was not significantly affected by packaging material or storage time and met the quantity declared on the label. PV was significantly influenced by yogurt type 7packaging material 7storage time interaction and TBARs by packaging material 7storage time interaction. Between the two packaging materials, the triple-layer plastic mini bottle with black coloured and completely opaque intermediate layer offered the best protection against lipid oxidation

Effect of dietary supplementation on lipid photoxidation in beef meat, during storage under commercial retail conditions

The effects of feeding composition on the photosensitized oxidation of lipids from beef meat, were evaluated during storage under commercial retail conditions. Feeding was enriched with linseed oil (LO), Dl-α tocopheryl acetate (vE) and conjugated linoleic acid (CLA) at different doses and provided for diverse periods, resulting in 7 diet groups (A-G). After slaughtering and 2 weeks of holding period, meat slices were packed in vessels with transparent shrink film and exposed to white fluorescent light for 8 h at 8 °C. Total cholesterol oxidation products (COPs) level varied from 4.0 to 13.0 μg/g of lipids, which corresponded to 0.1-0.6% oxidized cholesterol. The lowest peroxide value (PV) in the diet added with vE and LO for 90 days was found. Light exposure only had a significant impact on thiobarbituric acid reactive substances (TBARs). In general, Dl-α tocopheryl acetate supplemented for 90 days improved the oxidative stability of beef meat stored under commercial retail conditions