Verónica Alonso

Effect of crossbreeding and gender on meat quality and fatty acid composition in pork

This study considers the effect of crossbreeding and gender (barrows; gilts) on meat quality and intramuscular and subcutaneous fatty acid composition in pork. The sire lines included Large White (LW), Duroc (D) and Pietrain (P) and the dam line was Landrace (LR)×LW, producing LW×(LR×LW), D×(LR×LW) and P×(LR×LW). Pork samples were removed from Longissimus dorsi (LD) and Semimembranosus (SM) muscles and subcutaneous fat (SCF). There were no important differences in meat quality parameters but D×(LR×LW) had the highest percentage of intramuscular fat. Castrated males had more intramuscular fat and more intense meat colour than female pigs. The Large White and Duroc sire line had saturated fatty acids (SFA) in SM, whereas the Pietrain sire line was significantly higher than Duroc sire line in the concentration of polyunsaturated fatty acids (PUFA), PUFA/SFA (P/S) and the n-6/n-3 ratio. The concentrations of SFA and monounsaturated fatty acids (MUFA) in SCF were significantly higher in LW×(LR×LW) and P×(LR×LW), respectively. No differences were found in the percentage of PUFA, P/S and n-6/n-3 ratio between D×(LR×LW) and P×(LR×LW). Female pigs had the most polyunsaturated intramuscular and subcutaneous fat. The results demonstrate small differences in fatty acid compositions among sires.

Effect of protein level in commercial diets on pork meat quality

This study assessed the effect of protein level on meat quality, intramuscular and subcutaneous fat, instrumental texture and sensory attributes on Longissimus dorsi in pork. Animals were fed two experimental diets that produced two animal groups with different percentages of intramuscular fat (IMF) (1.76 vs. 2.63). There were no significant differences in meat quality or texture profile analysis parameters between IMF groups. The percentage of saturated fatty acids was also similar, but the percentage of monounsaturated was significantly higher in the group with higher IMF and the percentage of polyunsaturated fatty acids was higher in the group with lower IMF. IMF groups had little effect on the fatty acid composition of subcutaneous fat. Warner-Bratzler shear force (WBSF) values were significantly higher in the group with lower IMF, whereas tenderness was higher in the group with higher IMF. Finally, WBSF appeared to be a good predictor of the tenderness for grill-cooked pork.

Influence of dietary fat on pork eating quality

This study compared the influence of dietary fat sources on meat quality, fatty acid composition and sensory attributes in pork. The experiment was conducted with 43 entire male pigs (Pietrain×(Landrace×Large White)) which were fed a basal diet without added fat (control diet) or supplemented with different sources of fat: animal fat (1%, AF1; 3%, AF3), soyabean oil (1%, SBO1) and calcium soaps of palm oil (1%, CaSPO1). Dietary fat supplementation did not significantly affect ultimate pH, colour, Warner-Bratzler shear force values, sensory attributes or SFA. Pigs fed SBO1 had the lowest proportion of MUFA and the highest of PUFA. In conclusion, these dietary fat sources could be recommended for inclusion in diets, at these levels, with no detrimental effect on eating quality. Despite finding no significant differences, the PCA afforded a comprehensive view of the predominating attributes of pork from animals fed the different fats.

Antioxidant diet supplementation and lamb quality throughout preservation time

Diet supplementation (DS) (100, 200, 300ppm vitamin E -VE; 150ppm product rich in flavonoids-PRF; 100+100ppm VE-PRF; no supplementation) effect was evaluated on lamb quality throughout 10days after sampling (preservation time: PT). pH, colour, myoglobin forms and lipid oxidation were analyzed on Longissimus muscle. Trained panellists evaluated colour intensity of chops packaged in modified atmosphere under display up to 12days. PT had a larger effect on quality than DS. DS showed a clear antioxidant effect on lipids, especially at long PT and at high doses of VE. Visual test showed statistical differences among DS from day 4 of display where 200 and 300ppm VE improved visual colour score. In general, supplementation with antioxidants showed better meat quality and diets higher than 100ppm VE showed higher antioxidant capacity than the rest. The PRF diet was similar for a short PT but lower at a long PT. More research on flavonoids is necessary.

Survival of Vibrio parahaemolyticus and Aeromonas hydrophila in sea bream (Sparus aurata) fillets packaged under enriched CO2 modified atmospheres

The ability to survive of two pathogens (Vibrio parahaemolyticus and Aeromonas hydrophila) spread over sea bream fillets packaged under different modified atmospheres (MAPs) was studied at 0°C and 4°C under refrigerated storage. The atmospheres used were 60% CO2/40% N2, 70% CO2/30% N2 and 80% CO2/20% N2 and a control batch packaged in air. Head space gas analyses, microbial counts and confirming test of pathogenic bacteria were carried out during 16days. The results obtained showed that all the modified atmospheres studied were effective to reduce the microbial load of sea bream fillets when compared with air packaged samples although small differences were found among MAPs. Temperature storage was the main factor to reduce microbial growth. V. parahaemolyticus was unable to grow at both temperatures, 0°C and 4°C (except air batches) while A. hydrophila showed significant growth at 4°C and microbial inactivation at 0°C.

Survival of Listeria monocytogenes and Salmonella Enteritidis in sea bream (Sparus aurata) fillets packaged under enriched CO2 modified atmospheres

The effect of packaging of fresh sea bream fillets under different modified atmospheres (high levels of CO2 combined with N2) on the behaviour of Listeria monocytogenes and Salmonella Enteritidis was studied. Two different strains of each pathogen were spread over the sea bream fillets stored at either 0 °C or 4 °C for 16 days under standard supermarket lighting conditions (14 h a day). The atmospheres investigated were 60% CO2/40% N2, 70% CO2/30% N2, 80% CO2/20% N2 and air as control. Mesophilic, psychrotrophic and Enterobacteriaceae microbial counts were also performed in control batches. The results indicate that all the CO2 concentrations used favoured the control of pathogen bacteria inoculated, when compared with air conditions especially, when combined with storage at 0 °C. Both storage temperature (0 °C and 4 °C) resulted in a decrease in Salmonella count. The results were more significant for Listeria strains, because during the storage at 4 °C Listeria count increased in all batches, while for samples stored at 0 °C a significant reduction in microbial load except in control batch was observed. Sensitivity differences of inoculated strains against temperature and CO2 concentrations were also discussed.

The impact of short-term feeding of magnesium supplements on the quality of pork packaged in modified atmosphere.

This study compared the effect of dietary magnesium (Mg) supplementation on pork quality during 13 days of storage at 4±1°C under modified atmosphere. The experiment was conducted with 40 gilts (Pietrain×(Landrace×Large White)) which were fed one of four diets five days prior to slaughter: 1) control diet; 2) Mg oxide; 3) Mg sulphate; or 4) Mg chelate. Dietary Mg supplementation did not affect 24-h pH, colour, and Warner-Bratzler shear force values. Pork from pigs fed the Mg chelate-supplemented diet had the lowest (P≤0.05) drip, exudative, and cooking losses. Furthermore, pork from pig supplemented with Mg oxide had the lowest TBARS values. Visual assessment of pork from pigs supplemented with Mg chelate received higher colour and lower exudative scores, as well as overall acceptability scores, throughout display. Thus, Mg chelated supplementation could be effective in improving pork quality during 13 days of storage under modified atmosphere conditions.

Effect of borage and green tea aqueous extracts on the quality of lamb leg chops displayed under retail conditions

Different concentrations of two aqueous extracts from green tea leaves and borage seeds with potential antioxidant activity were evaluated in lamb leg chops. Chops were sprayed with 0.005, 0.05, 0.5, 5% (p/v) green tea extracts (T) and 0.5, 5 and 10% (p/v) borage seed extracts (B) and displayed under retail conditions for 13days. Total polyphenols, TBARS, colour, microbial and sensory analyses were performed. The extracts showed a concentration-dependent action; the minimum concentration of polyphenols which significantly reduced lipid oxidation was 2.08mgGAE/100cm2 of meat. Both 0.5% T and 10% B limited colour deterioration, reducing also metmyoglobin formation. The extracts showed no antimicrobial effect, exceeding microbial counts of 7logCFU/cm2 at 13days of display. Sensory analyses determined that none of the extracts added herb odours or flavours to lamb. In conclusion, 0.5% T or 10% B extracts extended lamb shelf life from 8 to 11days, so both would be recommended for lamb chops preservation.

The inclusion of Duroc breed in maternal line affects pork quality and fatty acid profile

The aim of this study was to evaluate the effect of including different percentages of Duroc (D) breed in maternal line [Landrace (LR) × Large White (LW); LR × (LW × D); LR × D] and gender on meat quality and intramuscular (IMF) and subcutaneous (SCF) fatty acid composition. No significant differences were found among dam lines in ultimate pH, L* values and drip and cooking losses. There were higher percentages of saturated fatty acids in LR × D and LR × (LW × D) lines and higher percentages of polyunsaturated fatty acids in LR × LW line in IMF and SCF. Also, LR × D line produced pork with a lower Warner-Bratzler shear force values and higher IMF content and potential of lipid oxidation. Furthermore, the L*, a* and b* values and drip loss were greater in pork from entire males than females. The IMF and SCF of females were more monounsaturated and less polyunsaturated than those from entire males.

Effect of dietary vitamin E on physicochemical and fatty acid stability of fresh and thawed lamb.

This study evaluated the effect of dietary vitamin E supplementation (1000mg of DL-α-tocopheryl acetate/kg of basal diet) on physicochemical and fatty acid stability of fresh and thawed lamb leg chops, frozen stored for 3, 6 and 9months. Legs were chopped, modified atmosphere packaged (70%O2/30%CO2) and maintained under retail conditions (4±0.5°C, with 14h fluorescent light) for 9days. Muscle α-tocopherol concentration was over 3.5-fold higher in supplemented samples than in control lambs. The effect of dietary vitamin E was independent of frozen storage, so these effects were analysed separately. Vitamin E supplementation reduced lipid oxidation (P≤0.001) and decreased metmyoglobin formation, leading to a more attractive colour of meat. Moreover, supplementation led to a higher percentage of polyunsaturated fatty acids. Therefore, vitamin E supplementation could be recommended for preserving either fresh or thawed lamb.