Pedro Roncalés

The effects of ascorbic acid, taurine, carnosine and rosemary powder on colour and lipid stability of beef patties packaged in modified atmosphere

This research was aimed at evaluating the inhibition of oxidative changes of beef patties packaged in modified atmosphere (70% O(2)+20% CO(2)+10% N(2)) by natural antioxidants: ascorbic acid (500 ppm), taurine (50 mM), carnosine (50 mM), rosemary powder (1000 ppm) and their combinations with the first. Beef patties stored at 2±1°C for 20 days were evaluated for colour (L*, a*, b*, C* and H*), TBARS, metmyoglobin formation (% of total myoglobin), psychrotrophic microbial counts and sensory odour and discolouration. Rosemary, either alone or with ascorbic acid, was highly effective in inhibiting both metmyoglobin formation and lipid oxidation; sensory analysis was in agreement with these results. Ascorbic acid, ascorbic acid+taurine and ascorbic acid+carnosine treatments showed a limited inhibitory effect of myoglobin oxidation, while carnosine and carnosine+ascorbic acid were effective in inhibiting lipid oxidation. Taurine alone failed to exert any antioxidant effect. Principal components analysis confirmed these results.

Extension of the display life of lamb with an antioxidant active packaging.

Fresh lamb steaks were treated with three different preparations of natural antioxidants: one group was packaged with a rosemary active film, the second group was packaged with an oregano active film, and the third group was sprayed on the meat surface with a rosemary extract before packaging in a high-oxygen atmosphere. Samples were stored under illumination at 1±1°C for 13days. Metmyoglobin formation, lipid oxidation (TBARS), instrumental colour (CIE a(∗)), psychrotrophic bacterial counts (PCA), sensory discolouration and off-odour were determined. The use of a rosemary extract, a rosemary active film or an oregano active film resulted in enhanced oxidative stability of lamb steaks. Active films with oregano were significantly more efficient than those with rosemary, exerting an effect similar to that of direct addition of the rosemary extract; in fact, they extended fresh odour and colour from 8 to 13days compared to the control.

Shear values of raw samples of 14 bovine muscles and their relation to muscle collagen characteristics.

Raw samples of 14 muscles: Mm. biceps femoris (BF), quadriceps femoris (CF), diaphragm (DI), flexor digitorum (FD), gluteus medius (GM), infraspinatus (IE), longissimus lumborum (LL), longissimus thoracis (LT), psoas major (PM), pectoralis profundus (PP), semimembranosus (SM), semitendinosus (ST), sternomandibularis (STER) and triceps brachii (TB) from four Swiss Brown (485±15 days old) young bull carcasses and weighing approximately 300 kg were evaluated for some chemical and physical properties. PM (2.11 kg) and DI (2.24 kg) were the muscles which had the lowest Warner-Bratzler shear force values, while PP (6.66 kg) had the greatest shear force (P<0.05). FD and IE muscles had the highest concentration of total collagen content while PM and DI had the lowest (P<0.05) contents, TB and IE muscles presented the highest insoluble collagen concentration while PM and LT had the lowest (P<0.05) contents. High positive correlation between total collagen content and Warner-Bratzler shear force of raw samples was found (r=0.723; P<0.01) and between insoluble collagen content and Warner-Bratzler shear force was (r=0.661; P<0.01). Significant differences (P<0.05) were observed among muscles for differential scanning calorimetry, sarcomere length, pH and colour parameters.

Ability of α-tocopherol, taurine and rosemary, in combination with vitamin C, to increase the oxidative stability of beef steaks packaged in modified atmosphere

Fresh beef steaks were sprayed on the surface with vitamin C (500 ppm), taurine (50 mM), rosemary (1000 ppm) and vitamin E (100 ppm), the three latter in combination with 500 ppm of Vitamin C, packaged in modified atmosphere (70% O2+20% CO2+10% N2) and stored at 1±1 °C for 29 days. Metmyoglobin formation, lipid oxidation (TBARS), instrumental colour (CIE a∗), psychrotrophic bacterial counts (PCA) and sensory discolouration and odour were determined. Results demonstrated that surface application of antioxidant combinations resulted in an effective delay of oxidative deterioration of fresh beef steaks. Shelf life was extended beyond that of control, according to evaluation of sensory attributes. Both combinations of vitamin C with either rosemary or taurine significantly (P<0.01) extended the shelf life of fresh beef steaks by about 10 days. Rosemary was the most effective in delaying oxidation processes. The combination of vitamins E and C was significantly (P<0.01) less effective than those combinations in delaying meat oxidation.

Beef shelf life in low O2 and high CO2 atmospheres containing different low CO concentrations

The use of atmospheres with low concentrations of CO (0.1 to 1%), in combination with O(2) (24%), high CO(2) (50%) and N(2) (25 to 25.9%), for preserving chilled beef steaks was investigated. The atmosphere used as reference contained 70% O(2)+20% CO(2)+10% N(2). Bacterial counts showed that all atmospheres containing CO greatly reduced total aerobic population numbers, including Brochothrix thermosphacta. Lactic acid bacteria, however, were not affected. CO concentrations of 0.5-0.75% were able to extend shelf life by 5-10 days at 1±1°C, as demonstrated by delayed metmyoglobin formation (less than 40% of total myoglobin after 29 days of storage), stabilisation of red colour (no change of CIE a* and hue angle after 23 days), maintenance of fresh meat odour (no variation of sensory score after 24 days) and significant (P<0.01) slowing of oxidative reactions (TBARS).

Shelf-life extension and colour stabilisation of beef packaged in a low O2 atmosphere containing CO: Loin steaks and ground meat

A combination of low O(2), high CO(2) and very low CO was investigated for packaging fresh beef steaks and ground meat. The following atmospheres were used: 70% O(2) + 20% CO(2) + 10% N(2) (CMA); 70% O(2) + 20% CO(2) + 9% N(2) + 1% CO (HOCO) and 24% O(2) + 50% CO(2) + 25% N(2) + 1% CO (LOCO). Bacterial counts showed that LOCO atmosphere greatly reduced psychrotrophic population, so that log cfu cm(-2) was under 7.5 at 29 days of storage at 1 °C. All the objective measurements related to meat colour (a(∗), hue, Chroma and metmyoglobin concentration) revealed that the bright-red colour was more stable in both HOCO and LOCO atmospheres, reaching 29 days of storage without appreciable signs of oxidation. Sensory analysis confirmed these results.

Effect of different concentrations of carbon dioxide and low concentration of carbon monoxide on the shelf-life of fresh pork sausages packaged in modified atmosphere.

This paper reports the effects of different concentrations of carbon dioxide and the presence of low levels of carbon monoxide on quality attributes throughout storage of fresh pork sausages. Four pork forelegs (initial pH 5.5-5.7) were used to prepare a total of 120 fresh sausages, which were packaged in different atmospheres containing (%O(2)/%CO(2)/%N(2)): 0/20/80; 0/60/40; 40/20/40; 40/60/0; 80/20/0; and 0.3% CO/30% CO(2)/rest argon. The packs were stored for 20 days at 2±1 °C in the dark. Three packs for each atmosphere were opened every 4 days for subsequent analysis of pH, colour CIE L*, a*, b*, TBARS formation, microbial psychotrophic aerobes and sensory discolouration and off-odour. Results showed that increasing concentrations of carbon dioxide promoted oxidation of both myoglobin and lipids, most probably due to its effect of lowering pH. Therefore, preservation of colour and odour of fresh pork sausages packaged in modified atmosphere was better achieved using atmospheres containing low CO(2) concentrations (20%) rather than high (60%). However, their shelf-life depended also on the concentration of O(2); 20% CO(2) with high O(2) (80%) enhanced the red colour, but shortened shelf-life, while 20% CO(2) in the absence of O(2) extended freshness to 16 days. The atmosphere containing 0.3% CO, together with 30% CO(2), maintained the red colour for 20 days, but failed to keep fresh odour longer than 16 days.

Effect of stress-induced high post-mortem pH on protease activity and tenderness of beef.

Forty-four Swiss Brown young bulls were stressed by regrouping unfamiliar animals before slaughter. M. longissimus thoracis (6-9th ribs) of carcasses were analysed for post-mortem pH, protease activities (m- and α-calpain, calpastatin and cathepsin B + L), Warner-Bratzler shear force and sensory tenderness and juiciness. Muscles were classified into three groups, according to ultimate pH values: > 6.3, 6.3-5.8 and < 5.8. The most significant difference related to high pH was a higher activity of m-calpain at 7th day post mortem. It was also found that meat showing the highest pH was significantly more tender and juicy. Sensory tenderness was highly correlated with activity of m-calpain at 7th day post mortem (r = 0.776) and with ultimate pH (r = 0.708). It is concluded that high ultimate pH induced by stress significantly increases m-calpain activity, and this results in a greatly enhanced tenderisation of beef meat.

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 different Duroc line sires on carcass composition, meat quality and dry-cured ham acceptability.

Carcasses of 399 malignant hyperthermia gene free pigs from crosses sired by three types of Duroc (Virgen de la Fuente, DU1; Diputación de Teruel, DU2; DanBred, DU3) were analyzed for carcass and meat quality. Carcass leanness and fat parameters were measured at the last rib and at the space between the 3rd and 4th last ribs counting from the last one. Weights, pH, electrical conductivity, colour and intramuscular fat were also measured. A sample of 133 legs per cross were processed by dry-curing. The ham portion including Biceps femoris, Semimembranosus and Semitendinosus muscles was evaluated for instrumental texture and colour, biochemical and sensory analyses and acceptability (trained panel and consumers). DU3 carcasses were well conformed but lean. DU1 carcasses had a lower conformation but higher marbling. DU2 carcasses were intermediate. Dry-cured hams from DU1-sired pigs had a higher overall acceptability, although fat content influenced a consumers group negatively. Leaner DU3 hams had the lowest acceptability.