E. Muela

Effect of freezing method and frozen storage duration on instrumental quality of lamb throughout display.

This study evaluated the effect of freezing method (FM) (air blast freezer, freezing tunnel, or nitrogen chamber) and frozen storage duration (FSD) (1, 3, or 6 months) on the instrumental measurements of quality of thawed lamb, aged for a total of 72 h, throughout a 10-d display period, compared to the quality of fresh meat. pH, colour, lipid oxidation, thawing, and cooking losses in Longissimus thoracis and lumborum muscle, were determined following standard methods. FM affected yellowness, FSD redness and thawing losses, and both affected oxidation (increased as freezing rate decreased and/or as storage duration increased). When compared with fresh meat, the main differences appeared on oxidation (where a significant interaction between treatment (3FM x 3FSD + fresh meat) with display duration was detected), and on total losses (thaw + cook losses). Oxidation was lower in fresh meat, but values were not significantly different from those stored frozen for 1 month. Fresh meat had smaller total losses than did thawed meat, but losses were not significantly different from meat frozen in the freezing tunnel and stored frozen for 1 month. Display duration had a greater effect on instrumental quality parameters than did FM or FSD. pH, b*, and oxidation increased, and L* and a* decreased with an increase in the number of days on display. In conclusion, neither freezing method nor frozen storage up to 6 months influenced extensively the properties of lamb when instrumental measurements of quality were measured in meat that had been displayed for 1d after thawing. The small deterioration shown in this study should not give consumers concerns about frozen meat.

Effect of freezing method and frozen storage duration on lamb sensory quality.

This study assessed the effect of three freezing methods with three frozen storage durations (1, 3, and 6 months) on the sensory quality of lamb. Methods were: air blast freezer, freezing tunnel+air blast freezer, and nitrogen chamber+air blast freezer. Meat was frozen after 48 h of ageing (0-4°C). Fresh meat (72 h ageing at 2-4°C) was used as control. Sensory analyses (trained panel and consumer tests) were performed on loin chops (Longissimus lumborum) after 24 h of thawing. Results from the trained panel test showed that freezing (method and/or storage duration) had no significant effect. Consumers found that freezing affected sensory quality. Cluster analysis for overall acceptability divided the population into four classes with different preference patterns, and none of them showed a significant preference for fresh meat. The small differences between fresh and thawed meat shown in this study should not give consumers concerns about buying frozen meat or consuming thawed meat.

Effects of cooling temperature and hot carcass weight on the quality of lamb.

The effects of cooling temperature (CT) (0-2, 2-4, or 4-6 degrees C) and hot carcass weight (HCW) (either <or= 10.5 or >or= 12.0 kg) on weight loss (WL) and meat quality were evaluated in 60 lamb carcasses of Rasa Aragonesa breed. Carcasses were exposed to CT throughout 90 h. WL was assessed at 18, 42, 66, and 90 h post-slaughter. pH, colour, instrumental measurement of texture, oxidation, and sensory parameters were evaluated in longissimus thoracis et lumborum aged for 96 h following standard methods. Sensory test involved a trained test panel. No significant interactive effects among the parameters evaluated were detected in the study. The lower the CT, the higher the WL after 90 h in storage (0.25% lost each 2 degrees C decrease), the higher final pH, and the lower lightness, the higher hue and chroma of the meat. Toughness was higher in meat cooled at 2-4 degrees C than in meat cooled at temperatures above or below this range. Neither oxidation nor sensory variables were affected by CT. Regarding on HCW, light carcasses exhibited higher WL (2.39% versus 2.04% after 90 h of cooling), higher final pH, and lower levels of oxidation than did heavier carcasses. Neither colour nor instrumental measurement of texture was affected by HCW. Lamb and fat odour and metallic and acid flavour intensities were significantly greater in the heavier carcasses, although it did not affect overall acceptability. Both CT and HCW should be considered as main effects on lamb quality, especially CT.

Key Factors Involved in Lamb Quality from Farm to Fork in Europe

Abstract World lamb consumption is approximately 2 kg per capita with large variations between continents, e.g., 17 kg in Oceania vs. 0.7 kg in North America. With less than one million tonnes, the international trade of sheep meat contributes to a small percentage of the total meat exchanged between countries. On the other hand, lamb represents the highest rate of species trading in relation to the total sheep meat produced. It is therefore likely to find a wide variability of different lamb products in the same market, and that the conservation procedures (such as refrigeration, packaging or freezing), chemical composition, especially the fat due to its implication in human health, flavour development and juiciness perception (affected, i.e., by the feeding or the age or slaughter weight of the animal) and acceptability (based on culinary background) could be considered important indicators of this advantageous situation. In this paper some studies related to the aforementioned indicators are discussed.

Meat quality of lamb frozen stored up to 21 months: Instrumental analyses on thawed meat during display

The study analysed the effect of frozen storage duration (FSD: 0, 1, 9, 15 or 21 months) and display duration (DD: 0-24 h post-slaughter-, 3 and 6 days) in modified atmosphere packaging (MAP) on lamb quality. pH, colour, lipid oxidation, water holding capacity and instrumental texture were performed on Longissimus muscle in displayed fresh and thawed meat. FSD affected all the variables showing lower differences between fresh and 1 month storage than among them and longer FSD. Only cooking losses were not affected by DD in thawed meats. It was observed a general decrease in quality (lower redness and water holding capacity; higher yellowness and lipid oxidation) as FSD or DD increased and only texture was improved over DD being thawed meat more tender. In conclusion, lamb storage at -18°C should not exceed 1 month if thawed meat would be later displayed in MAP while meat would have an acceptable quality up to 21 months without subsequent display.

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.

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.

Effects of castration age, protein level and lysine/methionine ratio in the diet on colour, lipid oxidation and meat acceptability of intensively reared Friesian steers.

A total of 64 intensively reared Friesian steers were used in a 2×2×2 design to study the effects of age of castration (15 days old v. 5 months old), dietary protein level (14.6% v. 16.8%; DM basis) and lysine/methionine (lys/met) ratio (3.0 v. 3.4) on meat quality. The lys/met ratio of 3.0 was reached with supplementation of protected methionine. Animals were slaughtered at a live weight of 443.5 ± 26.2 kg at around 12 months of age. Colour and lipid oxidation were measured in the longissimus thoracis muscle throughout the 14 days of display under modified atmospheric and commercial display conditions. A panel of 17 consumers assessed daily the visual acceptability of the meat on display. A consumer acceptability eating test was also performed with 120 consumers in meat aged for 7 days under vacuum conditions. Lipid oxidation was not influenced by castration age and the protein level in the diet. Castration age did not affect meat colour, but meat from the low protein level diet and the low lys/met ratio showed higher redness (a*) from 3 days of display onwards. Nevertheless, from 6 days onwards, consumer visual acceptability was below the level of acceptance in all treatments, and even from 5 days onwards in those animals that underwent early castration and were fed either a high protein diet or a combination diet low in protein content and high in lys/met ratio. The best accepted treatments throughout the display period were those from late castrated animals fed a low protein diet, probably related to other visual aspects. However, the best accepted meat after consumption was that from late castrated animals fed high protein and high lys/met. The addition of protected methionine to reach lys/met levels of 3.0 did not improve beef acceptability, with the high protein diet being preferred by consumers in terms of palatability in late castrated animals.

Effects of castration age, dietary protein level and lysine/methionine ratio on animal performance, carcass and meat quality of Friesian steers intensively reared.

The effects of castration age, dietary protein level and the dietary lysine/methionine (lys/met) ratio on animal performance, carcass characteristics and meat quality were studied in 64 intensively reared Friesian steers. Animals underwent castration procedures at 15 days old or at 5 months old. Dietary treatments started at 90 days old, with eight animals from each castration age randomly allocated to each treatment: 14.6% v. 16.8% CP (DM basis), and 3.0 v. 3.4 lys/met, on a 2×2×2 design. The recommended ratio of 3.0 was reached with supplementation of protected methionine. Steers were slaughtered at 443.5±26.2 kg live weight when they reached 12 months old approximately. Average daily gain, cold carcass weight or carcass classification were not affected by any studied effect. Muscle moisture (P=0.024), C18:2n-6 percentage (P=0.047), polyunsaturated fatty acid/saturated fatty acid (P=0.049) and n-6/n-3 (P=0.003) were higher in late castrated animals. Both high levels of dietary protein (P=0.008) and lys/met ratio (P=0.048) increased the percentage of muscle in the carcass. A level of 16.8% of CP in the diet also increased the percentage of monounsaturated fatty acids in the intramuscular fat (P=0.032), whereas a ratio lys/met of 3.4 decreased the percentage of saturated fatty acids (P=0.028). Thus, it is recommended using diets with a high protein level (16.8%) and a high lys/met ratio (3.4) in animals slaughtered at a young age, in order to obtain carcasses with high muscle content without negatively affecting productive traits or intramuscular fat composition.

Effect of the type of dietary fat when added as an energy source on animal performance, carcass characteristics and meat quality of intensively reared Friesian steers

The effects of different fats in the diet were evaluated on the basis of animal performance, carcass and meat-quality traits. Four groups of eight Friesian steers were intensively finished with concentrate and cereal straw given ad libitum. Four different types of fats were included at a 4% level in the diet, namely, palm oil, sunflower oil, tallow and hydrogenated fat. The feeding trial lasted for 84 days. There were no differences on animal performance or carcass characteristics, except for animals from the hydrogenated-fat diet, which had the greatest percentage of muscle and moisture, and the lowest percentage of fat in a 6th rib dissection. Meat colour, texture, lipid oxidation and consumer acceptability did not differ among the diets. Nevertheless, the effects of ageing or display time were more important than those of the source of fat. Intramuscular fatty acid profile was hardly influenced by the fat source. In conclusion, the type of fat added at the final stage of the rearing process, at a 4% of inclusion level, did not produce noticeable variations on productive parameters or product quality. This would allow to formulate rations for cattle, using the most profitable source of fat (added at low levels), without having variability on the product quality.