Effect of Animal Age at Slaughter on the Muscle Fibres of Longissimus thoracis and Meat Quality of Fresh Loin from Iberian × Duroc Crossbred Pig under Two Production Systems.

Two production systems and several ages at slaughter were used: 12, 14 and 16 months for outdoor rearing (with the final finishing phase in the Montanera system, in which fed was based on natural resources, mainly acorns and grass) and 8, 10 and 12 months for animals reared indoors (intensive system: with feed based on commercial fodder) to evaluate their effect on the muscle fibre population and size of the Longissimus thoracis, (LT) muscle, as well as fresh loin quality traits. Animals that were older at slaughter revealed increased fibre sizes of the LT muscles in the pigs reared in the Montanera system. The LT muscles of the animals reared in intensive systems had a lower percentage of type I fibres and higher size of type IIB than those reared in the Montanera system. The approximate composition and instrumental colour of Montanera fresh loins were affected by the animal slaughter age. In the case of the intensive system, the effect of animal slaughter age had an impact on the approximate composition, instrumental colour, water loss and textural properties. Therefore, different ages at slaughter of Iberian pigs showed variations in some quality parameters in the fresh loins in both the Montanera and Intensive systems, thus proving to be a factor of variability and homogeneity of the Iberian products. The meat from Iberian pigs reared in an intensive system and slaughtered at a younger age proved to be more tender. The production system affected all the above quality traits, with the exception of water loss.

Myosin heavy chain fibre types and fibre sizes in nuliparous and primiparous ovariectomized Iberian sows: Interaction with two alternative rearing systems during the fattening period.

To investigate the effects of the reproductive background (nuliparous/primiparous) on skeletal muscle phenotype and their interaction with two alternative finishing systems (indoors/outdoors) in Iberian sows, 32 contemporary piglets were assigned to four different groups: indoors-nuliparous, indoors-primiparous, outdoors-nuliparous and outdoors-primiparous. Nuliparous sows were ovariectomized at 4 months of age, whereas primiparous were castrated at 14 months of age, after their first lactation. Indoors sows were fattened (2 months prior to slaughter) intensively, whereas outdoors sows were finished in an extensive land with natural resources. Muscle samples (semimembranosus, gluteobiceps) were analyzed for myosin fibre types and fibre sizes. Sows finished out-of-doors had more type I and IIA fibres and smaller fibres than indoor-fattened pigs. Primiparous reared indoors had a significantly lower IIX:IIB fibre ratio and showed a clear tendency for having larger fibres than nuliparous reared indoors. Reproductive background effect interacted with rearing condition effect inducing relevant muscular adaptations. Thus, the influence of reproductive background on muscle characteristics was not significant in sows reared out-of-doors but highly significant in sows finished intensively. This interaction resulted in muscular traits less favourable for meat quality in primiparous vs. nuliparous reared indoors.

Effect of different temperature-time combinations on physicochemical, microbiological, textural and structural features of sous-vide cooked lamb loins.

Lamb loins were subjected to sous-vide cooking at different combinations of temperature (60, 70, and 80 °C) and time (6, 12, and 24 h). Different physicochemical, histological and structural parameters were studied. Increasing cooking temperatures led to higher weight losses and lower moisture contents, whereas the effect of cooking time on these variables was limited. Samples cooked at 60 °C showed the highest lightness and redness, while increasing cooking temperature and cooking time produced higher yellowness values. Most textural variables in a texture profile analysis showed a marked interaction between cooking temperature and time. Samples cooked for 24h showed significantly lower values for most of the studied textural parameters for all the temperatures considered. Connective tissue granulation at 60 °C and gelation at 70 °C were observed in the SEM micrographs. The sous-vide cooking of lamb loins dramatically reduced microbial population even with the less intense heat treatment studied (60 °C-6 h).