Rosario Ramírez

Carcass composition and meat quality of three different Iberian×Duroc genotype pigs.

Carcass composition and meat quality of Longissimus dorsi (LD) and Biceps femoris (BF) muscles from three different Iberian×Duroc genotype pigs were studied: GEN1: ♂ Iberian×♀ Duroc1; GEN2: ♂ Duroc1×♀ Iberian; GEN3: ♂ Duroc2×♀ Iberian. Duroc1 (DU1) were selected for the manufacture of dry-cured meat products while Duroc2 (DU2) were pigs selected for meat production, with high percentages of meat cuts and low carcass fat. Genotype had a significant effect on the differences found while sex had not. GEN2 showed the highest weights at days 180 and 238 of weaning and the highest slaughter weights (day 316) followed by GEN3, while the lowest weights were found in GEN1. GEN3 had well conformed carcasses in comparison with GEN1 and GEN2, since GEN3 showed the highest percentages of ham and loin and the highest weight of loin as well as the lowest back and ham fat thickness. However, the use of DU2 pigs in the cross with Iberian had negative effects on meat quality, as GEN3 gave the worst meat quality in both muscles, postmortem pH, cook and drip loss, and colour and the lowest percentages of intramuscular fat (IMF). In subcutaneous fat (SCF), GEN3 had higher percentages of polyunsaturated fatty acids (PUFA) than GEN2, while GEN2 had higher saturated fatty acids (SFA) levels. In LD, IMF from GEN3 showed the highest percentage of MUFA and PUFA; while the fatty acid profile of GEN2 was more saturated. BF muscle showed similar trends, but not significantly so. On the other hand, few differences were found between reciprocal crosses (GEN1 vs. GEN2). GEN2 showed higher IMF in LD than GEN1, agreeing with their carcass weight. As a result, GEN1 had a fatty acid profile of IMF in the LD that was more unsaturated.

Effect of the Iberian × Duroc reciprocal cross on productive parameters, meat quality and lipogenic enzyme activities

The aim of this study was to investigate the effect of the Iberian×Duroc reciprocal cross on: (i) productive parameters, (ii) physico-chemical traits of three muscles with different oxidative patterns (Longissimus dorsi, Biceps femoris and Psoas maior) and (iii) lipogenic enzyme activities (glucose-6-phosphate dehydrogenase and malic enzyme) in subcutaneous adipose and muscle tissues. Fourteen Duroc-sired (Duroc♂×Iberian♀) and 14 Iberian-sired castrate male pigs (Iberian♂×Duroc♀) were selected at weaning and were reared until 235 days of age. Iberian-sired pigs had significantly higher weight at slaughter (147.7kg vs. 138.8kg, p<0.05) as well as a greater ham and foreleg weight than Duroc-sired pigs. The fatty acid composition of subcutaneous adipose tissue of Duroc-sired pigs showed a higher percentage of C18:0 (13.21% vs. 14.34%, p<0.05) and a lower percentage of monounsaturated fatty acids (47.79% vs. 46.73%, p<0.05) compared to that from Iberian-sired pigs. Contrary to productive parameters, there were no noticeable differences between reciprocal cross in parameters defining meat quality, although there was a clear muscle effect on such parameters with this effect being significant for most of the traits. No differences were found between reciprocal crosses for glucose-6-phosphate dehydrogenase and malic enzymes activities in both muscular and subcutaneous adipose tissues. Lipogenic enzyme activities were considerably higher in subcutaneous adipose tissue compared to muscles. Glucose-6-phosphate dehydrogenase activity did not differ (p>0.05) between muscles, whereas malic enzyme activity was higher (p<0.05) in Psoas maior compared to Biceps femoris and those were higher than in Longissimus dorsi, which was consistent with the positive correlations (p<0.05) found between malic enzyme activity and traits defining oxidative metabolic type. On the contrary, negative correlations (p<0.05) were found between malic enzyme activity and intramuscular fat content, which could suggest that there are differences among muscles in the ability of depositing fatty acids from other tissues.

The crossbreeding of different Duroc lines with the Iberian pig affects colour and oxidative stability of meat during storage

Colour and oxidative stability of Longissimus dorsi (LD) and Biceps femoris (BF) muscles from 3 different Iberian×Duroc genotypes (GEN1: ♂ Iberian×♀ Duroc1, GEN2: ♂ Duroc1×♀ Iberian; GEN3: ♂ Duroc2×♀ Iberian) were analysed during 10days of refrigerated storage. GEN1 and GEN2 are reciprocal crosses, while the difference between GEN2 and GEN3 is the Duroc sire line. The genotype Duroc1 was selected for the manufacture of dry-cured-meat products while the genotype Duroc2 was selected for meat production. BF showed more intense colour and oxidative changes during storage than LD, which is in accordance with their different metabolic pattern, since BF is an intermediate oxidative muscle whereas LD is a glycolytic one. Important differences were found between crosses due to the genotype of the Duroc sire line; however, reciprocal crosses (GEN1 and GEN2) showed a similar pattern. The lowest post-mortem pH of GEN3 could be a deciding factor of the oxidative and colour stability during storage as GEN3 had higher drip and cook loss as well as higher susceptibility to iron-ascorbate-induced oxidation. In addition, chops from GEN3 were paler (lower L(∗)) and showed a higher discolouration (higher decrease of a(∗)) besides higher lipid (TBA-RS) and protein oxidation (carbonyl content) after the storage.

Volatile profile of breast milk subjected to high-pressure processing or thermal treatment.

The effect of Holder pasteurisation (HoP) (62.5°C for 30 min) or high-pressure treatments (400 or 600 MPa for 3 or 6 min) on the volatile compound profile of human breast milk was evaluated, in order to compare both preservation technologies. A total of 46 different volatile compounds was found in milk samples. The most abundant compounds detected were aliphatic hydrocarbons. In general, the effect of some high-pressure treatments on the volatile profile of human milk was less intense than that caused by HoP. The treatments at 400 and 600 MPa for 3 min maintained the volatile compounds at similar levels to those found in control milk samples. However, the application of 600 MPa for 6 min changed the original volatile compounds of human milk, even more than HoP. Since, HPP at 400 or 600 MPa for 3 min preserved the original volatile compounds of human milk, this novel process may be an alternative to thermal pasteurisation.

Free Fatty Acids and Oxidative Changes of a Raw Goat Milk Cheese through Maturation

Free fatty acids (FFA) and lipid and protein oxidation changes were studied throughout maturation process of a raw goat milk cheese with protected designation of origin. Cheeses were analyzed at 4 different times of maturation, at 1, 30, 60, and 90 d. All FFA significantly increased during maturation and the relative increase was higher for long-chain than medium- or short-chain FFA. At the end of maturation, oleic (C18:1 n9), butyric (C4:0), and palmitic (C16:0) acids were the most abundant. The higher levels of short-chain fatty acids (SCFA) regarding total FFA obtained at the end of Ibores cheese ripening compared with other raw goat milk cheeses, highlight the notable role of SCFA on the flavor of this cheese owing to their low-odor thresholds. Lipid oxidation values significantly increased during maturation process but low levels of malondialdehyde were reported; however, protein oxidation did not significantly change during ripening.

Effect of processing by hydrostatic high pressure of two ready to heat vegetable meals and stability after refrigerated storage

The effect of high pressure processing (HPP) (400 and 600 MPa for 1 and 5 min) and the stability during storage were studied in two ready to heat vegetable meals: meal A, mainly composed by pumpkin and broccoli, and meal B, mainly composed by eggplant, zucchini, chard and spinach. The treatment at 600 MPa/5 min was the most effective to reduce the initial microbial loads of the meals and maintained better the microbial safety during storage. HPP had no effect on the physico-chemical and sensory properties. HPP at 600 MPa increased the antioxidant activity of the meal A. In contrast HPP reduced the antioxidant activity of the meal B, although in general high levels of antioxidants were maintained after processing and during storage. In conclusion, treatments at 600 MPa for 5 min were the most suitable to increase the shelf-life of the meals without affecting their physico-chemical, antioxidant and sensory properties.

High-pressure processing of a raw milk cheese improved its food safety maintaining the sensory quality

The effect of high-pressure treatment (400 or 600 MPa for 7 min) on microbiology, proteolysis, texture and sensory parameters was investigated in a mature raw goat milk cheese. At day 60 of analysis, Mesophilic aerobic, Enterobacteriaceae, lactic acid bacteria and Listeria spp. were inactivated after high-pressure treatment at 400 or 600 MPa. At day 90, mesophilic aerobic, lactic acid bacteria and Micrococacceae counts were significantly lower in high-pressure-treated cheeses than in control ones. In general, nitrogen fractions were significantly modified after high-pressure treatment on day 60 at 600 MPa compared with control cheeses, but this effect was not found in cheeses after 30 days of storage (day 90). On the other hand, high-pressure treatment caused a significant increase of some texture parameters. However, sensory analysis showed that neither trained panellists nor consumers found significant differences between control and high-pressure-treated cheeses.

Effect of high-hydrostatic pressure and moderate-intensity pulsed electric field on plum:

Moderate intensity pulse electric fields were applied in plum with the aim to increase bioactive compounds content of the fruit, while high-hydrostatic pressure was applied to preserve the purées. High-hydrostatic pressure treatment was compared with an equivalent thermal treatment. The addition of ascorbic acid during purée manufacture was also evaluated. The main objective of this study was to assess the effects on microorganisms, polyphenoloxidase, color and bioactive compounds of high-hydrostatic pressure, or thermal-processed plum purées made of moderate intensity pulse electric field-treated or no-moderate intensity pulse electric field-treated plums, after processing during storage. The application of moderate intensity pulse electric field to plums slightly increased the levels of anthocyanins and the antioxidant activity of purées. The application of Hydrostatic-high pressure (HHP) increased the levels of bioactive compounds in purées, while the thermal treatment preserved better the color during storage. The addition of ascorbic acid during the manufacture of plum purée was an important factor for the final quality of purées. The color and the bioactive compounds content were better preserved in purées with ascorbic acid. The no inactivation of polyphenoloxidase enzyme with treatments applied in this study affected the stability purées. Probably more intense treatments conditions (high-hydrostatic pressure and thermal treatment) would be necessary to reach better quality and shelf life during storage.

Effect of tomato paste addition and high pressure processing to preserve pork burgers

The effect of the addition of different levels of tomato paste for the manufacture of pork burgers after high pressure processing (HPP) was studied after the treatment and during the refrigerated storage. HPP was effective for the inactivation of microorganisms, and the incorporation of tomato paste into the burger retarded the growth of microorganisms. Textural parameters and colour of burgers were affected by HPP although changes were not perceived after cooking. On the other hand, the inclusion of tomato paste allowed the incorporation of lycopene to meat products and it also increased the lipid oxidation stability of burgers during storage. Therefore, the addition of tomato paste to burgers retarded microbial growth and increased the oxidative stability, which combined with the application of HPP would be an interesting alternative to extend the shelf-life of burgers and incorporate bioactive compounds in burgers such as lycopene.