David Morcuende

Protein oxidation in emulsified cooked burger patties with added fruit extracts: Influence on colour and texture deterioration during chill storage.

The influence of protein oxidation, as measured by the dinitrophenylhydrazine (DNPH) method, on colour and texture changes during chill storage (2 degrees C, 12days) of cooked burger patties was studied. Extracts from arbutus-berries (Arbutus unedoL., AU), common hawthorns (Crataegus monogynaL., CM), dog roses (Rosa caninaL., RC) and elm-leaf blackberries (Rubus ulmifoliusSchott., RU) were prepared, added to burger patties (3% of total weight) and evaluated as inhibitors of protein oxidation and colour and texture changes. Negative (no added extract, C) and positive control (added quercetin; 230mg/kg, Q) groups were also considered. The significant increase of protein carbonyls during chill storage of control burger patties reflect the intense oxidative degradation of the muscle proteins. Concomitantly, an intense loss of redness and increase of hardness was found to take place in burger patties throughout refrigerated storage. Most fruit extracts as well as Q significantly reduced the formation of protein carbonyls and inhibited colour and texture deterioration during chill storage. Likely mechanisms through which protein oxidation could play a major role on colour and texture changes during chill storage of burger patties are discussed. Amongst the extracts, RC was most suitable for use as a functional ingredient in processed meats since it enhanced oxidative stability, colour and texture properties of burger patties with no apparent drawbacks.

Lipid and protein oxidation and sensory properties of vacuum-packaged dry-cured ham subjected to high hydrostatic pressure

The effect of HHP treatment (600 MPa) on the oxidative stability of lipids and proteins of vacuum-packaged Iberian dry-cured ham and the impact on the sensory characteristics of the product was investigated. In order to assess how different commercial presentations are affected by HHP treatment, three different presentations of vacuum-packaged Iberian dry-cured ham were considered, namely, (i) intact format (IF) corresponding to non-sliced vacuum-packaged dry-cured ham, (ii) conventional-sliced format (CSF) corresponding to dry-cured ham slices placed stretched out in the package and (iii) alternative-sliced format (ASF) corresponding to dry-cured ham slices piled up horizontally. The oxidation of dry-cured ham lipids and proteins was enhanced by HHP-treatment with the presentation being highly influential on these oxidative reactions. Pre-slicing dry-cured ham results in a more susceptible product to oxidative reactions during pressurisation and subsequent refrigerated storage. Possible mechanisms, by which HHP-induced oxidative reactions would affect particular sensory traits in vacuum-packaged Iberian dry-cured ham such as colour, texture and flavour attributes, are discussed.

Oxidative stability and fatty acid composition of pig muscles as affected by rearing system, crossbreeding and metabolic type of muscle fibre.

Muscle fibre type, fatty acid composition of phospholipids (PLs) and triacylglycerols (TGs) and susceptibility of muscle to lipid oxidation were studied in Biceps femoris (BF) and Tibialis cranialis (TC) muscles from Iberian and Iberian×Duroc pigs reared indoors and outdoors. Fatty acid composition of TGs was not affected by muscle fibre type and crossbreeding, but was strongly influenced by rearing system. In PLs crossbreeding slightly affected monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) content in BF muscle, whereas rearing system showed a great influence on fatty acid composition of PLs. Oxidative fibres showed a positive relationship with saturated fatty acid (SFA) and MUFA contents and a negative one with PUFA content of PLs. Susceptibility of muscle to lipid oxidation was strongly influenced by diet, animals reared indoors and fed on concentrates showing higher levels of 2-thiobarbituric acid reactive substances (TBARS). Iberian×Duroc pigs tended to show slightly higher values of lipid oxidation than pure Iberian pigs. With regards to muscle fibre type, BF had lower TBARS values than TC, although within muscle no relationship was found between muscle fibre type and lipid oxidation.

Avocado, sunflower and olive oils as replacers of pork back-fat in burger patties: effect on lipid composition, oxidative stability and quality traits.

The present study investigates the effects of avocado, sunflower and olive oils used as back-fat replacers, on the fatty acid composition, oxidative stability, volatiles profile and color and texture properties of cooked pork patties. The vegetable oils modified the fatty acid profiles of the patties by lowering the percentages of SFA (from 36.96% to ~25.30%) and reducing the atherogenic index (from 0.41 to ~0.24). Vegetable oils had higher amounts of antioxidant compounds such as tocopherols (10.8-53.9 mg/100 g) than back-fat (5.9 mg/100 g). Consistently, patties manufactured with the oils had significantly lower amounts of lipid and protein oxidation products than control patties. Avocado oil contributed with specific aroma-active terpenes to patties and had a significant impact on particular color and texture parameters. The results from this study highlight the technological applications of the vegetable oils as food ingredients in the design of healthier meat commodities.

Extensively reared Iberian pigs versus intensively reared white pigs for the manufacture of frankfurters.

Physico-chemical characteristics and different quality traits of the raw material (meat and adipose tissue) and the frankfurters elaborated from extensively reared Iberian pigs (IF) and intensively reared white pigs (WF) were evaluated. Hybrid frankfurters (HF) made with meat from white pigs and adipose tissue from Iberian pigs were also studied. The differences found between muscles and adipose tissues from Iberian and white pigs largely influenced the characteristics displayed by the frankfurters. Particularly remarkable are the higher amounts of substances with proven antioxidant activity such as tocopherols and phenolic compounds in tissues from Iberian pigs than in those from white pigs. No significant differences were found amongst frankfurters for their proximate composition though IF presented a higher iron content than WF and HF. IF exhibited a redder and darker colour than WF and HF. The latter were paler and showed higher hue values than IF. Concerning their fatty acid composition, IF had higher proportions of oleic acid and MUFA and smaller proportions of SFA and PUFA than WF. From a nutritional point of view, IF had a lower n-6/n-3 value than WF. The addition of adipose tissue from Iberian pigs to the HF modified its fatty acid composition compared to that of WF, significantly increasing the percentages of MUFA and reducing the proportions of PUFA, SFA and the n-6/n-3 value. Though no significant differences were found amongst frankfurters for their texture profile, a clear trend was detected, with the HF showing intermediate texture characteristics between IF and WF.

Characterization of Selected Wild Mediterranean Fruits and Comparative Efficacy as Inhibitors of Oxidative Reactions in Emulsified Raw Pork Burger Patties

In the present study, water, ethanolic, and methanolic extracts from seven selected wild fruits originally from the Mediterranean area, namely, strawberry tree ( Arbutus unedo L., AU), azarole ( Crataegus azarolus L., CA), common hawthorn ( Crataegus monogyna L., CM), blackthorn ( Prunus spinosa L., PS), dog rose ( Rosa canina L., RC), elm-leaf blackberry ( Rubus ulmifolius Schott, RU), and rowan ( Sorbus aucuparia L., SA), were analyzed for the total amount and profile of phenolic compounds and for the in vitro antioxidant activity against the DPPH and ABTS radicals (study 1). The seven fruits showed different chemical compositions, which consequently led to different antioxidant potentials. Among the seven fruits initially analyzed, AU, CM, RC, and RU had the highest amount of phenolic compounds and displayed the greatest antioxidant activity in vitro. Extracts from these four fruits were tested as inhibitors of lipid oxidation in raw pork burger patties subjected to refrigerated storage at 2 degrees C for 12 days (study 2). The quantitative measurements of thiobarbituric acid reactive substances (TBA-RS), hexanal content, and color stability were used as indicators of oxidative reactions. The four selected fruits displayed intense antioxidant activity against lipid oxidation, which highlights the potential usage of these fruits as ingredients for the manufacture of healthy meat products. Among them, RC and AU were particularly efficient as their protective effect against lipid oxidation was more intense than that displayed by quercetin (230 mg/kg of burger patty).

Membrane Lipids of the Stallion Spermatozoon in Relation to Sperm Quality and Susceptibility to Lipid Peroxidation

Lipids were extracted from ejaculated spermatozoa from seven individual stallions to distinguish neutral lipids (NL) and polar lipids (PL) and determine their variation among stallions and their relationship with sperm quality and sperm susceptibility to lipid peroxidation. The isolated fatty acids were correlated with sperm quality (membrane integrity, mitochondrial membrane potential (ΔΨm) and expression of active caspases) and the sensitivity of the sperm plasma membrane to LPO. The miristic (C14: 0), palmitic (C16: 0), stearic (C18: 0) and oleic (C18: 1n9) acids were predominant among the NLs. Within the phospholipid fraction, the docosapentanoic acid (C22: 5n6) was dominant, albeit varying among stallions. Surprisingly, the percentage of polyunsaturated fatty acids was positively correlated with sperm quality and a low propensity for LPO, probably because these particular fatty acids provide a higher fluidity of the plasma membrane. The stallion showing the poorest sperm membrane integrity plus a high level of LPO in his ejaculate had a lower percentage (p<0.05) of this fatty acid in his sperm plasma membranes.

Formation of Lysine-Derived Oxidation Products and Loss of Tryptophan during Processing of Porcine Patties with Added Avocado Byproducts

The effects of the addition of avocado oil and a phenolic-rich avocado peel extract on protein oxidation were studied in porcine patties subjected to cooking and chilled storage. Protein oxidation was assessed by means of tryptophan loss and the formation of specific lysine oxidation products, such as α-aminoadipic semialdehyde (AAS), α-aminoadipic acid (AAA), and Schiff bases. In the present paper, quantitative data of AAA are reported for the first time on a food matrix. The addition of the avocado extract inhibited the formation of AAS, AAA, and Schiff bases in patties during cooking and subsequent chilled storage. The antioxidant effect may respond to the protecting effect of phenolic compounds, mainly procyanidins, found on the avocado extract. Apparently, the combination of both strategies (back-fat replacement and addition of avocado extract) does not lead to an enhanced advantage on the oxidative stability of the product. The novel methodologies used in the present study enable a better comprehension of the mechanisms and consequences of protein oxidation in food systems.

Physicochemical characteristics of three muscles from free-range reared Iberian pigs slaughtered at 90 kg live weight

Three muscles from free-range reared pigs with different metabolic pattern were studied. m. Masseter (M), m. Longissimus dorsi (LD) and m. Serratus ventralis (SV) the first having an oxidative metabolism and the other two an intermediate and glycolytic metabolism. m. Masseter contained the highest content of myoglobin (M: 6.65 mg/g, LD: 3.00 mg/g and SV: 3.64 mg/g; P<0.001) and exhibited the highest CIE a* (M:17.10, LD: 14.83, SV:15.34, P<0.001) and C* (M: 17.95, LD: 15.61, SV: 15.54, P<0.001) values. m. L. dorsi and S. ventralis contained a higher intramuscular fat content than m. Masseter (M: 2.26 g/100 g muscle, LD: 4.79 g/100 g muscle, SV: 3.52 g/100 g muscle, P=0.001) and lower amounts of phospholipids (M: 0.33 g/g imf, LD: 0.12 g/g imf, SV: 0.19 g/g imf; P<0.001). Fatty acid profiles from total intramuscular fat and lipid fractions, neutral lipids and polar lipids, significantly differed among muscles, there being a higher content of unsaturated fats (especially in the C18:2 and C20:4 percentages) in the m. Masseter than in the other two muscles analysed. Comparatively, muscles from 90 kg live weight Iberian pigs contained more fat and heme pigments and were redder than those from the commercial pig crosses usually produced.

Tryptophan Depletion and Formation of α-Aminoadipic and γ-Glutamic Semialdehydes in Porcine Burger Patties with Added Phenolic-Rich Fruit Extracts

The effect of added fruit extracts on the oxidation of muscle proteins in porcine burger patties subjected to cooking and chill storage was studied. Extracts from arbutus berries (Arbutus unedo L., AU), common hawthorns (Crataegus monogyna L., CM), dog roses (Rosa canina L., RC), and elm-leaf blackberries (Rubus ulmifolius Schott, RU) were prepared, characterized, added to burger patties (3% of total weight), and evaluated as inhibitors of protein oxidation. Negative (no added extract, C) and positive control (added quercetin, 230 mg/kg, Q) groups were also included in the design. Protein oxidation was assessed by means of tryptophan loss using fluorescence spectroscopy (FS) and formation of the specific protein carbonyls alpha-aminoadipic (AAS) and gamma-glutamic semialdehyde (GGS) using liquid chromatography and mass spectroscopy (LC-MS). Both advanced methodologies (FS and LC-MS) were found to be reliable and specific protein oxidation measurements that allow us to gain chemical insight into protein oxidation. The mechanisms likely involved in the oxidative reactions affecting proteins during cooking and storage of burger patties are profusely discussed. Phenolic-rich fruit extracts protected tryptophan residues against oxidation and inhibited the formation of both semialdehydes in burger patties during cooking and subsequent chill storage. In general, RC, RU, and AU were the most effective inhibitors of protein oxidation, with this effect being more intense than that of pure polyphenols like quercetin. These fruit extracts could be considered functional ingredients as their antioxidant actions contribute to the enhancement of the nutritional value of the meat products.