Jorge Ruiz-Carrascal

Advanced glycation end products, physico-chemical and sensory characteristics of cooked lamb loins affected by cooking method and addition of flavour precursors.

The influence of the addition of a flavour enhancer solution (FES) (d-glucose, d-ribose, l-cysteine and thiamin) and of sous-vide cooking or roasting on moisture, cooking loss, instrumental colour, sensory characteristics and formation of Maillard reaction (MR) compounds in lamb loins was studied. FES reduced cooking loss and increased water content in sous-vide samples. FES and cooking method showed a marked effect on browning development, both on the meat surface and within. FES led to tougher and chewier texture in sous-vide cooked lamb, and enhanced flavour scores of sous-vide samples more markedly than in roasted ones. FES added meat showed higher contents of furosine; 1,2-dicarbonyl compounds and 5-hydroxymethylfurfural did not reach detectable levels. N-ε-carboxymethyllysine amounts were rather low and not influenced by the studied factors. Cooked meat seems to be a minor dietary source of MR products, regardless the presence of reducing sugars and the cooking method.

Volatile Compounds Profile of Sous-Vide Cooked Pork Cheeks as Affected by Cooking Conditions (Vacuum Packaging, Temperature and Time)

The volatile organic compound (VOC) profile of pork cheeks as affected by the cooking conditions was investigated. Pork cheeks were cooked under different combinations of temperature (60 °C or 80 °C), time (5 or 12 h) and vacuum (vacuum or air-packaged). As a general rule, the VOCs originating from lipid degradation were positively affected by the cooking temperature and negatively by the cooking time, reaching the highest amounts in pork cheeks cooked at 80 °C during 5 h and the lowest in samples cooked at 80 °C during 12 h. On the contrary, VOCs originated from amino acids and Maillard reactions were positively affected by both factors. The proportion between lipid degradation and amino acids reactions was estimated by the hexanal/3-methylbutanal ratio, which reached its highest values in samples cooked at 60 °C during 5 h in the presence of air and the lowest values in samples cooked at 80 °C during 12 h, regardless of the vacuum status.

Pork proteins oxidative modifications under the influence of varied time-temperature thermal treatments: A chemical and redox proteomics assessment

The impact of thermal processing on meat proteins oxidation was investigated. Cooking treatments included 58u202f°C for either 72u202fmin or 17u202fh (mimicking low temperature-long time sous vide cooking), 80, 98 and 160u202f°C for 72u202fmin (mimicking common cooked meat products, stewing and roasting, respectively) and 118u202f°C for 8u202fmin (autoclaving). Tryptophan degradation, fluorescent oxidation products, free thiol content and α-aminoadipic and γ-glutamic semialdehydes were tracked. For all of them, there was a consistent trend to increased levels of oxidative damage with higher cooking temperatures and longer cooking times, although the extent varied from one indicator to another. Through proteomics, peptide oxidative modifications like carbonylation, malonaldehyde adducts and hydroxykynurenin (tryptophan oxidation products) were also detected at residue level. Our findings indicate that protein oxidation is dependent upon the heat treatment, which point out to a different effect on the nutritional quality of proteins in meat products.

Cheese powder as an ingredient in emulsion sausages: Effect on sensory properties and volatile compounds

Different types of cheese powder were added to meat emulsion sausages in order to address its influence on chemical composition, volatile compounds profile and sensory properties, and its potential to reduce salt content through boosting saltiness. Addition of cheese powder to emulsion sausages modified their profile of volatile compounds. Blue cheese increased some ketones, alcohols, and esters, while brown cheese brought typical Maillard reaction compounds. Overall, addition of cheese powders to sausages enhanced the intensity of flavour traits. A mixture of hard and blue cheese powder showed the highest effect on boosting saltiness, while brown cheese powder showed the strongest umami and meat flavour boosting effect, and sausages with added blue cheese powder showed a more intense aftertaste. Hardness significantly increased due to the addition of blue cheese powder. Addition of cheese powder to emulsion sausages might be an interesting tool to boost flavour and reduce salt content in cooked sausages with no negative effect on saltiness or overall flavour.

Oxidative deterioration of pork during superchilling storage

BACKGROUNDnIn superchilling (SC), meat is kept at temperatures around 1 °C below its initial freezing point, leading to a significant increase in shelf life. This study aimed to address the oxidative changes taking place in pork loins during prolonged storage at SC temperature. Loins were stored either at chilling (CH) conditions (2-4 °C) for 4 weeks or at SC temperature (around -1 °C) for 12 weeks.nnnRESULTSnStorage at SC temperature diminished the rate of lipid and protein oxidation and discoloration in pork loins, so that final levels of most oxidation products and instrumental color values after 12 weeks of SC storage were similar to those after 4 weeks at CH conditions. However, hexanal content peaked by the end of SC storage, pointing to a potential accumulation of compounds from lipid oxidation during SC storage.nnnCONCLUSIONnSC storage of pork slows down the rate of lipid and protein oxidation. However, accumulation of volatile compounds from lipid oxidation could be a limiting factor for shelf life.

Tracking hydrophobicity state, aggregation behaviour and structural modifications of pork proteins under the influence of assorted heat treatments

Structural modifications of pork proteins under an assortment of industrial heat treatments were studied. With raw as control, assorted heat treatments involved were 58, 80, 98 and 160°C for 72min, 118°C for 8min and 58°C for 17h, resembling most common processing procedures. Protein denaturation, surface protein hydrophobicity state and protein aggregation behaviour were investigated. Modifications and molecular chemistry in protein structures were tracked by Fourier Transform Infrared Spectroscopy in order to extract relative proportions of β-sheet, α-helix and residual conformations. In comparison to uncooked samples, cooked ones showed more than two-fold increase in hydrophobicity and larger particles. Thermograms from differential scanning calorimetry showed endothermic transitions (positive enthalpy) indicating a different pattern of protein denaturation as a result of varied cooking temperatures and cooking times. Deconvolution and curve fitting procedures (R2=0.99) provided information on rise of the β-sheet to α-helix ratio that further confirmed aggregation with thermal rise and longer cooking time.

Development of Volatile Compounds during Hydrolysis of Porcine Hemoglobin with Papain

There is a growing market for the use of hydrolysates from animal side-streams for production of high-protein supplements. However, there can be issues with development of off-flavors, either due to the raw material in question or due to the hydrolysis process itself. This study examined the development of volatile compounds during hydrolysis of hemoglobin. Briefly, porcine hemoglobin was hydrolyzed by 0.5% papain for up to 5 h, and the development of volatile compounds was analyzed via gas chromatography-mass spectrometry. The results showed that there was significant development of a number of volatile compounds with time, e.g., certain Maillard reaction and lipid oxidation products, which are likely candidates for the aroma development during hydrolysis. Furthermore, it was shown that development of a number of the volatiles was due to the hydrolysis process, as these compounds were not found in a control without enzyme.

Proteolysis in pork loins during superchilling and regular chilling storage

This study aimed to address the proteolytic phenomena taking place in pork loins during prolonged storage at superchilling (SC) temperature. Loins were stored at either chilling (CH) conditions (2-4u202f°C) for 4u202fweeks or at SC temperature (around -1u202f°C) for 12u202fweeks. Storage at SC temperatures slowed down the rate of proteolysis in pork loins, so that final levels of most indicators for proteolysis, including after 12u202fweeks of SC storage were similar to those after 4u202fweeks at CH conditions. Consequently, the texture of SC pork under extended storage was not so different to that of CH pork. However, total amino acid content peaked by the end of SC storage, pointing out to a potential ongoing exopeptidase activity. Overall, proteolysis seemed to be slowed down in pork at SC conditions, with similar levels for most indicators after 12u202fweeks of SC storage or 4u202fweeks at CH conditions.

Advanced glycation end products, protein crosslinks and post translational modifications in pork subjected to different heat treatments

The aim of the study was to characterize Maillard reactions in meat under different cooking treatments. Considered temperature-time combinations included raw samples (control), 58, 80, 98 and 160u202f°C for 72u202fmin, 118u202f°C for 8u202fmin and 58u202f°C for 17u202fh. Furosine, a marker for heat treatment, was detected in all groups with roasting having a 4-fold increase over the control. Sous-vide treatment at 80u202f°C, boiling and autoclaving also contribute to a significant increase in furosine. Nɛ-carboxymethyllysine, an indicator for advanced glycation end products, showed negligible amount in control, but increased with cooking temperature, with oven samples showing the highest values. A similar increasing trend was observed in lanthionine, covalently bonded protein crosslinks, which arises due to severe thermal regimes. Simultaneously, glycation and deamidation formation were tracked in meat proteins through peptidomics to highlight residue level changes that might affect nutrient value in processed muscle based foods.

Improving the lipid profile of ready-to-cook meat products by addition of omega-3 microcapsules: effect on oxidation and sensory analysis: Oxidation and sensory quality of omega-3 enriched meat products

BACKGROUNDnThe omega-3 enrichment of ready-to-cook meat products by microencapsulated fish oil (MFO) addition was analyzed. Accordingly, three batches of chicken nuggets were prepared: (i) control (C); (ii) enriched in bulk fish oil (BFO); and (iii) with added MFO. Sensory features, acceptability, oxidative stability and volatile compounds were analyzed.nnnRESULTSnMFO nuggets did not differ from C ones with respect to any sensory trait. BFO showed increased juiciness and saltiness but decreased meat flavor. Acceptability was not affected by enrichment. Consumers were not able to differentiate between C and MFO in a triangle test, although they could clearly identify BFO nuggets. Higher levels of lipid and protein oxidation indicators and of volatile compounds from fatty acid oxidation were found in BFO nuggets compared to C and MFO nuggets.nnnCONCLUSIONnEnrichment of ready-to-cook meat products in omega-3 fatty acids with MFO provides both lipid and protein oxidative protection without changes in sensory quality.