Milagro Reig

Innovations in value-addition of edible meat by-products

While muscle foods are the more commonly consumed portion of an animal, meat by-products such as the entrails and internal organs are also widely consumed. Considered high-priced delicacies or waste material to be tossed away, the use and value of offal-edible and inedible meat by-products depend entirely on the culture and country in question. The skin, blood, bones, meat trimmings, fatty tissues, horns, hoofs, feet, skull, and internal organs of harvested animals comprise a wide variety of products including human or pet food or processed materials in animal feed, fertilizer, or fuel. Industry is using science and innovation to add value to animal by-products far beyond its usual profitability. Regardless of the final products destination, it is still necessary to employ the most up-to-date and effective tools to analyze these products for nutritional properties, to search for key active molecules in nutrition like bioactive peptides, food safety (antimicrobial peptides), medicine, cosmetics or other fields, to develop new technological applications and to continue innovation towards advanced value-addition of meat by-products.

Veterinary drug residues in meat: Concerns and rapid methods for detection

The use of substances having hormonal or thyreostatic action as well as β-agonists is banned in the European Union. However, sometimes forbidden drugs may be added to feeds for illegal administration to farm animals for promoting increased muscle development or increased water retention and thus obtain an economical benefit. The result is a fraudulent overweight of meat but, what is worse, residues of these substances may remain in meat and may pose a real threat to the consumer either through exposure to the residues, transfer of antibiotic resistance or allergy risk. This has exerted a great concern among European consumers. The control of the absence of these forbidden substances in animal foods and feeds is regulated in the European Union by Directive96/23/EC on measures to monitor certain substances and residues in live animals and animal products. Analytical methodology, including criteria for identification and confirmation, for the monitoring of compliance was also given in Decisions 93/256/EEC and 93/257/EEC. More recently, Decision 2002/657/EC provided rules for the analytical methods to be used in testing of official samples. A crucial step is the screening of veterinary drug residues in live animals, feeds and animal products in view of the remarkable number of samples and large variety of residues to be analysed. In recent years, different rapid methods having easy performance, high sensitivity and high throughput have been proposed and are being extensively used. These methods as well as other new methods are reviewed in this manuscript.

New insights into meat by-product utilization.

Meat industry generates large volumes of by-products like blood, bones, meat trimmings, skin, fatty tissues, horns, hoofs, feet, skull and viscera among others that are costly to be treated and disposed ecologically. These costs can be balanced through innovation to generate added value products that increase its profitability. Rendering results in feed ingredients for livestock, poultry and aquaculture as well as for pet foods. Energy valorization can be obtained through the thermochemical processing of meat and bone meal or the use of waste animal fats for the production of biodiesel. More recently, new applications have been reported like the production of polyhydroxyalkanoates as alternative to plastics produced from petroleum. Other interesting valorization strategies are based on the hydrolysis of by-products to obtain added value products like bioactive peptides with relevant physiological effects as antihypertensive, antioxidant, antidiabetic, antimicrobial, etc. with promising applications in the food, pharmaceutical and cosmetics industry. This paper reports and discusses the latest developments and trends in the use and valorisation of meat industry by-products.

Small peptides hydrolysis in dry-cured meats.

Large amounts of different peptides are naturally generated in dry-cured meats as a consequence of the intense proteolysis mechanisms which take place during their processing. In fact, meat proteins are extensively hydrolysed by muscle endo-peptidases (mainly calpains and cathepsins) followed by exo-peptidases (mainly, tri- and di-peptidyl peptidases, dipeptidases, aminopeptidases and carboxypeptidases). The result is a large amount of released free amino acids and a pool of numerous peptides with different sequences and lengths, some of them with interesting sequences for bioactivity. This manuscript is presenting the proteomic identification of small peptides resulting from the hydrolysis of four target proteins (glyceraldehyde-3-phosphate dehydrogenase, beta-enolase, myozenin-1 and troponin T) and discusses the enzymatic routes for their generation during the dry-curing process. The results indicate that the hydrolysis of peptides follows similar exo-peptidase mechanisms. In the case of dry-fermented sausages, most of the observed hydrolysis is the result of the combined action of muscle and microbial exo-peptidases except for the hydrolysis of di- and tri-peptides, mostly due to microbial di- and tri-peptidases, and the release of amino acids at the C-terminal that appears to be mostly due to muscle carboxypeptidases.

A chromatography method for the screening and confirmatory detection of dexamethasone.

Corticosteroids, such as dexamethasone, have been illegally used as growth promoting agents to obtain an economical benefit from increased muscle development. These substances remain in meat and other animal products and may have negative toxic consequences for consumers. A screening and confirmatory method for dexamethasone detection in feed and drinking water in livestock has been developed and validated. This method is based on immunoaffinity chromatography followed by reverse-phase high-performance liquid chromatrography (IAC-HPLC) with diode array detection (DAD) at 242nm. Flumethasone was used as internal standard. The method has been validated according to the European Union regulation 2002/657/EC for banned substances and, thus, the specificity, decision limit, detection capability, recovery and repeatability have been determined. The decision limits (CCα) were 26ng/mL for water and 190ng/g for feed while detection capabilities (CCβ) were 30ng/mL for water and 217ng/g for feed. The method showed good accuracy and precision. The stability of dexamethasone under frozen storage has been studied over a 3.5-month period. No losses were observed, thus confirming that water samples taken by inspectors can be stored frozen for a few weeks until analysis. This method has proved to be relatively simple and useful for rapid screening and confirmation of the presence of dexamethasone in water and feed used for meat-producing animals.

Variability in the contents of pork meat nutrients and how it may affect food composition databases

Pork meat is generally recognised as a food with relevant nutritional properties because of its content in high biological value proteins, group B vitamins, minerals especially heme iron, trace elements and other bioactive compounds. But pork meat also contributes to the intake of fat, saturated fatty acids, cholesterol, and other substances that, in inappropriate amounts, may result in negative physiologically effects. However, there are relevant factors affecting the content of many of these substances and somehow such variability should be taken into consideration. So, genetics, age and even type of muscle have a relevant influence on the amount of fat and the contents in heme iron. Also the composition in fatty acids of triacylglycerols is very sensitive to the contents of cereals in the feed; for instance, polyunsaturated fatty acids may range from 10% to 22% in pork meat. The content of other nutrients, like vitamins E and A, are also depending on the type of feed. Some bioactive substances like coenzyme Q10, taurine, glutamine, creatine, creatinine, carnosine and anserine show a large dependence on the type of muscle. This manuscript describes the main factors affecting the composition of pork meat nutrients and how these changes may affect the general food composition databases.

Generation of bioactive peptides during food processing

Large amounts of peptides are naturally generated in foods through the proteolysis phenomena taking place during processing. Such proteolysis is carried out either by endogenous enzymes in ripened foods or by the combined action of endogenous and microbial enzymes when fermented. Food proteins can also be isolated and hydrolysed by peptidases to produce hydrolysates. endo-peptidases act first followed by the successive action of exo-peptidases (mainly, tri- and di-peptidylpeptidases, aminopeptidases and carboxypeptidases). The generated peptides may be further hydrolysed through the gastrointestinal digestion resulting in a pool of peptides with different sequences and lengths, some of them with relevant bioactivity. However, these peptides should be absorbed intact through the intestinal barrier and reach the blood stream to exert their physiological action. This manuscript is reporting the enzymatic routes and strategies followed for the generation of bioactive peptides.

Effect of cooking and in vitro digestion on the antioxidant activity of dry-cured ham by-products

Dry-cured ham by-products have been traditionally used in Mediterranean household cooking of broths and stews. The aim of this work was to evaluate the effect of cooking treatments and in vitro gastrointestinal digestion on the antioxidant activity of natural peptides found in bones from Spanish dry-cured hams. The antioxidant activity was tested using five different assays and results demonstrated that cooking using conventional household methods increased the antioxidant activity of ham by-products when assessed using different antioxidant assays with the exception of the ABTS radical scavenging measurement assay. Simulated gastrointestinal digestion showed no significant effect on the antioxidant activity of ham by-products and antioxidant activity decreased when assessed using the ORAC and β-carotene bleaching assays. Analysis by MALDI-TOF MS revealed a considerable breakdown of peptides due to the action of gastrointestinal enzymes, mainly in samples cooked at 100°C for 1h. In addition, 459 peptides derived from 57 proteins were identified and quantified using mass spectrometry in tandem, evidencing that peptides derived from collagen protein were responsible for the differences in antioxidant activities observed between the uncooked and cooked samples after digestion. The results show the potential of dry-cured ham bones as a source of antioxidant peptides that retain their bioactivity after household cooking preparations and gastrointestinal digestion.

Stability of the potent antioxidant peptide SNAAC identified from Spanish dry-cured ham

Antioxidant peptides positively regulate oxidative stress in the human body as well as delay, retard or prevent protein and lipid oxidation in food products. Spanish dry-cured ham has been reported as a good source of bioactive peptides, being SNAAC the most active antioxidant peptide identified to date. In this work, the stability of this peptide against in vitro digestion, heat treatments and different salt concentrations was evaluated using three methods for measuring antioxidant activity: β-carotene bleaching assay, ABTS radical scavenging capacity and ORAC assay. The results evidenced a marked decrease in the antioxidant activity of SNAAC after gastrointestinal digestion, and the MALDI-ToF MS analysis revealed the degradation of the peptide after the process, the generation of the fragment SNAA and the presence of a peptide dimer throughout the in vitro digestion. On the other hand, the peptide SNAAC showed good heat stability after exposure to different temperatures (50°C, 72°C, and 90°C), but its antioxidant activity evaluated by ORAC assay decreased substantially when exposed to 100°C as compared with the control at 37°C. SNAAC remained stable in the presence of salt at concentrations ranging from 0 to 8% NaCl as well as it was able to inhibit about 40% of lipid oxidation in an emulsion system. These results reported the stability of the antioxidant peptide SNAAC to several conditions used in meat industry for the processing of dry-cured hams and ham-derived products and its effectiveness to partially prevent the lipid oxidation in these products. However, some strategies would be needed in order to increase the stability of the peptide during gastrointestinal digestion and thus improve its bioavailability to be used as functional food ingredient.

Methane generation from chemically pretreated cellulose by anaerobic fluidized-bed reactors

Abstract Alkali cooking of cellulose at 10% (w/v) consistency, performed at 250°C, gives a liquor containing organic acids as main components (lactic, acetic and succinic acids). A synthetic substrate, representative of this liquor, was used as feed for two anaerobic fluidized-bed reactors operating at 35°C. The effects of hydraulic retention time and influent substrate concentration on substrate consumption and methane generation were studied. Organic removals of up to 95% and methane generation rates of 1·09 litres CH 4 litre R −1 day −1 were achieved at a retention time ( θ R ) of 8·3h and at an influent substrate concentration of 1400 mg COD litre −1 . At θ R = 3·5 h, conversion decreased to 60%. When feeding the cooked liquor, conversions were slightly lower, around 50% at θ R = 4 h and 1300 mg COD litre −1 of influent substrate concentration. However, the methane volumetric production rate was as high as 2·5 litres CH 4 litre R −1 day −1 under the same conditions. The results suggest that alkaline cooking with subsequent methane fermentation offers a viable process for the treament of cellulosic materials, such as municipal solid waste.