[Music] and I have a great pleasure to give a floor to the next speaker and he was already introduced Mario Estevez he got his PhD in food science in 2005 his research is concerned not only with food quality but also in relation to human health he is published in a lot of papers he published more than hundred of those and his specific interest is related to oxidation and the process of protein oxidation Sampson which Mario was one of the first and for the last year he published quite a few reviews and his subject and when we're talking about meat quality the protein oxidation Sampson which actually came very recently and we started to realize that the protein oxidation in many cases even more importance and lipid oxidation especially when we are talking about drip loss when we're talking about other parameters omit quality therefore I think his presentation which is entitled the meat conservation and further processing it's actually the third part of the meat presentation because first was on muscle biology second the defects which actually develop due to different problems in processing and growing birds and it will show that oxidative stress in many cases is at the molecular level is imposed and Mario I think will be delivering this lecture and we are looking forward for your lecture please thank you thank you bitter so once again it is a pleasure to be here also as a speaker so basically as Peter said I will end up this session talking about meat preservation and further processing so this is basically the outline of my presentation I will start with an introduction in which I will talk about the connection between animal nutrition and mid quality then I will present the main the most relevant hazards that we may face during meat storage and meat processing then I will try to do something very practical which is to try to identify these hazards whenever we face these hazards in a real situation and naturally because we try to implement this knowledge into this real situation will try to give advices to avoid these hazards when they appear and they become a real problem and also to find solutions whenever it is possible and I will conclude my presentation with some final final remarks so it's basically the theme of this session which in a way illustrate in a very interesting way the connection between animal nutrition and human nutrition in a way that feed quality has actually an impact on meat quality so in a way the theme of this of this session reflects or in a way propose that animal nutritionists would be also responsible with the also responsible for the quality of the final meat product which is something to keep in mind something very interesting because in fact fish quality together with the genetics and animal handling will actually have an influence on meat quality meat quality has been said before but it's basically defined by the sensory properties healthy properties and also safety and some ethical issues that has also they have but been mentioned before and for instance the feed composition in terms of fatty acid composition would actually have a direct influence on the sensory properties of meat in terms of the onset of rancidity and also the flavor also once again the feed composition in terms of fatty acid composition and also the presence discipline tations with with antioxidants we also have an influence if we supplement the feed with aunty accidents we that will lead to a more stable and more healthy amid lipids also if we apply antibiotic free feeds of phyto genex that would also contribute to to have a more as a safer meat in terms of meat free from some potentially dangerous chemical compounds residues in the meat and finally the natural of extensive feeding feeding based on natural resources fruits and vegetables would also contribute to the image of environmentally friendly production system that it is actually in mind of some consumers with very specific ethical issues that we can actually address with this kind of natural and extensive feeding so as you can see the theme of this of this session relating the role of animal nutritionist or meat quality is actually very appropriate because as I said at the beginning the presentation of this session some decisions that we make at the forum will actually have an influence on meat quality so this is something to keep in mind because in a way when you as an animal nutritionist you design animal feeds to some extent you are also designing the the meat the quality of the meat that will be delivered to the final consumer so now let me move to the next point of the of the presentation to talk about the hazards that we may face during the during the during storage and and further processing of meat meats that we get from a slaughter after post mortem changes changes the transformation of muscle intimate this meat is actually very unstable from a microbiological point of view as you know very perishable which means that we need to preserve the meat usually using low temperatures refrigeration if we want to preserve the meat for several days or freezing if we need to preserve the meat for several weeks or months the meet is eventually delivered to the consumer and before naturally because we are talking of fresh raw meats we need to apply some kind of cooking procedure and the temperature time and that type of heat transfer that we apply to the meat will have consequences on the quality and safety of the of the of the meats the other possibilities that we process the meat so this means that basically we are we will transform we apply different technologies to transform the meat into different types of meat products we can do that directly from the meat coming from it slaughter or after a storage is it's very typical in the meat industry to freeze the meat for a certain bit of time several weeks a month no more than five months and then a defrost and process the meat to produce different types of meat products all the technologies that you may think of size reduction means in high temperatures in radiation salt in children all of them will have consequences on the quality and the safety of of meats and naturally processed meat will be delivered to the final consumer doing all these routes and pathways meats will be exposed to two different types of hazards chemical hazards basically oxidation and biological hazards microorganisms and I will elaborate elaborate a little bit more about these - starting with starting with the oxidation so you know oxidation is a chemical reaction typically initiated by free radicals even though some physical factors particularly meats such as light and irradiation they can also initiate this this reaction and let me discriminate here between lipid and protein oxidation because even though that the origin of the initiation is usually a governed or is usually initiated but these free radicals the truth is that the underlying mechanisms the pathways the oxidation products and the consequences for the meats and for the consumer fairly different as you will see lipid oxidation involves the degradation of unsaturated fatty acids and the presence in the presence of molecular oxygen it is a ubiquitous reaction it will be present from farm to fork this means that of course it will be present in the living animal what we call oxidative stress when this oxidation is actually affecting biomolecules molecules of biological significance and we will take place during the whole production chain storage processing and also in the final consumer we are also susceptible to oxidative stress but it will be particularly stimulated promoted by processing some processing techniques in particular by high temperatures and this lipid oxidation is something to keep in mind because it's the main cause of consumer reaction reduction of processed muscle foods basically because of their rancidity the onset of rancidity is probably the most striking and short-term effect of lipid oxidation in in in processed muscle foods then we SOC supposed to be responsible for the discoloration of fresh meat from red bright bright bread to a kind of brown we'll see some picture in a while there will be also an a loss of a nutritional value when because basically when seneschal fatty acid is oxidized its lost this oxidation is irreversible so and actually we know that some muscle foods and and also some other some other foods are very good sources of of essential fatty acids and but when these fatty acids oxidize then they are lost and there is an obvious loss of a nutritional value and finally this is not the least important actually but usually refer that the final when we list different consequences of lipid oxidation some products from lipid oxidation are potentially toxic to humans this is actually what we say potentially but in fact lipid oxidation products they have been shown to be involved in the pathogenesis of different disorders in humans some cardiovascular diseases and different types of cancer and so on what about protein oxidation protein oxidation involves not only the degradation of particular amino acids piroso sometimes the aggregation of proteins proteins when they are oxidized sometimes they aggregate to each other as well as lipid oxidation it will happen it happens certainly in the in the in the living animal and also during processing and storage of meats also in the in human beings which actually is a hot topic in medicine because of the relationship between protein oxidation in human beings and different very serious health disorders in addition to aging in in muscle foods it is also stimulated by high temperatures and compared to lipid oxidation we can say that it's a silent but very serious threat I say silent because compared to liquid oxidation there is no such striking remarkable modification of the sensory properties such as the rancidity that we mentioned before so in a way we can have protein oxidation in our myths of meat product and it actually can pass like unnoticed by the consumer or by the retailer or by the meat producer but actually I say that it's a serious threat because they it has some some consequences including some texture problems in particular a strengthening of the of the muscle tissue there is also a loss of the additional value basically because the loss of essential amino acids and actually we know that meat as well as some other foods coming from from animals they are very good sources of high high quality protein some of the essential amino acid sulfur continuing I mean I mean acids tryptophan:lysine all of them are very sensitive to oxidation and then we also have some digestibility problems I'm talking about human beings of course because some are oxidized proteins they will be more difficult to digest they may not be recognized by the our digestive enzymes and then they can actually travel through the guts without being digested digested would acts we in a way add more impairment to the nutrition to the loss of a nutritional value that involves the oxidative loss of the of the amino acids of the essential amino acids and finally as well as lipid oxidation this is quite rocketing topic but still we know that certain protein oxidation products they are also potentially toxic mutagenic and they can actually be involved in the onset of different health disorders in in humans now let me move I will describe inch very briefly the biological hazards in here we need to discriminate also between spoilage but microorganisms and pathogens the spoilage shall usually come in from carcasses and then machinery these are some of the species and some of the microorganisms that we may you know we have to meet through in the mid price s in and storage they are very typical to spoil meat during storage and compared to lipid oxidation we said that the oxidation is a main limiting factor in for the quality of processed muscle foods in this particular case this polish bacteria will be the main limiting factor of shelf-life in meats under refrigeration so basically fresh meat basically because these bacteria are able to spoil the meat and this is a a real spoilage the sensory properties are are spoiled the appearance the flavor the color everything what about the pathogens pathogens they are also coming from the carcasses from the animals but also they are very typically coming from from the manipulation from basically humans manipulating the meat after during processing or storage or delivery these are some of the most typical and most dangerous bacterial pathogens that we may find in meat as you all know and they are responsible very serious food borne diseases likely not so often anymore but a still they may occur in sometimes with very severe consequences for for human health and as well as protein oxidation they may be there in the myths but because there is no spoilage of the sensory properties sometimes they pass unnoticed and then we see the consequences when we eat the meat or the muscle food and then we have the symptoms of the particular disease of a foodborne disease we have a variety of diseases gastrointestinal infections botulism meningitis in the case of Listeria monocytogenes and so on now that we know which are the main hazards now let me move to the following topic to see how can we identify these hazards in in a real situation and how to deal with with these problems trying to propose some some strategies some solutions and I will start with these storage under refrigeration whenever we keep meat under refrigeration the temperature should be as low as possible typically between 7 and 0 but there's something which is quite innovated particularly in meat not that much in seafood and fish you said has been used for some time now but this is this super chilling involves that we keep the meat below zero but the meat remains unfrozen this is very interesting because there is no change in the state of water so there is no real freezing but that the meat will remain in a way without spoilage for a longer time of course this is particularly interesting when you are interested in trading or selling the meat in a distant country without using freezing because reason involves a loss of quality always but even if we are using this super chilling eventually we'll have some biological and chemical hazards I will describe the symptoms that in a way describe or reflect that something is going wrong with the meat I would try to identify the potential the most likely cause the reason and then the solution probably have seen before this slime together with off flavor and the discoloration I believe that there must be some kind of problem with pictures because the quality there with some missing pictures also at the beginning now here so something something wrong with the pictures but anyway whenever we have a slime of flavor and discoloration it is very likely that we have contamination the growth of some particular bacterium but in particular Pseudomonas which is very typical the spoiler the spoilage of fresh meat and by this by this bacteria and basically what we need to do is good hygiene practices packaging very typically a bottom packaging and the usage of antimicrobials those that are allowed to be used in fresh meat of course and then when we are packed when we pack meat in the vacuum we we may also find this line together with sourness in this in this particular case the reason is probably the growth of lactic bacteria the solutions are basically the same and then let's move to something that actually doesn't have an microbiological origin is a chemical problem which is the discoloration of the Lyne as I said before from a red bright to some kind of like brownish color this respond to the oxidation of the myoglobin which is the main responsible of the red color of of meats and because it's a chemical problem and related to oxidation it needs to be treated with antioxidants and I will mention I will elaborate a little bit more because knowing that we are in a conference in which the animal nutrition is one hot topic I will elaborate a little bit more about disease antioxidant solutions you see in fact we can control oxidation in needs Noro not only by adding antioxidants directly to the meat and muscle foot through formulation which is something that we can do of course but also through dietary means so basically supplementing these antioxidants in the diet of the animals and that will definitely you will have also a positive effect on the oxidative stability of the of the means will protect the my myoglobin from oxidation and also the bone whenever we have bone exposed to the air that can also suffer this discoloration and this is basically the result of the oxidation of another pigment which is present as you know in Blatt and also envy in the bone marrow which is the hemoglobin and basically the the strategies are pretty similar and then we have a problem with the texture this is very typical when we are aging meets particular beef in a high oxygen atmosphere this high oxygen at atmosphere is very typical for red red meat red mussels because it is very good to preserve the right red color of fresh meat for a long time this is actually mentioned here this high oxygen modified atmosphere packaging is actually good for keeping this ox ml good myoglobin which is responsible for the red bright red color of fresh meat but on the other hand will promote protein oxidation and protein oxidation is in fact the responsible for this impaired tenderization that will take place in meat in beef in particular aged in in this type of packaging so it is better to age before several weeks and then after that when the meat is truly tender will can store we can pack the meat in high oxygen or basically in the vacuum and then sell the meat because like this we can avoid this problem but another possibility if we have to use this high oxygen package in atmosphere which is as I said very typical nowadays in for marketing different types of beef muscles then we maybe we may combine this packaging with antioxidants once again it is proven that both dietary antioxidants and also antioxidant that we are directly in the meat will protect against this oxidative damage now what about freezing when we when we freeze meat basically we can forget about microorganisms because they will not grow but it doesn't mean that we forget about microorganisms because when we defrost meats the micro gram since we remain they're so freezing by freezing we are not killing bacteria all right so they will remain that but during freezing during freezing free air that then the length of freezing is not limited by the growth of bacteria because they will be they will be they will be completely controlled but then we have chemical hazards during during freezing once again that temperature should be as low as possible but for for obvious reasons we cannot use - a tree like when we store samples for analysis in the in the laboratory so at the industrial level useless - 18 - 20 and we shouldn't prolonged their destroyed for more than five months because of these chemical hazards which are the symptoms the most typical is the rancidity their own city will appear after we defrost the meats so I'm not doing freezing will not appear as such because they're basically the meat is frozen but after the frost in this rancidity will increase very fast and actually after processing the rigidity will increase also even even a faster so this is actually a very limiting factor because the quality of the final product will be very low if we keep meat for a long long time in this at these freezing temperatures another possibility is to have protein oxidation protein acceleration would be responsible for the severe drip that we may observe emit after the frosting and we also have protein oxidation responsible for the technological problems that we may face when we want to produce different meat products from frozen material sometimes we keep the meat for a long for a long time and then we try to produce sausages or we try to produce cooked or even dry cute hams and then we realized that we have some technological problems the proteins are oxidized and they are not able to form emulsions they are not able to form gels and then we have this this fail at processing which are the solutions basically try to avoid try to inhibit oxidative reactions usually meat is frozen back in packets this is very very typical and in addition to that we are also we can also use antioxidants and what about processing and cooking let's start with the chemical huh sure so basically oxidation as I said before and one Siddha tea in this particular case is the most limiting factor of the quality of processed and cooked meat products and what about the strategies I mentioned before antioxidants avoid avoid unsaturated fats and saturated fats may be good from a nutritional point of view and healthy point of view because answer treated fatty acids are supposed to be involved in lowering the high-density lipoprotein so they are good for lowering of or keeping good cholesterol levels and so on but unsaturated fatty acids are very susceptible to oxidation they are very easily oxidized and for processing there is not very good because the rancidity will appear very soon as long as we manipulate the meats and it's actually a problem for poultry because poultry is naturally unsaturated metal the the lipids from from poultry is naturally unsaturated more saturated and pork and pork is more saturated than than beef than remanence as we all know and then we can actually optimize this process this is also very typical we can optimize so that we can make a full cooking or food processing trying to a minimized lipid oxidation there is a particular cooking method that I don't know if you if any of you and know this sous-vide it involves vacuum package so first we we packed we packed the meat in the bathroom and then it is immersed in water and cook for a long time in low temperature so that the meat is very tender and lipid oxidation is is limited the flavor is not the same as putting the meat in the grill that I can tell but mmm there is that that's an adoption and then of course we have antioxidants that I will mention also a little bit later in my presentation and then we have to text your problem softening which is very typical when we are trying to decrease the concentration of sodium chloride in a meat products this is very typical when we are trying to which is actually a global strategy in the meat industry and some other food industry speaks of the problem of sodium chloride and hyper tense hyper tense consumers so basically when we lower when we decrease the sodium chloride a too much then we can have some texture problems because of their a very intense proteolysis and then if we have the opposite a strengthening that is always due to protein oxidation all right and then we need antioxidants and finally we may have toxic some toxicity hazards as a result of the formation of toxic compounds during processing and more particularly during cooking in particular when the cooking is very severe and the barbecue is one very very good example of a cooking procedure that depending on how it we deal with it we can actually promote the formation of some a toxic compounds that we all know that like the benzo a pyrene nitrosamine and very specifically these polycyclic aromatic hydrocarbons because of the affair of the exposure the direct exposure of the meat to the fire or the burning fat or the smoke that also contains some some potentially toxic compounds what about the biological hazards in processed meat most cases we don't have problems with the spoilage because usually cooking and processing involves a reduction of the microorganisms we are killing microorganisms by high temperatures but still we can have some problems like bone bone taint this deep needs spoilage anaerobic bacteria also the excess of mold and yeast particularly in dry food products but these programs are in a way easy to handle because just take into consideration that we need to a control very in a very precise way the humidity the the temperature during processing and sometimes using starters but it is more or less easy to handle the problems with processed meats regarding the biological hazards is definitely the pathogens that may be present and remain present in the mid even after processing and after cooking because of two reasons the I'm listing here some of the most relevant bacteria responsible for food borne diseases in humans we have two basically two options when these passages are present in the meat is because the meat has been undercooked this is one option and basically the the bacteria survived and then it will remain growing after the after this cooking when it's kept in under refrigeration this is very typical in ready-to-eat meals that are precooked then keep they are kept for for a certain period of time under refrigeration then there is reheated but this reheated which is usually performed in a microwave is not enough to kill this bacteria or and then the other possibility is the manipulation so we kill the bacteria if the if the meat is fully cooked so it's no problem but then if somebody manipulates the meat that can can be a rare contamination and then this bacteria can actually grow under refrigeration this is very typical for Listeria Listeria which is actually very dangerous because of that reason it's very easy to kill this bacteria with high temperatures but then the problem is that if it survives because the meat is undercooked or basically because somebody manipulated the meat after that and contaminated the meat then this bacteria is very is able to to grow even at low temperatures have very low temperatures its psycrow psycrow trophic bacteria so it's able to grow at very low temperatures and as you can see and now that we are in a you know conference talking about animal nutrition let me give very brief comment on the different strategies that we can apply through dietary means so basically through animal nutrition to protect meat against oxidation against lipid and protein oxidation during the storage and processing something that I mentioned before is controlling the fatty acid composition of the fields in terms of to keep the polyunsaturated fatty acids as low as possible I know that that can actually get into conflict with some other interests like some nutritional interest or even the the cost of the of the materials for preparing the for design in the feeds but from a oxidative point of view it is to have polyunsaturated fatty acids it's not convenient at all then we have supplementation with tocopheryl acetate this is very commonly used for for for both monogastric animals broilers Peaks and also remnants and but at least I've been involved in many many studies and well it's acting is perfectly proven that supplementation with tocqueville as acetate is a very good strategy for controlling lipid and protein oxidation during storage and processing in particular lipid oxidation for one reason is because as you know this tocopherol this vitamin e will be located is specifically accumulated in the membranes of the muscle cells and in this particular location they are very effective antioxidants because in that particular location we find phospholipids which are from the membrane B layer that contain very high a degree of polyunsaturated fatty acids so this is actually where oxidative reaction are supposed to begin in in muscle muscle tissue there are many studies proving these positive effects and then if we have a higher level of antioxidant protection protection we may need supplementation with some micronutrients because I don't have time now basically to mention the selenium which is also proven to be effective against lipid and protein oxidation cities and that table we have the the probably the most recognized expert in selenium so if some questions I received probably he should have should should handle this these questions we know that organic selenium is more effective than inorganic celimene in particular I would like to mention a study carried out by the members of aerosol actually the organizers of this of this of this advanced Academy because they used a hydroxyl analog of solano methionine and they they observed how supplementation with this as selenium ethylene led to an increase of the accumulation of of selenium in the muscle there was there was also an increase in the activity of some antioxidant enzymes endogenous antioxidants enzymes in particular the glutathione peroxidase and finally that was also reflected at a mid quality level because this D supplementation supplementation was able to reduce the levels of lipid oxidation measured by t bars and also the discoloration of means let me also mention very fast now this a feeding on natural resources this also has been proven in some particular animals to be effective to protect lipids and proteins and games oxidation these are a variant pics that we are that we are raising in the in the part of extra may of spain i'm coming from instrument aura we are having these Peaks extinct extensively weird they are fed with icon icons and and grass and this has been proven to increase their level of ammonia and saturated fatty acids and to corals in the muscles and livers and adipose tissue of these these animals with positive consequences in terms of oxidative stability and finally we have supplement with phytochemicals and phytonutrients any any questions regarding this this this possibility because he made a very interesting review on this particular topic and actually in a way maybe we can discuss that during the during the debate but basically these phytochemicals these phenolic compounds polyphenols flavonoids we have a large variety of different compounds which are naturally present in fruits and vegetables they can actually be not only antioxidants as such because of the chemical structure as radical scavengers they can actually be or act as modulators of the genus expression which is something very interesting and can be used not only as antioxidants and health and growth promoters etc but we need to study more about these phytochemicals and the possibilities that they have in animal nutrition and also in human nutrition by the way once again the theme of this of this of this session is missing in my in my conclusions I don't know why actually I wanted to emphasize this theme but basically it's the relationship between animal nutrition and the impact of meat quality so once again this responsibility of the animal nutrition is on meat quality because actually a lot of the author of the quality of the meat is based on the quality of the feeds that we are giving to the animals together with the with a genetic background the feeds that we have mentioned and also the animal handling and basically we need to preserve meat quality because basically which is the ultimate purpose of animal production to keep to keep the business life so and to keep it for keeping the business like we have to keep this cycle going on so basically we have to preserve meat quality and we have to guarantee the satisfaction of the consumer and that's all thank you very much for your attention and sorry because I spoke too [Music]