Journal Club – 5. The Effect of Beer Marinades on Cooking Food

 

Last time we had a lively discussion on the report linking red and processed meat to colorectal cancer. An issue that was raised (amongst many others) was that it depends on how you cook the meat.

This week we will look at our first paper with researcher generated data. i.e. the authors have actually done the experiments and are presenting their results. You will find the format of the paper different to the meta-anlayis studies we have previously looked at and you should read it in a different way. Click on the link below for the paper.

Beer Marinades

To get the most from this paper you should read it multiple times, make notes as you go along and consider the following;

  1. Do not read the abstract first. Read it last. This is the authors own summary of their research and you do not want to have their thoughts influence your own at this stage.
  2. Read the introduction and summarise where this research fits in with other research. What is the bigger picture? What are they proposing to do that is new? What is the purpose of this work? Also get to grips with some of the abbreviations (PAHs and HAs) and where they fit in the story. ( You may need to do a little bit of background research on these)
  3. Read the methods section but don’t worry about understanding the detail at this stage. Can you follow their logic in how the experiments were conducted? What have they controlled for? What key methods have they used?
  4. Note the results in figure 1, which we will come back to later. Table 1 shows the results from this study. What can you deduce from these results? Can you link the data from figure 1 & table 1? Does this imply a mechanism for the effects observed? What is the point of table 2?
  5. What are your conclusions from the study? If you were to summarise this work in a few sentences what would you say? Now read the abstract and see if you agree with the statements made.

Well done ! You have now read and critically assessed your first research paper.

As always post your views and thoughts for all to share.

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8 thoughts on “Journal Club – 5. The Effect of Beer Marinades on Cooking Food

  1. Journal Club 5
    They are proposing to see whether marinating your meat in beer helps remove some PAHs like it has removed HAs in other studies in order to make charcoal-grilled pork safer to eat as by removing PAHs you are less likely to get colorectal cancer. A Polycyclic aromatic hydrocarbon is a carbon chain which can be harmless or toxic depending on which type it is. There are 8 compounds which sum up the carcinogenic potency of PAHs as the introduction states. Their purpose is to try to see whether marinating red beef in beer/alcohol will make it safer to eat when you charcoal-grill it. They used 3 different types of marinate with different concentrations of alcohol in them. All loin pork steaks were purchased from the same place with the same dimensions and the time and temperature they were marinated was the same as well. They tried to re-create the normal conditions for a garden barbeque when charcoal-grilling the meat samples and then each sample was coded specific to its marinate. They used a centrifuge to extract the PAHs from the beef after they have been cooked and removed the supernatant like when removing organelles from cells in differential centrifugation. They have kept the marinade in acidic conditions and preparing it in such a way in that it can be used with DPPH to find out the amount of radicals by counting the change in the optical absorption at a specific point in its wavelength. To analyse the types of PAHs present in each sample they had to separate them and quantify them with liquid chromatography. Different wavelengths were used to isolate the individual PAHs and they looked for how many of each PAH was in each sample. Figure 1 shows that Pilsner Beer had the least DPPH inhibition, with POB having the second highest and BB having the greatest inhibition. Table 1 indicates that PB has a greater amount of PAHs present with POB having the second most and B having the least by far. Linking the table and the graph together indicates that the least amount of PAHs it had or least amount of the significant PAHs that it had the greater the inhibition of DPPH. Table 2 gives examples of other marinates and the inhibition properties of them and the PAHs that they include. To conclude, I would state that BB had the most inhibition to DPPH and was very effective at removing PAHs but all of the marinades had less PAHs than the control sample without marinade. I agree with the abstract but it fails to make the connection to making it safer for you to eat for a closing sentence.

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  2. Journal Club 5-Beer Marinades

    Polycyclic aromatic hydrocarbons (PAH) are a group of more than 100 different chemicals that are released from burning coal, oil, gas, waste or other organic substances.
    Heterocyclic amines (HA) are the chemicals formed when muscle meat is cooked using high temperature methods such as grilling over an open flame.

    The research was carried out to find out how different methods of cooking meats like beef can affect the amounts of polycyclic aromatic hydrocarbon chemicals and Heterocyclic amines released in the different methods. Also how marinating foods in different liquid like tea, wine and beer can affect the amount of these chemicals being released and by how much. Finding out how much these chemicals have been reduced by after being marinated. They are proposing to find out how these marinades inhibit the amount of PAH’s and Ha’s released by cooking these meats in high temperature cooking methods like grilling over an open flame etc. At the moment there is no information on how the marinades affect this so they are trying to find it out. The purpose of this work is to find out which is the best way to marinate food to make sure that they release the least amount of PAH and HA chemicals when cooking at high temperatures. Allowing restaurants to do this in the best way and most efficient way of reducing the chemicals so it is healthier to eat, as there are less chemicals.

    They bought three types of beer labelled PB (5.2% alcohol), POB (0.5% alcohol) and BB (5.0% alcohol). They also bought 32 pork loin steaks. Marinating 8 steaks per beer. Leaving 8 steaks as the control group with no marinating to compare the levels of chemicals released after being cooked at the end. Before they cooked the steaks they marinated the steaks in their respective beers for 4 hours at 5oC because of the results from another test from Farhadian. They cooked it on a bed of charcoal and heated the coals until they didn’t have a flame. They then placed the steaks on and turned them over after 5 minutes, which was half of the total cooking time. They did this for all of the 32 steaks. Then they made a homogenous sample (mixed it up) and froze the different marinated steaks and the control group. They were degassed and put in a centrifuge for 2 minutes at 2000 repetitions per minute to be able to collect the supernatant (the liquid above the solid meat). This was then split up onto different micro plates and the results of the reaction were recorded until the chemicals released plateaued (levelled off). They kept a control group of un-marinated steaks to be able to compare the amount of chemicals were produced after they had all undergone the same cooking process and extraction to be able to tell the difference. When each of the different marinated steaks levelled off this would tell you how much chemicals were given off from the cooking, comparing this to the control group. Which ever marinated set of steaks plateaued first would release the least amount of chemicals and therefore the best inhibitor for PAH and HA chemicals.

    Looking at the results in figure 1 you can tell that BB beer has the higher inhibition for the steaks both at T0 and T4 which means that it is the better antioxidant- best at removing chemicals. They found out that ale beers have a higher antioxidant capacity compared to lager beers> BB beer was an ale beer which backs up their findings as this was biggest antioxidant. Furthermore they found that the non- alcoholic POB had higher antioxidant capacity than PB which was Pilsner beer. They believe that this could be because of the addition of glucose, fructose and syrups. However at T4 in BB they found a significant loss of antiradical capacity. Using additives like onion or garlic used table 2 to compare different marinating techniques to beer marinating to see if there were any differences.

    I conclude from the study that marinating beer affect the amount of chemicals of PAH and HA released. In the ale beer BB it inhibited these chemicals by 53% which was the highest inhibitor. Followed by non- alcoholic Pilsner beer (25%) and then Pilsner beer (13%). Therefore you can conclude that marinating the Pork steaks in ale beer is the best and most efficient inhibitor for PAH and HA chemicals. Personally I agree with the statements made because if you look at table 1 the results shown portray the statistics shown in the abstract. Furthermore, by looking into the possible reasons why these results ocured it provides evidence for the statistics in the abstracts. SO by that conclusion I agree with the abstract.

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  3. Polycyclic aromatic hydrocarbons (PAHs) are organic compounds that are composed of multiple aromatic rings (rings of carbon atoms that have physical properties of pleasant aromas). They are found in fossil fuels and a normally produced when incomplete combustion occurs; this can be when food is cooked over an open flame. PAH is mutagenic and highly carcinogenic. Hence, it is important to try to minimise the frequency at which PAHs are taken in. Heterocyclic amines (HAs) are chemical compounds that are made up of a heterocyclic ring (that contains atoms at least two different elements) and an amine group. Depending on the amine group and elements involved, these compounds can be vitamins or carcinogens – formed particularly in the high-temperature cooking of meat.

    In a previous paper, this group identified that beer, tea, red and white wine can be used as marinades for meat to reduce the levels of HAs present after cooking. However, there was no data clarifying if the same technique reduced PAH levels hence this is the focus of their new work. The researchers used 3 types of beer (one non-alcoholic) to marinate and cooked the meat at well-done level alongside a sample without a marinate to allow them to compare the PAH levels. In the method there were a set list of controls: meat used, marinating time, marinate to meat ratio, cooking time, cooking distance, and grill size and type. These controls should allow for an even comparison of results.

    Table 1 clearly highlights that the use of beer marinate reduces the PAH formation in charcoal-grilled meats. Pilsner beer, even though it wasn’t a large improvement on the control, contributed a 2.75 difference in formation, which is the worst of the three marinates. The most successful was Black Beer with a 10.83 difference thus more than halving the formation of the carcinogenic compounds. Reasons for these results are described by the beer contents and compared with the results found by others. There is clear explanation, support and reasoning behind the effectiveness of Black Beer but more extensive testing into its use in other meat and at other concentrations would solidify these findings. Table 2 summarises many different findings within this field, clearly stating the treatment, meat, cooking method, and PAHs involved and measured in various experiments. This allows the comparison of different PAH inhibitors in order, perhaps, to find the most effective.

    In conclusion, the use of BB marinate will reduce the PAH8 levels significantly enough so that the pork loin is within the consumption/exposure guidelines. Out of the three beers used, it was the most effective and inhibited the most dominant PAHs by 55-60%. Although it is unclear on what particularly is the inhibitor ingredient in BB, other have hypothesised that (according to their research), onion and garlic have antioxidant properties (derived, possibly, from sulfur compounds) that can interfere with free radicals that can eventually form PAHs. Nonetheless, the results vary with ingredients and cooking method. The charcoal grilling method is the worst way of cooking and produces the most PAHs within foods. It is evident that some PAHs are more dominant than others and these are in higher concentration in charcoal-grilled meats.

    Summarise: The use of beer marinates on charcoal-grilled meats reduces the formation of polycyclic aromatic hydrocarbons over non-marinated meat. The radical scavenging activity of the Black Beer was most effective, followed by non-alcoholic Pilsner then Pilsner beer. After 4 hours of marinating and cooking to a well-done level, BB inhibited 58% of PAH8 and is identified to reduce the carcinogenicity significantly. These levels are within the given PAH exposure guidelines.

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  4. In this experiment, the researcher attempted to develop on some research around marination and how this can subdue levels of chemicals in the meat. Previously it had been proven that it reduced HA’s and they wanted to examine the affect on PAH’s – hydrocarbons that develop due to smoke from complete combustion, contact between a substance that is being combusted and the meat, and pyrolysis (decomposition due to high heat) – as this has been linked to the processed meat correlation with colorectal previously examined.

    Overall, i felt that their experiment was well done in that they had multiple variables and controls in order to ensure that their end results would be as informative as possible. Their test could have been more fair if they had ensured that all of the meat had been the same weight, and if they had cooked 1 of each marinated meat at a time or all the meat at once as the temperature would not have been consistent. Despite this the correlation would have still been the same (different temperatures would not alter the inhibition results to a great enough level that the same conclusions would not be made.) Overall, i feel it is safe to say that marination can inhibit the PAH in meat with Black Beer having the greatest affect. Despite this, these results couldn’t be used without more tests with different types of meat as this only refers to pork from Portugal and so would be improved with a larger range if it was reattempted in the future.

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  5. From the paper it is clear that well done meat can create carcinogens on the surface of the meat which are harmful the consumer as they increase the risk of cancer later in life, but now they are trying to test to see if there is a coloration between reduced risk and alcohol marinating. PAH’s seem to be the main factor which they are trying to see a reduction in in well done meats via the use of alcohol marinating. For me, how can you define if a meat is well done or not and meat which has been chargrilled will contain more carcinogens than well done meat which has been fried due to the method of cooking which is clearly stated. Therefore from the beginning I can tell that the writer’s aim is to cook the meat in a way that will create the most carcinogens makings it very focused to one way of cooking. Polycyclic Aromatic Hydrocarbons form due to incomplete combustion (soot) meaning that they will be in their highest concentration in a meat which has been barbequed due to the method of cooking. This therefore supports my statement on how the test is very focused to one kind of cooking which is far from the most common in the UK.

    From the experiment they conducted I can tell that the steaks and the marinating process where the control variables as they aimed to buy steaks which were a similar size and weight. Also they marinated 8 steaks in each marinade at a controlled temperature (-5oc) and for a set amount of time (4 hours), but there is no mention of them standardising the amount of charcoal they placed back on the BBQ after each grilling. This would have been important as each steak should haven cooked under the same conditions, or as close to as possible. They then reacted NaCl with an extract of the ground up meat till the reaction plateaued; this is what they based their evidence off.

    From the results I can deduce that Black Beer marinade has the highest inhibition to the PAHs, followed by POB and finally by PB. This therefore means that from the 3 marinades, the Black Beer will reduce the formation of PAHs by up to a half. Form this I can also deduce that a Black Beer marinade is the best form of marinade to reduce the risk of carcinogens entering the body in the case of chargrilling/BBQ, Figure 2 supports this as BB has the highest percentage of inhibition on the set of PAHs than any of the other marinades by a large portion. From what I can make of table 2 that also supports the claim as it represents the percentage of inhibition on various types of meat which have been chargrilled and marinated in the same/similar way.

    After reading the abstract I agree that BB has the most influence on inhibiting the production of PAH 8 specifically and also its influence on inhibiting PAH production in the 8 that where tested for. This test does not take into account the lifestyle of the people who consume said food meaning they cannot collate the reduction in PAHs and a reduction in cancer risk in the public as there are too many other factors which may increase the risk hugely such as smoking. Also the test does not show that the marinating process completely inhibits PAH production meaning people must still be wary of how much of this meat is consumed as the recommended is >100g per meal. Overall this experiment proves marinating in alcohol is beneficial to the consumer but it only targets a specific range of people who eat chargrilled meat making its usefulness limited in my view.

    http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=121&tid=25

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  6. Journal Club 5

    This research mirrors that of the «Meat causes cancer» investigation however this reports more on how the methods of cooking and marinating could cause cancer rather than the mutagenic content of meat therefore perhaps it this has been derived from the same concept. This paper presents that smoked and charcoal-grilled products contain a high concentration of Polycyclic aromatic hydrocarbons (PAHs) which are a ubiquitous group of several hundred chemically-related, environmentally persistent organic compounds of various structures and varied toxicity. Nevertheless from my own research, i found that Although unmetabolized PAHs can have toxic effects, a major concern is the ability of the reactive metabolites, such as epoxides and dihydrodiols, of some PAHs to bind to cellular proteins and DNA. The resulting biochemical disruptions and cell damage lead to mutations, developmental malformations, tumors, and cancer. On the contrary, i also found that because PAHs exist naturally in the environment and are man-made, you can be exposed in a number of ways. Fumes from vehicle exhaust, coal, coal tar, asphalt, wildfires, agricultural burning and hazardous waste sites are all sources of exposure. Hence, this implies that we as humans experience some sort of PAH exposure on a daily basis but aren’t having any major effects from it therefore would PAH really give sinister health issues such as cancer from grilled or marinated meat? It has been demonstrated that marinating meat with beer, red or white wine,and tea can be effective strategies for reducing levels of heterocyclic aromatic amines (HAs) in cooked meat, However due to no information available concerning any link with PAH and marination of meat, present work has been evaluated. But how accurate are these investigations?-As i believe that one difficulty with conducting such studies is that it can be difficult to determine the exact level of HCA and/or PAH exposure a person gets from cooked meats so this would surely be the same for marinating products such as Pilsner Beer.

    In preparation of Marinated Meat Samples three different types of beer marinades were tested: Pilsner beer, nonalcoholic Pilsner beer, and Black beer. There are distinct differences between them which mainly highlights Black Beer to be an outsider in terms of its contents by containing sugar and a colouring agent (E150C(ammonia caramel)) of which the others don’t have and not containing unmalted cereals for instance. Therefore this may have a bigger effect of PAH compared to the rest. The Key points of the experiment was the specific timing of marination (4 h at 5 °C), the proportion of meat amount and marinade volume was 1:1 (g/mL)
    and Extraction of phenolic compounds of beer marinades was performed according to the method of Zhao et al.15 and Viegas et al as well as the analysis of PAH with some modifications. Both extraction using ultrasound-assisted solvent extraction and centrifugation at 2000 rpm for 2 min at 20 °C were used. . The results were statistically analyzed by analysis of variance. Comparison of mean values was made using the Duncan test.

    Figure 1 supportsmy suspection that black beer would be have a bigger effect as it has a higher inhibition percentage that the others however its optimum percentage is before the addition of meat. These results indicate that the contents of the marination products is what causes PAH exhibation and not necessarily how the meat is cooked because the products that had the presence of food colouring, sweeteners, flavours, and other additives had a higher percentage. Also it was concluded that Ale beers have a higher antioxidant capacity than lager beers. BB is an ale beer in contrast with the rest of the beers studied and with the presence of food colouring (E150C) could be another factor that explains its higher antioxidant activity. Therefore the flavourings and sweeteners in POB could also increase this as well which is why it was still relatively high in PAH. Table 1 shows that CH was the prominent type of PAH released but had a higher concentration on unmarinated meat than marinated, However the higher concentrations of the marinations were in PB AND POB which contradicts the results of Figure 1. Table 2 compliments my argument of the contents being the main issue because the marinating treatments given have similar contents to each other but aren’t the same as the ones used this investigation.

    With regard to the three types of beers used as marinades, the less effective in reducing the PAH8 content was PB, followed by P0B. BB had the strongest inhibitory effect on the PAH8 in grilled pork, reducing by more than half the PAH8 content of the control samples. Although not statistically significant, a positive correlation was found between the higher radical-scavenging activity of marinades and a decrease of PAH8 formation.
    «A decrease in antioxidant activity was observed for BB after 4 hours» answers my previous question of how the exposure could be monitored but doesn’t suggest the dangers from it and wether this means its capable of causing cancer and the fact that «Inhibitory effects of different marinating treatments and additives on PAH formation in grilled meat are scarce.» means that either charcoaling meat has more risks of causes cancer due to more PAH release or it could be an anomally and the cause of cancer isnt related to how the meat is cooked therefore marinating meat may only help slightly in avoiding PAH exhibition unlike what the abstract says as the results were plausible for different types of PAHs.

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  7. Heterocyclic amines (HAs) and polycyclic aromatic hydrocarbons (PAHs) are chemicals formed when muscle meat, including beef, pork, fish, or poultry, is cooked using high-temperature methods, such as pan frying or grilling directly over an open flame. In laboratory experiments, HCAs and PAHs have been found to be mutagenic- they cause changes in DNA that may increase the risk of cancer.
    HCAs are formed when amino acids (the building blocks of proteins), sugars, and creatine (a substance found in muscle) react at high temperatures. PAHs are formed when fat and juices from meat grilled directly over an open fire drip onto the fire, causing flames. These flames contain PAHs that then adhere to the surface of the meat.
    PAHs:
    • Toxic by inhalation, ingestion or skin absorption
    • Carcinogen, mutagen and reproductive toxin
    • Long-term inhalation can cause a decrease in lung function, chest pain and irritation
    • Benzo[a]pyrene (BaP) is commonly used as an indicator species for PAH contamination and most of the available data refer to this compound

    These HAs and PAHs are seen to be dangerous for our health, therefore in this journal, scientists are building on their earlier studies, which proved that marinating meat with beer, red or white wine and tea can be effective strategies for reducing levels of Has, with Pilsner Beer having the best inhibitory effect. Therefore, they are now investigating the effect of different beers- pilsner beer, non- alcoholic pilsner beer and black beer on the formation of PAH8 in grilled pork.
    For their method, they have used 32 pork loin steaks (8 for each marinade and 8 unmarinated). They all had almost the same dimensions- 0.75cm thick and 100g. Each were marinated for 4 hours at 5 degrees Celsius. Each pork sample was barbecued 15cm from the heat source (charcoal) at 200-230 degree Celsius. They were each cooked for 10 minutes.
    From table 1, I can see that the unmarinated meat had the highest content of PAH8, with black beer having the lowest. Figure 1 links with this table, suggesting that black beer has the highest inhibiting value of 68%.
    This implies that the black beer is the bet for marinating meat, as the pork marinated in it showed the smallest levels of PAH8. I agree with the statement made in the abstract, although I think it should say pork rather than meat, as someone reading only the abstract would think they had investigated many different meat types. From one type of meat I don’t think they an accurately draw up the conclusion that they have.

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  8. The journal was funded by the University of Porto, which indicates that the journal is probably reliable and true because the University would not want to be associated with a bad journal therefore the article is mostly likely to be trustworthy. The article describes how previous tests were carried out on red or white wine, beer and tea. These results portray that it was effective for a reduction in the heterocyclic aromatic amines (Has). The results sowed that beer marinated meat has the least Has. Never the less the results for the PAHs seem to be unclear.

    The introduction states that this evidence shows that beer marinated meat is a lot safer and un marinated meat was tested and PAH (carcinogen) levels were shown here but these have not been specified. Other types of beer are going to be tested to see if the same thing happens. Charcoal-grilled meat have a closeness to the heat source, the amount of fat in the raw products=, and the cooking time.

    Overall I believe the evidence does show that beer marinated meat is appears better for you judging by figure one and the method they followed. However, I think a little more explanation was needed into why beer had a better Ha level and what they are going to do about the lack of evidence about the PAH with the experiments in the intro. In the main body of text it was fairly clear what they were doing and was fine to follow after a few times reading through. The evidence was fairly reliable and accurate but further testing is needed

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