Fermentation Conditions for the Production of Ethanol - Assignment Example

Alcohol Fermentation Conditions for the Production of Ethanol DAmore, T. 1992, ‘Cambridge Prize Lecture Improving Yeast Fermentation Performance’, Journal of the Institute of Brewing, Vol. 98, pp. 375-382 Ethanol production through fermentation is not entirely clear as many factors interplay to determine the performance of the yeast in the amount of alcohol produced. The most important factor is the ability or inability of the yeast to tolerate high alcohol content in the medium. In trying to understand the issue of tolerance, it is also important to study other factors that affect yeast fermentation which include; Strain of yeast used in fermentation Substrate feeding modes Osmotic pressure Ethanol concentration Intracellular constituent concentrations Membrane composition Inhibitory Effects of Ethanol High ethanol concentrations have been known to have negative regulatory mechanism on the production of alcohol by the yeasts. These effects are manifested through yeast growth, viability and the progress of fermentation. Ethanol concentration depresses fermentation through causing cell deaths in different yeast strains which varies at different concentrations. This can be represented graphically as shown below where Saccharomyces uvarum and Saccharomyces Cerevisiae strains. (O) Saccharomyces uvarum (carbbergensis) ( . ) Saccharomyces Cerevisiae According to this graph, although there are some variations in the way the strains respond to elevated ethanol concentration in the media, generally elevated ethanol concentrations inhibited cell growth while slightly higher concentrations blocked fermentation. This alcohol acts through the cell membrane which leads to lysis of the membrane leading to leaking of internal constituents which affects the cell performance. Effect of Osmotic Pressure It has been known that an increase in substrate (glucose) concentration results into decreased fermentation. In order verify that the observed effect is due to repression of the catabolite, a similar experiment is carried out replacing the glucose with sorbitol. Even in the second experiment, observations are similar which indicates that an increase in osmotic pressure corresponds with decreasing cell viability and reduced fermentation. For the maintenance of optimal fermentation levels and cell viability at high sugar concentrations, it is necessary to minimize osmotic pressure effects. Changing the concentration of the media is instrumental in counteracting the effects of osmotic pressure. In these experiments, it was deduced that there are no changes on cell viability and rate of fermentation when substrate concentration is increased. In the case of substrate supplementation is undertaken; there is an improvement in cell viability and the rate of fermentation. In order to deal with the challenge of osmotic pressure, it is necessary to carry out investigations with regards to substrate feeding modes by the yeast. Previous done research has shown that stable fermentation rates and cell viability are possible through using fed-batch scheme and not single batch fermentation. This kind of observation supports the inference that limiting substrate concentration plays a part in lowered rates of fermentations. Effect of Temperature The mechanism through which temperature affects the fermentation process has been studied in depth and several conclusions made. In general, yeast responds to temperature change by increasing the fluidity of its membrane through a change of fatty acid composition. Increased temperatures lead to increased ethanol intolerance and decreased ethanol fermentation. However, this challenge can be overcome through supplementation which just like in the case of osmotic pressure alleviates the challenges that elevated temperatures present. Role of Nutrients Research carried so far show that high ethanol production can be achieved through conditions of elevated temperature and osmotic pressure through varying additions of supplements. Key supplement that has been shown to lead to high ethanol production is the addition of both magnesium and calcium elements to the medium. This has been exploited commercially as the metals act as important co-factors during the fermentation process. Winemaking has occurred for centuries. In today’s wineries the process makes use of technology but the same basic principle remains the same. Draw a flow chart showing the process of wine making from harvesting the grapes to bottling the wine. Discuss the difference in the manufacture of red and white wine Wine Making Process Flow Chart White Wine Red Wine Grapes Grapes Determining and crashing Determining and crashing Maceration Maceration & Fermentation Pressing Pressing Fermentation Malolactic Fermentation Clarification Maturation Fining/Stabilization The primary difference is the manufacture of red and white wine is that the red wine is usually made from crushed grapes (both skins and flesh of the grapes) whereas white wine is made from grape juice (after removing the skins and flesh of the grapes). The skins of grapes contains a lot of tannins which basically allow the red wine to be aged for longer periods than white wines which contain relatively fewer tannins. Tannins act as preservatives. Like wine, beer is produced by the fermentation process, except beer makers use grains instead of grapes. (a) Draw a flow chart outlining the beer making process Beer process flow diagram Cold water Brine Sterile air filter Arrangement Sample Cock Drain Brine Hot Water Yeast Fermenting Vessel Cleansing/ Sterilizing H2O Cleansing/ Sterilizing H2O Sight glass Drain Discuss the difference between beer and wine making For starters, beer is made from malt which is acted upon by yeast which has to follow an elaborate process which is akin to a scientific process. The art of beer making is quite old and can be traced as far as during the nomadic era. However, this process has been perfected to meet some specifications that are stringent for good quality and taste of the beer. The yeast has to be introduced from outside sources and many regulations have to be put in place. For wine making process, wine is primarily made from grapes and other fruits and the process is simple enough for almost everybody to make wine at home. The process has barely changed and after crushing fruits and extracting the juices, fermentation occurs naturally since the fruits contain the yeast necessary for fermentation. Wines and beers vary in taste due to natural chemical called esters and tannins. Discuss what esters and tannins are, how they are formed and how they change the taste of wine Tannins are compounds that are polyphenolic in nature and participate in chemical reactions through binding proteins. A good example of tannins is the anthocyanins which control pigmentation in plants and especially in grapes. These tannins are principally found in leaves or barks of plants and they are concerned with plants defense. They have astringent taste that is bitter in the mouth of animals that eat the plants. In the case of wine, tannins give the wine a bitter taste or off flavor. On the other hand, esters are chemical compound that are formed through carboxylic acids combination with alcohols during fermentation. These esters are usually used to flavor wines especially when they occur in small or minute contents. The most common ester is ethyl acetate Sometimes wine can spoil if it is exposed to air. A chemical reaction occurs between the ethanol and oxygen in air. Describe, using a chemical equation, how wine can spoil. RCH2–O–Cl   +   base    RCH=O   +   H–Cl Binge Drinking Among the Teenagers Binge drinking is defined differently in different countries but the common description is the consumption of high amounts of alcohol in a short period of time. This consumption is usually way above the legal or permissible daily quantity for one person and has become the epithet of modern day drinking. During adolescence stage, the brain is still developing and engaging in alcohol drinking activities can be detrimental to the health of that person (Oei & Morawska, 2004). In the modern times, cases of teenagers and young people engaging in risky drinking behaviors has become a problem with many young people especially the ones in high school and colleges. This problem has almost reached endemic levels which is not apparent to the alcohol abusers especially when the consequences are considered to the person and the society at large (Grønbæk, 2009; Miller, et al. 2007). Binge drinking has been associated with many mental and social problems among those people that engage in it. There has been a connection between binge drinking and unhealthy mental problems like suicide among teenagers and young people that over indulge in drinking. This connection is also blamed on improper brain development since at adolescence the brain is still developing and alcohol affects its development. Besides causing unhealthy mental states, it causes or worsens diabetes in. Studies done so far have shown that over alcohol consumption leads to excess sugars in the body which in turn desensitizes the body and hence diabetes results (Shanmugam, Mallikarjuna1& Reddy, 2011). Other problems associated with binge drinking include; Development impairment Unplanned and unsafe sex Assault and aggressive behavior Poor academic performance In the end, the whole life of the person involved in binge drinking is left in a mess and they is a big chance that young alcohol abusers will abuse other types of drags (Oei & Morawska, 2004). Many strategies have been employed that are geared towards changing personal attitudes of people about drinking. Mostly, these strategies entail carrying out awareness campaigns, counseling and treatment which have not borne much profit. These strategies are countered by external forces such as media and advertisements which portray drinking in a different light. Young people are made to believe that drinking is a cool thing which erodes the gains made by public awareness. A more effective approach that is currently under use is through price regulation and imposition of very stringent rules against drinking. This includes regulating drinking time and also raising the threshold of minimum age for drinking. Besides this, media should also be regulated on what they advertise and the contents of their advertisement with regards to alcohol (Hoover, 2002). In my opinion, undertaking the two strategies of tackling the problem the old way and the new way can be effective. However, it takes concerted efforts of both the affected people and the government to make and actualize the effectiveness of campaigns to stop binge drinking. Annotated Bibliography Alba-Lois, L. & Segal-Kischinevzky, C. 2010, ‘Beer & Wine Makers’, Nature Education, vol. 3, no. 9, pp.17-19- This article is concerned with the concerned microorganisms that make both wine and beer. It is discussed from an historical point of view where yeast and fermentation are articulated at length. Different aspects of fermentation are presented and why different microorganisms are chosen for beer and alcohol making. Besides all these, the chemical aspects of fermentation also tackled. DAmore, T. 1992, ‘Cambridge Prize Lecture Improving Yeast Fermentation Performance’, Journal of the Institute of Brewing, Vol. 98, pp. 375-382- An investigation is done about the factors that impede fermentation by yeasts. The factors include the mode of substrate feeding, nutrient supplementation, temperature, osmotic pressure, oxygen, intracellular ethanol accumulation, and yeast ethanol tolerance. After the investigations, inferences are also drawn as to how to overcome the barriers that presented by these factors. Dequin, S. 2001, ‘The potential of genetic engineering for improving brewing, wine-making and baking yeasts’, Appl Microbiol Biotechnol, Vol. 56, pp.577–588- Advances in biotechnology and DNA recombinant technologies are discusses which are geared towards improving yeast strain for fermentation purposes. Among the things discussed are off flavor elimination, increased substrate use by the microorganisms and by product formation enhancement. Although these new technologies have not been fully embraced in the highly conservative fermentation industry, it is hoped that soon they will be welcomed. Dombek, K.M. & Ingram, L.O. Ethanol Production during Batch Fermentation with Saccharomyces cerevisiae: Changes in Glycolytic Enzymes and Internal pH, Applied & Environmental Microbiology, Vol. 53, No. 6, pp. 1286-1291- Alcohol fermentation is mostly done in batches so that between one batch and the other, the yeast can be given some time to recover. This article is concerned with the effect of alcohol intolerance on yeasts during batch fermentation. The factors that cause alcohol intolerance for Saccharomyces cerevisiae are discussed that are deeply entrenched in Glycolytic Enzymes and Internal pH. Grønbæk, M. 2009, ‘The positive and negative health effects of alcohol- and the public health implications’, Journal of Internal Medicine, vol. 265, 407–420- As the name of the article suggests, a review is done about the effects of alcohol which may be beneficial or detrimental to the health of human beings. Among the negative effects of alcohol are cirrhosis, alcohol dependency, and many types of cancers besides other social ills. On the positive side, alcohol can be beneficial by helping to prevent thrombosis of the heart. Hoover, S.A. 2002, ‘Policy Strategies to Reduce Underage and Binge Drinking’ viewed 2nd Nov 2011, This polices are formulated to curb binge drinking after the conventional approaches have failed to yield any results. It has been recognized that public awareness through campaigns, changing individual substance use behavior, counseling and treatment have not been effective in eliminating binge drinking especially the youth. This article calls for such strategies as minimizing access to alcohol for underage drinkers, price increases, restriction of alcohol adverts and changing of social norms. Legras, J., Merdinoglu, D., Cornuet, J. and Karst, F. 2007, Bread, beer and wine: Saccharomyces cerevisiae diversity reflects human history, Molecular Ecology, Vol. 16, 2091–2102- The article is about the diversity that exists in the fermentation microorganisms. The main microorganism of concern here is Saccharomyces cerevisiae which is discussed along the continuum of geographical location and human history. The viability of the species is traced along different regions of the world and how it has evolved to become a key player in the fermentation industry. Miller, J.W., Naimi, T.S., Brewer, R.D. & Jones, S.E. 2007, ‘Binge Drinking and Associated Health Risk Behaviors Among High School Students’, Pediatrics, vol. 119, pp. 76- 88. This is an investigative article that articulates statistics about binge drinking in high school students and the resultant harmful effects in the society. Among some of the findings including the ages that binge drinking is most pronounced in adolescence and a high likelihood of engaging in other socially unacceptable behaviors like smoking and engaging in risky sexual behaviors. Oei, T.P.S. & Morawska, A. 2004, A cognitive model of binge drinking: The influence of Alcohol expectancies and drinking refusal self-efficacy’, Addictive Behaviors, vol. 29, pp.159–179- This paper attempts to form a theory as to why people indulge into binge drinking which is considered a social menace. A model is formulated and discussed which consists of alcohol expectancies and drinking refusal self efficacy (DRSE). These two constructs attempt to explain why people indulge in binge drinking and how they continue engaging in the undesirable trait. Pretorius, I.S. 2000, ‘Tailoring wine yeast for the new millennium: novel approaches to the ancient art of winemaking’, Yeast, vol. 16, pp. 675-729. The viability of Saccharomyces cerevisiae in alcohol fermentation is discussed within the context of increased demands of neo-wine making practices. This has necessitated the need for yeast strains that have oenological potential so as to keep in match with the sophisticated modern day wine industry demands. Among the key review of the article include the currently available genetically modified strains of yeasts and the potentials that can be exploited to refine the art of wine making. Shanmugam, K.R., Mallikarjuna1, K. & Reddy, K.S. 2011, ‘Effect of alcohol on blood glucose and antioxidant enzymes in the liver and kidney of diabetic rats’ Indian Journal of Pharmacology, Vol. 43, no. 3, pp. 330-337- Many cases of diabetes have been reported in those people that are associated with excessive consumption of alcohol. Alcohol contains a lot of sugars which when consumed in excess tamper with metabolism of the sugars. This leads problems with either production or utilization of the insulin hormone. According to this study, it is harmful to consume alcohol for people that are diabetic which worsens the condition. Theunissen, M., Jansen, M. & Gestel, A. 2011, ‘Are mental health and binge drinking associated In Dutch adolescents? Cross-sectional public health study’, BMC Research Notes, vol. 4, no.100, pp. 1-7 A connection between binge drinking and mental illnesses is investigated since many of these conditions and highly prevalent among alcoholics. This study is inspired by the high number of students involved in binge drinking. The findings of the article are astonishing with a link being found between those children involvement in binge drinking and mental health. This is attributed to the alcohol which destroys brain cells at a young age leading to mental health complications. Read More