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Chemistry vocabulary- acids and bases
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The purpose of this lab was to determine the pH and total acidity of grape juice and wine. A second purpose was to experimentally determine the pKa of a monoprotic weak acid, polyprotic weak acid, as well as, a free amino acid, alanine. Acids and bases were defined by Bronsted-Lowry in 1923, in which acids were described as substances capable of donating a proton and bases are substances capable of accepting a proton (Thompson and Dinh 2009). In addition to defining acids and bases, Bronsted-Lowry further classified acids and bases as being either strong or weak. By definition, a strong acid or base is a substance that is completely dissociated in aqueous solutions and in contrast, weak acids only partially dissociate and reach their equilibrium with their conjugate base (Harris 2003). Buffers are comprised of weak acids and their conjugate bases. In the food industry, buffers are commonly used to protect changes in pH of food stuffs. The two conjugate components of the buffer resist changes in pH by absorbing the addition of any hydrogen or hydroxyl ions (Christen and Smith 2000). When weak acids and their conjugate bases are at equilibrium, their concentrations can be expressed in terms of the dissociation constant, Ka. For a strong acid, the Ka value is greater than 1 x 10-2M and less than 1 x 10-2M for a weak acid (Thompson and Dinh 2009). For weak acids, the relationship of hydrogen ion concentration and pH can be defined by the Henderson-Hasselbach equation (Thompson and Dinh 2009). Wine quality greatly depends on the quality of the grapes and the microorganisms involved in the fermentation process (Husnik and others 2006). When compared to lactic acid bacteria, yeasts are better suited for growt... ... middle of paper ... ... Son HS, Hong YS, Park WM, Yu MA, Lee CH. 2009. A novel approach for estimating sugar and alcohol concentrations in wines using refractometer and hydrometer. J. Food Chem. 74:106-111. Thompson LD, Dinh T. 2009. Acid-Base Chemistry. FDSC 4303/5303 food chemistry laboratory manual. Lubbock, Tx.: Texas Tech University, Department of Animal and Food Sciences. Ugliano M, Moio L. 2005. Changes in the concentration of yeast-derived volatile compounds of red wine during malolactic fermentation with four commercial starter cultures of Oenococcus oeni. J. Agric. Food Chem. 53:10134-10139. Waite JG, Daeschel MA. 2007. Contribution of wine components to inactivation of food-borne pathogens. J. Food Sci. 72:286-291. Wintersteen CL, Andrae LM, Engeseth NJ. 2005. Effect of heat treatment on antioxidant capacity and flavor volatiles of mead. J. Food Chem. 70:119-126.
The Roman writer and naturalist Pliny the Elder, in his treatise Naturalis Historia states “there is nothing more useful than wine for strengthening the body, while, at the same time, there is nothing more pernicious as a luxury, if we are not on our guard against excess.” Years before he wrote those words, wine had in fact come from humble origins outside Italy itself. Furthermore, the process of fermenting grapes goes back thousands of years, and its beginning can be traced to where the wild grown grape-vine, vitis vinifera, flourished and was actively utilized for this reason.
In the span of only a few pages, L.B. Church has given us an overview of the winemaking process. He has done so with sufficient detail for those in the chemistry community to follow along, yet still in a cursory enough manner as to not bog them down with the unnecessary. Written as if it were the procedure of an experiment, he has given enough information for the experiment to be repeated, tested, validated and improved upon. And that is almost assuredly his goal from the very beginning, as it must be for any published author in the chemistry community.
Louis Pasteur had been studying fermentation to explain why dairy and meat was going bad. He didn’t believe that it was spontaneous but rather there had to be a scientific explanation. When working with grapes and understanding that yeast was the driving agent in fermentation of grapes, he hypothesized that if you can protect grapes from fermentation, that people could be protected from infectious disease.
The purpose of this investigation is to test the effects of multiple sugar substances on the respiration of yeast. Most people think of yeast when they think of what makes bread rise, cheese, alcoholic beverages, or other food products. Another type of yeast can also cause yeast infections, an infection of the skin. Yeasts (Saccharomyces) are tiny, microscopic organisms with a thin membrane and are usually oval or circular-shaped. They are a type of single-celled fungi of the class Ascomycetes, capable of processing sugar into alcohol and carbon dioxide (CO2 ) ; this process is known as fermentation. Fermentation and the products are the main focus points for this experiment being that cellular respiration of yeasts happens via the process of fermentation, which creates by-products of alcohol and CO2. The level of CO2 produced by the yeasts will show how effective each sugar substance is in providing cellular energy for the yeasts.
The global wine industry is being influenced by numerous factors, specifically consumer demand and changes in the way wine is produced and sold (Old vs. New). In regards, consumers and producers have shifted away from the traditions of the Old World and have transitioned to accept the innovating techniques the New World has brought to the wine industry, thus the challenge the new world is presenting upon the old.
Wine quality is an inherently subjective matter which is used as a reflection on the chemical composition of wine itself (Factors Influencing Wine Quality, 2001). Wine quality is in regards to the compound that the taster associates with pleasurable experiences which is defined in various ways. The ‘ideal’ wine is dependent upon its nearness to a specific target wine, depending on the nearness of its composition to that of a higher wine, however it can also be defined in ways such as is harmonious complexity (in reference to the characters, tastes and aromas produced by the wine and the combination which they produce) or its inharmonious notes (which centres the concept of the importanc...
B2. The curve of the new 0.05M acid has a much steeper curve when compared to the first theoretical curve and the other weak acids. This would mean that the new acid is a worse buffering acid because it resists a change in pH less than those of a higher concentration. It has a similar trend of a tailed start and end point as boric acid, but the mid point is much stepper in the new acid titration.
Acid-Base balance is the state of equilibrium between proton donors and proton acceptors in the buffering system of the blood that is maintained at approximately pH 7.35 to 7.45 under normal conditions in arterial blood. It is important to regulate chemical balance or homeostasis of body fluids. Acidity or alkalinity has to be regulated. An acid is a substance that lets out hydrogen ions in solution. Strong acid like hydrochloric acid release all or nearly all their hydrogen ions and weak acids like carbonic acid release some hydrogen ions.
The shape of any titration curve of a weak acid can be described by using the Henderson-Hasselbach equation. This equation was useful in estimating the pH of a buffer solution (CH3COOH), and allows for an understanding of the acid-base balance within the blood and tissues of vertebrates. This equation fits the titration curve of all weak acids and showed why the pKa of a weak acid was equal to the pH of the solution at the midpoint of the titration (Nelson & Cox, 2008 pg.60-61). When the titration began, the CH3COOH was partly ionised. This means that it was mostly in the form of CH3COOH. When the NaOH was added, the amount of CH3COOH that was dissociated to form acetate ions and H+ ions increased. These ionised protons (H+) reacted with the added OH from the NaOH and formed H2O, which then neutralised them (Joesten, M. 2007). Where the slope of the graph was shallow, the pH changes very slowly with the addition of NaOH and this was where the CH3COOH displayed its maximum buffering ability. This occurred when the pH was resisting change from the addition of NaOH, and it occurred at this point because the amount of CH3COOH was equal to the amount of acetate ions (CH3COO-) (Thorne, A. 2016). This point is also known as half the equivalence point, and this was where half the NaOH added equalled half of the total
There are literally hundreds of compounds in a glass of red wine. As wine ages the number of compounds change into more complex molecules, then add to that the effects of oak compounds. Don't take the value and complexity of wine too cavalier. This drink has been around since the beginning of civilization and until about 1960 we did not know the health benefits and the magic of wine. In fact, the discovery of resveratrol did not come about until
When cooking with wines, you need to consider the type of meat that you are cooking, and the way the meat will be prepared. For instance, a food...
Throughout the course of this Investigation, how sugar influences the rate of fermentation and how this in turn, affects the overall quality of wine was explored. Three wines were produced, each with varying sugar levels. The Investigation was designed so that one wine had a fairly low sugar content; one had an ideal sugar content and one had a high sugar content. After the fermentation process stopped, a taste test was conducted in order to assess the quality of the wine. The taste testers were blindfolded in order to reduce the chance of biased opinions. Each taste tester not only sampled each wine, but also sugar water and tonic water. This enabled the validity of the results to be assessed. It was found that the majority of the conclusions drawn by the taste testers were legitimate.
Acids are a material that releases a proton or hydrogen ion (H+). Acids always generate an H+ whenever the solution is aqueous, which can be easily identified. On the contrary, in an aqueous solution involving bases always produce an OH- ion. There are many different ways to identify whether a substance is an acid or a base. An acid is always sour, changes litmus, conduct an electric current, react with a base to form salt and water, and whenever there is a reaction, acids helps advance an hydrogen gas with an active metal, such as the alkaline earth metals, zinc, and many more. Some well known or common acids are citric acid, which are from citrus fruits, such as oranges, lime, and lemons. Vinegar and carbonic acid (soda/soft drinks) are also some common acids. Bases are the opposite of acids. They can be identified by their bitter taste, soapy or slippery feeling, and cannot change the color of litmus. Bases can become red litmus to reverse back to the blue litmus. Similarly, acids and bases conduct an electrical current in an aqueous solution, thus they are...
Based on the experiment using the red cabbage, I can tell if a liquid is an acid, base or neutral using red cabbage juice as an indicator.
The descriptive sensory evaluation is an important tool in determining the detailed description of products and how process or ingredient affect the final product characteristics and sensory attributes. In this study, sensory evaluation of adlay vinegar was conducted on the 10th, 20th, and 30th day after storage. This method was taken in order to assess viable changes of the product’s organoleptic properties. Vinegar produced from fruits and grains’ ethanolic solution contains certain amount of phenolic compounds which may contain some antioxidant properties (Pinsirodom et al., 2010). However, the most essential aspect that contributes to the vinegar flavor is aging. In this process, fundamental integration of different compounds present occurs. Reduction in the pungency of acetic acid