Journal Critique: Dissolved Cations In Coffee Extraction

Many manufactures release the caffeine content of their products publically, but not always, and new products and flavors are continuously introduced to the market. If quality checks are not performed, manufactures may alter the caffeine and benzoic acid content to suit the demands without public knowledge. To ensure the levels of caffeine and benzoic acid in products do not exceed the established safe limits and to inform the public of the amount of these compounds being consumed, various methods of analysis have been performed. Before the introduction of modern techniques, spectrophotometric methods alone were used to determine concentration of a compound in a mixture.6 The caffeine content in coffee, tea, soft drink, and energy drinks were determined using an immunoassay.7 The caffeine content in mixtures also used to have to be extracted before quantification.8

This science fair project was performed to find out the effect on plant growth of adding caffeine to the soil. The experiment was done by using mung bean plants and watering them daily with water, water mixed with caffeine and with a coffee mixture.

Acidic Relations in Chemistry is the topic of this experiment. In this experiment, the scientists will be testing the strength of pH and the amount of TDS (total dissolved liquids) in both gunpowder green tea and caffeinated black coffee. The independent variables are the caffeinated beverages and the dependent variables are the pH and TDS levels of the gunpowder green tea and black coffee. The constants are the way we measure the pH and TDS of the caffeinated beverages

The objective of this experiment was to isolate caffeine from tea bags and purify the caffeine by a sublimation process. To accomplish this a liquid-liquid extraction technique was used along with the process of sublimation. During the liquid-liquid extraction the sodium carbonate deprotonates the caffeine so that it is more soluble in the organic layer. The organic layer is colorless because it contains the caffeine while the dark colored tannins move into the aqueous layer. Sublimation is the process by which a solid transitions directly into the gas phase.

In the solid-liquid extraction all water soluble components were sepreated along with the caffeine including the tannins. To further isolate the caffeine and obtain a purer product it was necessary to add sodium carbonate(Zhao et al. 208). This acidic- base reaction (tannins being the acid electrophile and sodium carbonate the base nucleophile) forms conjugate base phenolic salts. Tannins are acidic and thus have an–OH group directly bound to their aromatic ring the addition of a weaker base allows for the deprotonation of said –OH group. Then when the methylene chloride was added the tannins, now a phenolic salt, were insoluble thus resulting in the formation of two layers (organic and aqeous). The aqeuous layer now contains the tannins and chlorphyll and the organic layer the caffeine. This occurs because caffeine is more soluble in the methylene chloride and thus is separtaed into the same layer and the tannin salts and chlorophyll which are insoluble in the methylene chloride remain in the aqeous layer. The organic layer is extracted and undergeos this same washing process again in order to extract the maximum amount of product. Once enough caffeine was extracted a drying agent of anyhydrous sulfate was added to remove any of the excess water in the organic layer and placed in a hot chamber to evaporate off the methylene chloride. The remaining crystals underwent recrystalization to obtain a pure substance. (Zhao et al. 208).

Solutions are formed by mixing a solute in a solvent. A unique characteristic of solutions is that they have colligative properties, which can be defined as properties that solely depend on the solute’s concentration of molecules, not the identity of the solute. Colligative properties include reducing the vapor pressure, elevating the boiling point, depressing the freezing point, and osmotic pressure.1 In this particular experiment, the colligative property freezing point depression will be focused on. Freezing point depression was discovered by a French chemist named Francois-Marie Raoult. Raoult found that adding a solute to a solvent resulted in an overall decrease in the freezing point temperature of the solvent.2 Calculations involved in this experiment include two basic equations. One equation will calculate molality, and the other will calculate the change in freezing point temperature using the freezing point depression constant, the solution’s molality, and the van’t Hoff factor. The van’t Hoff factor is determined by finding the number of ions that a compound will dissociate into. In this experiment, freezing point depression will be utilized to determine the molecular weights and identities of two unknown compounds.

Essentially the warm water will run through the coffee beans and extract its properties. The flavor of the coffee beans would disperse into the water. The water would change color and smell like the coffee beans as these properties are drained from the coffee beans.

In this experiment the caffeine had the greatest amount of precipitate. This means that it has the smallest chance to be absorbed and the smallest bioavailability. However, many substances in this experiment such as Ascorbic Acid and Fructose had no precipitate form. This increases their chances for absorption, also increasing their

The second major flaw in the coffee taste studies is the existence of external variables. It is evident that the first and third studies had underlying variables that may have significantly affected their outcomes. The first study notes that “the author of this study personally purchased coffee to go at four places, took them to his office, tasted them, made notes and drew conclusions” (pg. 63). This indicates a major flaw of this particular study because the time frames for which each cup of coffee was obtained and then consumed are inconsistent.

Brewing or sometimes referred to as percolation is the infusion of hot water in the ground coffee to extract the aromatic and organic compounds from the coffee ground at approximately 100 °C and 101.3 kPa. Similar to the coffee maker at home, industrial percolation has larger quantity but also performed at a slightly higher pressure and temperature sometimes. The reason that higher working pressure and temperature would be because of the higher efficiency, and higher extraction percentage of the desired compounds (solid content from 36–46 %). Cold brewing is also available with slightly higher pressure (17 °C and 338 kPa). Higher yield of solid content could be reached by percolation at 200 °C and 1500 kPa. The latter would be higher capital cost operation, but also effective in extracting more volatile compounds [11].

Backlot Coffee was founded by John and Isaac in Summer of 2016. John, a seasoned barista and entrepreneur, has been operating coffee shops in Evanston for about 12 years. His other business ventures include Brother’s K and Other Brother Coffee, which he owned alongside his brother, and Boltwood, a New American Restaurant. While working at Boltwood, John met Isaac a bartender at Boltwood. More comfortable with operating coffee shops, John sold Boltwood and decided to pursue a new venture with Isaac as his co-owner. Together, the two desired to create a coffee shop experience that was unlike any other. Described as a “third wave coffee shop”, John and Isaac founded Backlot Coffee with the following mission statement:

Caramel macchiato: Steamed milk with vanilla-flavoured syrup, marked with espresso and topped with caramel sauce.

Feria – Morales (2002), stated that coffee is one of the popular beverages in the world. Coffee drink is assumed to be a healthy alternative to alcoholic beverages in social gatherings (Cristoram et. al, 2000). Coffee has been stereotyped as an adult beverage. In a study conducted by Asioli, et. al, (2013), shows that the main motivations for iced coffee consumption are enjoyment and relaxation as well as energy and caffeine intake. The study also found that the most preferred product is latte with low calories at the lowest price. This result indicates that there may be a market potential for calorie reduced iced coffee product. Coffee gives consumers pleasure and satisfaction through flavor, aroma and

This investigation aimed to determine the effect of caffeine on the growth of bacteria. The research question developed is: How Does the Presence of Caffeine Affect the Growth of Bacteria of the Digestive System? Using agar diffusion test, the effect of caffeine on the growth of bacteria is measured by the zones of inhibition established around the caffeine impregnated filter paper discs. Different concentrations of caffeine were tested, from 0.2 mg/mL to 1.0 mg/mL. The sizes of zones of inhibition was

During roasting, chemical compositions of coffee bean changes due to evaporation and roasting reactions. At first, moisture content decreases down by 75% from its original value and then complex chemical reactions including the non-enzymatic browning of Maillard reactions took place. The intensity of coffee bean changes increases towards the end of roasting in terms of colour, volume and aroma formation (Farah, 2012). In a short period of time, these multiple changes contribute to the complexity of coffee roasting.