Coffee stability

Lecithin is used to improve the wettability and dispersibihty of various milk powders including whole milk powder (229, 230) and casemates (231). Oldfield et al. (232) demonstrated that lecithinated whole milk powder had increased coffee stability, with decreased coffee sediment levels over a water hardness range of 0-308 mg/L. 

Table 14. Effect of Protein and Emulsifier on Coffee Whitener Stability ...

Lactones and acid anhydrides are also seen in roasted coffee, presumably secondarily to the production of the corresponding acid, which finds enhanced stability as an anhydride or a lactone. 

The presence of tocopherols,114 as well as caffeic acid,108 accounts for the remarkable stability of green coffee bean oils toward oxidation. In coffee beans from different origins, a-tocopherol concentrations are in the range 89 to 188 pg/kg and (p + y)-tocopherol concentrations are in the range 252 to 530 pg/kg.114 Since p- and y-tocopherols have better antioxidant properties than a-tocopherol,114 it is not surprising to see coffee oil patented as an antioxidant material.115117... 

Roasted Robusta coffee contains 16-O-methylcafestol, mostly in its esterified form 128 and it has been recognized as useful for detecting the addition of Robusta to Arabica coffee because of its stability during roasting.129... 

Rouge, F., Gretsch, C., Christensen, K., Liardon, R., Thermal stability of 2-methylisoborneol in Robusta coffee. Colloq. Sci. Int. Cafe, 15th(Vol.2), 866, 1993. (CA121 33729q)... 

Table 4 shows worldwide imports of coffee, listing the primary importing nations.17 22 Since 1980, there has been an increase in overall coffee trade. Coffee imports have risen from 3.8 million metric tons overall to 4.9 million in 1993. Trends in coffee exports are reflecting in the patterns and volume of coffee imports. After a dramatic increase during the 10 year period from 1980 to 1990, there has been an apparent stabilization from... 

The U.S. is responsible for consuming the most coffee overall in the world in 1991, it was estimated that each person consumed nearly 27 gallons (101.4 liters) of coffee.10 Decaffeinated coffee is consumed less frequently in the U.S., at levels of 24% in 1987 to 15% in 1993.10 Table 11 shows that the U.S. by far consumed the most coffee in weight than any other nation in the world, nearly double that of Germany as the second highest consumer.38 Estimates for the U.S. up to the early 1990s did not show a great increase in total consumption, but rather a stabilization that is consistent with coffee trade to and from the U.S. 

Coffee, R. D., "Chemical Stability," in Safety and Accident Prevention in Chemical Operations, H. H. Fawcett and W. S. Wood (editors), p. 305, John Wiley, New York, NY (1982). 

To determine enthalpy changes in high school laboratories, a coffee-cup calorimeter provides fairly accurate results. A coffee-cup calorimeter is composed of two nested polystyrene cups ( coffee cups ). They can be placed in a 250 mL beaker for added stability. Since a coffee-cup calorimeter is open to the atmosphere, it is also called a constant-pressure calorimeter. 

Coffee has been the focus of many studies regarding formation of ochratoxin A, its destruction during roasting, and its presence in brews. Mechanical color sorting leads to minor reductions in ochratoxin A levels, however steaming produces approximately 25% reduction. The effect of heat on stability is considerable, 80% of ochratoxin is destroyed during bean... 

The composition and properties of particular types of creams depend upon their intended use. Half and half, with 10 to 12% fat, is used as a coffee whitener and cereal cream. It may have additional milk solids and a stabilizer added. Usually half and half is homogenized and either pasteurized or ultrapasteurized for longer shelf life. In some countries it is sterilized. Most states in the United States require it to contain a minimum of 10.5% and a maximum of 18% milk fat. 

Some food O/W emulsions, including milk, cream, ice cream, and coffee whiteners and toppings, are stabilized by proteins such as casein that form a coating around the fat globules. These products also need to have some of the fat (oil) be partly crystalline to link the droplets in a network structure and to prevent complete coalescence of the oil droplets, especially under shear [78,825]. 

In coffee products, such as espresso, a stable foam is an important aspect of overall product quality, in addition to smell, taste, colour, and body [857]. In addition to appearance, a foam layer helps trap coffee aromas, providing a more gradual release. The degree of foaming has been found to increase with the degree of roast and the amount of protein in the coffee, while the stability of the produced foam has been related to the amounts of galactomannan and arabinogalactan [857]. 

Hoffmann, W., Moltzen, B., Buchheim, W. 1996. Photometric measurement of coffee cream stability in hot coffee solutions, Milchwissenschaft. 51, 191-194. 

The viscosity of modified peanut protein increased with the extent of succinylation (Table V) and this was most pronounced at high concentrations of the protein (43,45). Despite the increased electronegativity of succinylated proteins the addition of calcium to dilute dispersions resulted in no apparent increase in viscosity (12,37). Melnychyn and Stapely (47) noted a reduced viscosity in succinylated vegetable proteins. They noted the thermal stability of these proteins when heated to 100°C and suggested their use for coffee whiteners. 

A 100-W immersion heater (such as VWR Scientific Inc. 33897-140 a 200-W to 300-W tea/coffee immersion heater can also be used), controlled by a Variac magnetic stirrer and stir bar 1000-mL beaker thermometer with a resolution of 0.02 K (platinum resistance thermometer or calibrated thermistor such as Vernier model TMP-BTA) 1- to 5-mW He-Ne laser (633 nm) or a red (545 mn) or green (532 nm) laser — a battery-operated laser pointer is suitable, but a module with a separate 3-volt power supply, available from Z-Bolt and other sources, will give better power stability for long rans two Polaroid sheets in rotation holders photodetector such as photomultiplier tube or Thorlabs model 201/579-7227 silicon photodiode analog-to-digital data collection system such as Vernier LabPro. 

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