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How to make coffee more delicious and healthier

Foreword

The most important source of caffeine is coffee beans. The content of caffeine in commercial coffee beans is 0.7 to 3.0%. Coffee beans are also the raw material of coffee. Coffee is one of the world's three largest beverages, and it is popular all over the world. The caffeine contained in the coffee is harmful to the human body because of the excessive drinking. Therefore, the decaffeinated coffee is popular with consumers. Moreover, caffeine removed from plants can be used medicinally, so caffeine extraction from coffee is a double benefit. The extraction of coffee beans with supercritical CO2 not only resulted in caffeine, but also preserved the original flavor of the coffee.


Introduction

Caffeine is a Methylxanthines alkaloid. Chemical formula C8H10N4O2, soluble in water. White crystalline powder, odorless, bitter, slightly alkaline.

Caffeine is a central nervous system stimulant that refreshes and relieves fatigue and keeps the body in a better condition. However, high-dose intake can cause caffeine poisoning, causing the body to produce a series of adverse reactions.

Definition of supercritical fluid

• Pure substances present changes in the state of liquids, gases, solids, etc., depending on temperature and pressure.

• When the gas-liquid equilibrium substance continues to be heated and boosted, the thermal expansion causes a decrease in the density of the liquid, and the increase in pressure causes the gas phase density to increase. When the temperature and pressure reach a certain point, the gas-liquid two-phase The phase interface disappears and becomes a homogeneous system, which is called the critical point.

•The liquid with a temperature and pressure above the critical point is called supercritical fluid (SCF).




Phase

Density

(m/mL)

Viscosity

(g/cm•s)

Diffusion coefficient

(cm2/s)

Gas phase

10-3

10-4

10-1

Supercritical fluid

10-1

10-4

10-3

Liquid phase

1

10-2

10-5

The main characteristics of supercritical fluids

• Density is similar to that of a liquid and therefore has a strong solvation power. Minor changes in pressure and temperature can cause significant changes in density;

• Has a similar gas diffusion coefficient and low viscosity;

• Pressure and temperature changes can change the phase change;

• Due to the above characteristics, the supercritical fluid can quickly penetrate into the interior of the object to dissolve the target substance and quickly reach the extraction equilibrium.

The principle of supercritical CO2 extraction

• In the supercritical state, the supercritical fluid has good fluidity and permeability, and the supercritical fluid is brought into contact with the material to be separated, so that the components having the polarity size, the boiling point and the molecular weight are selectively Extract it.

• The method of decompression and temperature increase is to convert the supercritical fluid into a common gas, and the extracted material is completely or substantially precipitated, thereby achieving the purpose of separation and purification.

Extraction of caffeine

• First, the coffee beans are pretreated, and the coffee beans are cleaned mechanically to remove dust and impurities; then steam and water are pre-blistered to increase their moisture content by 30% to 50%;

• Then, extract, pre-soaked coffee beans into the extraction tank, continue to send CO2 into the tank, caffeine will be gradually extracted;

• Next, CO2 with caffeine is sent to the cleaning tank and the caffeine is transferred to the tank;

• Finally, caffeine in the tank is then recovered by distillation and CO2 is recycled;

• In 10 hours, the caffeine content in the SFE-treated coffee beans was reduced from 0.7 to 3% to 0.02%.



A flow chart of caffeine in a supercritical CO2 out of coffee