Coffee: Volume 2: Technology

ISBN-13: 9789401080286 / Angielski / Miękka / 2011 / 321 str.

R. J. Clarke

Opis

The present volume, Volume 2 in this planned series on coffee, deals with processing and follows on naturally from the first volume on the chemistry of coffee, which described its numerous constituents in the green (raw) and various product forms. We have already remarked that coffee has great compositional complex- ity, and this complexity of understanding extends when we come to that is, the many processes involved in the roasting consider its processing; of green coffee and its subsequent conversion into a consumable brew, especially through extraction and drying into an instant coffee. The simple brewing of roasted and ground coffee with water in the home also possesses considerable mystique and needs know-how for optimal results. The choice of green coffees from an almost bewildering array of different types available, through species/variety differences and different methods of processing from the coffee cherry to the green coffee bean, needs understanding and guidance. Furthermore, various forms of pre-treatment of green coffee before roasting are available. Some of these are little known, but others such as decaffeination, for those who desire roasted or instant coffee with little or no caffeine, are now becoming well established. Finally, both the processing of coffee cherries to coffee beans, leaving a range of different waste products (pulp, hulls, husk, parchment, etc.), and of roasted coffee after industrial aqueous extraction, leaving spent coffee grounds, provide waste products that have found considerable commercial value in different ways.

Spis treści

1 Green Coffee Processing.- 1. Introduction.- 2. Dry Processing Method.- 2.1. Natural drying.- 2.2. Artificial drying.- 3. Wet Processing Method.- 3.1. Receiving.- 3.2. Pulping.- 3.3. Separation/classification.- 3.4. Fermentation.- 3.5. Washing.- 3.6. Draining and pre-drying.- 3.7. Drying of the parchment coffee.- 4. Curing.- 4.1. Redrying.- 4.2. Cleaning.- 4.3. Hulling.- 4.4. Size grading.- 4.5. Density sorting.- 4.6. Colorimetrie sorting.- 5. Storage.- 6. Handling.- References.- 2 Grading, Storage, Pre-treatments and Blending.- 1. Introduction.- 2. Marketed Grades.- 2.1. Systems of specification.- 2.2. Liquoring/flavour characteristic.- 2.3. Bean size and shape.- 2.4. Defects.- 2.5. Colour.- 2.6. Roasting characteristics.- 2.7. Bulk density.- 2.8. Crop year.- 3. Storage.- 3.1. Storage conditions.- 3.2. Isotherms.- 3.3. Storage stability.- 3.4. Methods of storage.- 4. Pre-treatments.- 4.1. Cleaning and destining.- 4.2. ‘Health’ coffees.- 5. Selection and Blending.- 5.1. Availability.- 5.2. Selection.- 5.3. Blending methods.- References.- 3 Decaffeination of Coffee.- 1. Introduction.- 2. Solvent Decaffeination.- 3. Water Decaffeination.- 4. Supercritical Carbon Dioxide Decaffeination.- 5. Decaffeination of Roasted Coffee and Extract.- 6. Caffeine Refining.- References.- 4 Roasting and Grinding.- 1. Introduction.- 2. Process Factors in Roasting.- 2.1. Mechanisms and methods.- 2.2. Chemical changes.- 2.3. Heat factors.- 2.4. Physical changes.- 2.5. Measurement of roast degree.- 2.6. Emission control of organic compounds and chaff.- 3. Roasting Equipment.- 3.1. Horizontal drum roasters.- 3.2. Vertical fixed drum with paddles.- 3.3. Rotating bowl.- 3.4. Fluidised beds.- 3.5. Pressure operation.- 3.6. Roaster ancillaries.- 4. Process Factors in Grinding.- 4.1. Mechanism of grinding.- 4.2. Size analysis.- 4.3. Bulk density of ground coffee.- 5. Grinding Equipment.- References.- 5 Extraction.- 1. Introduction.- 2. Mechanisms and Methods.- 2.1. Methods.- 2.2. Mechanism of soluble solids extraction.- 2.3. Mechanism of volatile compound extraction.- 2.4. Compositional factors.- 2.5. Balances and rate and productivity factors.- 2.6. Volatile compound handling.- 3. Process Equipment.- 3.1. Percolation batteries.- 3.2. Continuous countercurrent screw extractor.- 3.3. Process control measurements.- References.- 6 Drying.- 1. Introduction.- 2. Process Factors in Spray-drying.- 2.1. Methods.- 2.2. Compositional changes.- 2.3. Spray formation.- 2.4. Spray-air contact.- 2.5. Mechanisms of water removal.- 2.6. Mechanisms of volatile compound retention.- 2.7. Fines separation.- 2.8. Agglomeration.- 3. Process Factors in Freeze-drying.- 3.1. Methods.- 3.2. Mechanism of water removal.- 3.3. Mechanism of volatile compound retention.- 4. Process Factors in Pre-concentration.- 4.1. Evaporation.- 4.2. Freeze-concentration.- 4.3. Reverse Osmosis.- 5. Process Equipment.- 5.1. Spray driers.- 5.2. Agglomerai ors.- 5.3. Evaporators.- 5.4. Freeze concentrators.- 5.5. Freeze driers.- 5.6. Other driers.- 5.7. Process control.- 5.8. Dust and fire hazards.- References.- 7 Packing of Roast and Instant Coffee.- 1. Introduction.- 2. Packing of Roast Whole Bean Coffee.- 2.1. Carbon dioxide evolution.- 2.2. Stability factors.- 2.3. Types of pack.- 3. Packing of Roast and Ground Coffee.- 3.1. Carbon dioxide evolution.- 3.2. Stability factors.- 3.3. Types of pack.- 4. Packing of Instant Coffee.- 5. Packing Equipment.- 5.1. Degassing plant.- 5.2. Roast and ground coffee.- 5.3. Instant coffee.- 5.4. Weight control.- References.- 8 Home and Catering Brewing of Coffee G. PICTET.- 1. Introduction.- 2. Bibliographic Review.- 2.1. Solid-liquid extraction.- 2.2. Brewing of roast coffee.- 2.3. Properties of the coffee brew.- 3. Personal Research.- 3.1. Introduction.- 3.2. Experimental data.- 3.3. Discussion of results.- 4. General Conclusions.- References.- 9 Waste Products.- 1. Primary Processing: the Production of Green Coffee.- 1.1. Dry or natural processing.- 1.2. Wet processing.- 2. Secondary Processing: the Production of Instant Coffee.- 2.1. Coffee grounds.- 2.2. Spent coffee grounds as fuel and feed.- References.- 1. Units.- 1.1. SI base units.- 1.2. Some SI derived units used in engineering.- 1.3. Some prefixes for SI units.- 1.4. Some conversions of SI and non-SI units.- 1.5. Dimensionless units used.- 2. Symbols for Physical Quantities in Equations.- 3. Abbreviations.- 4. Flavour Terminology.- 5. Process Engineering Terminology.- 5.1. Food engineering and unit operations.- 6. Listing of British and International Standards Relating to Coffee.