Coffee & Tea PDF

FNSC2001 Intro to Food Science & Technology Coffee & Tea Dr. Erika Kwek Food & Nutritional Sciences Programme School of Life Sciences 3943 4403 ∙ erika...

FNSC2001 Intro to Food Science & Technology Coffee & Tea Dr. Erika Kwek Food & Nutritional Sciences Programme School of Life Sciences 3943 4403 ∙ [email protected] Compound annual growth rate (CAGR) Beverages Water Aromatic beverages (Coffee and Tea) Carbonated beverages Functional beverages Fruit/vegetable beverages Dairy beverages Alcoholic beverages Water “Universal solvent” For transport and cell use of substances (e.g., oxygen or nutrients) Remove waste Regulate body temperature … Source: North Carolina Water Consultants Water Harvard Medical School suggests average daily water for men ~15.5 How much cups and for women ~11.5 cups (healthy individuals) water to drink in a day? Some factors influencing water needs: activity levels, outside temperature, individual health conditions and age. Quick signs of dehydration: dark yellow urine colour, feelings of dizziness/confusion/weakness, low blood pressure. LeWine H.E (2023) Bottled Water Water purification: by distillation or deionization o Distilled Water: boiled (double) and condensation  o Deionized Water: Ion-exchange resins/beads for removal of ions Source: Green Power Equipment https://www.kurita.co.jp/english/technology/core_technology/deionized.html Ozone Treatment https://news.panasonic.com/global/stories/823 https://www.swirecocacolahk.com/about-bonaqua/? Other Types of Drinkable Water o Mineral Water: (e.g. spring water, well water, artesian water) ▪ Contains natural or fortified minerals (Na, K, Ca, Mg, Fe, P, etc.) Spring Water Artesian Water https://science.howstuffworks.com/environmental/green-science/bottled-water.htm Source: Berkey Water Filter o Sparkling Water: ▪ With CO2 naturally dissolved or by carbonation (soda water) Water Quality Hard water vs. Soft water ▪ Water contains dissolved substances (i.e. minerals) from the natural sources (e.g. rock, soil, spring, underground water sap, reservoir) or environment ▪ Dissolved substances affect water properties (i.e. Hardness) ▪ No universal/common definitions and standards; depends on types of mineral (mainly: Ca & Mg), pH, alkalinity, etc. ▪ Generally, [Calcium carbonate] is referred to as an index: o US: Soft: 0-60ppm; Moderately hard: 60-120ppm; Hard: 121-180ppm; Very hard: >181ppm o Canada: Soft: 0-75ppm; Moderately hard: 75-150ppm; Hard: 150-300ppm; Very hard: >300ppm pH of water ▪ Vary in locations: e.g. Surface water vs Ground water ▪ Change with the ambient temperature (due to CO2 dissolvability) Water Qualities (by WHO) Risks of Drinking Water Water Intoxication ▪ Drinking large amounts of water can cause Imbalance of Electrolytes (Na+) in the body: ▪ Hyponatremia (symptoms include: nausea and vomiting, headache, confusion, lethargy, fatigue, loss of appetite, restlessness and irritability, muscle weakness, spasms, cramps, seizures and decreased consciousness, coma) Water Contamination (esp. in developing countries) ▪ Safety o Microbial hazards (e.g. Vibrio cholerae, Parasites) o Chemicals (e.g. Heavy Metals) o Radiological hazards ▪ Acceptability aspects: WHO Guidelines for Drinking Water Quality Water Purifier (Disinfection) Tablet Stronger oxidant (chlorine, iodine, chlorine dioxide, etc.) as active ingredients  C ffee Origin: Africa (Ethiopia; ~ 3rd century AD) Coffee: Water + Compounds extracted from coffee beans during brewing. Species: Coffee arabica & Coffee robusta Source: Kau Coffee Mill - Raw Bean (outer parchment coat & silver skin) Coffee Beans: Arabica vs. Robusta Coffee Bean Processing (in general) 1. Harvesting (usually hand- picked coffee cherries) 2. Processing Methods: a. Washed b. Natural (Dry/Sun-dry) c. Semi-washed (Wet Hulled) d. Honey https://www.technoserve.org/wp-content/uploads/2022/03/TechnoServe-Wet-Mill-Processing-Guide.pdf Washed Coffee Beans (best clarity of flavour) Cherries are sorted in a floatation tank Cherries’ pulp is mostly removed Placed in water tanks to ferment (18-36 hrs) Rinsing of beans and sun-dried (1-2wks) Dehulling (remove the papery ‘parchment’ and silver skin) https://www.pactcoffee.com/farms/cherry-processing-methods Natural Coffee Beans (Most traditional method) Coffee cherries are picked at their optimum ripeness Cherries are laid out on tables or patios for sun-drying Frequent raking and turning (for even fermentation) After several weeks, they reach their optimum moisture level Cherries are dehulled to separate out the green beans Natural vs Washed Coffee Beans Processing: ROASTING Drying, Pyrolysis (development of aromas and flavors) and Quenching (rapid cooling down by cold air/water spray) Roasting develops bean flavor, aroma and appearance. Changes physical and chemical makeup during process. Beans dehydrate, becomes lighter and more porous. Roasting time determines classification of coffee: light, medium or dark roast. Quality: Richness/Body, Sweetness, Flavour, Aroma Brightness/Acidity, Bitterness Quality deterioration after roasting due to: Oxidation, Volatilization, Hydrolysis and Greasing. (Exothermic) Coffee Brewing Grinding and Water extraction Beans are ground after roasting – to maximize surface area for water extraction. Types of grind – Fine, Drip or Regular (depends on equipment to be used for brewing) Coffee: Water Ratio American preference (~1:15-20) Asian preference (~1:13-18) Water Type (Soft/Hard; w/oxygen) Water Temperature (88-93℃) Time (depends on grinder size) Equipment Percolator, Vacuum (Syphon/siphon), Drip, Filter, French press, Moka, Automatic, Espresso (Specialty coffee), etc. Coffee Brewing Espresso o Black coffee extract, using high-pressure steam through ground coffee. Crema o Signature oily foam on top Varieties (adding different portion of milk and other ingredients) Source: BigCupofCoffee.com o Espresso, Ristretto, Espresso macchiato, latte macchiato, latte, flat white, caffe mocha, cappuccino, etc. Instant Coffee Dehydrate the coffee extract Spray Dry with Agglomeration (clumping) https://www.youtube.com/watch?v=ZKCk7K4Ew7c  Freeze-dryer Instant Coffee Freeze Dry and pulverization Dry the coffee by water sublimation At a very low pressure and low temperature (freezing temperature) Higher cost: with higher qualities retained Better Aroma preserved! Robusta instant freeze-dried coffee  Caffeine Naturally found in many plants o Tea leaves, cocoa plants, coffee, etc. Also exists in many soft drinks (coke) and energy drinks Health effects o Extensively studied o With both positive and negative effects; o Addiction, tolerance, overdose and intoxication Caffeine Decaffeination Extract with dichloromethane or ethyl acetate: o Steam (~30min), rinse with (~10hr) and steam (~10hr) to remove residual solvent; repeat several cycles. Extract with compressed CO2 Breeding/Genetic Engineering: ”Decaffito” (coffee derived from Arabica plants with beans naturally low in or almost devoid of caffeine) Swiss Water Process No chemicals used Just dissolve caffeine in water By filtration with Activated carbon/charcoal Repeated: 8-12 times (~8 hours) Standard: 97% free or 99.9% free by mass Swiss Water Process  ~2500BC Tea Tea: Usually refers to the infusion of leave cultivars from Camellia sinensis Herbal teas: Infusion of other plants/herbs/fruits Most consumed beverage aside from water ~1000 leaves needed to make 1 pound of of manufactured tea Source: Vihaba Trade and Export  Tea Types Maturity of leaf determine quality/price (more fresh/tender, higher price) Fully matured leaves cannot be processed for tea leaves Classification of tea are based on brewed liquid color (due to tea-leaf processing): o White (白茶) e.g. White Peony 壽眉 o Yellow (黃茶) e.g. Yinzhen 銀針 o Green (綠茶) e.g. Longjing 龍井, Biluochun 碧螺春 o Oolong (青茶/烏龍茶) e.g. DaHongPao大 紅袍, Tieguanyin; 鐵觀 音, Dongding凍頂 o Black (紅茶) e.g. Sri Lanka 錫蘭 o Post-fermented (黑茶) e.g. Pu-erh 普 洱 Tea Leaves Processing Chart Oxidation *Kill Green: “de-enzyming” Pu-erh Tea Processing Tea “Fermentation” Three major categories of tea: Black (Fully fermented), Green (unfermented) and Oolong (Partially fermented) Black Tea: “fermentation” refers to oxidation Mainly catalyzed by Polyphenol Oxidases (PPOs) Leaves are allowed to wither and dry under hot blown air (27-93℃) and rolled to break membranes between cells. Moisture and temperature are carefully controlled for desirable quality Post-fermented tea (Pu-erh) o With microbial fermentation (Piling) (steamed tea and compacted) o Mainly by Aspergillus spp. Penicillium spp., Yeasts Phenolic Compounds in Tea Catechins (Major flavonoids in raw tea) 5 Catechins identified in tea: Catechin (C), Epicatechin (EC), Epigallocatechin (EGC), Epicatechin Gallate (ECG), Epigallocatechin Gallate (EGCG) *main catechin in green tea (“unfermented” tea) Strong antioxidant properties (Beneficial effects to health) Theaflavins Products formed after catechins oxidation Rich in “fermented tea” Other types of health effects o (anticarcinogenic, reduce blood LDL, total cholesterol, etc.)  Matcha https://www.youtube.com/watch?v=nmzj4FBH_Qg Sheltering tea plants several weeks before harvesting to reduce sunlight: to increase plant chlorophyll content, and turn leaves into dark green (matcha distinct colour)