Course:FNH200/Projects/2024/White Tea

Introduction

The Camellia Sinesis is the most common type of tea tree, and people use its leaves to make tea. Tea can be separated into different branches by using leaves with different looks and different production methods. White tea is a type of the tea, which uses the simplest production method, and is the least produced and rarest compared with Green tea or Black tea in the world view. The tea tree leaves,used to make white tea, have to be not exposed to the sunlight, which can keep the leaves in the colour of white (the chlorophyll has not developed yet), and keep their buds with white hair.

Based on the record, white tea was discovered and used in the Tang Dynasty (around 618-907 A.D.). The way of making white tea also changed with time. In 1200 A.D., during the Song Tea Ceremony, the white tea was produced by steam and ground into powder. To compare with that, the current common production method of white tea is to keep the shape as its original leaves. White tea is mainly produced from China (especially Fujian province).

Chemical structure of main catechins in white tea

White tea contains about 4000 bioactive components, which include polyphenols, methylxanthines, amino acids, minerals and caffeine. Polyphenols (natural chemical compounds found in plants and fruits, which can adjust cholesterol level) take up 26%-30% of weight of dried leaves, which contain catechin as a key component. The catechin can derive into Epicatechin, Epigallocatechin, Epicatechin Gallate, and Epigallocatechin Gallate. These chemical structures can act as electron/hydrogen donors to reduce free radicals and provide antioxidant function for white tea. However, the chemical composition could be affected by different factors, not only by production methods, but also climate change, soil and harvest time.

Processing and Production

Unlike green tea and black tea, white tea undergoes the least processing steps to create the distinctive, delicate flavour and sweetness of the tea, also to ensure the retention of catechins, amino acids and other constituents. It does not involve rolling, roasting, or fermentation but emphasizes on two stages of gradual and uninterrupted dehydration processes after harvesting.

Stage 1: Withering

Solar Withering of White Tea

This process takes one to three days, and most sensory qualities of white tea are formed in this process. Three main methods used are Natural Indoor Withering, Sunlight Withering and Heated Withering. Withering has three stages: rapid water loss and physical shrinking, formation of key characteristics and lastly cumulative effect of sustained water loss causing chemical changes. This “dehydration shock” causes the physical and chemical changes to the tea such as maintaining trichomes integrity, adding brisk flavours, and downy aromas. Approximately 75% of the tea's total water loss is achieved in withering.

Withering Factors

A warm ambient temperature, gentle air flow, gentle light, and low humidity are key factors of withering. This process does not have to be rapid because it will cause more oxidation and redden the edges of the tea leaves.

Stage 2: Drying

Once withering is complete, tea leaves are piled together then baked or dried to reduce more moisture content in the leaves, leaving only around 5% to 6% moisture for long-term storage.

Drying Conditions

An Electric Drying Machine

Drying temperature and rate of evaporation have to be controlled appropriately to prevent tea flavour and quality from being affected through oxidation and case hardening .

Drying Methods

Traditional methods are sun drying and charcoal drying while contemporary methods include electric baking machines

Packaging Considerations

Prolonged storage time may cause quality deterioration of white tea, with tea polyphenols most prone to degradation during storage.

Factors that cause tea deterioration

• Light
• Temperature
• Humidity
• Tea moisture content
• Oxygen
• Microorganisms

Packaging Materials

Dryness and seal should be taken into consideration to ensure long shelf life for the aging of tea.

Packaging suggestions:

• Tin bottle
• Porcelain jar
• Coloured glass bottle
• Three-layer wrap includes a light-blocking cardboard box, a sealable plastic bag, a aluminum bag

Grading

White tea is divided into four grades based on the tenderness of fresh tea shoots .

White Tea Grades

Grade	Highest to Lowest
Names	Bai Hao Yin Zhen (Silver Needle)	Bai Mu Dan (White Peony)	Gong Mei	Shou Mei
Characteristics	Silver-white colour Long, thin needles Made only from unopened buds	Made from buds with one or two leaves	Made from a single bud with two or three young and mature leaves Colloquially known as "Little White" as opposed to "Big White (大白)" or "Big Down (大豪)" which are higher grades.
			Non-premium buds, leaves and stems	Lower quality than Gong Mei; may include darker coloured leaves
Infusion colour and flavour	Light yellow with a delicate flavour	Light golden-brown colour and a pleasing roasted aroma	Golden yellow colour and stronger in taste	Golden colour with black and red leaves, stronger taste

Food Quality Specifications

Since the climate in Canada is not appropriate for growing tea, raw materials are imported for processing and resale into local and international markets.

* Food Quality Specifications by Government of Canada

All tea made from Camellia sinensis from outside of Canada and the import of raw materials must meet the criteria listed under section FQS-28-02 Tea in Food Quality Specifications - Foods Purchased by Federal Government Departments.

Benefits of White Tea

The potential positive benefits of white tea primarily originate from catechins, a plant compound belonging to the polyphenol group, which have positive correlations to antioxidant activity, blood vessel expansion and oxidation of fat. In particular, white tea has a high presence of Epigallocatechin gallate (ECGC), a catechin associated with health benefits as it reduces LDL cholesterol, which normally builds up cholesterol in the arteries and causes heart and artery issues. White tea also contains antioxidants like caffeine and theophylline, essential amino acids and various minerals (F, Mn, Cr) that may have positive effects on metabolic syndrome and type 2 diabetes.

Taste

White tea taste varies depending on factors such as the raw tea leaves used and minor differences in processing based on regions of China. White tea's flavour is notably unique, as L-theanine, an amino acid responsible for the development of umami flavour and aroma, while improving unpleasant tastes of bitterness (from compounds like caffeine) and sourness, composes 30-50% of the tea’s total acid content. Alongside this, the minimal processing steps means white tea is considered to taste less bitter and have a mild/delicate taste with a hint of sweetness, as flavours are not harshly extracted or oxidized.

Exam Question

In the grading process of white tea, what is a distinguishing factor between the highest grade and lowest grade?

a. The colour of the final product is yellow, rather than golden

b. Buds with one to two leaves are used, rather than buds with two to three leaves

c. Tea leaves are withered for a longer duration for teas of a higher grade

d. Two of the above

e. All of the above

Answer: A is the correct answer, as the grading process of white tea takes the colour of the final product into consideration, and a lighter colour is considered higher grade.

Why your question should be on the final exam: Food Grading was covered in section 4.5 and plays a key role in the production of many foods, including white tea, and helps consumers identify the quality of product they are consuming.