Zhang Yu in the whole process of wine brewing set up six levels of tests, and finally according to the quality of the high and low levels of the four levels of "Master Class", "Reserve Class", "Special Selection Class" and "Preferred Class" selected. Finally, the wines are selected according to their quality: "Master Grade", "Reserve Grade", "Special Selection Grade" and "Preferred Grade". The higher the grade, the more difficult the level, the stricter and harsher the control standards, and the lower the production. The highest level of "Master Class" wines need to meet the highest standards in every aspect of the wine, and ultimately show a balanced, harmonious and perfect realm, so the production of this level accounted for less than 2% of the total production, which is called the best in the selection of the best wines.

Hong Kong's renowned wine-tasting expert Wong Nga-li, using a bottle of master-class Zhangyu Cabernet dry red wine as an example, gave the "six passwords" for buying good wines

Password 1: Vineyards

Vineyards' microclimate conditions and soil are crucial to the quality of wines. Yantai is the most suitable area for growing grapes in China, and of Zhangyu's four vineyards, only raw materials from the highest-level vineyards have the basic qualifications to produce "master-class" wines.

Code 2: Raw material

The "limited yield" is also a necessary means to ensure the quality of the grapes - the vineyards that provide the raw material for the master wines must have a yield of less than 600 kilograms per acre, and the grapes must reach the optimal maturity level of no less than 21 degrees of sugar content.

Code 3: Vinification

The grapes are crushed and fermented for two to three months before becoming "raw wine". Winemakers from China and abroad, with their sensitivity and talent for wine intuition, evaluate the raw wine on a variety of physical, chemical and organoleptic parameters.

Code 4: Barrel aging

The wine is stored in oak barrels in order to extract tannins and other aromatic substances from the oak, and the small oak barrels from the Allier region, a famous French oak production area, selected for the Masters wines, allow the wine to have a larger contact area with the oak, making the wine's flavor more intense.

Code 5: Blending

At this point, the winemaker selects the highest-quality wines and blends them, so that the physical, chemical and organoleptic indicators of the Master Class wines satisfy the discerning winemaker.

Code 6: Bottle Storage

In the absence of oxygen, the best of the bottled wines are bottled for several years, waiting for the balance, richness and elegance to come. At this point, good wines that have passed the six highest standards can enter the Hall of Masters.