Things You Must Know About Wine Quality

Creative Diagnostics - Food & Feed Analysis

Things You Must Know About Wine Quality

The quality of the grapes is the key factor in affecting vintners can produce wine with high quality. The quality of wine grapes should be controlled from the beginning of planting. We should not only control the harvesting time, but also control the pesticide residues. Immature or damaged grapes, mildew, spoilage or pesticide residues will affect the growth and reproduction of the yeast during the brewing process, and bring unsafe factors (such as pesticide residues and biotoxins) to the final product, which will seriously affect the flavor and quality of the wine. Therefore, we should vigorously develop the construction of grape bases, strengthen the management of the grape base and provide a strong guarantee for the quality and safety of raw material for the wine production. Here are some aspects you must know about wine quality.

Production equipment

The vehicles for transporting grapes and production equipment for processing wine should comply with the food safety regulations. All processing tools and equipment should be thoroughly cleaned and disinfected. Those iron and copper metal equipment must be treated with a non-toxic coating before operation, which could avoid the content of the copper and iron ion in wine becoming too high due to the direct contact between the wine and the metal equipment. Therefore, tools and containers made of stainless steel and oak should be used as much as possible. At the same time, cleaning and disinfection management system should be strictly implemented. For all kinds of key equipment, a detailed management system and operation records should be formulated.

Fermentation and storage process control

1. Sulfur dioxide residues

Sulfur dioxide plays an important role in the processing of wine. The proper amount of sulfur dioxide is vital for sterilization, inhibiting the proliferation of bacteria, dissolving some beneficial substances in grape skin, clarifying, acidifying and anti-oxidation. However, when the amount of sulfur dioxide is too much, it not only affects the quality of the wine, but also makes damages to the human body: Therefore, the use of sulfur oxides should be a small amount but frequently. And if the quality of wine is ensured, you can use no sulfur oxides or as little as possible.

2. Prevention of oxidative browning in white wine

White wines contains a variety of phenolic substances, such as tannins and aromatic substances. These substances have strong aerobic properties, and are easily oxidized to form brown polymers during contact with air, causing browning of white wines. The fresh fruit flavor of the wine will be reduced, and even the oxidized taste will present, which deteriorates the appearance and flavor of the wine. Therefore, strict process measures should be taken to control it:
Choose to harvest at the best grape ripening period, which could avoid mouldy due to overripe.
Quickly squeeze the juice to minimize the time the juice is in contact with the air.
Use pectinase at low temperature to clarify and centrifuge.
Pump the juice into the fermenter to conduct a low temperature (16-20 °C) and closed fermentation.
Use bentonite to clarify and filter to reduce the oxidation of grape juice due to oxidizing substances and oxidase.
Avoid contact with all kinds of substances containing copper, iron and other metals.
Add a right amount of sulfur dioxide during the entire process of white wines brewing.
Seal the wine storage container with an inert gas such as nitrogen or carbon dioxide.
Add an appropriate number of antioxidants such as vitamin C before white wines is bottled.

3. The abiotic factors of the instability of wine

The abiotic instability factors mean factors that are non-microorganism (for example, tartrate, protein, and metal ions) but would cause some physical or chemical changes such as precipitation, turbidity and discoloration in wine. These changes will affect sensory quality of wine. In the production process, a variety of measures are generally used to control: we should minimize the contact between corrosive materials (such as copper and iron) and grapes and base wine during fermentation and storage processes. For the base wine with high copper and iron content, phytic acid or potassium ferrocyanide can be used; for the content of tartrate is too high, we should strengthen the process management and reasonably determine the barreling time; for other abiotic unstable substances, fining and filtration are optional. However, the excessive fining will result in the retained of protein in wine, which will lead to the turbidity and decline of quality of the wine, especially in the case of insufficient tannin content in wine. For the final product, currently one of the most effective way for solving abiotic precipitation of wine is freezing, fining and filtering.

4. The biotic factors of the instability of wine

The biotic instability factor of wine refers that due to the presence of microorganisms, the appearance and the internal quality of wine change, which deteriorates the quality of the wine. The production process is generally controlled by the following methods:
Choose an excellent yeast strain.
Control the microbial pathogens in wine.


Apply CIP (cleaning in place) to all packaging container equipment and pipelines to ensure that the entire filling system is in a sterile state.
All bottle should be cleaned and sterilized.
Apply membrane filtration sterilization or heat sterilization before wine bottling.

The establishment and follow of the HACCP

HACCP is short for Hazard Analysis and Critical Control Point. All wine standards management plans (WSMPs) must be based on the principles of HACCP. It is effective and economical.

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