to preserve cider. Tartaric acid In hot climates, tartaric acid is added when grapes become too ripe for natural acidity. Most people agree that grapes should be picked when there is a balance between optimum ripeness and acidity, and there are many factors that can reduce the acidity of the wine-making process. Acidification is widespread in Argentina, Australia, California, Washington, Italy and South Africa. It is not common in northern France, Germany, Austria, Oregon and New Zealand. Calcium carbonate In contrast to tartaric acid, if the grapes are too acidic, calcium carbonate is used to bring them down to the level needed to make wine. In addition, many also use oak, oak slices, fermentation agents, tutu, and more, according to the quality of grapes and the different styles of wine. The need for additives and the amount used depends on the winemaker, as different winemakers make different choices. The basic principle of preservatives against oxidation Wine has different preservatives from other drinks such as milk, juice and beer. Its preservatives work primarily by inhibiting the growth of microorganisms through oxidation. However, because different kinds of wine have different aromas, colors and flavors, they should not use the same preservatives. For example, the preservatives added to white wine are mainly ascorbic acid (vitamin C) and sorbic acid. Ascorbic acid is used as an antioxidant, while sorbic acid is used to inhibit the growth of yeast in white wine. Sorbic acid cannot be used in red wine because it can cause pollution. Sulfites, or small molecules of sulfur dioxide (SO2) and hydrogen disulfide (H2O2), are commonly used as preservatives in wine and even other fruit drinks. Their principle is basically to make microbial protein coagulation or denaturation, thereby interfering with their growth and reproduction. Sulfites are mainly in the form of sulfur dioxide at different pH concentrations. Experiments show that only the sulfur dioxide molecule has an antibacterial effect. That's the active ingredient in preservatives. Sulfur dioxide inactivates by combining with compounds derived from wine. Because of the nature of sulfur dioxide, it is more effective at lower pH concentrations and at higher ethanol concentrations, finally achieving the function of anti-corrosion. Preservatives controversy Allergy to preservatives has aroused people's concern. Studies have shown that a possible cause of allergy in wine ingredients is an adverse reaction to sulfur dioxide by asthma patients. Sulfur dioxide allergy was the cause of 1.7% of asthma