Amino acid

Amino acids are biologically important organic compounds containing amine (-NH₂) and carboxylic acid (-COOH) functional groups, usually along with a side-chain specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen, though other elements are found in the side-chains of certain amino acids. About 500 amino acids are known and can be classified in many ways. They can be classified according to the core structural functional groups' locations as alpha- (α-), beta- (β-), gamma- (γ-) or delta- (δ-) amino acids; other categories relate to polarity, pH level, and side-chain group type (aliphatic, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acids comprise the second-largest component (water is the largest) of human muscles, cells and other tissues. Outside proteins, amino acids perform critical roles in processes such as neurotransmitter transport and biosynthesis.

Yeast assimilable nitrogen

Yeast assimilable nitrogen or YAN is the combination of Free Amino Nitrogen (FAN), ammonia (NH₃) and ammonium (NH₄⁺) that is available for the wine yeast Saccharomyces cerevisiae to use during fermentation. Outside of the fermentable sugars glucose and fructose, nitrogen is the most important nutrient needed to carry out a successful fermentation that doesn't end prior to the intended point of dryness or sees the development of off-odors and related wine faults. To this extent winemakers will often supplement the available YAN resources with nitrogen additives such as diammonium phosphate (DAP).

However, the addition of excessive amounts of nitrogen can also create a hazard as other organisms besides beneficial wine yeast can utilize the nutrients. These include spoilage organisms such as Brettanomyces, Acetobacter and Lactic acid bacteria from the Lactobacillus and Pediococcus genera. This is why many wineries will measure the YAN after harvest and crushing using one of several methods available today including the nitrogen by o-phthaldialdehyde assay (NOPA) which requires the use of a spectrometer or the Formol titration method. Knowing the YAN in the must allows winemakers to calculate the right amount of additive needed to get through fermentation, leaving only "nutrient desert" for any spoilage organisms that come afterwards.

Acids in wine

The acids in wine are an important component in both winemaking and the finished product of wine. They are present in both grapes and wine, having direct influences on the color, balance and taste of the wine as well as the growth and vitality of yeast during fermentation and protecting the wine from bacteria. The measure of the amount of acidity in wine is known as the “titratable acidity” or “total acidity”, which refers to the test that yields the total of all acids present, while strength of acidity is measured according to pH, with most wines having a pH between 2.9 and 3.9. Generally, the lower the pH, the higher the acidity in the wine. However, there is no direct connection between total acidity and pH (it is possible to find wines with a high pH for wine and high acidity). In wine tasting, the term “acidity” refers to the fresh, tart and sour attributes of the wine which are evaluated in relation to how well the acidity balances out the sweetness and bitter components of the wine such as tannins. Three primary acids are found in wine grapes: tartaric, malic and citric acids. During the course of winemaking and in the finished wines, acetic, butyric, lactic and succinic acids can play significant roles. Most of the acids involved with wine are fixed acids with the notable exception of acetic acid, mostly found in vinegar, which is volatile and can contribute to the wine fault known as volatile acidity. Sometimes, additional acids, such as ascorbic, sorbic and sulfurous acids, are used in winemaking.

Acid (disambiguation)

An acid is any chemical compound that, when dissolved in water, gives a solution with a pH less than 7.0.

Acid or ACID may also refer to:

Science

Computing

Music

Genres

Bands

Acid (band)

Acid was a Japanese rock band originally created by Hideki after Siam Shade disbanded.

Musical styles

In the beginning, Hideki had a huge influence on Acid and they played a mix of alternative metal and emo with emphasis placed on his and Junpei's twin vocals. After he left the band in 2005, their songs became less focused on vocals and turned a bit more pop-ish, but still kept their "heavy" sound due to having three guitarists.

History

Acid formed in August 2003 through auditions held by Hideki. Their live setlist was made up of both of Hideki's solo albums at the beginning and, after one year of excessive touring through Japan, the group went into the studio at the end of 2004 to record their first album. Acid 1.5: Punk Drunker was released in March 2005.

With the end of Siam Shade, Hideki didn't want people to always compare his new band with the old one when he was singing. That's why he drew back to the position behind the keyboard at first and later on left Acid completely in June 2005 so that the band were able to go their own way. Furthermore, he says that this group is his pride and that he'd like to see them in Tokyo Dome one day.