Metabolomics is the study of metabolites (small organic molecules generated via metabolism) and the field has become increasingly popular over the last two decades because of its widespread application in clinical and biological research. The study involves quantitative measurements of thousands of metabolites using various analytical techniques.

Dr. David Wishart, founder of The Metabolomics Innovation Centre (TMIC, https://metabolomicscentre.ca ) is one of the pioneers in the field of metabolomics. He has led the Human Metabolome project which resulted in the development of Human Metabolome Database (HMDB, https://hmdb.ca ), a thorough and comprehensive database for human metabolites. The database contains clinical data obtained by extensive spectroscopic studies on biological samples. The HMDB is also associated with a few other databases, for e.g., Drugbank (drug metabolites, https://go.drugbank.com ), T3DB (toxins and pollutants, http://t3db.ca ), FooDB (food components and additives, https://foodb.ca ), etc.

Historically, GC-MS was the first technique used in the field of metabolomics. Amongst other techniques, LC-MS is the most commonly used method because of its high accuracy and sensitivity. NMR was first used back in 1974 for the detection of metabolites in biological samples. With the improvement in the NMR spectroscopic methods and the use of higher magnetic field instruments, the NMR method has now become quite popular in the field of metabolomics as a cost-effective and time-efficient technique.

Wine is one of the most consumed alcoholic beverages worldwide and an important part of the Mediterranean diet. Preliminary studies found that drinking small quantities of wine (up to one standard drink per day for women and one to two drinks per day for men), particularly of red wine, may be associated with a decreased risk of cardiovascular diseases, cognitive decline, stroke, diabetes mellitus, metabolic syndrome, and early death. Other studies found no such effects.

Early food and beverage testing focused on measuring pH, fat, sugar, protein and/or alcohol content using standard wet chemistry or manually intensive approaches. Even today most beverage testing uses hydrometers (density testing), pH paper and simple “wet” tests for certain acids or fats. More extensive testing for vitamins, contaminants and polyphenols content started emerging in the 1980s with the appearance of spectrophotometry, chromatography/separations, and liquid chromatography mass spectrometry (LC-MS) as well as nuclear magnetic resonance (NMR) spectrometry. However, these “high-end” tests were typically limited to specialized labs measuring a small number of compounds (10-15) and would often cost hundreds of dollars. Immunosorbent tests such as ELISAs for testing for drugs, antibiotics and toxins started to emerge in the late 1990s and early 2000s. These tests also cost hundreds of dollars and can take hours for the detection of just one or two compounds. The development of metabolomics in the early 2000s led to a significant improvement in the ability to detect and measure hundreds of compounds in foods and beverages.

Only a few bacteria can grow in beer. Higher the hop rate, lower the bacterial growth; hop resins from hop flowers are added to control bitterness of beer. Other reasons for low bacterial growth in beer are high ethanol concentration, low pH, lack of oxygen during the brewing process, limited sugar and temperature. α-acids and β–acids are the main components of hops with the former being mainly responsible for the bitterness; humulone, cohumulone, adhumulone, posthumulone and prehumulone are the main α-acids. Hops are added to control the bitteness and add fruity aroma to beer. Some Gram-positive bacteria present in beer are: Lactobacillus (produces lactic acid, acetoin and diacetyl, the last one being responsible for the buttery flavour), and Pediococcus (diacetyl production). Some Gram-negative bacteria are Acetic Acid Bacteria (Acetobacter and Gluconobacter, the former causes oxidation of ethanol to acetic acid to create vinegar flavor and the later causes pellicle on the beer surface, oxidizes ethanol to acetic acid and oxidizes sugars to gluconic acid), Obesumbacterium proteus (increases the level of dimethyl sulfide, dimethyl disulfide and diacetyl in beer), and Zymomonas (increases the level of acetaldehyde and hydrogen sulfide). Oxygen-free brewing condition will minimize the bacterial contamination by acetic acid bacteria.

Beer is one of the oldest and most widely consumed alcoholic beverages in the world, and its production involves a complex biochemical process of fermentation by yeast. Although the basic principles of fermentation are well established, the chemical composition of beer is still not fully understood. Recent advances in analytical techniques have enabled scientists to identify and quantify many different chemical compounds that affect the flavor and aroma of beer. Their study reveals the chemical diversity and complexity of beer and its relationship with the brewing process, the geographical origin, and the style of the beer. Beer is a complex mixture of water, carbohydrates, hops, yeast, and various chemical compounds that determine its sensory properties. The carbohydrates are derived from malted barley and are hydrolyzed into simple sugars during the mashing process. The sugars are then fermented by yeast, which produce ethanol, carbon dioxide, and other metabolites. The hops are the flowers of Humulus lupulus, which contain over 440 essential oils and bitter acids that contribute to the aroma and flavor of beer. The water is the main ingredient of beer and its mineral composition can affect the yeast metabolism and the beer quality. Recently, scientists performed a comprehensive chemical characterization of 467 beers from 40 countries. They identified at least 7,700 different chemical formulas and tens of thousands of unique molecules in beer, many of which have not been reported before.