Beer colour is measured spectrophotometrically and is used to classify different beer kinds. With a factor colour intensity is converted into beer colour expressed in EBC units.
For the determination of bitter units of beer primarily the bitter substances iso-octane are extracted. Furthermore, beta-acids and delta-acids are in beer wort, these contribute also to the bitter taste. For beer classification, the concentration of bitter units plays an important role.
During the chemical technical production of glycerine, some by-products result, such as cyclic diglycerides and 3-Methoxy-1,2-propandiol (3-MPD), whereby the detection of these compounds into wine is an indication of illegal glycerine addition. If these compounds are detected into wine, then this wine is assessed as not marketable. 3-MPD can occur into wine in lower levels through allowed enzyme treatment, therefor there exist an intervention level for 3-MPD of 0,1 mg/l. The intervention level is only used, when the addition of glycerine containing enzyme preparation was done.
Under the group of glycols, we differentiate several compounds, which are analyse for various reasons.
Ethylene glycol is a colourless, viscous, slightly sweet, toxic fluid with a strong hygroscopic character.
Naturally, into wine ethylene glycol can be formed in concentrations lower than 10 mg/l from the amino acid L-serine. Higher concentrations indicate contamination or falsification of wine with cooling agent, so that OIV has set a reference value of 10 mg/l.
Diethylene glycol is a derivate of ethylene glycol and is also used as antifreeze.
For wine, the compound become important into the year 1985, when some Austrian winemakers are added this sweet compound to their wine to get full-bodied “Spätlese”. Therefor OIV has set a reference value of <10 mg/l.
Propylene glycol is colourless, clear, almost odourless and strong hygroscopic fluid. This compound serves as carrier material for aroma.
OIV sets a reference value of maximum 150 mg/l for wine and 300 mg/l for sparkling wine.
There exists a legal limit of concentrations up to 1 g/l for other drinks.
Hydrocyanic acid is able to be formed as a result of treatment error of blue fining into wine, whereby hydrocyanic acid is formed out of potassium hexacyanoferrate (II) through spin-off into acidic environment. Hydrocyanic acid is perceived sensorial as bitter almond tone. However, the threshold of perception is subjective (around 50 to 100 µg/l). Wine with increased concentrations of hydrocyanic acid is not marketable, so that it is advisable to control the level after blue fining.
During making of stone fruit spirits cyanide can be formed in end product, so that it exists a legal limit value for spirits from stone fruits, with this analysis meeting the limit value is checked. Legal limit of cyanide exists for other alcoholic drinks, so that it is also important to controlled the content of cyanide in such products.
Ash is sum of substances, which remain after ashing of evaporation residue, whereby main elements are alkaline metals and alkaline earth metals (e.g. potassium, calcium, magnesium, sodium) and non-metal phosphorus. Trace elements like manganese, zinc, copper and iron are represented too. Ash content of products can be determined gravimetric or can be calculated through the analysis of cations and anions. In addition to determining ash content, Alkalinity of ash can also be determined as parameter.
Ash content into wine lie normally between 1,3 and 3,5 mg/l and is strongly influenced by water balance of vine. All relevant substances are absorbed during grape ripeness through the soil, whereby minerals are the biggest part of ash. Because of the link between ash and content of minerals and trace elements, it is possible to assess quality of wine with this parameter.
The relation between ash and quality of product leads to legal regulations for minimum ash content for example for vinegar, therefor the analysis of ash is also important for assessment of product specifications.
Gravimetric analysis of ash is based on incineration of wine extracts until complete combustion of carbon at 500 to 550 °C. Content of ash is expressed in g/l.
The principle of the method is based on the calculation of ash content from the sum of different minerals and salts. For the calculation, we need: phosphate content of wine, expressed as K3PO4, rest content of potassium as well as content of sodium, magnesium and calcium were expressed as carbonate. The sum of these values describes the ash content.
The alkalinity of the ash is defined as the sum of cations, other than the ammonium ion, combined with the organic acids in the wine. The alkalinity of ash will be expressed in milliequivalents per litre or in grams per litre of potassium carbonate.
The content of parameter “free sodium” is calculated from the content of sodium and chloride. In most cases, there is a balance between sodium and chloride or there is excess chloride. Excess chloride has no maximum levels. OIV determines a guide value for excess sodium of 80 mg/l.
Glycerine is a three-valent alcohol of syrupy consistency, furthermore it has a sweet flavour.
In grape must of healthy grapes, glycerine is detectable only in traces, but this kind of grape musts are in practice really rare, therefore low contents of glycerine are already found into normal pressed grape must. During the fermentation glycerine is formed as fermentation by product, whereby 10 percent glycerine is formed from the ethanol formation by spontaneous fermentation, while lower contents are formed by fermentations with pure culture yeast.
Formation of glycerine depends not only on the kind of fermentation, it also depends on temperature, whereby higher temperatures favour glycerine formation.
Into wine, glycerine is essential component of extract and largely defines the “body” of wine. Significantly increased concentrations into wine indicate glycerine supplement, whereby the addition may be verified through by-products of glycerine formation such like 3-MPD or diglycerine.
Into beer, glycerine is formed as fermentation by-product during the alcoholic fermentation.
The content of parameter “free tartaric acid” is calculated from the content of tartaric acid and the content of potassium. In most cases, there is a balance between tartaric acid and potassium or there is an excess tartaric acid. This value allows conclusions to the wine stability or falsifications are recognized.
Casein is a milk protein with allergenic characteristic (Allergens), therefor it must be declared on the label, when the content in the end product is above 0,25 mg/l. Casein occur not only in milk products, it can also occur in other food products, through input from treatment products or additives.
Casein is used in wine as a traditional wine treatment agent for removing of undesired tannin agents. Especially white wine can have high contents of tannins, when the grapes are heavily pressed. These tannins are removed by the use of casein.
With Elisa, we are able to verify casein in wine, but it is also possible to determine casein in other products. That we can be sure, if the allergen labelling is necessary or not.
Just like casein is albumin an allergenic substance. It is a protein for example in eggs. Due to its allergenic characteristic, it must be declared on the label, when the content in the end product is above 0,25 mg/l.
Albumin and casein occur into wine through wine treatment products (flavor fining agents). Albumin is applied in red wine for reducing the tannins, thereby the anthocyanins are bound. Through this treatment, the wine get more tender and it get less color.
Albumin occur in other products also through treatment products. To ensure that albumin has to be declared or not, the analysis of albumin is advisable.
Lysozyme is an enzyme from chicken protein, which fall under obligation to declare like casein and albumin.
Since autumn 2001 lysozyme may be used like wine treatment agent for control of biological acid reduction or for stabilization of wine blending or of sweetening.
This enzyme decomposes the cell wall of gram-positive bacteria (e.g. lactic acid bacteria), so that have no more effect. Other germs and yeasts are not influenced, so that alcoholic fermentation is not being hindered.
The use of lysozyme in other products against gram-positive bacteria is possible, so that for these products the declaration of allergens is also obligatory, if the content of lysozyme into end product is above 0,25 mg/l.