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Visual and, if applicable, an aural assessment of the barley.

Viscometric Determination of Gelatinization Temperature (GT)

The gelatinization temperature (GT) can be determined using a rotary viscometer (e.g., amylograph or viscograph, Brabender GmbH & Co. KG, Germany [7] or Rapid-Visco-Analyser (RVA), Perten Instruments, a PerkinElmer Company, USA [8]). 

Unlike the analysis method for adjuncts which do not contain a large amount of enzymes, for the analysis of barley malt, a mash with a mash to sparge ratio of 1 : 4 (similar to that commonly found in the brewing process) is used [9]. The sample is heated according to a programmable temperature/time program (refer to table 1) and the viscosity is measured using measuring stirrer throughout the process. 

A gelatinization begins to occur, an increase in viscosity is registered; temperature of the sample is measured and identified as the corresponding gelatinization temperature. An increase in viscosity of a minimum of 24 cP (mPa × s) within six seconds is the evaluation criterion for the pasting temperature.

DMDC (Velcorin®) is used for the cold sterilization of non-alcoholic beverages. It essentially kills yeasts, bacteria and molds, with little effect on mold spores or yeast ascospores. Certain species of Lactobacillus possess an elevated resistance to Velcorin®. 

There should be fewer than 500 microbes/cm³ at the time the dosage is added. 

According to the EU guideline EG 1129/2011 [1], up to 250 mg/l DMDC may be added to flavored non-alcoholic beverages, non-alcoholic wine and liquid tea concentrates.

Dimethyl dicarbonate (Velcorin®) quickly dissociates in aqueous solutions almost completely to carbon dioxide and methanol. In addition, small amounts of ethyl methyl carbonate are formed through the reaction of DMDC with ethanol, which can be detected through GC-MS analysis techniques [2]. The  amount of DMDC added to a beverage can be determined by measuring the content of EMC and ethanol. The Velcorin® dosage can be checked by measuring the amount of methanol quantitatively using GC analysis; however, the initial amount of methanol present in the product prior to adding Velcorin® must be determined.

H₂O + C₄H₆O₅ (DMDC) → 2CH₃OH + CO₂

250 mg Velcorin  → 119.5 mg methanol + 164.1 mg carbon dioxide

C₂H₅OH + C₄H₆O₅ (DMDC) → C₄H₈O₃ + CH₃OH+ CO₂

These preservatives are separated by means of HPLC and determined through UV detection. Identification is performed on the basis of the retention times and quantification by using the area under the peaks according to the external standard method.