## 1 Introduction
### Production of Wort then Beer  
#### 1.4.1. _Mashing_  
Wort is the liquid extracted during the mashing process (Figure 2) [59]. Milled malt is mixed with hot water over approximately one hour to extract water soluble components. To achieve this, enzymes synthesized during the malting process hydrolyze malt protein, starch, and non-starch polysaccharides as described above. During mashing, the typical sensors would be for temperature and pH. However, the addition of sensors to monitor the progression and level of the hydrolyzed products would give brewers an indication of the sugars and amino acids required for optimal fermentation, as well as potentially monitoring the amount of hydrolyzed hordein and individual foam positive proteins such as LPT, the level of bittering compounds from hops and word color and would therefore give brewers more control. Figure 2: The stages of malting and brewing through to packaging [59]. Reproduced with permission from [PERSON] and [PERSON], [Amylopectin synthesis and hydrolysis—understanding isoamylase and limit dextrinase in barley (Hordeum vulgare)]; published in Trends in Food Science and Technology (Elsevier), [2017]. The first test of word quality is a measure of the total solubilized malt components, usually reported as hot water extract (HWE (%)) or as degrees Plato (\({}^{\circ}\)P). Extract is the main specification on a malt analysis sheet and it is used to calculate brewhouse yield. There are numerous reports for using NIR or MIR to predict malt extract in malt from a standard laboratory mask [6; 7; 60; 61; 62; 63] but other reports using industry style mash show NIR and MIR can also be calibrated for word Plato or Brix [64; 65; 66; 67] which are more common brewing nomenclature. Through it has been shown, using partial least squares--discriminant analysis (PLS-DA), it was possible to predict lautering efficiency [68]. Clearly, all these studies, using different malts, mashing conditions and infrared instrumentation show the potential of measuring the total amount of solubilized components in word. There will be many brewers who would use the real-time word content to make any adjustments in the mash, the additional benefit is the use of the data for future mashing control. Within the post-mash word, and prior to boiling where hop compounds will add bitterness, there are hundreds of compounds from the malt [28]. Two key groups of compounds are required for the fermentation process, with these being sugars and amino acids. Sugars are more easily measured with high performance liquid chromatography or gas chromatography, although the former is the easier of those two. Maltose (glucose-glucose) is the dominant fermentable sugar and beta-amylase specifically cleaves maltose from amylose and amylopectin chains. Maltotriose (glucose-glucose-glucose) and glucose are the other remaining fermentable sugars, whereas the longer sugars such as maltotetrose are not fermentable. Near infrared and MIR have been used for calibrations for fermentable sugars [63; 67; 69; 70]. Along with the capacity to measure the fermentable sugars, reports have shown NIR can measure fermentation efficiency or what is called the apparent attenuation limit (AAL) [71]. In addition, there have been a number of reports showing NIR and MIR calibrations specifically for ethanol [57; 70; 72; 73] with specific studies reporting a flow-through FTIR for ethanol measurement [57; 72]. The latter would be ideal during and post-fermentation to ensure targeted ethanol levels were achieved. The second important group of compounds solubilized during mashing are proteins. As mentioned above, there are hundreds of individual proteins and peptides that survive the kilning process of malting and further heating steps of mashing and boiling during brewing [26; 27]. The amount of total protein solubilized during mashing is called soluble protein.