Optimization of Grist Composition for Mash Production from Unmalted Wheat and Wheat Malt of Red Winter Wheat with Hybrid Endosperm Type

Abstract

Since wheats used for use in brewing mainly belong to the winter red hard hybrid endosperm type, this paper examined the influence of different proportions of wheat of this type (seven varieties) in the ratio of 0–100% in the grist, both unmalted and as wheat malt. The quality of the starting wheats, the resulting malts and mashs with different added wheat proportions (100, 80, 60, 40, 20 and 0%) were examined. The obtained results show that the maximum shares of wheat/wheat malt in the infusion are significantly different between varieties of similar initial quality. However, they can differ considerably for the same variety when it is used as unmalted raw material and when it is used as wheat malt. Wheat malt can be added to the mixture in a significantly larger proportion compared to unmalted wheat. Furthermore, when an extended number of criteria (parameters) are applied, some varieties may be acceptable that otherwise would not be if the basic number of parameters were applied (total protein—TP, total soluble protein—TSP and viscosity—VIS) and vice versa. The inclusion of other parameters—filtration speed (FIL), saccharification time (SAC), color (COL), proportion of fine extract (EXT) and fermentability of pomace (FAL) (some of which have the character of so-called “cumulative parameters”)—complicates a clear classification into the aforementioned qualitative groups but also increases the number of varieties acceptable or conditionally acceptable for brewing.

1. Introduction

Wheat, either unmalted or as malt, has been used in beer production for probably as long as barley, if not longer. Wheat has certain advantages over barley, such as the absence of chaff (which causes faster water absorption), a technologically more favorable ratio of starch to non-starch parts of the grain, etc. In the mid-20th century, its use died out and it was used as wheat malt in the production of German beers and as unmalted raw materials in the production of Belgian types of wheat beer. At the end of the century, interest in wheat as a brewing raw material grew in the USA due to the increased demand for wheat beer style, which emerged as a response to the need for a refreshing taste due to consumers’ fatigue with the traditional flavors of “lager” and “ale” types of beer. With the rapid growth of the “craft” beer market at the beginning of this century, the need for a recognizable specific flavor suddenly increased, which implied an expansion of the raw material base and a new way of processing the existing ones. The consequence of this was a significant “return” to wheat, which led to a more fundamental, scientific study of wheat as a raw material for brewing. Although there are no target values in the professional literature, it is generally accepted that wheat for brewing should have the following characteristics: crude protein (TP) max. 11–12%; 1000 kernel mass (TKW) as high as possible; starch content as high as possible (preferably > 70% d.m. in grains) with as large starch granules as possible; low grain hardness (NIR-hardness) < 50; endosperm vitreousness as low as possible with as high a transient vitreousness as possible; and low content of soluble pentosans [1,2]. The indicators most often taken into consideration are the TP, TKW, NIR-hardness and starch content. The negative effects of using wheat and wheat malt include an increased protein content (+0.5–2.5%) in wort, a longer saccharification time (+2–15 min), an increased content of high-molecular-weight (HMW) and medium-molecular-weight (MMW) protein fractions (+3–15 mg/100 mL), a lower FAN content (20–50 mg/L), an increase in wort viscosity (+0.1–1.5 mPa×s), and poorer filterability [3,4]. The only professional classification of wheat used in Europe is its division into quality groups according to the requirements of the baking industry (E, A, B and C). Some German authors also introduce the so-called “brauweizen” into this classification [5]. This group would consist of varieties that would have desirable malting properties, but such varieties are rare and are mainly related to the Northern European agro-climatic region, and each large malting house has its own selection of varieties based on many years of practical experience. White soft wheat varieties, which are otherwise very suitable for the spirits industry, as well as confectionary varieties (group C in the above classification), would be the most similar to the required properties [5]. However, in the area of Southeastern Europe, there is almost no cultivation of white soft wheat varieties, while starchy/confectionery varieties are also rare and their malting and brewing properties have not been studied in detail. Red hard wheat varieties with a hybrid endosperm texture make up the largest share in the range of the mentioned region. Research has shown that among them there are certain varieties that exhibit very good malting properties [6,7] but also varieties that have shown very good brewing properties as unmalted raw material [8]. When it comes to the individual parameters of the quality of starting wheat, finished malts and mash, according to individual authors, they differ (sometimes significantly) both in terms of the target values and in the number of parameters that are minimally necessary to provide as objective an assessment as possible of the influence of the quality of unmalted wheat or wheat malt on the quality of mash and, indirectly, beer [3,5,9,10]. Depending on which parameters and values you take into consideration, the proportion of wheat that can be added to the fill can vary significantly. This work aimed to determine the maximum proportion of unmalted wheat or wheat malt that can be added to the mixture for the production of mash, without violating the most commonly recommended values from the professional literature for selected varieties of red hard wheat for which very good malting properties have been established in previous studies. Furthermore, the goal was to look at the interrelationships of individual parameters that can either positively or negatively affect the quality of mash.

2. Materials and Methods

Five domestic red hard wheat varieties (1—Tika-Taka; 2—Felix; 3—Olimpija; 4—Anica; 5—Indira) were selected for this experiment. They are typical wheat varieties belonging to the B quality group, which have medium hardness and vitreosity, a high degree of transient vitreosity of the grain, and a hybrid (mixed, marbled) endosperm type with alternating glassy and floury regions. Although they belong to the red hard type, they show some typical characteristics of soft wheat varieties during processing, primarily a very high degree of transient vitreosity and a lower proportion of soluble proteins in the total proteins, and have shown themselves to be suitable for the production of light wheat malt [6,7]. These varieties also grow well in areas with a typical continental climate, often exposed to “forced maturation” phenomenon, which negatively affects various aspects of grain quality, primarily the protein content and the ratio of insoluble and soluble protein fractions [11]. In order to avoid the influence of location and agrotechnical measures on the tested wheat, samples were obtained from the same varietal experiment from the same location belonging to the Institute of Agriculture Osijek-HR, and under the same agrotechnical growing conditions. The grain collected (10 kg) from these experiments was refined and untreated, separated, packaged, and stored in a dry and dark place for 3 months. One German variety used for malting (6—Foxx, breeding house L. Stroetmann Saat-Deutschland, Greven, Germany), and one French (7—Euclid, breeding house Axereal-France, Orgères-en-Beauce, France) were tested as well. For the preparation of grist for the production of mash, i.e., combining with unmalted wheat and wheat malt, standard light barley malt was used.

Wheat, Wheat Malt and Mash Preparation and Analysis

Analyses of the starting wheat, finished malts and mash were carried out according to the following analytical manuals: (1) Middle European Brewing Analysis Commission—MEBAK; Band I, Band II [12]; (2) European Brewery Convention EBC—Analysis Committee, Analytica EBC [13]; (3) American Association of Cereal Chemistry AACC—Approved Methods of the AACC, 10th ed. [14]; (4) Hashimoto, S., Shogren, M. D., Bolte, L. C. and Y. Pomeranz.: Cereal Pentosans: Their Estimation and Significance. III. Pentosans in Abraded Grains and Milling By-Products [15]; and (5) International Association for Cereal Science and Technology—ICC Standard Method [16]. In the initial wheat, the following indicators were determined: moisture (EBC 3.2), NIR-hardness; NIR-protein content (AACC Method 39–70A) and starch (ICC method 169) using an Infratec 1241 Grain Analyzer (Foss, Hilleroed, Denmark); thousand corn weight (EBC 3.4); and total and transient vitreosity (ICC visual method Standard 129) [16], which were determined using Pohl’s grain cutter (Farinotom, Sadkiewicz Instruments, Komorniki, Poland). The vitreosity of the cut grains was expressed as a percentage as described in [17]. The processed grain (removal of broken and stubby grains and impurities, kernel size > 2.2 mm) was kept in a dry and cool place for 60 days to overcome the post-harvest dormancy. After that, micromalting was carried out on a Schmidt-Seeger micromalter (Belingries, Germany) according to the standard MEBAK procedure (method 2.5.3.1) with the correction of the air humidity during germination to 85% because wheat grain absorbs more water than barley due to the lack of bran. On the third day of soaking (the first day of germination), the humidity of the grain was adjusted to 44% by misting. After micromalting and degermination, the malt was stored in a cold place to stabilize the enzymes and humidity. The analysis of the finished malts was carried out by preparing laboratory mash using the congress method for the mashing procedure (MEBAK R-207.00.002). The finished malts were determined as follows: moisture (EBC 4.2), extract-grain (MEBAK 3.1.4.2.2), proteins (MEBAK 1.5.2.1), soluble proteins (MEBAK 4.1.4.5.2), soluble N (EBC 4.3.1), total N (MEBAK 4.1.4.5.1.1), Kolbach index (MEBAK 3.1.4.5.3), color spectrum (EBC 4.7.1), boiled color spectrum (EBC 4.19), free α-amino N (EBC 4.10), turbidity (EBC 4.1.4.2.6), viscosity (EBC 4.8/8.4), β-glucans and soluble β-glucans (4.16.2), pH, diastatic power (EBC 4.12.1/4.12.2), alpha amylase (EBC 4.13/4.13.2), flavor (MEBAK 4.1.4.2.3), saccharification time (MEBAK 4.1.4.2.4), final attenuation limit (EBC 4.11.1), Hartong VZ°45 (MEBAK 4.1.4.11), and friability (EBC 4.15). Unmalted wheat–barley malt and wheat malt–barley malt mash were prepared by isothermal mash combining them in a batch in a ratio of 0–100% unmalted wheat and wheat malt according to the proportion of barley malt in the amount of 0:100; 80:20; 60:40; 40: 60; 20:80 and 0:100 barley malt. The following parameters were determined in the mash: moisture (only for standard barley malt) (EBC 4.2); viscosity (EBC 4.8/8.4); proteins (MEBAK 1.5.2.1); total N (4.1.4.5.1.1) (MEBAK 4.1.4.5.1.1); soluble N (EBC 4.3.1); Kolbach index (%) (MEBAK 3.1.4.5.3); filtration time (R-205.04.730); extract fine (MEBAK 2.5.3); and saccharification time (MEBAK 4.1.4.2.4). The results were subjected to analysis of variance (ANOVA) and Fisher’s least significant difference test (LSD). The p-value was set to be significant at <0.05. Statistics 13.1. (TIBCO Software Inc., Palo Alto, CA, USA) was the software of choice for this analysis. All the analyses were performed in duplicate.

3. Results and Discussion

3.1. Quality of Wheat and Wheat Malt

From the results shown in

Table 1. Basic raw material quality parameters used for the production of wheat mash.

	Parameters		Unit	Samples
				1	2	3	4	5	6	7
1	Protein		%dm	11.50 e	13.50 b	15.60 a	12.00 d	9.90 f	12.05 d	12.45 c
2	Moisture		%	12.05 ab	12.20 a	11.70 c	11.70 c	11.80 bc	12.20 a	11.60 c
3	Starch		%dm	71.45 b	68.70 d	64.20 e	69.60 c	72.50 a	69.80 c	68.55 d
4	Vitreosity	Total	%	44 c	40 d	100 a	100 a	56 b	40 d	20 e
		transient		28 d	26 d	96 a	66 b	44 c	22 e	14 f
5	NIR-hardness			65.80 bc	75.00 a	67.15 b	45.30 d	47.00 d	64.35 c	46.80 d
6	TGW		g	47.08 b	44.4 c	39.18 e	35.44 f	43.40 d	48.12 a	34.48 g
7	Pentosans	Total	%	9.11 b	7.66 d	8.34 c	7.20 e	6.78 f	9.45 a	7.64 d
		soluble		0.69 ab	0.75 ab	0.81 a	0.60 b	0.70 ab	0.79 a	0.85 a

^a–g Means within rows with different superscripts are significantly different (p < 0.05); 1—Tika-Taka; 2—Felix; 3—Olimpija; 4—Anica; 5—Indira; 6—Foxx; 7—Euclid.

, it is evident that the tested varieties are typical hard red varieties of the hybrid endosperm type and express the previously mentioned properties. For brewing, the most important thing is that they behave more of a soft type than a hard type during processing. The best indicator of this is the ratio of permanent and transient vitreousness, which is extremely shifted in favor of transient vitreousness (namely, it is considered that during soaking, the hard type of endosperm would have to retain ≥85% of vitreous grains) [18], so all the tested varieties can be considered medium hard. The endosperm hardness is an important parameter for the use of wheat as a raw material in brewing because a harder endosperm slows down the rate of hydration and enzyme modification during the malting process and leads to worse results for the mash quality indicators when using wheat as an unmalted raw material [3]. The endosperm hardness is essentially related to the vitreousness, which had a very high percentage of transient character, namely, in no variety did the % of grains with permanent vitreousness exceed 50% of the total, or it was often significantly lower. Although this leads to a higher proportion of fine extract in the mash, it does not necessarily imply the higher fermentability of the mash because it also depends on the ratio of fermentable and non-fermentable extract in the total fine extract.

The chemical composition of varieties potentially suitable for use in brewing is not specifically stated, but it is generally believed that these should be varieties with a lower total protein content to produce not too viscous mash [3], which, according to the classification provided by Narziss [9], would fall into the first qualitative malting group. It should be noted that the total protein (TP) in the grain is not fully correlated with the total soluble protein (TSP), because recent research has shown that with an increase in the TP in the grain, the TP:TSP ratio changes in favor of the insoluble protein fraction that is separated from the mash, so it does not necessarily affect the fermentability and utilization of the extract, but it increases the proportion of high-molecular-weight protein fraction (HMWP) in the mash and consequently in the beer, which, in addition to having a positive effect on the foam [19], also has a negative effect on the colloidal stability of the finished beer [20]. It can be seen from Table 1 that the starting share of TP in the tested varieties varies (9.90–15.60%), where higher TP is not accompanied by a corresponding increase in the TSP in malt (

Table 2. Initial quality indicators of wheat malts and referent barley malt.

	Parameters	Unit	Samples
			1	2	3	4	5	6	7	Ref. Malt
1.	Moisture	%	5.4 bc	5.8 a	5.6 a	5.3 b	5.1 c	5.4 bc	5.3 b	4.7
2.	Extract fine	%	80.2 b	75.9 f	79.8 c	79.6 c	81.8 a	78.7 d	78.6 d	76.5
3.	Extract fine	%dm	84.8 b	80.6 e	84.5 b	84.1 c	86.2 a	83.2 d	83.1 d	80.2
4.	Color spectro.	EBC	4.6 ab	5.3 ab	6.1 a	5.0 ab	6.4 a	4.0 b	4.2 b	3.9
5.	Color visual	EBC	4.5 abc	5.5 ab	6.0 a	4.5 abc	6.0 a	3.5 c	4.0 bc	3.7
6.	Boiled color spectro.	EBC	6.9 cd	7.1 cd	9.1 a	7.6 bc	8.9 ab	6.0 d	5.8 d	6.0
7.	Boiled color Vis.	EBC	7.0 ab	7.0 ab	9.0 a	7.5 ab	8.5 a	5.5 b	5.5 b	5.8
8.	Turbidity	EBC	1.2 b	5.3 a	1.2 b	0.6 c	0.6 c	0.9 bc	0.7 c	12.2
9.	Total protein	%	11.6 e	14.7 b	16.3 a	12.8 c	12.4 d	12.4 d	12.9 c	10.2
10.	Soluble protein	%dm	4.0 c	4.1 bc	5.4 a	4.4 b	5.1 a	4.1 bc	4.1 bc	4.3
11.	Soluble N	mg/L	708.0 g	731.0 d	960.0 a	781.0 c	901.0 b	726.0 e	722.0 f	-
12.	Soluble N	mg/100 g	641.0 g	663.0 d	870.0 a	706.0 c	814.0 b	657.0 e	653.0 f	-
13.	Kolbach ind. (S/T)	%	34.5 b	27.9 e	33.1 c	34.4 b	41.1 a	33.1 c	31.8 d	42.2
14.	Free α-amino N	mg/L	110.0 c	103.0 d	147.0 a	97.0 e	138.0 b	81.0 g	87.0 f	149.0
15.	Free α-amino N	mg/100 g	100.0 c	93.0 d	133.0 a	88.0 e	125.0 b	73.0 g	79.0 f	136.0
16.	Viscosity	mPa×s	1.66 c	1.97 a	1.80 b	1.72 bc	1.60 c	1.96 a	1.85 ab	1.52
17.	Soluble β-glucans	mg/L	54.0 c	59.5 b	60.0 b	60.0 b	54.0 c	66.0 a	66.0 a	178
18.	β-glucans	mg/100 g	49.0 c	53.0 b	59.0 a	54.0 b	49.0 c	60.0 a	60.0 a	60.0
19.	pH		6.06 b	6.01 c	5.93 d	6.07 b	5.98 c	6.12 a	6.13 a	5.97
20.	Diastatic power	WK°	373.0 c	339.0 d	426.0 a	456.0 a	406.0 b	406.0 b	428.0 a	-
21.	Alpha amylasis	DU	40.0 bc	38.0 c	43.0 b	38.0 c	48.0 a	38.0 c	34.0 d	-
22.	Flavor		1	1	1	1	1	1	1	1
23.	Sachharif. time	min.	12.0 a	12.0 a	9.0 a	9.0 a	9.0 a	12.0 a	12.0 a	15
24.	Final attenuation limit	%	79.7 c	79.2 cd	80.9 b	79.1 d	81.8 a	79.2 cd	80.6 b	80.8
25.	Hartong VZ°45	%	-	-	-	-	-	-	-	34.1
26.	Friability	%	-	-	-	-	-	-	-	89.1

^a–g Means within rows with different superscripts are significantly different (p < 0.05); 1—Tika-Taka; 2—Felix; 3—Olimpija; 4—Anica; 5—Indira; 6—Foxx; 7—Euclid.

). Proteins are macromolecules that significantly determine the potential suitability of a particular wheat variety for beer production, where the proportion of proteins and the distribution of their fractions (HMW N, MMW N, LMW N, as well as FAN) are of crucial importance for the production of certain types of beer but also generally affect the production process and quality of each type of beer [4]. For this consideration, it is important to note that the different proportions of TP for individual varieties (which otherwise behave very similarly during processing) are expected and are a consequence of the hybrid (marbled) structure of the endosperm in which glassy (richer in proteins) and floury (richer in starch) surfaces alternate randomly, which additionally indicates that the variety factor will have a very significant influence on the brewing quality and that it is difficult to evaluate it by only comparing the final values for the specified individual parameters. In addition to proteins, non-starch polysaccharides (arabinoxylans (pentosans) and β-glucans) form another group of macromolecules whose values determine which malting group (I–IV) certain varieties will be classified into [9]. Beer viscosity and turbidity are strongly associated with the content of non-starch polysaccharides, especially pentosans, when using wheat [21]. It is generally accepted that wheat β-glucans (≈0.6–1% of the whole kernel weight) are not problematic for the quality of mash like the β-glucans of barley, while pentosans (≈6–8% of the whole kernel weight and 1.5–2.5% in the endosperm [4]) and dextrins are said to have the greatest influence on the increase in viscosity of mash and accompanying problems in production (extension of filtration time and increase of viscosity to unacceptable limits [4,21], reduction of the colloidal stability of beer obtained from wheat malt [22] and in beer obtained using wheat as an unmalted raw material [8]. It should be noted that some authors believe that the parts most responsible for the increase in viscosity are the undegraded parts of the starch molecules. These are primarily high-molecular-weight dextrins with 2–6 polymerization, malto-oligosaccharides, trisaccharide, and tetrasaccharide) [23], while the most responsible for the deterioration of filterability are pentosans and high-molecular-weight proteins and the formation of protein–pentosan gel on the filter [21,24]. It is evident from Table 1 that the proportion of total and soluble pentosans at the lower limit is common for this type of wheat, with the proportion of soluble in total pentosans (soluble/total pentosans ratio) being somewhat lower compared to Northern European wheats, which is also characteristic of Southern European wheats [25]. The very high transient vitreousness in the total indicates that the nature of the vitreousness, and not only its proportion in the endosperm surface, is important for the amount of water that the grain can absorb. Starch is the third group of macromolecules whose proportion in the grain and the properties of starch grains are of crucial importance for the proportion of fine extract and its fermentability, and it makes up about 80% of the grain. Any change in the proportion and composition of starch in the endosperm of the grain significantly affects the properties of the grist and finished beer [4]. Starch is combined with proteins in the so-called formal correlation (two quantities complement each other up to almost 100, so increasing one decreases the other), where the obtained values for the starch content follow the values for the total protein in the grain, which is noticeable from Table 1, and accordingly the grain hardness, which is closely related to its (starch) hardness. When we summarize the results from Table 1, it is evident that varieties 5, 1 and 6 could be considered as potentially the most suitable for brewing, based only on the TP and starch parameters. If we also include some parameters related to the TP content (hardness, permanent and transient glassiness) or the parameter related to the starch content (TGW), we already see significant deviations.

3.2. Quality of Mash from Unmalted Wheat and Wheat Malt

The further fate of the starting wheat in terms of brewing raw material is that it can be used as unmalted or wheat malt. Its quality in both forms determines the quality of the mash obtained by combining it with barley malt in various proportions. When considering the quality of wheat malts obtained by micromalting (Table 2), it is necessary to primarily pay attention to the basic indicators according to which the quality is assessed for classification into a certain quality group (I–IV) for use in brewing (TP, TSP) and the viscosity (VIS) of the obtained mash. The protein content in the starting wheat (TP) is one of the key quantities that affects the quality of malt, and it is significant that their high content is consequently associated with their lower solubility and a decrease in the depth of their decomposition during malting and subsequent malting [26], which requires deeper consideration of the “TSP:TSP” factor [27].

Consequently, in addition to the TSP, the TP affects the color of the finished beer and the concentration of “haze active” and “foam active” proteins [5]. This is particularly pronounced for wheat group II of the malting quality group of the hybrid endosperm type, where varieties with similar malting quality have significantly different initial TP and TSP. A lower degree of protein degradation (lower TSP) consequently leads to a lower Kolbach index (KI) [27]. The KI showed good values as recommended only for variety 5 (Table 2). It is also observed that when it comes to the TP in the starting wheats (Table 1) and the TP in malt (Table 2), there is an increase in the TP in malt (varieties 2, 3, 4, 6, 7) or, in the best case, it does not change significantly (varieties 1, 5). From Table 2, it is evident that there is no expected close relationship between the TP and TSP in malt, with varieties with a relatively high initial TP content (varieties 2, 6, 7) having very good TSP values, as expected, as well as variety 1, which had the lowest TP, while varieties with a very high TP content (variety 3) and a variety with a medium TP content have an unacceptable TSP content. Varieties 3 and 5 had an increased TSP content, in which the initial TP content in the malt was not followed by the TSP results, while interestingly, these varieties (with the highest TSP) had the highest final attenuation limit (FAL), which indicates a certain change in the ratio of fermentable to total extract with an increase in the TSP in malt. When the results for the ratio of extract fine to FAL (Table 2) are compared in relation to varieties 6 and 7, it is observed that some varieties have very good EXT fine but too low TSP, and relatively low FAL (var. 1) or acceptable EXT fine, satisfactory TSP and relatively low FAL (var. 2), while some had very good EXT fine and acceptable FAL but too high TSP (var. 3). Varieties 4 and 5 had very good EXT fine but differed significantly in FAL. Expanding the consideration of the relationship between the TSP and fundamental parameters such as the color of the mash and the beer with which it is highly correlated [5], as well as the relationship between the TSP and the viscosity or filtration time, because elevated TSP is highly correlated with the high-molecular-weight fraction in the TSP, which also affects the increase in viscosity [26], as well as considering the relationship between the VIS and indicators of the success of the amylolysis and cytolysis processes, would make the consideration even more confusing, so the characteristics for classifying varieties into qualitative groups according to recommended values are summarized in

Table 3. Labeling for matching results for the selected quality parameters’ classification into qualitative groups (I–IV) according to the recommended values and additional parameters.

Parameters/Ref. Values	Not Acceptable	Acceptable		Good		Not Acceptable
	Min/Max	Min	Max	Min/Max	Max	Min/Max
Total protein (%)	<9.9	10	10.9	11	12.5	13.5/-
Soluble (mg/100 g dm malt)	<0.649	0.66	0.669	0.700	0.780	0.901/-
Extract fine (%dm)	-	-	84	>84		-
Viscosity (mPa×s)	<1.800	>1.800				-
FAN mg/100 g dm malt)	-	90≤		120≤
Final atten. limit %	-	>79		>80		-
Quality mark →	―	+		++		―

. The VIS of the mash and ultimately of the finished beer can be considered as a cumulative value that tells us about the initial relationships between the macromolecules that most influence it (the proportion and structure of arabinoxylans [24], the proportion and properties of starch molecules as well as the depth of their decomposition [4], and the concentration of high-molecular-weight (HMW) protein fractions in TSP), which, either independently or in complexes with the other two groups of macromolecules mentioned, also influence the increase in the VIS. It should be borne in mind that these macromolecules (primarily dextrins and arabinoxylans) influence the so-called “fullness of flavor”, while HMW proteins contribute crucially to the stability of the foam. These molecules also negatively affect the colloidal stability of the finished beer due to the reaction with polyphenolic compounds and the filtration time due to the formation of complexes with arabinoxylans that make filtration more difficult [24].

In

Table 4. Marks for the quality of the parameters for the tested assortment based on which classification is made into the malting quality groups (I–IV).

Parameters/ Ref. Value	Samples							Not Acceptable	Acceptable	Good	Not Acceptable
	1++	2−	3−	4++	5+/−	6−	7+/−		Min	Max
Total protein	++	―	―	+	++	++	+	<9.9	10	10.9	11
Soluble N	+	+	―	++	―	+	+	<0.649	0.66	0.669	0.700
Extract fine	++	+	++	++	++	+	+	-	-	84	>84
Viscosity	++	―	+	++	++	―	―	<1.800	>1.800		-
FAN	―	―	―	―	―	―	―	-	90≤	120≤	-
Final atten. limit	+	+	++	+	++	+	++	-	>79	>80	-
Quality mark								-	+	++	-

Total acceptability of malting varieties: ⁺⁺ good, ⁺ acceptable, ^+/− conditionally acceptable; ⁻ unacceptable; 1—Tika-Taka; 2—Felix; 3—Olimpija; 4—Anica; 5—Indira; 6—Foxx; 7—Euclid.

, the results of the assessment of the brewing quality of wheat malts from the tested varieties are presented. This is the case when applying an expanded number of quality parameters. It is observed that the number of “good”, “acceptable” and “conditionally acceptable” varieties increases with their application. The term “good” implies that the value of all the so-called basic parameters (TP, TSP and VIS) is optimal according to the recommended values [4]. The term “acceptable” implies that at least one of the basic factors (TSP and VIS) must have optimal values while the other basic parameter may show a certain deviation, and the largest number of other indicators have good or acceptable values. The term “conditionally acceptable” (variety 7) implies acceptable values for the basic and an expanded number of indicators, with unacceptable values for one of the basic parameters, but for economic or other reasons it can be used, especially if the malting process is performed in such a way as to improve the values for that parameter (specifically, a moderately restrictive malting process can reduce the viscosity of the mash).

When looking at the results for the VIS and TSP (Table 3), it is observed that some varieties have good or acceptable values for both the TSP and VIS of the mash (var. 1, 4, 5). It is also observed that the Northern European varieties (var. 6 and 7) have a significantly higher VIS compared to the domestic varieties, for which it was found that the VIS of the mash is rarely a difficult factor in their application and that they mainly belong to the II malting quality group (characterized by increased TP and TSP), which can be influenced by the malting process, e.g., malting with a moderately restrictive process [6]. The normal FAL for wheat malt (congress wort) is 80%, i.e., it varies from 75.7–82.2% [4] (although significantly higher values have also been obtained [6,7]). The FAL is a typical so-called cumulative indicator of quality because it is a consequence of the starting ratios of the key macromolecules of the grain, the depth of their decomposition during the process of cytolysis, proteolysis and amylolysis, and the interaction of the products of this decomposition, and from an economic point of view, it is, along with the fine extract, the main indicator of the success of the milling process and should be viewed as a kind of result of the interweaving of the previously mentioned processes. It can be considered that the best way to evaluate its values is to follow it through a relevant statistical period (at least three years, preferably more) in consecutive growing seasons and locations for a particular variety. The results of the application of unmalted wheat in the production of mash are shown in

Table 5. Results of the quality indicators of mash for different ratios of unmalted wheat/barley malt.

Ratio: Unmalted Wheat/ Barley Malt (%)		Moisture (%)	Viscosity (mPa×s)	Soluble N (%dm)	Soluble N (mg/L)	Kolbach Index (%)	Filtration Rate (min)	Extract Fine (%)	Extract Fine (%dm)	Saccharif. Time (Min)	Total N (%)	Proteins (%)
1	20/80	-	1.57 fg	0.62 a	661 a	-	25 h	74.49 a	79.37 a	20 e	-	-
	40/60	-	1.60 ef	0.50 ab	536 e	-	40 g	66.85 h	78.06 d	25 e	-	-
	60/40	-	1.62 e	0.41 def	447 h	-	105 c	68.20 f	74.46 h	60 b	-	-
	80/20	-	1.73 c	0.33 efg	361 j	-	200 a	62.68 i	68.94 j	60 b	-	-
	100/0	10.1	2.05 a	0.23 gh	260 n	12.4	200 a	26.01 l	27.38 m	60 b	1.85	11.5
2	20/80	-	1.57 fg	0.59 ab	641 b	-	20 i	74.20 b	78.90 c	20 e	-	-
	40/60	-	1.61 e	0.52 abcd	555 d	-	25 h	71.98 d	77.33 f	25 e	-	-
	60/40	-	1.69 d	0.44 cd	468 g	-	95 d	67.49 g	73.26 i	60 b	-	-
	80/20	-	1.81 b	0.30 fg	326 k	-	180 b	62.29 j	68.33 k	60 b	-	-
	100/0	9.8	1.78 b	0.25 g	287 m	11.3	200 a	19.20 m	20.21 o	200 a	2.21	13.8
3	20/80	-	1.55 g	0.56 abc	594 c	-	20 i	74.39 a	79.14 b	15 f	-	-
	40/60	-	1.56 g	0.49 bcd	522 f	-	25 h	72.47 c	77.92 e	20 e	-	-
	60/40	-	1.57 fg	0.42 de	436 i	-	85 e	68.93 e	74.92 g	55 c	-	-
	80/20	-	1.61 e	0.41 def	316 l	-	75 f	42.09 k	62.96 l	60 b	-	-
	100/0	10.0	1.49 h	0.13 h	141 o	6.9	200 a	18.31 n	20.34 n	60 b	1.89	11.8
Barley malt		5.0	1.51	0.67	727	43.5	25	76.42	80.44	10	1.54	10.3

^a–o Means within rows with different superscripts are significantly different (p < 0.05); 1—Tika-Taka; 2—Felix; 3—Olimpija; 4—Anica; 5—Indira; 6—Foxx; 7—Euclid.

for wheat from the tested assortment, which in earlier tests was found to be suitable for brewing.

It is observed that in a grist of 100% unmalted wheat, increasing the proportion of TP and, accordingly, decreasing the proportion of starch leads to a decrease in the VIS of the grist. Wheat with the highest starch and total pentosans and the lowest TP had the highest VIS (var. 1). This variety had the only unacceptable VIS of the grist (>1.8 mPa×s). Increasing the proportion of wheat in relation to barley malt leads to a clearly pronounced increase in VIS, a decrease in filterability and an increase in the saccharification time, which is expected. The second key parameter, the TSP, decreases with an increase in the proportion of unmalted wheat in the grist and already reaches an unacceptable value (<0.669%dm) at a proportion of 20% (Table 3). This is consistent with the results of a study on the use of unmalted wheat for lager beer production, where it was found that the proportion of unmalted wheat in the mash should not exceed 16% [8] in order to avoid a certain taste gap due to too low TSP.

Also, no clear relationship was observed between the TP in the starting wheat and the TP and TSP in the mash, so that, for example, varieties 1 and 3 have very similar values for the TP for a 100% unmalted wheat grist and markedly different values for the TSP in the mash (Table 5). In mash produced from wheat and barley malt in the same proportions, the VIS and TSP parameters were also observed (

Table 6. Results of the quality indicators of mash for different ratios of wheat malt/barley malt.

Ratio: Wheat Malt/ Barley Malt (%)		Moisture (%)	Viscosity (mPa×s)	Soluble N (%dm)	Soluble N (mg/L)	Kolbach Index (%)	Filtration Rate (min)	Extract Fine (%)	Extract Fine (%dm)	Sachharif. Time (min)	Total N (%)	Proteins (%)
1	20/80	-	1.59 stu	0.70 no	746 z	-	20 n	76.87 fghi	81.54 klmno	15 h	-	-
	40/60	-	1.67 pqr	0.74 lmno	786 v	-	25 m	77.43 ef	82.76 fgh	20 g	-	-
	60/40	-	1.78 klm	0.78 ijkl	816 r	-	35 k	77.88 de	83.89 de	20 g	-	-
	80/20	-	1.89 hi	0.80 ijk	828 q	-	55 g	78.24 cd	84.94 c	25 f	-	-
	100/0	8.6	2.00 def	0.83 fghi	854 o	47.4	70 e	79.00 b	86.43 b	35 d	1.75	10.9
2	20/80	-	1.62 rstu	0.69 o	735 a	-	20 n	76.21 ijkl	80.95 opqr	20 g	-	-
	40/60	-	1.76 klmn	0.75 klmn	788 v	-	30 l	75.71 klmno	81.17 nopqr	25 f	-	-
	60/40	-	1.95 fg	0.76 jklm	797 u	-	45 i	75.31 no	81.49 lmnop	30 e	-	-
	80/20	-	2.19 b	0.78 ijklm	806 t	-	70 e	75.29 no	82.23 hijk	40 c	-	-
	100/0	9.3	2.42 a	0.79 ijkl	816 r	36.1	120 a	74.22 q	81.83 ijklmn	45 b	2.19	13.7
3	20/80	-	1.59 stu	0.76 jklm	811 s	-	25 m	75.82 jklmn	80.45 r	10 i	-	-
	40/60	-	1.64 qrs	0.86 efgh	913 k	-	35 k	75.50 mno	80.77 pqr	15 h	-	-
	60/40	-	1.73 mno	0.95 bc	1002 c	-	45 i	75.09 op	80.99 r	20 g	-	-
	80/20	-	1.84 ij	0.98 b	1019 b	-	45	74.49 pq	81.00 opqr	25 f	-	-
	100/0	8.8	1.98 efg	1.05 a	1082 a	41.7	110 b	74.17 q	81.33 mnopq	30 e	2.52	15.8
4	20/80	-	1.58 stu	0.74 lmno	786 v	-	25 m	76.49 fghi	81.17 nopqr	15 h	-	-
	40/60	-	1.67 pqr	0.81 hij	862 m	-	30 l	76.76 fghi	82.11 hijkl	20 g	-	-
	60/40	-	1.75 lmn	0.88 def	919 j	-	35 k	76.93 fgh	82.97 fg	25 f	-	-
	80/20	-	1.88 hi	0.90 cde	933 i	-	55 g	77.00 fg	83.73 e	30 e	-	-
	100/0	8.8	2.01 de	0.96 b	985 e	49.0	75 d	77.07 fg	84.51 cd	35 d	1.96	12.3
5	20/80	-	1.57 u	0.70 no	744 z	-	20 n	76.88 fghi	81.56 jklmno	10 i	-	-
	40/60	-	1.60 stu	0.74 jklmn	786 v	-	20 n	78.01 de	83.42 ef	15 h	-	-
	60/40	-	1.63 rst	0.80 ijk	841 p	-	35 k	78.86 bc	85.00 c	15 h	-	-
	80/20	-	1.67 pqr	0.90 cde	938 h	-	40 j	79.32 b	86.18 b	15 h	-	-
	100/0	8.7	1.69 opq	0.96 b	991 d	57.1	75 d	80.18 a	87.82 a	15 h	1.68	10.5
6	20/80	-	1.60 stu	0.73 mno	778 x	-	20 n	76.30 hijk	80.98 opqr	15 h	-	-
	40/60	-	1.72 nop	0.74 lmno	781 w	-	30 l	76.57 ghi	81.94 ijklm	20 g	-	-
	60/40	-	1.81 jk	0.82 ghi	855 no	-	40 j	76.45 fghi	82.50 ghi	25 a	-	-
	80/20	-	1.96 efg	0.87 efg	895 l	-	50 h	77.01 fg	83.81 de	30 e	-	-
	100/0	8.9	2.09 c	0.94 bc	971 f	49.0	80 c	76.98 fgh	84.50 cd	35 d	1.92	12.0
7	20/80	-	1.60 stu	0.71 mno	766 y	-	20 n	75.85 jklmn	80.74 qr	15 h	-	-
	40/60	-	1.69 opq	0.75 klmn	797 u	-	30 l	75.85 jklmn	81.66 iklmno	20 g	-	-
	60/40	-	1.80 jkl	0.82 ghi	857 n	-	45 i	75.75 klmno	82.28 ghij	25 f	-	-
	80/20	-	1.93 gh	0.86 efgh	895 l	-	60 f	75.56 lmno	82.81 fgh	35 d	-	-
	100/0	8.7	2.04 cd	0.93 bcd	958 g	46.5	70 e	76.19 ijklm	83.45 ef	40 c	2.00	12.5
Barley malt		5.0	1.51	0.67	727	43.5	25	76.42	80.44	10	1.54	10.3

^a–z Means within rows with different superscripts are significantly different (p < 0.05); 1—Tika-Taka; 2—Felix; 3—Olimpija; 4—Anica; 5—Indira; 6—Foxx; 7—Euclid.

). When wheat malt is used, the viscosity increases with the increase in the proportion of wheat malt in the grist, but unlike unmalted wheat, it had satisfactory values, i.e., it did not exceed the limit value of ≤1.8 mPa×s up to a share of 60% (var. 1, 2, 3, 4, 5 and 7), while variety 6 was at the upper limit of the value. Variety 5 had a satisfactory value even for a 100% wheat malt grist. When looking at the results for the TSP in the mash, it is also observed that it has a satisfactory value for the shares of wheat malt lower than the values for viscosity (max. share 20% for var. 3, which had by far the highest TP for 100% share in the grist, and var. 4, which had a much lower TP; max. share 40% for var. 5, which had the lowest TP for 100% share in the grist; var. 6 and 7; max. share 60% for var. 1, max. share 80% for var. 2, which had 13.7% TP for a grist of 100% wheat malt). From this, large differences in the degree of protein solubility between the varieties are observed. The values during filtration (FIL) were unacceptable for all the varieties for a grist of 100% wheat malt, while most had acceptable values for a grist composition of 80%, and all for a grist composition of 60% wheat malt. The saccharification time (SAC) increases regularly with an increasing wheat malt content in the grist but is satisfactory for wheat malt contents up to 40%. Variety 5 had excellent SAC even for the maximum wheat malt content (100%). Furthermore, it is observed that with increasing SAC, the FIL and VIS of the mash increase, which may mean that the main cause of the increase in the VIS of the mash is actually undecomposed or insufficiently decomposed starch parts.

4. Conclusions

The results obtained show that the maximum proportions of wheat/wheat malt that can be added to the mash to meet the required criteria differ significantly by variety and that they differ significantly for the same variety when it is applied as an unmalted raw material and when it is applied as wheat malt. Furthermore, when an extended number of criteria (parameters) are applied, some varieties may be acceptable that would not otherwise be if the basic number of parameters were applied and vice versa. When, in addition to the TP, TSP, and VIS parameters, others are included, such as the filtration rate (FIL), saccharification time (SAC), color (COL), fine extract content (EXT), and mash fermentability (FAL) (some of which have the character of so-called “cumulative parameters”), it complicates a clear classification into the aforementioned qualitative groups and increases the number of so-called acceptable and conditionally acceptable varieties. In order to improve the classification of varieties for use in brewing, future studies should include cumulative quality indicators (e.g., mash fermentability, “haze active”, filterability, etc.). This would imply that, in addition to the basic ones (TP, TSP and VIS), multi-parameter evaluations should also be taken into account in order to better capture the complex interactions that affect malting and brewing performance.