# Characterization of Beer Produced with the Addition of Brown Macrolgae _Fucus virsoides_
## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Quality Indicator** & **Unit** & **Algae Beer** & **Control Beer** \\ \hline Specific gravity & mg/L & 1.02935 a \(\pm\) 0.00012 & 1.02495 b \(\pm\) 0.00010 \\ Real extract & \% & 8.70 a \(\pm\) 0.1 & 7.60 b \(\pm\) 0.2 \\ Original extract (wort) & \({}^{\circ}\)P & 14.30 a \(\pm\) 0.5 & 12.80 b \(\pm\) 0.3 \\ Apparent extract & \% & 7.40 a \(\pm\) 0.1 & 6.30 b \(\pm\) 0.1 \\ Alcohol content & \% & 3.80 a \(\pm\) 0.45 & 3.55 b \(\pm\) 0.23 \\ Polyphenol content & mg/L & 513 b \(\pm\) 1 & 590 a \(\pm\) 1 \\ pH & & 4.25 a \(\pm\) 0.02 & 4.07 b \(\pm\) 0.05 \\ Bitterness & IBU & 42 a \(\pm\) 1 & 42 a \(\pm\) 1 \\ Color & EBC & 100 a \(\pm\) 2 & 98 a \(\pm\) 1 \\ \hline \hline \end{tabular} Means \(\pm\) SD; a, b within rows with different superscripts are significantly different (\(p<0.05\)); IBU—international bitterness unit.  
\end{table} 
Table 1: Basic physical–chemical indicators of produced beers. reacts mainly with high-molecular-weight proteins [31]. As algae were added to the boiling phase in the brew, it is possible that some of the polyphenolic substances were precipitated with proteins during cooling. Thus, lower polyphenolic levels were determined in beer with alga addition. However, this is yet to be investigated. The results of metal analysis in the samples are presented in Tables 2-4. Metals were determined in alga dry matter (Table 2) and in beer and spent yeast (Tables 3 and 4). Macroalgae are known to retain heavy metals such as chromium, cadmium, copper, nickel, arsenic, mercury, lead, and zinc, which are globally the most commonly detected metals [32; 33]. Some of them are crucial for the normal functioning of metabolism, but in higher concentrations, they are surely toxic to humans and animals [34]. Concentrations of heavy metals, and trace metals, can be used as a bioindicator of the pollution of an ecosystem [35]. However, heavy metals exhibit a harmful impact on algae by initiating oxidative stress [36]. The results of this research indicate that alga biomass contains high concentrations of different metals, or \"potentially toxic elements\", as they are referred to in studies [37]. Alga biomass contained extremely high concentrations of K, 24,035.00 mg/kg, then S, 23,855.00 mg/kg, and Ca with 18,305.00 mg/kg. Mg, Ni, P, and Co showed high concentrations in alga biomass, over 1000.00 mg/kg. Alga dry matter contained significant amounts of As (25,390.00 mg/kg), Ni (2685.00 mg/kg), and Co (1268.00 mg/kg). Such high concentrations of heavy metals are not surprising since algae are an excellent bioremediation medium [38]. Cr, Cd, Pb, and Mo were below 500 mg/kg. The most surprising finding in alginic biomass was the low Se concentration (<20 mg/kg). The beer produced with the addition of alga showed higher levels of all metals in comparison to the control sample (Table 2). Beer with _F. virsoides_ addition had approximately 25% higher levels of all elements than control beer. However, only a small portion of heavy metals transferred from alga biomass to the brew. As levels were determined to be high, reaching 77.94 mg/L, which is significantly higher than the tolerable intake level (TIL) of 3 mg/kg body weight per day, recommended by the World Health Organization (WHO) [39]. By drinking 0.5 L of such beer, one would take over 35 mg of As in the system. Thus, the idea of sensory analysis was dropped. On the other hand, the levels of As in control beer were significantly lower, reaching 0.42 mg/L. Zn showed a certain deviation. Specifically, its concentration was significantly lower in beer produced with _F. virsoides_. Zn is necessary for yeast growth and metabolism, and it was probably utilized by yeast biomass during fermentation [40]. Alcohol dehydrogenase is the terminal enzyme of the fermentation process and it is a zinc-dependent enzyme [41]. Its job is to reduce acetaldehyde to ethanol during glucose fermentation [42]. Yeast samples were also tested for heavy metals.