## 2 Materials and Methods
### Analysis of Beer and Carob Syrup Samples  
#### 2.2.1 Physicochemical Characteristics (pH, Brix, Plato, Specific Gravity, Alcohol Content, Color)  
The determination of soluble solids for all carob syrup samples was performed using the XS instruments Digital Refractometer LDR-500-DRB 95 at room temperature. In detail, a few drops of the sample were uniformly placed on the prism of the refractometer, avoiding bubble formation, which could lead to deviations in value calculations. Brix units were used as the measurement unit of the refractometer, corresponding to the mass fraction of sucrose, where 1 Brix equaled 1 g of sucrose per 100 g of solution. Finally, pH was measured (Hanna instruments, HI 8010 pH meter). All measurements were conducted in triplicate to calculate the mean and standard deviation of the values. For beer samples, the measurements of pH (ASBC Method beer-9), specific gravity (SG), as well as Plato degrees (ASBC Method beer-2B and 3), were conducted throughout the fermentation. Specifically, samples were measured at the beginning of fermentation (t = 0 days), before bottling (t = 30 days, 1 st fermentation), and after the completion of maturation (t = 60 days, 2 nd fermentation). A crucial step before Plato and pH measurements is the deaeration, centrifugation, and filtration of samples. In detail, 80 mL of the sample is placed in falcon tubes and centrifuged at 3500 rpm for 10 min. Subsequently, samples are filtered through 0.45 \(\upmu\)m filters to achieve the desired clarity, which is a necessary step before measurement. For Plato and specific gravity measurements, the handheld digital densitometer Anton Paar-DMA 35 was used, which takes samples through its integrated pump. The pH measurements were performed using the pH meter HANNA Instruments-HI 8010. All measurements were conducted in triplicate when samples were at ambient temperature (-25 \({}^{\circ}\)C). The measurements of alcohol content (ASBC Method beer-4), density (g/cm\({}^{3}\)), original extract % \(w/w\), and real extract % \(w/w\) were carried out using the Anton Paar-Alex 500 instrument (alcohol and extract meter). The combination of absorption measurement via NIR spectroscopy and density measurement based on the oscillating U-tube principle constitutes the mechanism through which analysis is achieved by the instrument. The procedure preceding the sample analysis in the spectrophotometer is the same as described earlier. Therefore, sample clarification, achieved through centrifugation at 3500 rpm for 10 min and subsequent filtration through a 0.45 \(\upmu\)m filter, is a necessary step before each analysis in the spectrophotometer. The results of the apparent final extract (\({}^{\circ}\)P) were used for the final calculation of the degree of fermentation and, consequently, the ethanol yield (% \(v/v\)). The measurement of color in beer samples (ASBC Method beer-10) was achieved through absorbance measurement at 430 nm and 700 nm using a single-beam spectrophotometer (Shimadzu-UVmini 1240 Model Spectrophotometer) in 1 cm cuvettes. Color measurement was performed at the beginning of the fermentation process, prior to bottling the samples, as well as on the final beers after maturation. The units of color measurement are expressed in EBC (European Brewery Convention). The sample is considered clear when the absorbance value at 700 nm (A\({}_{700\text{nm}}\)) is less than or equal to the absorbance value at 430 nm (A\({}_{430\text{nm}}\)) multiplied by 0.039. The measurement of the color value in EBC units is calculated by the followingformula: Beer Color EBC: 25 \(\times\) A\({}_{\rm 430 nm}\)\(\times\) D, where D = dilution factor (in case dilution was performed on the initial sample).