# Quantifying Fermentable Sugars in Beer: Development and Validation of a Reliable HPLC-ELSD Method
## 1 Introduction  
Sugars are fundamental to the beer production process, particularly during fermentation, and they impact several critical characteristics of the final product. The sweetness of beer, for instance, is directly influenced by the presence of simpler sugars that remain unfermented. These sugars, derived from malt or added as primings, contribute residual sweetness and, in the case of priming, help achieve specific CO\({}_{2}\) levels by encouraging secondary fermentation [1]. Additionally, carbohydrates with more than four glycosidic units, while contributing little to sweetness, enhance beer's body and texture by increasing its viscosity. These high-molecular-weight polysaccharides are less relevant to foam stability but do influence viscosity, which may, in turn, impact foam retention [2]. Residual components, such as undegraded starch and \(\beta\)-glucans, if present in the final product, can lead to turbidity due to increased resistance to enzymatic breakdown upon cooling [1].  
Various analytical methods have been developed for determining sugars in beer and other fermented beverages. High-performance liquid chromatography (HPLC) with different detectors, such as ultraviolet (UV) and refractive index (RI), has been widely usedfor the individual quantification of sugars [3]. High-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) has shown effectiveness in quantifying oligosaccharidescharides in beer without pre-treatment [4]. Spectrophotometric methods, including phenol sulfuric acid (PSA) and 3-methyl-2-benzo thiazol hydrazone hydrochloride (MBTH), are commonly used for total sugar estimation [5]. Enzymatic biosensors have demonstrated potential for rapid and cost-effective sugar analysis during fermentation [6]. Novel approaches include the use of gold nanoparticles for localized surface plasmon resonance measurements [7] and capillary electrophoresis with laser-induced fluorescence [8] or indirect UV detection [9]. Gas chromatography-mass spectrometry has also been employed, utilizing solid-phase microextraction and on-fiber derivatization [10]. These methods have been applied to various stages of beer production, including word analysis and final product testing. Additionally, HPLC-ELSD has been previously used to characterize sugar profiles in beer, as shown by [PERSON] et al. [11], demonstrating its potential for evaluating carbohydrates in dry-hopped beer. However, that work did not include full analytical validation or application to industrial batches under process control conditions.  
Although refractive index (RI) detectors have historically been used for carbohydrate analysis, limitations in sensitivity and susceptibility to baseline drift make them less ideal for more precise applications [12]. ELSD is a quasi-universal detection method for compounds lacking chromophores, offering advantages over UV detection [13; 14]. ELSD's sensitivity is generally better than that of the RI, but the detector's response is affected by analyte properties, including melting point and volatility [15]. Quantification can thus be challenging due to the lack of linear response and the impact of molecular structure on detection [16; 17]. Despite its limitations, ELSD remains a valuable tool for various applications in pharmaceutical, food, and natural product analyses [14; 18].  
In this study, an HPLC-ELSD method was developed, optimized, and fully validated for the quantification of fermentable and reducing sugars in brewing matrices. The primary goal was to establish a reliable analytical tool suitable for routine application in industrial settings. The method was subsequently applied to real brewing samples to demonstrate its utility in monitoring fermentation progress and supporting process control decisions.