Study of the Feasibility of Using Food-Grade Lactose as a Viable and Economical Alternative for Obtaining High-Purity β-Lactose

Abstract

β-lactose is an anomer of interest for the pharmaceutical and food industries due to its techno-functional properties; however, its production is often costly and complex. In this study, the feasibility of using food-grade lactose (F-αL) to produce β-lactose was evaluated as an accessible and cost-effective alternative. For this purpose, the physicochemical characterization of this lactose was carried out through X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Modulated Differential Scanning Calorimetry (MDSC), Fourier Transform Infrared Spectroscopy (FTIR), and Raman Spectroscopy. The mutarotation process was also performed using alcoholic KOH solutions. Physicochemical characterization confirmed that commercial lactose consists mainly of α-lactose monohydrate, which is an ideal precursor for β-lactose production. Likewise, the conversion process efficiently yielded β-lactose, validating the feasibility of using food-grade lactose in this process, with a residual α-lactose content below 10%, indicating a high conversion efficiency. Thus, food-grade lactose emerges as a viable alternative for producing high-purity β-lactose. This finding represents a 90% reduction in production costs of this anomer, promoting the development of high-quality products in the pharmaceutical and food sectors.

1. Introduction

The commercial and scientific interest in lactose increased considerably during the 19th century, when methodologies for its isolation, crystallization, and applications were reported [1]. Lactose is a disaccharide composed of galactose and glucose, linked through a β (1→4) glycosidic bond. Owing to the presence of the glucose unit in its structure, it can exist in solution in two forms: α-pyranose and β-pyranose [2]. These two forms depend on the mutarotation process (interconversion of their stereocenters), which is influenced by pH, the presence of acidic or basic catalysts, ionic strength, solvent and temperature [3,4]. In the solid state, lactose may crystallize in different polymorphic forms, including α-lactose monohydrate (αL⋅H₂O), stable hygroscopic α-lactose anhydrate, unstable hygroscopic α-lactose anhydrate, and β-lactose anhydrate. Each of these polymorphs exhibits distinct characteristics that can significantly affect the properties and quality of lactose-derived products [5,6,7].

α-Lactose monohydrate is the most common crystalline form obtained from whey, the main industrial source of lactose, exhibiting low hygroscopicity and high stability, and produced through concentration and crystallization processes in aqueous solutions under moderate temperature conditions [8]. In contrast, β-lactose can be obtained in the solid state as an anhydrous crystal. Compared to αL⋅H₂O, it displays lower hygroscopicity, higher solubility, higher critical relative humidity, and greater sweetness [9]. To convert α-lactose into β-lactose, the primary mechanism is mutarotation, a natural chemical process in which both anomers interconvert in aqueous solution until equilibrium is reached. This process can be accelerated or controlled through specific industrial conditions. At the chemical level, dissolving α-lactose in water and adjusting the temperature (25–50 °C) promotes ring opening and subsequent closure in the β form; the final equilibrium typically contains about 37% α-lactose and 63% β-lactose. Under mild alkaline conditions (pH 8–10), mutarotation occurs much faster, although higher pH is generally avoided to prevent side reactions such as degradation or lactulose formation [10]. Industrially, the conversion is achieved through controlled dissolution, agitation, and directed crystallization: lactose is dissolved at higher temperatures (≈55–60 °C) and then slowly cooled to favor β-lactose crystallization, which is more soluble; this higher solubility ensures that the β form remains in solution and crystallizes preferentially under suitable conditions [3]. Other industrial methods involve the use of vacuum evaporators, where a rapid temperature drop allows the formation of crystals rich in β-lactose, and roller drying at temperatures above 93.5 °C, yielding mixtures containing anhydrous α-lactose in a 70:30 β:α ratio [11,12]. These processes are widely used in the production of lactose powders and functional derivatives.

Commercially, lactose can be found in highly pure forms (≥99% for α and ≥70% for β) and as a mixture of α and β anomers. Because β-lactose is considerably more expensive than the α-anomer, this limits its industrial use despite its superior physicochemical properties [4,13]. In recent years, β-lactose has gained increasing attention due to its higher solid-state stability compared to α-lactose, which may offer advantages for pharmaceutical and food applications. In particular, previous studies have shown that β-lactose exhibits improved stability, making it a promising material for formulations requiring consistent performance and shelf stability [14,15,16]. Despite these advantages, the commercial use of β-lactose remains limited, mainly due to its high production cost and restricted availability. Currently available commercial products typically contain no more than 70% β-lactose, which significantly increases market price and limits a broader commercial implementation. In this context, the development of cost-effective methodologies capable of producing high-purity β-lactose from widely available raw materials represents a relevant opportunity to expand its use in high-value applications.

In this sense, different works have reported the production of β-lactose from stable anhydrous lactose and α-lactose monohydrate employing hydroxide alcoholic solutions [17,18,19]. This approach has led to a research line focused on evaluating process variables, with special attention on the purity of β-lactose and production yield. For example, Parrish, Roos and Valentine [17] employed potassium hydroxide in methanol for obtaining β-lactose from stable anhydrous lactose. They found that the addition of a small fraction of β-lactose may promote the interconversion process as in a solid-solid transformation. López-Pablos et al. [18] reported a simple methodology based on dissolution of αL⋅H₂O in 0.2% (wt%) sodium hydroxide methanol solution, and the static crystallization of high purity β-lactose (>99.9%). In their study, interconversion was carried out in a narrow temperature range of 29–31 °C. Lara-Mota et al. [19] tested the interconversion of αL⋅H₂O under different process variable such as catalyst type, temperature and stirring. They found that β-lactose could be obtained in shorter reaction times of 2–16 h, in reflux at 65 °C and relatively low concentration (0.014M) of catalysts (NaOH and KOH) dissolved in methanol. According to these authors, the combined effect of stirring and pH promoted a better dissolution of the α-lactose, while the catalyst inhibited the growth of this anomer and promoted the crystallization of β-lactose particles. As can be inferred, most of the works reported in this field are focused on the interconversion of αL⋅H₂O and on stable anhydrous lactose to obtain β-lactose.

Another type of lactose is commercial food grade lactose (F-αL), which, although cheaper than αL⋅H₂O, has not yet been considered as a possible source for obtaining β-lactose. For example, the price of reagent-grade αL⋅H₂O is approximately $70 USD/kg, while F-αL is only $5 USD/kg. Evidently, this difference may result in a substantial reduction in the production cost of β-lactose [20]. However, scare studies dealing with F- αL have been found in the literature. In a recent work, Toxqui-Terán et al. [21] compared the adsorption phenomena of four types of lactose with the aim of establishing their potential applicability. For this purpose, they employed three commercial lactose powders identified as αL⋅H₂O, F-αL and commercial grade β-lactose (C-βL), and one synthetized as high purity β-lactose (S-βL). Among their findings is a similar adsorption behavior (i.e., sorption isotherm type III, and monolayer water content about 0.5), and particle size and morphology between the two commercial α-lactose powders.

To date, no studies have reported the use of F-αL as a precursor for the production of β-lactose. Consequently, evaluating the feasibility of employing F-αL to obtain high-purity β-lactose is of considerable interest. In this context, the present study aims to carry out a physicochemical characterization of food-grade lactose and assess its suitability as a raw material for β-lactose production. Given that food-grade lactose exhibits physicochemical properties comparable to those of α-lactose monohydrate, its use may represent a viable and cost-effective alternative. Although food-grade materials permit a higher level of impurities than pharmaceutical-grade counterparts, the proposed approach offers an innovative pathway to enhance the availability of β-lactose. Ultimately, this strategy may reduce production costs and expand the application of β-lactose in both the food and pharmaceutical industries.

2. Materials and Methods

2.1. Materials

Food-grade α-lactose (F-αL, 99.8% α-lactose, Leprino Foods, Denver, CO, USA) was used as raw material without any further purification or processing. The interconversion process was carried out using distilled water, methanol (99.9% purity, CTR Monterrey, Nuevo León, Mexico), and potassium hydroxide (99% purity, CTR Monterrey, Nuevo León, Mexico) as the catalyst. Finally, neutralization was performed with nitric acid (70% purity, CTR Monterrey, Nuevo León, Mexico).

2.2. Interconversion Process of β-Lactose from Food Grade α-Lactose

High-purity anhydrous β-lactose was synthesized following the method described by Lara-Mota et al. [16]. In a typical reaction, 15 g of food-grade α-lactose were mixed in an Erlenmeyer flask with 150 mL of 0.014 M KOH in 95% MeOH. The mixture was refluxed at 65 °C for 2 h and then filtered after cooling. The pH of the wet powder was adjusted to 7.25 by washing with a 0.00014 M HNO₃ solution in 95% MeOH. The samples were dried at room temperature for three days. All experiments were performed in triplicate.

2.3. Physical Characterization

2.3.1. X-Ray Diffraction (XRD)

The crystalline phases were characterized through X-ray Diffraction (XRD) analysis employing a D8 Advance ECO diffractometer (Bruker, Karlsruhe, Germany). The instrument was outfitted with Cu-K radiation (λ = 1.5406 Å) and operated at 45 kV and 40 mA, utilizing an X’Celerator Detector in Bragg-Brentano geometry. Scans were conducted in the 2θ range of 5–50°, with a step size of 0.016° and 20 s per step.

2.3.2. Thermogravimetric Analysis (TGA)

Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were conducted utilizing a simultaneous TGA-DTA SDT Q600 instrument (TA Instruments, New Castle, DE, USA). The baseline was calibrated using indium, featuring a melting temperature of 156.6 °C and a melting enthalpy of 28.47 J/g. Samples weighing 5–10 mg were enclosed in standard aluminum cells. Thermograms were recorded at a heating rate of 5 °C/min within a temperature range of 25–500 °C. Subsequently, the thermograms were analyzed using the Universal Analysis 2000© software to determine mass loss (% w/w), melting temperature (Tm), and degradation temperature (Td).

2.3.3. Modulated Differential Scanning Calorimetry (MDSC)

The Tg was determined following the calorimetric protocol to generate amorphous structures from crystalline lactose samples, based on the methodologies proposed by [22,23] (Figure 1). A modulated differential scanning calorimeter (MDSC), model Q200, from TA Instruments (Lukens Drive, New Castle, DE, USA), equipped with an RCS90 cooling system, was employed. The instrument underwent calibration for temperature and enthalpy using indium as a standard, with sapphire serving as the standard for heat capacity. Each sample, weighing about 10 mg, was placed into sealed Tzero™ aluminum cells (New Castle, DE, USA). The thermal program used included heating and cooling ramps with a modulation of 40 s and an amplitude of 1.5 °C. Thermograms for samples were acquired following the thermal protocol described next: (i) isothermal at −30 °C for 1 min, (ii) heating from −30 to 190 °C at 20 °C/min, (iii) isothermal at 190 °C for 1 min, (iv) cooling from 190 to −30 °C at 10 °C/min, and (v) heating from −30 to 250 °C at 10 °C/min. The first heating ramp in the thermal protocol is designed to fully melt the lactose crystals. Once melted, the material undergoes rapid cooling to achieve the amorphous state and complete vitrification. Finally, the amorphous sample obtained through this process is subjected to a second heating, during which the Tg is observed as a step change in the reversing heat flow. The resulting thermograms were analyzed using Universal Analysis 2000 software, version 4.4A.

2.3.4. Morphological Characterization

Field emission scanning electron microscopy (FESEM) was carried out to observe the particle morphology of sample submitted to the interconversion process. This analysis was performed in a microscope JEOL JSM-7401F (JEOL, Tokyo, Japan) operated at 2 kV. Powder sample was dispersed on a carbon tape, and coated with a thin film of gold (5 nm thick) to avoid charging effects.

2.4. Chemical Characterization

2.4.1. Fourier Transform Infrared Spectroscopy (FTIR)

FTIR analysis was conducted on the powders using a Thermo Scientific Nicolet iS50 FTIR spectrophotometer (Waltham, MA, USA). The instrument was equipped with a Smart Orbit attenuated total reflectance (ATR) accessory featuring a diamond crystal. Spectral data were collected across the range of 4000 to 600 cm⁻¹ and subsequently analyzed using Omnic 9.3.32 software.

2.4.2. Raman Spectroscopy

Raman spectroscopy analysis was conducted utilizing a Horiba LabRam HR Evolution instrument equipped with a Jobin Yvon spectrometer and a 633 nm wavelength He-Ne red laser. A 100× objective Olympus BXFM-ILHS microscope facilitated laser beam focusing on the sample. Raman spectra were acquired within the range of 50 to 1500 cm⁻¹.

3. Results

3.1. Physical Characterization of Food-Grade α-Lactose

3.1.1. X-Ray Diffraction (XRD)

Figure 2 shows the XRD diffractograms of commercial F-αL. The sample exhibits well-defined and high-intensity diffraction peaks, confirming its fully crystalline nature. For the F-αL sample, the characteristic diffraction peaks observed at 2θ angles of 12.5°, 16.4°, 19.5°, and 20.5°, suggested that the food-grade sample consists predominantly of the α-lactose monohydrate anomer. These findings are consistent with those reported by Nijdam et al. [24], who conducted an XRD investigation of crystallized whey and crystallized whey permeate. They reported that the characteristic diffractions for α-lactose monohydrate were observed at these angles. Similarly, in a study that performed X-ray diffraction on lactose polymorphs, those diffractions peaks are attributed to the α-lactose monohydrate anomer [25], thereby validating the polymorphic composition of F-αL.

3.1.2. Thermogravimetric Analysis (TGA)

Differential thermogravimetric analysis (TGA-DTA) enables the determination of relevant thermal properties, such as evaporation, oxidation, degradation temperature, melting point, moisture content, and material purity [26]. Figure 3 shows the thermogram of sample F-αL, in which three thermal events were identified. The first thermal event occurred at 150 °C with a 5% weight loss, which was associated with the evaporation of water molecules present in the lactose structure. The subsequent events took place at 225 °C and 290 °C, with weight losses of 15% and 40%, respectively, corresponding to the thermal decomposition of glucose and galactose. These results are consistent with those reported by Listiohadi et al. [5] who studied the thermal analysis of amorphous lactose and α-lactose monohydrate. They reported three weight-loss events at 153 °C, which was attributed to the loss of crystallization water, and at 222 °C and 300 °C, which were associated with lactose crystal melting and thermal decomposition. Smith et al. [27] quantified the residual crystallinity in commercial ground lactose using thermoanalytical and spectroscopic techniques. Through TGA, they identified the temperature at which the release of crystallized water from the lactose molecule occurs. For commercial lactose, water evaporation was reported to begin at 144 °C, while lactose crystal melting was observed above 200 °C. More recently, Melnikova et al. [28] conducted thermal analysis on confectionery products containing lactose. They reported that pure lactose exhibits three thermal events at 150 °C, 240 °C, and 280 °C, which are consistent with the findings of the present study.

3.1.3. Modulated Differential Scanning Calorimetry (MDSC)

Given the importance of lactose in both the food and pharmaceutical industries, understanding its thermal behavior is crucial for defining appropriate processing and storage conditions [29]. First-order transitions involve changes in thermodynamic properties such as entropy, enthalpy, or volume, and are associated with processes such as crystallization, melting, condensation, or evaporation. In contrast, second-order transitions do not affect latent heat or volume but alter properties such as heat capacity (Cp), isothermal compressibility, thermal expansion coefficient, and time-dependent phenomena [30,31]. In polymeric materials and small molecules such as disaccharides, the most common time-dependent kinetic phenomenon is the glass transition temperature (Tg), which is related to changes in molecular mobility and system relaxation time. This property can be determined using modulated differential scanning calorimetry.

Prior to presenting the MDSC results, it is important to highlight that F-αL was subjected to heating–cooling cycles (as described in the experimental section) to obtain an amorphous state. This was achieved by heating the samples to 190 °C for 1 min, followed by rapid cooling to –30 °C. Subsequently, they were reheated to 250 °C to determine Tg. The selection of 190 °C as the heating temperature was made to prevent thermal degradation of the samples, as melting begins at 200 °C and thermal decomposition occurs above 225 °C.

The analysis of the thermograms, based on modulated, reversible, and non-reversible heat flow, enabled the differentiation of Tg from other thermal events such as evaporation or melting, thus revealing the characteristic thermal events of F-αL. In the thermograms, Tg is observed as a small change in the slope of the reversible heat flow curve. Figure 4 shows the thermogram obtained by MDSC for F-αL. Three signals are included: (i) modulated total heat flow (blue sinusoidal curve), (ii) reversible heat flow (black curve), and (iii) non-reversible heat flow (red curve). In the reversible heat flow the slope change was pronounced, showing a Tg value of 60.47 °C. This result is consistent with those reported by Haque et al. [32], who conducted a study on the glass transition and enthalpic relaxation of α-lactose. For Tg specifically, they reported a value of 101 °C for dry lactose. However, this value may decrease with increasing moisture content due to the plasticizing effect of water. When the sample reached 4% of moisture content, Tg decreased to 60 °C. Similarly, in the study by Fitzpatrick et al. [33], who investigated Tg, flowability, and caking of lactose-containing powders, crystalline lactose was reported to be strongly influenced by the increase in moisture content. They reported a Tg of 90 °C for lactose stored at 20 °C with 5.8% moisture, while at 14.7% of moisture content, Tg decreased to 8 °C.

3.1.4. Morphological Characterization

According to the research conducted by Wong and Hartel [34] on lactose crystallization, the crystallization rate has been reported as a determining factor in particle morphology. The crystalline structure of lactose has been documented by various authors, who describe α-lactose particles as irregular, pyramidal, or tomahawk-type shapes, whereas the β-lactose anomer typically forms elongated needle-like or curved prismatic structures [35,36]. Figure 5 presents the characterization of F-αL, where only particles with irregular morphology are observed. This evidence suggests that the sample is predominantly composed of the α anomer.

3.2. Chemical Characterization of Food-Grade α-Lactose

3.2.1. Fourier Transform Infrared Spectroscopy (FTIR)

FTIR has been widely employed to identify the characteristic vibrations of lactose anomers, which are associated with the stretching of hydroxyl groups (3700–3200 cm⁻¹) and C–H bonds present in glucose and galactose molecules (3000–2800 cm⁻¹), the bending of OH groups from crystallized water molecules (1650 cm⁻¹), the bending of the glycosidic C–O–C bond (1200–1070 cm⁻¹), the stretching of the glycosidic C–O bond (1150–950 cm⁻¹), and the out-of-plane bending of OH groups (950–750 cm⁻¹) [5,37]. Figure 6 shows the FTIR spectrum of F-αL, where the observed bands were characteristic of the α-lactose anomer. High-intensity vibrations corresponding to the out-of-plane bending of OH groups were observed at 916, 899, and 876 cm⁻¹, along with a band associated with the bending of OH groups from crystallized water molecules at 1660 cm⁻¹. Finally, a low-intensity vibration detected at 3525 cm⁻¹ corresponded to hydroxyl group stretching.

The results obtained in this study are consistent with those reported by Kirk et al. [9], who investigated different analytical techniques for identifying polymorphic forms of lactose. Similarly, in a study on the synthesis of anhydrous β-lactose using alcoholic solutions and inorganic salts as a conversion medium; they reported that for α-lactose monohydrate, the characteristic vibrations appear at 3521, 1650, 915, 898, and 875 cm⁻¹ [19]. In this sense, Fan et al. [38], investigated the vibrational spectra of amorphous lactose, as well as the effect of temperature and water plasticization on the formation of crystalline lactose anomers and molecular mobility. They identified the FTIR characteristic vibrations of α-lactose monohydrate at 3494, 1670, 1045, 1008, and 979 cm⁻¹. Clearly, all of these results are in agreement with those reported here for the F-αL sample.

3.2.2. Raman Spectroscopy

Raman spectroscopy is considered a useful tool for characterizing lactose anomers [39]. Although the interpretation of the complete spectrum is often complex, typically only the molecular vibrations that help confirm the presence of the anomer of interest are reported. For instance, the vibration mode at 357 cm⁻¹ is associated with the torsion of CO–OH and H–OH groups. For α-lactose monohydrate, this vibrational mode appears as a single high-intensity peak. In addition, the vibration mode observed at 1100 cm⁻¹ is associated with the rotation of the C–O–C bond, which enables the formation of the anomeric linkage. At this frequency, α-lactose monohydrate displays a single high-intensity vibration [9,40,41,42].

Figure 7 shows the Raman spectrum of F-αL, where the two vibrational modes characteristic of the α-lactose anomer, appeared as single high-intensity bands at 357 and 1100 cm⁻¹. The results obtained in this study are consistent with those reported by López-Pablos et al. [18], who prepared and characterized anhydrous β-lactose derived from α-lactose monohydrate. To identify the different anomers, they relied primarily on the Raman vibrations at 357 cm⁻¹ and 1100 cm⁻¹. At these Raman shifts, the vibrations of α-lactose are observed as single high-intensity peaks. Based on the previously described investigations and the data obtained from the various physicochemical analyses, it is confirmed that the F-αL sample consists predominantly of α-lactose monohydrate, suggesting its potential suitability for undergoing mutarotation to obtain β-lactose.

3.3. Characterization of F-αL After the Mutarotation Process

Once the mutarotation process of F-αL was completed, the resulting powders were physicochemically characterized using the techniques described in the experimental section. As previously mentioned, these analyses allow differentiation of the anomeric forms of lactose and are therefore suitable for evaluating the degree of interconversion from F-αL to β-lactose.

The microstructural characterization by XRD of F-αL subjected to the mutarotation process (Figure 8) revealed the presence of well-defined diffraction peaks characteristic of β-lactose at 2θ angles of 10.5, 19, and 21°. These findings are consistent with those reported by Lara-Mota et al. [16], who evaluated the stability of β-lactose under different storage conditions.

According to McSweeney & O’Mahony [43], lactose crystallization follows a standard mechanism comprising the stages of concentration, nucleation, growth, and collection/washing, with the crystallization rate being a key factor determining the final particle size and morphology. Figure 9 presents the SEM micrographs of F-αL sample after subjected to the mutarotation process. These images reveal the characteristic structures of β-lactose, observed as curved needle-like prisms (highlighted with red ellipses). These findings are consistent with those reported by López-Pablos et al. [18] and Lara-Mota et al. [19], who evaluated different methodologies for obtaining high-purity β-lactose.

Furthermore, the chemical characterization performed by FTIR confirmed the exclusive presence of the β-lactose anomer. As shown in Figure 10, the characteristic vibration bands associated with this anomer were clearly identified at 950, 890, 875, and 835 cm⁻¹. These findings are consistent with those previously reported by Altamimi et al. [14] and Fan et al. [38], who analyzed the vibrational spectra of lactose anomers using FTIR techniques.

4. Discussion

Currently, the production of β-lactose has attracted increasing interest due to its properties, which differ from those of α-lactose. Several studies have evaluated the properties of β-lactose, highlighting its solubility and dissolution rate [44,45]. Specifically, these characteristics are particularly relevant in the pharmaceutical field, as they allow their application in formulations requiring concentrated solutions and efficient availability of active ingredients [46]. Likewise, the crystalline structure and physical properties of β-lactose favor the design of drugs developed by direct compression and immediate release [47]. In the food sector, the higher solubility of β-lactose enables its incorporation into liquid matrices and dairy products, resulting in a wide range of techno-functional applications [20]. In this field, solubility is of vital importance, since, according to Parrish et al. [17], α-lactose monohydrate is more prone to crystallization than even stable anhydrous α-lactose. When the size of these crystals exceeds 30 μm, the textural properties of the food can be affected.

The food and pharmaceutical industries invest substantial resources in the search for new materials that enable the formulation of high-quality, safe, and functional products, while remaining economically viable [15,20]. In this context, innovating in the production process of β-lactose represents a strategic opportunity, as this anomer exhibits superior techno-functional properties that support its application as an excipient in pharmaceuticals and as an additive in specialized foods. From an economic perspective, obtaining high-purity β-lactose through more efficient methodologies helps reduce production costs, facilitating industrial access to this compound. Moreover, having a standardized, cost-effective, and scalable process for β-lactose would enable the global production of high-quality medicines [20].

Therefore, the methodology proposed herein addresses the need for efficient (yield > 90%) and economically viable routes for β-lactose production by offering a simple and practical process that does not require specialized equipment or costly reagents. The use of low concentrations of KOH as a catalyst, together with straightforward product separation by conventional filtration and solvent removal by evaporation at room temperature, contributes to the feasibility and low cost of the process. Additionally, the implemented washing step allows catalyst neutralization and pH standardization without the need for complex post-treatment steps. As a result, high-purity β-lactose is obtained, with a residual α-lactose content below 10%. Although further study of the properties and performance of this product is still needed (such as toxicity and sensory testing), the approach reported herein shows a potential scalable and competitive alternative for β-lactose production.

5. Conclusions

The present study demonstrated the technical feasibility and potential economic viability of using food-grade α-lactose (F-αL) as a precursor to produce high purity β-lactose. Physicochemical characterization confirmed that F-αL is mainly composed of α-lactose monohydrate, making it an alternative precursor for the mutarotation process. The physicochemical results validated the interconversion of F-αL into high-purity β-lactose. The interconversion process was a simple and scalable method based on the dissolution of F-αL in 0.014 M KOH methanol solution, in reflux conditions at 65 °C for 2 h. In this regard, the use of F-αL represents an interesting alternative to reduce production costs, increase the availability of β-lactose in the market, and leverage its techno-functional properties for the development of innovative and high-value products in the pharmaceutical and food industries.