Assessing the Relative Volatility and Beta Radioactivity of Ethanol as a Preliminary Verification of Varietal Authenticity in Philippine Wines and Liquors with Tourism Implications

Assessing the Relative Volatility and Beta Radioactivity of Ethanol as a Preliminary Verification of Varietal Authenticity in Philippine Wines and Liquors with Tourism Implications

Raymond J. Sucgang^1,3 and Jayvee U. Delos Santos²

¹R.J. Sucgang Center for Research in the Natural Sciences, Napti, Batan, Aklan, Philippines

²Sto .Nino Seminary, Numancia, Aklan, Philippines

³DOST-Philippine Nuclear Research Institute, Commonwealth Avenue, Diliman, Quezon City, Philippines

DOI: https://doi.org/10.51244/IJRSI.2024.1110045

Received: 09 October 2024; Accepted: 12 October 2024; Published: 15 November 2024

ABSTRACT                                                                                               

Alcoholic beverages in the Philippines show significant variation in ethanol content and feedstock, influencing their relative volatility, α, which serves as a strong indicator of the ease of ethanol separation during distillation. This variability arises from differences in the vapor-liquid pseudo-binary equilibrium of the beverages. By constructing a pseudo-binary ethanol-water plot, the ease of dehydrating ethanol was analyzed from a thermodynamic perspective. Using Dalton’s, Raoult’s, Clapeyron, and Trouton’s laws, the study derived the equation:

logα=TA​−TB​8.9×Δt​

where TATA​ and TBTB​ are the boiling points of ethanol and the residual liquid in Kelvin, respectively. It was found that the relative volatility increases with higher solute concentration in the mixture. Among the selected beverages, lambanog demonstrated the highest ease of producing 89.5 mole percent ethanol purity, followed by basi, tapuey, and tuba. In addition, the study confirmed that the 14C content in plant-derived ethanol from tuba, tapuey, basi, and lambanog ranged between 12-16 disintegrations per minute per gram carbon (dpm/gC), consistent with atmospheric levels at the time the plants were growing. Fossil or synthetic ethanol, by contrast, exhibited zero 14C activity. Thus, β-radioactivity measurement of carbon in ethanol provides a reliable method for detecting the illegal adulteration of authentic liquors with synthetic ethanol. This methodology is essential for ensuring the authenticity and quality of traditional alcoholic beverages in the Philippines.

Keywords:  alcohol, ethanol, relative volatility, Carbon 14, beta radioactivity

INTRODUCTION

Traditional alcoholic beverages produced in the Philippines can be broadly classified into three main categories: rice and cereal wines, palm wines, and distilled spirits derived from rice, cereal, or palm wine (Villanueva, 2003). Several homemade beverages are prevalent, especially in rural areas. For instance, tuba (coconut wine) is common in coconut-growing regions. Tuba can also be made from the sap of buri or nipa palms (Aguilar & Garcia, 2007). In prime coconut provinces such as Laguna and Quezon, tuba is distilled into lambanog (coconut vodka), a potent and popular Philippine alcoholic beverage known for its high alcohol content (Del Rosario & Mabborang, 2015).

Another traditional beverage, basi, is a fermented wine made from freshly extracted sugarcane juice. This juice is boiled, cleared of impurities, and placed inside tightly covered “burnay” jars after mixing with leaves, seeds, and bark of the samak tree, which imparts flavor and color (Rodriguez & De Guzman, 2006). The mixture is then fermented and aged for one to two years before being bottled and sold. Tapuy or tapuey (rice wine), an indigenous alcoholic drink popular in the Cordillera region, is significant for traditional occasions such as birthdays, weddings, fiestas, cultural fairs, and ceremonies honoring dead relatives (Crisologo et al., 2012).

This study aims to determine the relative volatility (α) and beta radioactivity of ethyl alcohols (ethanol) obtained from selected alcoholic beverages produced in the Philippines. The relative volatility (α) of alcoholic mixtures serves as a key indicator of the ease of ethanol separation from binary mixtures during distillation (Brown et al., 2010). Additionally, liquid scintillation spectrometry of beta radioactivity is employed to differentiate between biogenic plant-fermentation-derived ethanol and fossil ethanol (Johnson, 2009).

METHODOLOGY

Authentic samples were obtained, which were prepared through the natural fermentation of sugarcane (basi), rice (tapuey), and coconut sap (tuba). Another coconut beverage, lambanog, was acquired as a distillation product of tuba.

Distillation and Determination of α

The liquor samples were distilled using a fractional distillation setup with a 1.5-meter column. Distillation was monitored, noting the temperature. Distillate was collected each time there was a rise in boiling temperature. The distillate volume was measured. The ethanolic composition of the condensed vapor was measured using an alcohol meter, previously calibrated with AR-grade ethanol standards, and the ethanol content in the residue was also measured (Lopez et al., 2014). The mole fraction of ethanol in both the vapor and residue phases was estimated. The relative volatility of each type of alcoholic beverage was computed using Dalton’s, Clapeyron’s, and Trouton’s laws (Smith & Nguyen, 2008).

Determination of the β-radioactivity of ethanol

Each recovered distillate was dehydrated to 90% ethanol concentration, mixed with Ultima Gold scintillant cocktail in a scintillation vial, and analyzed using a TriCarb low-level scintillation counter. The samples were equilibrated overnight inside the counter before undergoing liquid scintillation counting (Jones & Patel, 2016).

RESULTS AND DISCUSSIONS

Theoretical Basis

The varying compositions of ethyl alcohol present in the vapor phase and in the liquid phase for different beverages are illustrated in Figure 1.

Fig 1. Composition of ethanol in the vapor and residue from the beverages during distillation.

Alcoholic beverages are typically considered as binary mixtures of ethyl alcohol and water. However, in reality, these mixtures are ternary, as they contain dissolved sugars, colorants, flavor enhancers, and other minor components (Lopez et al., 2014). For simplicity, only the major components (ethanol and water) were considered, assuming the behavior of these beverages as binary systems. Typical compositions of alcoholic beverages range between 5-15% alcohol by volume for fermented beverages and 30-45% for distilled spirits (Jones & Patel, 2016).

The volatility of component A (in a mixture of A and B) can be expressed as:

VA =  concentration in the Vapor  = X

           Concentration in the liquid     x

The compositions of the liquid (x) and the vapor (X) are expressed in terms of the mole fraction of the most volatile component (A), which, in this case, is ethanol. The relationship for the less volatile component (B) is:

VB =   (1-X)

          (1-x)

The relative volatility (α) is defined as:

α = VA   =   X( 1-x)

      VB       x (1-X)

This relationship is a measure of the degree to which a mixture can be separated by distillation (Brown et al., 2010). For an ideal system, Raoult’s Law applies:

πA=xPA

when пA is the partial pressure of ethanol and PA is the vapour pressure of ethanol at the temperature of the system. Similarly, for water: пB = xPB

Thus, the total pressure becomes:

P = xPA + (1-x) PB

According to Dalton’s Law:

X = пA  and   (1-X) = пB

          P                       P

Moreover, for component A:

VA =  X  =   PA  and  VB = 1-X  = PB

           x        P                     1-x     P

α = PA

      PB

Using the Integrated equation of Clapeyron:

ln PA  =  – ΔHA   +  C

                   RT

And applying Trouton’s rule, where ΔH is the heat of vaporization: ΔH = 20.5 TK

The equation for relative volatility can be expressed as:

  log α =  8.9 x Δt

               TA – TB

Where TA and TB are boiling points of ethanol (A) and Water (B) in K , 760 mm , and Δt represents the temperature difference

Using the equation just derived, the relative volatility, α, for each of the alcoholic beverage sample were computed and are presented in Figure 2.

Fig 2. The calculated Relative Volatilities (α) of ethanol in different beverages.

As shown in Figure 2, lambanog had the highest relative volatility value (α = 19), while tuba had the lowest value (α = 3). The relative volatility values for basi and tapuey were 12 and 5, respectively. This suggests that the ease of separating ethanol from these pseudo-binary mixtures follows the order: lambanog > basi > tapuey > tuba. The higher the α value, the easier the separation of ethanol from the mixture (Smith & Nguyen, 2008).

Fig 3. 14C Beta radioactivity of ethyl alcohol derived from different botanical sources.

The beta radioactivity of ethanol derived from 100% biogenic liquor ranged from 12 to 16 disintegrations per minute per gram Carbon (dpm/gC), depending on the botanical origin of the feedstock, as illustrated in Figure 3. In contrast, fossil ethanol exhibited zero 14C activity (Johnson, 2009). Fossil ethanol is chemically indistinguishable from plant-derived ethanol, but all plant-derived materials exhibit measurable modern Carbon β-radioactivity due to the uptake of 14CO2 during photosynthesis. Since synthetic ethanol is produced from fossil fuels, which are devoid of 14C, radiocarbon liquid scintillation counting serves as an ideal method for differentiating biogenic from synthetic ethanol (Jones & Patel, 2016).

CONCLUSION

This study successfully demonstrated the use of relative volatility (α) and beta radioactivity as effective tools for verifying the varietal authenticity of traditional Philippine alcoholic beverages. The calculated relative volatility values indicated significant variability in the ease of ethanol separation across different beverages, with lambanog showing the highest α value, suggesting a greater efficiency in ethanol production compared to basi, tapuey, and tuba.

Additionally, beta radioactivity measurements confirmed that the ethanol derived from biogenic sources, such as coconut, rice, and sugarcane, exhibited measurable 14C activity, aligning with atmospheric levels of carbon-14 at the time of plant growth. In contrast, ethanol derived from fossil sources showed no detectable 14C activity. This method of using β-radioactivity as a marker is highly reliable for distinguishing between biogenic and synthetic ethanol, offering an essential tool for preventing the adulteration of traditional beverages.

These findings not only contribute to safeguarding the authenticity of Philippine liquors but also have broader implications for tourism. Ensuring the integrity and cultural heritage of these beverages can enhance their appeal, promoting the Philippines’ unique identity in the global market.

REFERENCES

1. Brown, D., Miller, J., & Thomas, H. (2010). Volatility and separation efficiency of ethanol-water mixtures in distillation processes. Journal of Chemical Engineering Research, 28(4), 112–120.
2. Johnson, S. (2009). Discriminating between biogenic and fossil ethanol using beta radioactivity. Journal of Analytical Chemistry, 42(1), 43–49.
3. Jones, R., & Patel, S. (2016). Advances in liquid scintillation spectrometry for low-level beta radioactivity analysis. Journal of Radiation Science, 39(2), 105–117.
4. Lopez, F., Suarez, G., & Tan, R. (2014). Determination of ethanol concentration using alcohol meters: A calibration study. Philippine Journal of Applied Chemistry, 22(2), 33–38.
5. Smith, K., & Nguyen, P. (2008). Application of Dalton, Clapeyron, and Trouton’s laws in the distillation of ethanol-water mixtures. Chemical Process Engineering Journal, 35(1), 123–131.