CE Tells You What’s Really in Your Food
Capillary electrophoresis has emerged as a powerful tool in the fight against adulterated food and beverage.
Nowadays, it can be somewhat challenging to identify the food and drink products you consume as natural ones. Stories that could be found only in science fiction novels 40 to 50 years ago—where people were forced to eat only fully artificial foods—are closer to reality than ever before. And increasing concerns about the overall amount of food left on Earth move us further away from natural products. In some cases, consumers are aware if a food or drink product is fully artificial; but in other cases, the correct information may not always be available. This happens especially when dealing with partially artificial food products, where “something” is added, but consumers have no any idea how far the additives are from the natural components and to which extent they can trust the product label. Artificial additives can “convert” spoiled meat into fresh, can drastically improve the taste of a low-grade fish or can mask falsification of a noble wine or cognac. Earth-shattering news, which we get from time to time from different parts of the world about food falsification, prove how serious the actual situation is.
The beverage industry is the field where additives are used most frequently. Combination of several artificial additives like sweeteners, dyes, preservatives, emulsifying agents, aromatizers, stabilizers and more, can improve properties, but sometimes do not meet any sanitary norms. Only with savings consideration in mind, some food and beverage manufacturers are using more cheap raw materials, higher amounts of low-grade artificial additives and low-quality technologies. Three tasks are especially important in food and beverage analysis: determination of safety parameters (preservatives, sweeteners, dyes); determination of quality parameters (amino acids, organic acids, inorganic anions and cations, sugars); and determination of identification parameters (authenticity confirmation).
The last task partially covers determination of both safety and quality parameters. For example, in beverages, the concentrations of certain dyes as safety parameters are strongly regulated and should not exceed the specified upper limit. On the other hand, the mixture of dyes presented in a wine can serve as a clear confirmation of wine falsification. The same is true of quality parameters—concentrations of amino acids, organic acids, phenolcarboxylic acids and aromatic aldehydes can serve as additional identification parameters for certain beverages.
Determination of all these components can be executed with different methods. In the last decade, however, capillary electrophoresis (CE) has gained popularity in this field due to its numerous benefits. CE needs very low sample amount and consumes a small amount of reagents, provides highly reliable quantitative results, is well-suited for automation and exhibits enhanced separation efficiency. Wine and spirits are especially well-suited for analysis by CE since many of their components are charged or can be charged under certain conditions. The absence of any packed material inside the capillary eliminates the problems of its aging or unspecific binding and, on the other hand, gives rise to a high universality of the capillary. Just by varying buffer pH, ionic strength or additives, it is possible to analyze different classes of compounds using the same capillary.
CE offers complete solutions for determination of: inorganic cations and anions in water samples, beer, wines and brandies; biogenic and aliphatic amines in wines; organic acids in alcoholic and non-alcoholic beverages; caffeine, ascorbic acid, sweeteners and preservatives; amino acids; and hop and bitter acids in beer. Of course, this list is not complete. Only the most frequently used protocols are listed. Additional components like catechins, vitamins, sugars and alkaloids can also be easily determined in many types of beverages. Next, some of the most representative examples are demonstrated.
Inorganic cations in wines and brandies
The most commonly present inorganic anions and cations in beverages are chloride, sulphate, nitrate, nitrite and phosphate as anions, and potassium, sodium, magnesium and calcium as cations. Their concentrations (especially for cations) can be very informative. Wines and brandies, stemming from the same wine-making region, exhibit a similar range of cations concentration.
Working with Lumex Instruments’ Capel series of CE systems for wine analysis, the company’s customers have composed such ranges for some of the most important wine-making regions of East Europe. Deviation from this range can indicate falsification. Two examples of cations determination in wines can be seen in Figures 1 and 2. Whereas the electropherogram in Figure 1 comes from natural wine, with all the cations being in the estimated range, Figure 2 shows a much less amount of potassium, indicating clear falsification. Increased amounts of potassium or calcium in wines can also indicate that it is full of impurities.
Remarkably, under the same CE conditions and simultaneously with inorganic cations, some aliphatic and biogenic amines, as well as two important aminoacids, can also be determined. Specifically, the amounts of biogenic amines (putrescine, cadaverine, histamine and thyramine) are informative because their presence reveals severe deviations in production technology and indicates product spoiling. Amines and amino acids can clearly be seen in Figure 1. Here, aliphatic amines migrate as minor peaks around the peak of sodium, whereas amino acids lysine and arginine migrate just before the peak of calcium.
It is also important to know the cations concentration in brandies and vodkas. An increased amount of iron or calcium makes brandy feculent, and even changes its color. An increased amount of sodium in vodka may indicate aging problems with ion-exchange cartridges, normally used to treat the water before its mixing with ethanol. A significantly decreased amount of all cations in brandy (normally less than 10 mg/L) points to the fact that the brandy is most likely fully false.
Preservatives and sweeteners
A combination of additives, specifically preservatives and sweeteners, is commonplace in non-alcoholic and weak alcoholic beverages like energy drinks, long drinks, cola, etc. Sodium benzoate and sorbic acid are widely used as preservatives, and saccharine, aspartame and acesulfame K as sweeteners. However, ascorbic acid can be present in such drinks as both an antioxidant and vitamin. Of course, caffeine is added to all energizing drinks. Most of these components are strongly regulated; their amounts should not exceed the specified upper limit. The developed CE-based method offers a detailed protocol on how to determine these additives in one run. Solid food examples like mayonnaise, soy sauces, and ketchups can also be easily analyzed for preservatives and sweeteners.
Organic acids in wines and beers
Organic acids’ profiles in wines at different stages of production can be very telling, as they reveal the important features of the technological process used. Alcoholic fermentation, malolactic fermentation, wine maturation, bacterial contamination—all these processes can be followed by analyzing organic acids profiles. It is also one of the most important criteria of wine authentication.
An analytical method, developed by Lumex, offers a protocol, which gives complete information about almost all organic acids in just 5 to 6 minutes. It also allows simultaneous determination of other acids, like ascorbic, benzoic and sorbic.
As volatile acidity in wines can be attributed by more than 98 percent to the amount of acetic and formic acids, this parameter can be quantified with this kit just by quantifying the corresponding acids. Thus, the typically laborious and time-consuming distillation stage required in the classical analysis of volatile acidity is eliminated.
Figures 3 through 5 show just how informative total organic acids analyses in wines can be. Figure 3 demonstrates analysis of high-quality white wine, in which malolactic fermentation has been completed. Alternatively, Figure 4 is an example of the analysis of so-called “house wine,” in which the high amount of malic acid clearly indicates the incompleteness of malolactic fermentation.
Organic acids analysis also allows researchers to identify fully false wine, as seen in Figure 5. Instead of several organic acids, only two of them—tartaric and lactic—are present in the sample; no traces of phosphate were found. In this case, the standard analysis for the total acidity, which is obligatory for each enological laboratory, did not indicate any falsification and was thus useless. The same protocol is applied for the analysis of organic acids in beer.
Bitter acids in beer
Hop acids, such as humulons (α acids) and lupulons (β acids), are very important components of beer as they are served as certain biochemical markers of the definite hop type. Hop α acids are tasteless but easily convert into bitter iso α acids (isohumulons) by wort boiling. Bitter iso α acids stabilize the beer foam, suppress the growth of undesirable microorganisms and give the beer its bitter taste. Both types of hop acids define the beer taste and must be controlled in the beer production process and in the final product.
In Lumex’s laboratory, a CE-based method for the analysis of bitter and hop acids in beer and wort was recently developed. Using features of spectrophotometer detection, two parts of analysis were automatically run under different wavelengths, enabling high sensitivity and selectivity. The analysis can be completed in just nine minutes, which is much faster than the standard HPLC-based method for hop acids determination, demanding more than one hour.
In the history of human civilization, we have drastically changed our attitude toward our food. Indeed, it is hard to imagine a prehistoric man about 10,000 years ago eating a mammoth’s trunk and pondering the potential health risk from the high content of cholesterol. But nowadays, we estimate the risk, we distinguish between safe and potentially unsafe food and we carefully read small print on the labels. While capillary electrophoresis can’t fully solve the problem of food safety in just a minute, it can help provide knowledge—which is the difference between us and prehistoric man.