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Keywords:

  • caffeine;
  • carbonated beverages;
  • soft drinks

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results and Discussion
  6. Conclusion
  7. References

ABSTRACT:  Caffeine is a well-known stimulant that is added as an ingredient to various carbonated soft drinks. Due to its stimulatory and other physiological effects, individuals desire to know the exact amount of caffeine consumed from these beverages. This study analyzed the caffeine contents of 56 national-brand and 75 private-label store-brand carbonated beverages using high-performance liquid chromatography. Caffeine contents ranged from 4.9 mg/12 oz (IGA Cola) to 74 mg/12 oz (Vault Zero). Some of the more common national-brand carbonated beverages analyzed in this study with their caffeine contents were Coca-Cola (33.9 mg/12 oz), Diet Coke (46.3 mg/12 oz), Pepsi (38.9 mg/12 oz), Diet Pepsi (36.7 mg/12 oz), Dr Pepper (42.6 mg/12 oz), Diet Dr Pepper (44.1 mg/12 oz), Mountain Dew (54.8 mg/12 oz), and Diet Mountain Dew (55.2 mg/12 oz). The Wal-Mart store-brand beverages with their caffeine contents were Sam's Cola (12.7 mg/12 oz), Sam's Diet Cola (13.3 mg/12 oz), Dr Thunder (30.6 mg/12 oz), Diet Dr Thunder (29.9 mg/12 oz), and Mountain Lightning (46.5 mg/12 oz). Beverages from 14 other stores were also analyzed. Most store-brand carbonated beverages were found to contain less caffeine than their national-brand counterparts. The wide range of caffeine contents in carbonated beverages indicates that consumers would benefit from the placement of caffeine values on food labels.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results and Discussion
  6. Conclusion
  7. References

Caffeine, 1,3,7-trimethylxanthine, is an odorless, slightly bitter substance found in numerous plant species (Tarka and Hurst 1998). Extracts derived from these plants, such as coffee and tea beverages, naturally contain caffeine and other methylxanthines. Caffeine is intentionally added as an ingredient to many carbonated soft drinks, including colas, pepper-type beverages, and citrus beverages. Although soda manufacturers may explain that caffeine contributes to the flavor of soft drinks, only 8% of adults were able to differentiate between caffeinated and caffeine-free colas at the concentration of caffeine contained in most cola beverages (Griffiths and Vernotica 2000). These beverages appeal to many consumers because of the stimulatory effect caffeine provides.

Caffeine has drawn more attention in the past decades due to its widespread consumption and physiological effects beyond that of its stimulatory effect (James 1991; Bernstein and others 2002; Mandel 2002). Caffeine is quickly absorbed by the body. The human salivary caffeine level, which indicates the extent of absorption, peaks around 40 min after caffeine consumption (Liguori and others 1997). Various physiological effects on the central nervous, cardiovascular, gastrointestinal, respiratory, and renal systems have been reported (Nehlig and others 1992; Spiller 1998; Hartley and others 2004; Savoca and others 2005). For example, Hartley and others (2004) reported that caffeine causes a mild elevation in blood pressure. In addition, caffeine's diuretic effect is widely known (Spiller 1998).

Various governmental bodies have specified the maximum level of caffeine allowed in carbonated beverages. The U.S. Food and Drug Admin. limits the amount of caffeine in carbonated beverages to a maximum of 0.02% (FDA 2006). Therefore, the highest legal amount of caffeine allowed in a 355 mL (12 oz) can of soft drink is about 72 mg. Likewise, Canada limits caffeine to cola-type beverages at a level of 200 ppm or about 71 mg/12 oz (Dept. of Justice 2007). In Australia, the maximum caffeine level in cola-type beverages must not exceed 145 mg/kg or about 51 mg/12 oz while in New Zealand, the caffeine level is limited to 200 mg/kg or about 71 mg/12 oz (FSANZ 2000).

The amount of caffeine contained in various foods and beverages has been analyzed, including coffee (Bell and others 1996), tea (Hicks and others 1996; Friedman and others 2005; Pena and others 2005; Yao and others 2006), carbonated beverages (Bunker and McWilliams 1979; Strohl 1985; Grand and Bell 1997; Pena and others 2005), and chocolate products (Caudle and others 2001; Tokusoglu and Ünal 2002). The last large-scale study involving the caffeine contents of carbonated beverages was conducted 10 y ago where the caffeine contents of 24 fountain, 20 prepackaged national-brand, and 16 prepackaged private-label store-brand carbonated beverages were determined; the store-brand beverages were limited to products from 4 stores (Grand and Bell 1997). The U.S. Dept. of Agriculture Natl. Nutrient Database for Standard Reference, Release 19, provides broad classifications of carbonated beverages and includes average caffeine contents for 8 types of carbonated beverages (USDA 2006). Caffeine data for some national-brand beverages are also reported on manufacturer websites (A&W 2006; Coca-Cola 2006; Pepsi-Cola 2005; Dr Pepper 2006a, 2006b, 2006c; Sundrop 2006). Caffeine data for private-label store-brand beverages are not available.

New flavors, formulas, and brands of carbonated beverages continue to be introduced into the market. Manufacturers may gradually lower caffeine contents due to health concerns of some consumers or increase it to correspond to the demand for greater stimulatory effect by other consumers. Without caffeine values placed on the label, consumers are left relatively uninformed regarding the amount of caffeine contained in these beverages. In addition, comprehensive databases on the caffeine contents of specific carbonated beverages are lacking. Therefore, the specific objective of this research project was to measure the caffeine contents of national and private-label store-brand carbonated beverages so that current data will be available to the scientific community and public.

Materials and Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results and Discussion
  6. Conclusion
  7. References

Chemicals and reagents

Anhydrous caffeine used for preparing the standard solutions was purchased from Sigma Chemical Co. (St. Louis, Mo., U.S.A.). Sodium phosphate monobasic, phosphoric acid, and high-performance liquid chromatography (HPLC) grade acetonitrile were obtained from Fisher Scientific (Pittsburgh, Pa., U.S.A.). Deionized water was obtained from a water purification system (18 MΩcm−1 quality).

Samples and sample preparation

Fifty-six varieties of national-brand prepackaged (cans and bottles) carbonated beverages were collected across the southeastern United States; these are listed in Table 1 along with their manufacturers. Seventy-five types of private-label store-brand beverages were acquired from 10 grocery stores, 2 pharmacies, 2 general merchandise stores, and 1 mini-market. Names of these stores, along with the beverage names, are provided in Table 2. Carbonated colas, pepper-type beverages (that is, like Dr Pepper), and citrus beverages (that is, like Mountain Dew), as well as their diet varieties, were analyzed in this study. Average caffeine contents of each carbonated beverage were determined from a minimum of 2 different lots. The beverages analyzed in this study were purchased between June 2005 and July 2006. The unopened beverages were stored at room temperature until analysis.

Table 1—.  National-brand carbonated beverages listed by company
Company (headquarters)Beverages
Coca-Cola Company (Atlanta, Ga., U.S.A.)Coca-Cola, Diet Coke, Cherry Coke, Diet Cherry Coke, Coke with Lime, Diet Coke with Lime, Vanilla Coke, Diet Vanilla Coke, Coca-Cola C2, Diet Coke with Splenda, Coke Zero, Coca-Cola Black Cherry Vanilla, Diet Coke Black Cherry Vanilla, Tab, Pibb Xtra, Pibb Zero, Vault Citrus, Vault Zero, Barq's Root Beer, and Mello Yello
Pepsico Inc. (Somers, N.Y., U.S.A.)Pepsi, Diet Pepsi, Cherry Pepsi, Diet Cherry Pepsi, Pepsi with Lime, Diet Pepsi with Lime, Vanilla Pepsi, Diet Vanilla Pepsi, Pepsi One, Mountain Dew, Diet Mountain Dew, Mountain Dew Code Red, Diet Mountain Dew Code Red
Natl. Beverage Co. (Ft. Lauderdale, Fla., U.S.A.)Faygo Cola, Faygo Moon Mist, Ritz Cola, Shasta Cola
Carolina Beverage Corp. (Salisbury, N.C., U.S.A.)Cheerwine, Diet Cheerwine
Dr Pepper/Seven Up Inc. (Plano, Tex., U.S.A.)Dr Pepper, Diet Dr Pepper, Dr Pepper Berries & Cream, Diet Dr Pepper Berries & Cream, Cherry Vanilla Dr Pepper, Diet Cherry Vanilla Dr Pepper, RC Cola, Diet RC, SunDrop, Diet SunDrop, A & W Cream Soda, Sunkist, and Diet Sunkist
Buffalo Rock Co. (Birmingham, Ala., U.S.A.)Dr. Wham, Diet Dr. Wham
Big Red Inc. (Waco, Tex., U.S.A.)Big Red
Red Rock Corp. (Indianalopis, Ind., U.S.A.)Red Rock Cola
Table 2—.  Private-label store-brand beverages listed by store
Store (headquarters)Beverages
Kroger (Cincinnati, Ohio, U.S.A.)Big K Cola, Big K Diet Cola, Big K Cherry Cola, Big K Diet Cherry Cola, Big K Cola with Lime, Big K Diet Cola with Lime, Dr. K, Diet Dr. K, Big K Citrus Drop, Big K Diet Citrus Drop
Winn-Dixie (Jacksonville, Fla., U.S.A.)Chek Cola, Chek Diet Cola, Chek Cherry Cola, Chek Vanilla Cola, Chek Diet Vanilla Cola, Chek Diet Cola with Lime, Chek Mate Cola, Dr. Chek, Diet Dr. Chek, Chek Kountry Mist, Chek Diet Kountry Mist, Chek Red Alert
Wal-Mart (Bentonville, Ark., U.S.A.)Sam's Cola, Sam's Diet Cola, Dr Thunder, Diet Dr Thunder, Sam's Mountain Lightning
Bruno's (Birmingham, Ala., U.S.A.)Rally Cola, Rally Diet Cola, Dr. Bob, Diet Dr. Bob, Ramp, Ramp Red
Publix Super Markets (Lakeland, Fla., U.S.A.)Publix Cola, Publix Diet Cola, Publix Cherry Cola, Dr. Publix, Publix Citrus Hit
Dollar General (Goodlettsville, Tenn., U.S.A.)CloverValley Cola, CloverValley Diet Cola, Dr Topper, CloverValley Citrus Drop
Save-a-Lot Food Stores (Earth City, Mo., U.S.A.)Bubba Cola, Diet Bubba Cola, Dr Pop, Diet Dr Pop, Mountain Holler
Piggly Wiggly (Memphis, Tenn., U.S.A.)Piggly Wiggly Cola, Piggly Wiggly Diet Cola, Mr. Pig, Mountain Yeller
7-Eleven (Dallas, Tex., U.S.A.)Big Gulp Cola, Big Gulp Diet Cola
Supervalu (Eden Prairie, Minn., U.S.A.)Superchill Cola, Superchill Diet Cola, Dr. Chill, Mountain Chill
Food Lion (Salisbury, N.C., U.S.A.)Food Lion Cola, Food Lion Diet Cola, Dr. Perky, Mountain Lion
Ingle's Markets (Asheville, N.C., U.S.A.)Laura Lynn Cola, Laura Lynn Diet Cola, Laura Lynn Cherry Cola, Dr Lynn, Diet Dr Lynn, Mountain Moon Drops
IGA (Chicago, Ill., U.S.A.)IGA Cola, IGA Diet Cola, IGA Spring Mist, Dr. IGA
Walgreens (Deerfield, Ill., U.S.A.)Walgreens Cola, Walgreens Diet Cola
Rite Aid (Harrisburg, Pa., U.S.A.)Big Fizz Cola, Big Fizz Diet Cola

Each sample was degassed via sonication and diluted 3-fold with deionized water (1 mL sample + 2 mL water). Duplicate dilutions were made for all samples. An aliquot of each diluted sample was injected into the HPLC system to quantify the caffeine concentration.

Apparatus

The caffeine content was determined by isocratic reverse-phase HPLC equipped with a UV/visible detector, adapted from that used by Grand and Bell (1997). The chromatographic separation occurred on a Prodigy (150 × 4.6 mm) C-18 column (Phenomenex, Torrance, Calif., U.S.A.) in series with a Novapak (150 × 3.9 mm) C-18 column (Waters, Eatontown, N.J., U.S.A.). The mobile phase consisted of 20% (v/v) acetonitrile mixed with 80% (v/v) 0.1% aqueous sodium phosphate monobasic, acidified to pH 3 with phosphoric acid. The combination of these 2 analytical columns eliminated interference caused by other components in some samples, such as colors, artificial sweeteners, flavors, and preservatives. The wavelength of detection was set at 254 nm, and flow rate was set at 1 mL/min. Separation was performed at room temperature. Caffeine eluted around 4.1 min. Data were recorded by a Hewlett Packard HP3395 integrator (Palo Alto, Calif., U.S.A.). From spiking Caffeine-Free Diet Coke (Coca-Cola, Atlanta, Ga., U.S.A.) with known amounts of caffeine, the percentage recovery for this method was determined to be 96.7% to 100.8% with a coefficient of variation of 0.6%. These values were similar to those reported by Grand and Bell (1997). A sample chromatogram for the analysis of a pepper-type beverage is shown in Figure 1.

image

Figure 1—. Representative HPLC chromatogram for the analysis of caffeine in Dr Pepper. Separation occurred on 2 C-18 columns in series using a mobile phase of 20% (v/v) acetonitrile and 80% (v/v) 0.1% aqueous sodium phosphate monobasic, acidified to pH 3 flowing at 1 mL/min. Detection occurred at 254 nm.

Download figure to PowerPoint

Data analysis

Every type of beverage underwent duplicate measurements per lot; these were averaged to give the mean caffeine content for that lot. Data from these duplicate dilutions were typically found to vary by less than 2%. The caffeine contents for the various lots were then averaged to give the mean caffeine contents of the beverages along with the standard deviation. Because these beverages are so commonly distributed and consumed in 12-ounce cans, the caffeine values are reported in terms of milligrams per 12 oz.

Results and Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results and Discussion
  6. Conclusion
  7. References

National-brand colas

The caffeine contents of 31 national-brand colas are listed in Table 3 along with available manufacturer data. The caffeine contents of this group ranged from 10.3 to 57.1 mg/12 oz. The highest value (57.1 mg/12 oz) was found in Pepsi One. Except for the lower caffeine contents of Ritz Cola and Red Rock Cola and the higher caffeine content of Pepsi One, the remaining samples contained 33.3 to 48.1 mg caffeine/12 oz. The caffeine values of some national-brand colas (Coke, Diet Coke, Pepsi, and Diet Pepsi) were 13% to 20% higher than determined 10 y ago (Grand and Bell 1997). Caffeine values for Tab, RC Cola, and Shasta Cola were similar to those reported previously (Grand and Bell 1997). The caffeine values determined in this study were consistent with the available manufacturer data. However, the USDA nutrient database gave an average caffeine content of 29 mg/12 oz beverage for regular cola products (USDA 2006), which was lower than most of the values determined in the present study. For diet cola products, the USDA gave an average caffeine content of 43 mg/12 oz, which also does not adequately represent the range of caffeine values.

Table 3—.  Caffeine contents (mean ± standard deviation) of national-brand colas
BeverageCaffeine content (mg/12 oz)
Current studyManufacturer data
  1. cn: number of lots.

  2. dn/a: not available.

  3. eThese products have been discontinued.

Pepsi One (n= 2)c57.1 ± 3.354a
Diet Cheerwine (n= 2)48.1 ± 1.1n/ad
Tab (n= 2)48.1 ± 1.946.5b
Cheerwine (n= 2)47.5 ± 1.4n/a
Diet RC (n= 2)47.3 ± 1.6n/a
Diet Coke (n= 3)46.3 ± 1.746.5b
Diet Coke with Lime (n= 2)46.3 ± 2.746.5b
RC Cola (n= 4)45.2 ± 4.1n/a
Diet Vanilla Cokee (n= 1)44.546.5b
Shasta Cola (n= 2)42.9 ± 2.2n/a
Faygo Cola (n= 2)41.7 ± 3.0n/a
Diet Cherry Pepsi (n= 2)40.5 ± 2.737.5a
Cherry Pepsi (n= 2)39.7 ± 3.237.5a
Pepsi (n= 3)38.9 ± 1.037.5a
Pepsi with Lime (n= 2)38.4 ± 2.037.5a
Diet Vanilla Pepsie (n= 1)38.137.5a
Vanilla Pepsie (n= 1)37.437.5a
Diet Coke Black Cherry Vanilla (n= 2)36.8 ± 1.434.5b
Diet Pepsi (n= 3)36.7 ± 0.636a
Diet Pepsi with Lime (n= 2)36.4 ± 0.937.5a
Coke Zero (n= 2)35.8 ± 2.634.5b
Coca-Cola Black Cherry Vanilla (n= 2)35.1 ± 1.134.5b
Diet Cherry Coke (n= 2)35.0 ± 2.034.5b
Cherry Coke (n= 2)34.4 ± 1.834.5b
Coca-Cola C2 (n= 2)34.4 ± 1.534.5b
Diet Coke with Splenda (n = 2)34.4 ± 1.334.5b
Coca-Cola (n= 3)33.9 ± 0.934.5b
Coke with Lime (n= 2)33.6 ± 1.134.5b
Vanilla Cokee (n= 1)33.334.5b
Red Rock Cola (n= 2)26.1 ± 1.0n/a
Ritz Cola (n= 2)10.3 ± 0.9n/a

National-brand pepper-type beverages

The caffeine contents of 10 national-brand pepper-type beverages are reported in Table 4. All samples in this group contained similar caffeine contents, with values ranging from 39.4 to 44.1 mg/12 oz. These caffeine values were similar to those of national-brand pepper-type beverages determined previously (Grand and Bell 1997), as well as data on the available manufacturer websites. The USDA nutrient database gave an average caffeine content of 43 mg/12 oz for diet pepper-type beverages (USDA 2006), which is consistent with the current data. On the other hand, the database gave an average caffeine content of 37 mg/12 oz for regular pepper products (USDA 2006), which is slightly lower than the values determined in this study.

Table 4—.  Caffeine contents (mean ± standard deviation) of national-brand pepper-type, citrus, and miscellaneous beverages
BeverageCaffeine content (mg/12 oz)
Current studyManufacturer data
Pepper-type beverages
 Diet Dr Pepper (n= 2)h44.1 ± 2.341c
 Dr Pepper (n= 3)42.6 ± 2.041c
 Diet Dr Pepper Berries & Cream (n= 2)42.0 ± 1.141e
 Diet Dr. Wham (n= 2)41.9 ± 0.8n/ai
 Dr. Wham (n= 2)41.6 ± 0.3n/a
 Pibb Zero (n= 2)41.2 ± 0.240.5b
 Dr Pepper Berries & Cream (n= 2)41.1 ± 0.541d
 Pibb Xtra (n= 2)40.3 ± 2.540.5b
 Diet Cherry Vanilla Dr. Pepper (n= 2)40.1 ± 1.037c
 Cherry Vanilla Dr. Pepper (n= 2)39.4 ± 1.337c
Citrus beverages
 Vault Zero (n= 2)74.0 ± 1.770.5b
 Diet SunDrop (n= 2)71.5 ± 1.969f
 Vault Citrus (n= 2)70.6 ± 0.770.5b
 SunDrop (n= 2)64.7 ± 2.063f
 Diet Mountain Dew Code Red (n= 2)55.4 ± 1.354a
 Diet Mountain Dew (n= 2)55.2 ± 0.354a
 Mountain Dew (n= 2)54.8 ± 2.554a
 Mountain Dew Code Red (n= 2)54.3 ± 0.354a
 Mello Yello (n= 2)49.5 ± 1.852.5b
 Faygo Moon Mist (n= 3)19.7 ± 3.0n/a
Miscellaneous beverages
 Diet Sunkist (n= 2)41.5 ± 0.3n/a
 Sunkist (n= 2)40.6 ± 0.2n/a
 Big Red (n= 2)34.0 ± 0.5n/a
 A & W Cream Soda (n= 2)28.6 ± 1.428.8g
 Barq's Root Beer (n= 2)22.4 ± 1.422.5b

National-brand citrus beverages

The caffeine contents of 10 national-brand citrus beverages are also reported in Table 4. The caffeine contents of this group ranged from 19.7 to 74.0 mg/12 oz. The greatest caffeine content (74.0 mg/12 oz) was found in Vault Zero. Except for the lowest caffeine content of Faygo Moon Mist (19.7 mg/12 oz), the other beverages contained more than 49 mg caffeine per 12 oz. These data were consistent with the available caffeine data from manufacturer websites. The caffeine contents of regular and diet Mountain Dew and Mello Yello from the present study and those from Grand and Bell (1997) were also similar. The USDA nutrient database gave an average caffeine content of 55 mg/12 oz beverage for regular caffeinated lemon-lime beverages (USDA 2006). For the purpose of this study, it is assumed that the lemon-lime caffeinated beverage classification by USDA refers to regular citrus products because there is no other carbonated citrus beverage category. Another USDA classification (carbonated beverage, low calorie, other than cola or pepper, with aspartame, contains caffeine) could include diet citrus beverages; this beverage category had an average caffeine level of 53 mg/12 oz (USDA 2006). Five out of 10 national-brand citrus products were found to be similar to the data from USDA. The other 5 citrus products were quite different from that in the USDA database. The caffeine contents of regular and diet SunDrop as well as Vault Citrus and Vault Zero were 17% to 34% greater than the values listed by USDA. For the citrus beverages, it was challenging to determine which USDA category was appropriate to use. Clearer descriptions of database categories would reduce this ambiguity.

Miscellaneous national-brand beverages

The caffeine contents of 5 miscellaneous national-brand beverages are also reported in Table 4. The caffeine content of Big Red (34.0 mg/12 oz) was similar to the majority of national-brand cola beverages. The USDA nutrient database gave no caffeine content for carbonated orange products (USDA 2006), but the regular and diet Sunkist beverages were found to contain 40.6 and 41.5 mg caffeine per 12 oz, respectively. These values were comparable to caffeine values reported previously (Grand and Bell 1997). In addition, the USDA nutrient database gave no caffeine content for root beer or cream soda products (USDA 2006). However, caffeine contents of 22.4 and 28.6 mg/12 oz were found in Barq's Root Beer and A & W Cream Soda, respectively. The USDA caffeine values for these beverage categories are inaccurate based on both current and previous data. Because these products may or may not contain caffeine, careful evaluation of the product's ingredient list is advised.

Private-label store-brand colas

The caffeine contents of 41 private-label store-brand regular and diet colas are reported in Table 5. The caffeine contents of regular colas ranged from 4.9 mg (IGA Cola) to 46.4 mg (Rite Aid's Big Fizz Cola) caffeine per 12 oz. The caffeine contents of diet colas ranged from 10.3 mg (IGA Diet Cola) to 61.9 mg (Rite Aid's Big Fizz Diet Cola) caffeine per 12 oz. The range of caffeine contents of this group was unlike the spread of national-brand colas, being much wider. Big Fizz Diet Cola contained more caffeine than any cola product, national or store brand; many other store brands contained less than 20 mg caffeine per 12 oz. Because of the large caffeine content range of these products, it is difficult to generalize the amount of caffeine being consumed from such products.

Table 5—.  Caffeine contents (mean ± standard deviation) of private-label store-brand regular and diet colas
BeverageCaffeine content (mg/12 oz)
Regular colaDiet cola
  1. aRite Aid; bKroger; cWalgreens; d7-Eleven; eWinn-Dixie; fSave-a-Lot; gDollar General; hFood Lion; iIngle's; jSupervalu; kPublix; lBruno's; mPiggly Wiggly; nWal-Mart; °IGA; pn: number of lots; and qn/a: not available.

Big Fizz Colaa  46.4 ± 15.8 (n= 3)p61.9 ± 2.4 (n= 3)
Big K Cherry Colab43.0 ± 2.9 (n= 2)39.9 ± 1.8 (n= 2)
Walgreens Colac39.2 ± 8.1(n= 3)45.0 ± 6.7 (n= 3)
Big K Colab38.8 ± 2.2 (n= 3)30.0 ± 1.6 (n= 3)
Big Gulp Colad38.6 ± 0.6 (n= 3)30.0 ± 1.6 (n= 2)
Chek Vanilla Colae36.3 ± 2.3 (n= 2)28.9 ± 2.0 (n= 2)
Bubba Colaf35.4 ± 1.6 (n= 3)42.0 ± 2.2 (n= 4)
Chek Colae34.7 ± 1.8 (n= 3)27.5 ± 1.7 (n= 3)
Big K Cola with Limeb30.3 ± 0.5 (n= 2)18.6 ± 0.3 (n= 2)
CloverValley Colag28.8 ± 5.7 (n= 6)22.9 ± 6.4 (n= 7)
Chek Cherry Colae26.3 ± 1.2 (n= 2)n/aq
Food Lion Colah25.3 ± 0.8 (n= 3)11.9 ± 0.8 (n= 3)
Laura Lynn Colai24.4 ± 1.8 (n= 4)11.3 ± 0.6 (n= 3)
Superchill Colaj24.2 ± 0.9 (n= 3)34.5 ± 0.6 (n= 3)
Publix Colak23.1 ± 2.2 (n= 3)35.2 ± 2.9 (n= 3)
Rally Colal13.3 ± 1.5 (n= 3)13.0 ± 2.1 (n= 3)
Piggly Wiggly Colam12.7 ± 1.5 (n= 3)11.9 ± 2.0 (n= 3)
Sam's Colan12.7 ± 1.0 (n= 3)13.1 ± 1.3 (n= 3)
Publix Cherry Colak12.4 ± 2.1 (n= 2)n/a
Laura Lynn Cherry Colai 8.4 ± 1.8 (n= 2)n/a
IGA Cola° 4.9 ± 1.1 (n= 3)10.3 ± 1.2 (n= 3)
Chek Mate Colaen/a26.2 ± 1.4 (n= 2)
Chek Diet Cola with Limeen/a45.8 ± 4.2 (n= 2)

The caffeine values of Winn-Dixie's Chek Diet Cola, Kroger's Big K Diet Cola, Wal-Mart's Sam's Cola, and Sam's Diet Cola were comparable to those determined previously (Grand and Bell 1997). Big K Cola was found to contain 38.8 mg caffeine/12 oz, which is over 600% higher than the value of 5.2 mg caffeine/12 oz, reported 10 y ago by Grand and Bell (1997). Similarly, Chek Cola contained 29% more caffeine in this study (34.7 mg/12 oz) than that reported previously (27.0 mg/12 oz) by Grand and Bell (1997). These products have clearly been reformulated over the past decade. The USDA nutrient database gave average caffeine contents of 29 and 43 mg/12 oz beverage for regular and diet cola products, respectively (USDA 2006). However, the USDA database is impractical to use due to the wide range of caffeine values in private-label store-brand colas (4.9 to 61.9 mg/12 oz).

Private-label store-brand pepper-type beverages

The caffeine contents of 18 private-label store-brand pepper-type beverages are reported in Table 6. The caffeine contents of this group ranged from 18.2 to 59.8 mg/12 oz. The lowest and highest caffeine concentrations were found in Ingle's Diet Dr Lynn and Dr IGA, respectively. The caffeine contents of the samples were distributed evenly within this range. The distribution of this group was different from national pepper-type beverages, all of which contained around 40 mg caffeine per 12 oz. Dr IGA was found to contain more caffeine than any pepper-type beverage, national or store-brand, while several store-brand beverages contained less than half the caffeine of the national-brand products. The caffeine contents of Kroger's regular and diet Dr K were much higher (> 150%) than those analyzed by Grand and Bell (1997), indicating that the products have been reformulated. Similarly, the caffeine content of Winn-Dixie's Dr Chek analyzed in the present study was 33% higher than that reported previously (Grand and Bell 1997). The USDA nutrient database gave average caffeine contents of 37 and 43 mg/12 oz for regular and diet pepper-type drinks, respectively, which again does not adequately represent the wide distribution of the current results.

Table 6—.  Caffeine contents (mean ± standard deviation) of private-label store-brand pepper-type and citrus beverages
BeverageCaffeine content (mg/12 oz)
  1. aIGA; bSave-a-Lot; cKroger; dDollar General; ePublix; fBruno's; gPiggly Wiggly; hWal-Mart; iSupervalu; jWinn-Dixie; kIngle's; lFood Lion; and mn: number of lots.

Pepper-type beverages
 Dr IGAa (n= 2)m59.8 ± 3.7
 Diet Dr Popb (n= 2)56.8 ± 2.0
 Dr Popb (n= 5) 47.5 ± 11.0
 Dr Kc (n= 2)41.2 ± 2.8
 Diet Dr Kc (n= 2)40.7 ± 2.5
 Dr Topperd (n= 2)34.0 ± 2.7
 Dr Publixe (n= 2)31.6 ± 2.0
 Dr Bobf (n= 2)31.3 ± 1.6
 Mr. Pigg (n= 2)31.2 ± 2.3
 Diet Dr Bobf (n= 2)30.9 ± 0.6
 Dr Thunderh (n= 2)30.6 ± 1.3
 Dr Chilli (n= 2)29.9 ± 1.8
 Diet Dr Thunderh (n= 2)29.9 ± 0.8
 Dr Chekj (n= 2)24.4 ± 1.3
 Diet Dr Chekj (n= 2)22.3 ± 1.3
 Dr Lynnk (n= 2)19.3 ± 0.9
 Dr Perkyl (n= 2)18.8 ± 1.5
 Diet Dr Lynnk (n= 2)18.2 ± 1.0
Citrus beverages
 Chek Kountry Mistj (n= 2)55.1 ± 4.9
 Ramp Redf (n= 2)54.6 ± 1.0
 IGA Spring Mista (n= 2)54.2 ± 4.4
 Publix Citrus Hite (n= 2)54.1 ± 1.0
 Rampf (n= 2)53.8 ± 1.0
 Mountain Chilli (n= 2)53.5 ± 0.8
 Chek Red Alertj (n= 2)53.2 ± 1.8
 Mountain Hollerb (n= 2)53.1 ± 0.4
 Mountain Yellerg (n= 2)53.1 ± 0.1
 CloverValley Citrus Dropd (n= 2)52.0 ± 0.3
 Sam's Mountain Lightningh (n= 2)46.5 ± 1.0
 Chek Diet Kountry Mistj (n= 4)46.3 ± 7.7
 Mountain Lionl (n= 2)30.9 ± 0.1
 Laura Lynn Mountain Moon Dropsk (n= 4)27.5 ± 7.2
 Big K Citrus Dropc (n= 2)26.2 ± 0.5
 Big K Diet Citrus Dropc (n= 2)25.1 ± 0.5

Private-label store-brand citrus beverages

The caffeine contents of 16 private-label store-brand citrus beverages are also reported in Table 6. The caffeine contents of this group ranged from 25.1 to 55.1 mg/12 oz. The lowest and highest caffeine concentrations were found in Kroger's Big K Diet Citrus Drop and Winn-Dixie's Chek Kountry Mist, respectively. Ten beverages within this group contained over 50 mg caffeine per 12 oz. The USDA nutrient database gave an average caffeine content of 55 mg/12 oz for lemon-lime (citrus) products (USDA 2006). Most of this group's results were similar to the value from USDA. Kroger's Big K products contained approximately half the caffeine of the value listed by USDA. The amounts of caffeine existing in Chek Kountry Mist, Sam's Mountain Lightning (from Wal-Mart), Big K Citrus Drop, and Big K Diet Citrus Drop were similar to the values reported by Grand and Bell (1997).

Quality control of store-brand beverages

Based upon the standard deviations listed in Table 3 to 6, the quality control of national-brand beverages appeared generally better than that for the store-brand beverages. Additional lots were obtained and analyzed for some beverages whose duplicate lots had quite different caffeine values. Products displaying large variations between lots included Rite Aid's Big Fizz Cola, Walgreens Cola, Walgreens Diet Cola, Dollar General's CloverValley Cola, CloverValley Diet Cola, Save-a-Lot's Dr Pop, Winn-Dixie's Chek Diet Kountry Mist, and Ingle's Laura Lynn Mountain Moon Drop. In addition, 1 lot of Food Lion's Mountain Lion was found to contain no caffeine (this sample was not included in the data analysis). Thus, there appears to be less stringent quality control with store-brand products than with the national-brand products.

Mean caffeine contents in different beverage types

The average amounts of caffeine existing in each beverage classification are tabulated in Table 7. The average caffeine values for national-brand cola and pepper-type beverages were similar. The national-brand citrus beverages contained more caffeine than cola and pepper-type beverages. National-brand diet colas contained, on average, more caffeine than the regular colas. One may suggest that this result is due to caffeine being diluted by the bulk from added sugar. However, the 9% to 11% sugar added to regular colas causes the solution volume to increase by less than 7% (Weast 1972). Therefore, adding 11% sugar to a beverage containing 42 mg caffeine/12 oz would only dilute the caffeine content to 39 mg/12 oz. Furthermore, the data in Table 1 do not show a pattern with regard to the differences between caffeine levels in regular and diet colas. Thus, specific formulation changes, not simply dilution from the sugar, account for the different caffeine levels. With respect to store-brand beverages, their caffeine contents were, on average, lower than the national-brand counterparts. In addition, the variation between store brands was generally greater than between national brands.

Table 7—.  Mean caffeine contents (mg/12 oz) with standard deviation by beverage classification
BeverageNational brandStore brandOverall averageUSDA (2006)
  1. an: number of beverage types.

Cola with sugar35.8 ± 8.626.6 ± 12.230.6 ± 11.629
(n= 16)a(n= 21)(n= 37) 
Diet cola42.1 ± 6.728.0 ± 14.334.0 ± 13.543
(n= 15)(n= 20)(n= 35) 
Pepper-type41.0 ± 1.233.3 ± 11.635.6 ± 10.337
(n= 5)(n= 12)(n= 17) 
Diet pepper41.9 ± 1.533.1 ± 14.037.1 ± 10.943
(n= 5)(n= 6)(n= 11) 
Citrus 52.3 ± 17.747.7 ± 10.849.1 ± 12.955
(n= 6)(n= 14)(n= 20) 
Diet citrus 64.0 ± 10.135.7 ± 15.054.6 ± 17.953
(n= 4)(n= 2)(n= 6) 

The USDA data in Table 7 represent the average caffeine values for a given beverage type. Interestingly, the overall caffeine averages for the regular colas, regular pepper-type beverages, and diet citrus beverages were close to the USDA values. Contrary to this result, the average caffeine contents of the diet colas, diet pepper-type beverages, and regular citrus beverages were lower than listed by USDA. When the beverages were categorized into national and store brands, additional discrepancies appeared. For the diet cola, diet pepper, and regular citrus beverage categories, the mean national-brand data were similar to the USDA values. However, for the national-brand regular cola, regular pepper-type, and diet citrus beverages, the average caffeine values were greater than those reported in the USDA database. The average caffeine data from store-brand beverages were all lower than those listed by USDA. The USDA classifications of caffeinated carbonated beverages should be broadened to differentiate between national-brand and store-brand categories, recognizing there remains a wide distribution within each beverage type.

Conclusion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results and Discussion
  6. Conclusion
  7. References

The caffeine data collected in the present study suggest that consumers concerned about limiting daily caffeine ingestion from carbonated beverages may select the lower caffeine-containing store-brand beverages; however, a limited number of these beverages actually contain substantially more caffeine than national-brand products. In addition, although the store-brand beverages are less expensive, their caffeine levels tend to vary more between brands, and in some cases between different lots of the same brand, than the national-brand beverages. Consumers desiring caffeine may likewise select from higher caffeine-containing beverages. Because of the wide range of caffeine values (5 to 74 mg/12 oz.), broad generalizations about the caffeine contents of national and store-brand carbonated beverages are difficult to make. Our data may be used to update and expand the USDA nutrient database so that consumers have more current and accurate information. However, the best way for universal access to caffeine data is to place values on food labels so all consumers can be better informed about the amount of caffeine they are ingesting. Consistent with this recommendation, the Coca-Cola Co. and PepsiCo announced in February 2007 their intent to place caffeine contents on the labels of various carbonated beverages (IFT 2007). If all manufacturers placed caffeine contents on food labels, consumers would have the ability to instantly compare products, enabling them to make more informed purchasing decisions.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Materials and Methods
  5. Results and Discussion
  6. Conclusion
  7. References