The carbonated soft drink has emerged as the most prominent product segment within the non-alcoholic beverage industry. While the growth of this segment is not expected to match other segments in coming years due to different factors (most prominent being an increase in health consciousness of consumers), it still represents over one-third of the global demand in the non-alcoholic beverage market. Soft drinks consist primarily of carbonated water, sugar, and flavorings. The market is very competitive and manufacturers are quick to respond to consumer preferences and demand, as has been shown over the years by the advent of diet colas, caffeine-free drinks, low-sodium drinks, and preservative-free beverages. Brand name companies often keep their formulas and required manufacturing procedures a closely guarded secret. Carbonated water makes up to 94% of a soft drink. It adds sparkle and bites as well as acting as a mild preservative. Carbon dioxide is an ideally suited gas for soft drinks because it is inert, non-toxic, less expensive than other gases, and easy to liquefy. Sugar (or artificial sweetener) is the second main ingredient and makes up 7 to 12% of a soft drink. Sugar can be added in dry or liquid form. It adds sweetness and body to the beverage as well as balancing flavor and acids. The overall flavor of a soft drink depends on a balance of sweetness, tartness, and acidity. Citric acid is the most common acid in soft drinks and has a lemon flavor. Acids add a sharpness to the background taste and stimulate saliva flow, as well as acting as a mild preservative. Other additives add taste, aroma, and enhanced appearance to soft drinks.
Soft Drink Manufacturing
Removing impurities from the water is the first step in soft drink manufacturing. Suspended particles, organic matter, and bacteria can degrade taste and color. Impurities are removed by a traditional process of coagulation, filtration, and chlorination. Alkalinity is adjusted by adding lime to reach the desired pH level. Dissolved sugar and flavor concentrates are pumped into pressurized batch tanks and carefully mixed to prevent unwanted aeration. Syrup can be sterilized while in the tanks and fruit-based syrups are almost always sterilized. Machines called proportioners carefully regulate the flow rates and ratios of the liquids.
In most cases, carbonation occurs after the finished product is made. Temperature is carefully controlled because carbon dioxide solubility increases as temperature decreases. The amount of pressure and carbonation varies by the individual drink. The finished carbonated product is then transferred into bottles or cans and sealed immediately. Containers are brought to room temperature before labeling and then packed for shipping.
Tea is the world’s second-highest consumed beverage after water and is categorized into two types: black tea and green tea. Black tea accounts for about 80% of world tea production and green tea accounts for the other 20%. Various fermentation processes are used to produce over three hundred different types of tea worldwide. It has a similar appeal to the consumer as coffee for its physiological and psychoactive properties. Some important quality control parameters in both powder tea and tea soft drink, such as Soluble Solids Content, amino acids, caffeine, theaflavins (an antioxidant indicator), and water extract have been successfully analyzed using NIR spectroscopy.
As is the case with fruit juices, sugar and acidity are the two most important components in soft drinks and NIR spectroscopy has been examined as a potential tool to replace traditional time-consuming and expensive methods. There are strict quality regulations for all ingredients used to manufacture soft drinks. Clean water, raw material inspection, and sanitary conditions are essential for avoiding bacterial and other forms of contamination. Low-quality sugar can create particles in the beverage and spoil it. It is vital to monitor sugar and acidity in soft drinks to ensure a product that meets quality control standards and will not spoil. Most soft drinks have a shelf life of at least a year if stored under proper conditions. Because soft drink manufacturers not only closely guard their recipes but also their testing procedures, there is little-published documentation on measuring parameters of interest in soft drinks. However, it is known that Soluble Solids Content and pH are measurable constituents using NIR spectroscopy and these are two of the most important quality parameters in soft drinks. Other potential applications include glucose, sucrose, and fructose measurements in syrup and citric acid. Studies are measuring these parameters in many types of fruit juice (especially orange juice) and with proper calibration work, they should be measurable in soft drinks as well. While less studied using NIR spectroscopy because they are newer to the market, the manufacturing process for energy drinks is similar to cola. As with cola, Soluble Solids Content and pH are important quality parameters in energy drinks and have been successfully measured using NIR spectroscopy. Advancements in application development and online analysis continue to move forward to realize the potential of NIR spectroscopy as a method for real-time, online implementation as a process control tool.
Quality Analysis, Classification, and Authentication of Liquid Foods by Near-Infrared Spectroscopy: A Review of Recent Research Developments – Wang, Sun, Pu, and Cheng, Critical Reviews in Science and Nutrition, 2017, Vol. 57, No. 7, 1524-1538
Quantitative Determination and Classification of Energy Drinks Using Near-Infrared Spectroscopy – Racz, Heberger, Fodor, Analytical and Bioanalytical Chemistry, 2016, 408:6403-6411
Prediction of Amino Acids, Caffeine, Theaflavins, and Water Extract in Black Tea Using FT-NIR Spectroscopy Coupled Algorithms – Zareef, Chen, Ouyang, Analytical Methods, Issue 25, 2018