Testing for Tea and Coffee Adulterants

Tea and coffee are among the first of the food commodities Wimpey Laboratories, part of the Cotecna Group, has tested from years back. In fact, this is why Wimpey’s expertise in various commodities is widely accepted by national and international regulatory bodies.

Tea and Coffee components

Tea powder contains small quantities of tannic compounds called polyphenols, Vitamin A, B2, C, D, K, and P, plus a number of minerals in trace amounts and also aromatic oils. On the other hand, the main constituents of coffee are caffeine, tannin, fixed oil, carbohydrates, and proteins.

Classifications of tea and coffee

There are thousands of varieties of tea, with four of the main types being black, green, white, and oolong — all of which are produced in various parts of the world.

Coffee beans can be classed into four types: Arabica, Robusta, Liberica, and Excelsa. These are the four main species of the coffee plant, and all types of coffee will generally be a variety of one of these plants. The most common types of coffee beans are Arabica and Robusta, which account for 90% of global coffee production when combined.

Food Testing for tea and coffee products

Tea leaves and coffee beans are natural agricultural products. Because of this, the composition of tea leaves and coffee beans will not always be the same from year-to-year or across continents. As a result, the quality of these products should be tested to ensure consistency of the end products. During the process of harvesting, extraction, and refinery of the leaves/beans, many elements are put in place to make varieties of flavored products.

Risks connected to adulterated tea and coffee powders

Tea and coffee are two of the most used beverages in India and are thus highly adulterated. Tea leaves are usually adulterated with same-colored leaves, some of which might be inedible. Several cases of liver infections across the country have been reported due to consuming adulterated tea.

Coffee seeds, on the other hand, are adulterated with tamarind seeds, mustard seeds and also chicory. These adulterants are the main cause of diarrhea.

Food Adulteration Testing for tea and coffee powders

The procedures to test adulteration in tea and coffee powders are a twofold process:

• Qualitative Tests: Physical tests and solubility tests
• Quantitative Tests:

  • Determination of Coffee Adulteration via Chromometer:
    Comparing the value of luminosity, the degree of coffee-roasting can be classified into three groups: light (23.5 < L* < 25.0), medium (21.0 < L* < 23.5) and dark (19.0 < L* < 21.0). The color measurement was performed to evaluate whether the appearance of the roasted adulterants and the coffee were similar after roasting and grinding.

  • Determination of Coffee Adulteration via HPLC HPLC analysis was directly performed after sample extraction and the generated chromatogram was utilized as a “fingerprint”. Figure 1 shows the HPLC chromatograms of pure coffee, pure adulterants and adulterated coffee containing 20% soybeans. Coffee beans (Figure 1A), soybeans (Figure 1B) and green mung beans (Figure 1C) showed very distinct chromatograms because each material presented their own special compounds, such as caffeine, tannic acid, linoleic acid, nicotinic acid, chlorogenic acids and trigonelline in coffee. Soybeans contained isoflavones. Green mung beans contained polyphenols, polysaccharides, and peptides. However, the chromatograms of coffee, spent coffee grounds (Figure 1D) and adulterated coffee beans (Figure 1E) showed high similarities but can be clearly distinguished.

• • Determination of Tea Adulteration via ACQUITY UPLC H-Class System with Mass Detector
    Figure 1 shows the 15 dyes and selected isomers that were separated with the ACQUITY UPLC H-Class System and Mass Detector

Food Adulterant Testing Synergies within Cotecna

Cotecna is strongly involved in agriculture, which also encompasses the production of spices and condiments. By working together with other affiliates, we are present throughout the entire supply chain. Sometimes there is only inspection of raw products needed, but in several cases, customers also require some analysis, in which Wimpey Laboratories can intervene, along with other laboratories in Romania, Ukraine, and Argentina, with which we collaborate.

In addition, food adulteration testing is of high interest in East Asia, where we can support the network with our expertise.

For more information, please contact us.