Various quality control requirements have been framed in the food regulations for tea, which begin with procurement of quality raw material to storage and distribution of tea as a product. Tea is tested for constituents like caffeine, polyphenols and essential oils because these contribute to the body, aroma and flavour of tea. Quality control of tea means it must also be contaminant free and a good quality beverage. Tea testing services for quality control carried out by food testing laboratories includes measuring the quantity of anti-oxidants and other essential nutrients. Some other important aspects for quality control that are tested by are
- Colouring matter
- Foreign matter
- Caffeine content
- Tannin content
- Crude Fibre
- Iron filings
Tea is tested by food testing laboratories according to various Indian Standards (IS) methods. The analytical services of food testing labs include quantifying heavy metals and pesticide residues that can make their way into fresh green leaves, dried green leaves, infusion, soil and black tea. The presence of certain heavy metals like copper, chromium, nickel, zinc, cadmium, lead and arsenic must also not be found in tea above permissible regulatory limits. Some testing laboratories also undertake to carry out periodic checks in the tea gardens so residues of ethion, dicofol, quinalphos, chlorpyrifos, fenpropathrin, fenvalerate, lambda-cyhalothrin, beta-cyfluthrin, propargite, endosulfan, fenpyroximate and hexythiazox can be quantified as all pesticides have a maximum residue level. NABL accredited and FSSAI recognised food testing laboratories have qualified technicians and state-of-art instrumentation to be able to detect pesticide and heavy metal residues at even very low levels.
Testing labs also carry out microbiological testing for contaminants like salmonella. Microbiological contamination can reach tea because of incorrect harvesting and drying techniques. Cross-contamination can also occur in the factory due to gaps in separation of clean and unclean zones within the factory premises. Food safety from microbiological contamination is also a criterion for quality control of tea. Other important aspects in tea testing carried out by food testing labs are
- Loss on Drying
- Total ash
- Acid insoluble ash
- Water soluble ash
- Alkalinity of water soluble ash
- Water extract
Aflatoxins are highly toxic and carcinogenic secondary fungal metabolites and like other food commodities, tea can also be contaminated with these fungi. The constituents of tea as well as the temperatures in which tea is grown can make tea susceptible to aflatoxin contamination. Testing laboratories can detect the presence of aflatoxins during all stages of tea processing and manufacturing whether it is withering, rolling, fermentation and firing. Sometimes aflatoxin contamination can reach the final product during sorting and packaging. Therefore, fresh tea leaves and finished tea products are tested for aflatoxins by food testing laboratories.
Most tea manufacturers hire independent accredited food testing laboratories to carry out tea testing services that cover all the above mentioned parameters analysis. The testing labs undertake regular as well as random analysis to inhibit any kind of contamination. Through tea testing the tea industry ensures food safety and quality control of tea.