Sustainable valorization of tea flower (Camellia sinensis) blossoms: bioactive phytochemicals and functional food applications – a review

Abstract

Tea (Camellia sinensis) is the second most widely consumed drink after water, with an annual production of 6.5 million tons worldwide. Black tea (78%) and green tea (20%) account for the majority of global tea production, resulting in large amounts of waste, such as tea flowers, which are an underexploited resource. The theoretical fresh weight of Assam tea flowers alone is 1.4–4.6 billion kg per year, but only 600–3000 kg per ha of dry matter is recovered after processing. This review discusses the biochemistry of tea flowers, which are rich in catechins (24.85–28.02 mg g⁻¹), polysaccharides (30–38%), and saponins (0.47–4.23%). Antioxidant, anti-inflammatory, antiproliferative, antidiabetic, and anti-obesity properties have been reported in preclinical models, but the human equivalent doses (243 mg per day to 2.4 g per day) are considered impractical. Hot air and microwave drying methods are optimal for preserving phenolic compounds, but freeze-drying preserves the highest quality at a high cost. Toxicity studies have revealed low toxicity (LD₅₀ > 12 g kg⁻¹) with a safe daily intake of 24 g for a 60 kg human; however, efficacy, variety standardization, EU novel food approval, and US GRAS status are yet to be established. The next research priorities should focus on human bioavailability, allergenicity, and processing effects. Until then, tea flowers should be considered novel food ingredients with traditional use rather than evidence-based functional foods.