In Vitro Bioactivity, Polyphenols, Antioxidant Properties, and Sensory Quality of Al-Qassim Berry-Enhanced Matcha Tea as a Function of Extraction Temperature

Matcha tea (Camellia sinensis) contains high levels of catechins but has a near-neutral pH (6.2–6.3), which limits the stability of its bioactive compounds. Blending matcha with acidic berries may enhance phenolic stabilization, antioxidant capacity, and sensory properties. This study evaluated pure matcha (MT) and a matcha beverage blended with 7.5% strawberry and 7.5% blackberry powder (Mix), extracted at 5 °C, 70 °C, and 100 °C. Sensory evaluation using a 9-point hedonic scale (n = 50) identified 15% berry substitution (Mix) as optimal, with overall acceptability scores ranging from 8.28 to 8.32 across all extraction temperatures. Sensory evaluation using a 9-point hedonic scale (n = 50) identified 15% berry substitution (Mix) as optimal. Total phenolics (Folin–Ciocalteu), flavonoids (AlCl3), anthocyanins (pH differential), vitamin C (HPLC), and individual phenolic compounds were analyzed. Antioxidant activity (DPPH, ABTS) and anti-inflammatory activity (egg albumin denaturation) were assessed, and color parameters (L*, a*, b*, chroma, hue, browning index, ΔE) were measured. Results and Discussion: The Mix exhibited significantly higher total phenolics (24.4% increase at 100 °C) and flavonoids (31.6% increase at 100 °C) compared to MT. Anthocyanins, absent in MT, reached 52.35 mg/100 g at 5 °C, and vitamin C content was 2.6-fold higher than MT under cold extraction. HPLC profiling showed increased levels of gallic acid, protocatechuic acid, catechin, epicatechin, epicatechin gallate, and rutin in the Mix. The Mix demonstrated superior antioxidant activity with DPPH inhibition of 84.08% at 100 °C (IC50 = 165.0 µg/mL) and ABTS inhibition of 83.67% at 100 °C (IC50 = 105.1 µg/mL). Anti-inflammatory activity was highest at 70 °C (IC50 = 72.2 µg/mL), representing a 3.5-fold improvement over MT. Color parameters were similar to MT at 5 °C and 70 °C but darkened at 100 °C. The acidic pH (~3.7) of the Mix remained stable, contributing to catechin stabilization. Conclusion: The 15% strawberry-blackberry matcha blend shows potential as a functionally enhanced beverage with improved phenolic content, vitamin C, anthocyanins, and bioactivities. Temperature selection allows customization: 100 °C for maximal antioxidant activity, 70 °C for anti-inflammatory benefits, and 5 °C for nutrient preservation and vibrant color.