Evaluation on stability and quality characteristics of black tea-roselle mixture during storage

Noor Fadzlina I. Z. A.¹*, Faridah H.², Mohd. Nazrul Hisham D.³, Tun Norbrillinda M.¹, Nur Baizura S.¹, Mohd. Romainor M.¹ and Nur Intan Farina S.¹

Abstract
Black tea-roselle mixture is a newly developed tea product that combines black tea from Camelia sinensis and Hibiscus sabdariffa chunks or known as roselle. The tea leaves undergo natural fermentation followed by drying at 110 °C before being mixed with roselle chunks. A study was conducted to assess the quality of black tea-roselle mixture during 12 months of storage at ambient temperature. Every three months, the individual sachet of the black tea-roselle mixture was analysed for its physical properties, microbiological, sensory qualities, and phytochemical levels. During the storage period, the moisture content of the product remained constant, while water activity varied between 0.30 to 0.49. Microbial analysis showed safe levels of total viable count, yeast and mold and coliform count throughout the storage. The phytochemical content of the tea changed during storage. Catechins, a beneficial compound, decreased significantly by almost 50% by the end of the 12 months storage. Theaflavins content vary unpredictably, peaked at month 6. Overall, the black tea-roselle mixture remained physically stable and safe for consumption for at least 12 months when stored at ambient temperature. However, the degradation of the catechins content over time suggested that the product may experience a decrease in its health-promoting properties.

Keywords: black tea-roselle, physicochemical changes, phytochemical content, microbial quality, sensory acceptance

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