MECHANICAL DE-SEEDING OF ROSELLE AND ITS EFFECTS ON QUALITY OF BREWED ROSELLE TEA
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Date
2023
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Abstract
The manual deseeding of Roselle is time-consuming and labour-intensive process. Dealing with bulk quantities manual, deseeding can result in loss of edible parts of calyx due to human error and drudgery. Therefore, considering the need and expectations of the small-scale manufactures of Roselle products, an efficient, low-cost, fast deseeding design was developed and compared with hand/manual deseeding. The developed machine has a foot paddle and link mechanism. Coil spring mechanism has been provided for return action of the punching tool to its original position. The machine cost was estimated to be Rs.1800/-. The rate of deseeding by the machine was 2.5 kg/h with minimum broken percentage producing good quality of deseeded calyces. When compared with manual deseeding, it was found that manual deseeding capacity was 1.5 kg/h apart from quality degradation of the calyces. Brewed Roselle tea was taken for quality tests to see the effect of mechanical deseeding against manual deseeding. Mechanically and manually deseeded whole calyx and powder (dried at 80 °C) were selected as treatments. The quality parameters like Anthocyanin (monomeric), Total phenol content, Total flavonoid, Antioxidant activity, Total soluble solids, Colour, Sensory Analysis, Bulk density, True density, Porosity were determined for both mechanical and manual deseeded calyces and powders. The highest mean of monomeric-anthocyanin content was found in mechanically deseeded powder and whole calyces’ tea (39.83 mg/ml and 16.59 mg/ml), same trend was observed for the phenol content (26.03 mg/ml and 14.58 mg/ml), flavonoid content (24.37 mg/ml and 16.56 mg/ml) and antioxidant activity (88.70% and 87.60%). Sensory assessment of the Roselle tea revealed that mechanically deseeded whole calyx dried at 80 °C was highly accepted and judged best among other Roselle tea samples. Mechanically deseeded calyces dried at 80 °C exhibit higher porosity (51.41%) and lower bulk density (0.69 gm/cm3), which plays important role for production of tea or herbal infusion of dried Roselle because a lower bulk density allows for better infusion and extraction of flavours and compounds. The result obtained from the quality parameters opened up a possibility having a good impact on the small-scale manufactures, marginal farmers and Self-help groups (SHGs) for having a good quality Roselle’s products and smooth deseeding operation with the deseeder.