Influence of sweeteners and freeze-drying on the quality attributes of sorrel (zobo) drinks

Abstract

Aiming to add value to sorrel drink, effects of sweeteners (sugar and honey) and freeze-drying on the physicochemical properties, micronutrients and sensory attributes of sorrel drink were evaluated. Freeze-dried sorrel drink sweetened with honey was higher in yield (30% vs 10%) and solubility index (44.2 vs 44.19). Freeze-drying and sweetener type significantly (p ˂ 0.05) affected the moisture (9.84-86.08%), pH (3.64-4.51), total soluble solids (8.20-15.10 ˚Brix) and ash (0.56-2.19%) contents of sorrel drink. Freeze-drying led to more concentrated calcium (0.10-1.15 mg/100g), potassium (0.80-4.30 mg/100g), magnesium (0.21-1.99 mg/100g), iron (0.07-0.10 mg/100g) and sodium (10.00-17.00 mg/100g) contents, with sugar-sweetened samples recording higher mineral contents. Both freeze-drying and honey addition resulted in increased vitamin C content, while the anthocyanin content was reduced. Sweetener type showed no significant effect on sensory attributes of the fresh and reconstituted drink samples but the mean sensory scores of the reconstituted drinks were significantly lower than those of fresh drink samples. Nevertheless, all the samples were accepted by the panelists. After 4 weeks of storage, 63.47% and 61.83% vitamin C losses were recorded for sugar- and honey-sweetened drink powders, respectively. This study therefore revealed the potential application of honey and freeze-drying in the production of functional instant sorrel drink powder.