Food Research (Oct 2017)
Optimization of important production factors of a non-alcoholic beverage from roselle calyx, sorghum stem sheath and local spices
Abstract
RSM was used to optimize the important processing variables for a non-alcoholic beverage (NAB) from roselle calyx, sorghum stem sheath and two local spices. A CCRD consisting of six variables reduced to five for mathematical convenience [Roselle Calyx/Sorghum Stem Sheath, (RC/SSS, 0-75/25-100 g), ginger (0-1.50 g/100ml), Alligator Pepper (AP, 0-1.50 g/100ml), Extraction Temperature (ET, 80-100oC) and Time of Extraction (TOE, 20-40 min)] with five coded levels (-2,-1, 0, +1, +2) were studied with two replications, making 54 experiments. Mathematical models were developed for the responses [Vitamin C (VC), Total Carotenoids (TC), 1, 1 -Diphenyl-2-picrylhydrazyl (DPPH), Total Phenols (TP), pH, Total Titratable Acidity (TTA)] for making a prediction during NAB production. Storage stability indices [pH, VC, TTA, Total Viable (TVC) and coliform counts] of the beverage were monitored for 28 days. The optimum processing variables were RC/SSS, 66.67 g/33.33 g; ginger, 0.375 g/100ml; AP, 0.375 g/100ml; ET, 85°C; and TOE, 35 min, yielding actual values of 15.33, 1757.2, 0.306 (mg/100ml), 89.21% for VC, TC, TP and DPPH respectively. The developed mathematical models for the measured responses could be successfully used for their prediction during non-alcoholic beverage production with a correlation coefficient (R2) ranging from 0.84-0.99. Reduction in pH (4.98-2.66) and VC (15.33 -12.69 mg/100 ml) were observed while TTA increased (1.70-5.02%) during storage. There was no coliform growth throughout the storage period, however, after 7 days, TVC was 7x102 CFU/ml.
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