Optimization of herbal health tea flavored with roasted rice germ (Khao dawk mali 105) using response surface methodology

Abstract

Herbal health tea flavored with roasted rice germ was formulated using mixture design and response surface methodology (RSM). The ranges for dried bael fruit powder (Aegle marmelos (L.) Correa), dried pandan (Pandanus amaryllifolius) leaf powder and roasted rice germ were 20–50%, 20–50% and 30–70%, respectively. At optimum condition, the herbal tea flavored with roasted rice germ consisted of 45.25% of dried bael fruit powder, 21.68% of dried pandan leaf powder and 33.07% of roasted rice germ. The product contained 4.22% moisture and 3.18% total ash. For antioxidant activity, it was found that herbal health tea had 69.03% DPPH scavenging activity and 75.16 mg GAE/g total phenolic content. Water activity of the product was 0.374. The aerobic plate count was less than 1×102 CFU/g as well as yeast and mold were not found. Color with L*, a*, b* values and transmittance of brewed herbal tea were 60.11, -1.43, 14.10 and 75.87%, respectively with almost clear greenish-yellow appearance. Consumer acceptability test on 150 consumers indicated that the product was liked very much (Overall liking score = 7.6) with 99.3% of them accepted the product.