สภาวะที่เหมาะสมของกระบวนการความดันสูงในการยืดอายุการเก็บรักษาเครื่องดื่มมอลต์จากข้าวบาร์เลย์สายพันธุ์สะเมิงเสริมพรีไบโอติก

Abstract

The objective of this research was to study the condition for malting process from barley variety Samoeng 1 for prebiotic-fortified malt beverage production and to optimize a high-pressure processing (HPP) using a Box-Behnken experimental design and response surface method with three independent variables including pressure, holding time, and initial temperature then compare with a heat pasteurization. The surrogate bacterial strains used in this study were Escherichia coli K12 and Listeria innocua. As a result, the malting was successfully performed with soaking and air-rest (soaking/air-rest) in 2 cycles, 5/16 and 4/24 hours at 14 °C, allowed to germinate for a period of 8 days, then dried and stored at 4 °C. In developing malt beverages, it was found that the appropriate amount of roasted malt and FOS syrup were 20 percent (w/w) and 10 (w/v), respectively. After that, the HPP was optimized as using a pressure of 600 MPa, a holding time of 6 minutes and an initial temperature of 24 °C. With the optimal condition, log reduction of E. coli K12 and L. innocua were exhibited as 5.92 ± 0.13 and 5.00 ± 0.01 CFU/mL, respectively, which passed the standard criteria of the Food and Drug Administration of Thailand. Furthermore, the factor significantly affecting the HPP efficiency (p<0.05) against both bacteria was pressure level. In addition, it was found that the HPP process was effective in reducing the total plate count and yeast and mold count, comparable to heat pasteurization. This allowed Samoeng barley malt drink supplemented with prebiotic to be stored for at least 77 days under a temperature of 8 °C. The developed product also provided physicochemical quality, color value, bioactive compounds, aroma volatile compounds and sensory qualities similar to the untreated sample.