Abstract:
The objectives of this study were to: 1) analyze chemical properties of Satho residues from manufacturing processes, 2) optimize fermentation conditions for the production of Satho residue vinegar, 3) develop an optimal beverage formulation made from Satho residue vinegar and rice syrup, 4) investigate consumer acceptance of the beverage made from Satho residue vinegar and rice syrup, and 5) study the storage shelflife of the vinegar and rice syrup beverage. Firstly, the chemical properties of Satho residues including moisture, carbohydrate, lipid, protein, ash, pH, total soluble solids and alcohol contents were examined. Then, two fermentation factors consisting of three strains of bacteria (Acetobacter aceti TBRC 474, Acetobacter aceti TISTR 40 and Acetobacter sp.IFRPD) and the percentages of starter cultures (10, 20 and 30%), were analyzed using factorial experiment in CRD. Later, the suitable condition according to the Notification of the Ministry of Public Health (No. 204) B. E. 2543 (2000) Re: Vinegar comprised alcohol iccontents, acetic acid contents by titration, pH and total soluble solids was selected. After that, four levels of resulting vinegar concentration (2, 4, 6 and 8 %) were mixed with rice syrup to develop vinegar beverages. The sensory evaluation of the experimental beverages was conducted with 50 panelists. The preference of appearance, color, odor, sour taste and aftertaste of the beverages was evaluated using 9 - Point Hedonic Scale. The selected beverage was then pressurized with carbon dioxide (CO2) gas and subjected to consumer acceptance testing. Finally, the storage shelf- life comprised physical, chemical and microbiological properties of the vinegar and rice syrup beverage was carried out at different temperatures.
The research results revealed that: 1) Satho residues contained 93. 27% of moisture content, 10.80 % of total nitrogen, 0.02 % of lipid, 64.26 % of protein, 0.17% of ash, a pH of 3.40, total soluble solids (TSS) of 8.0 Brix and 3.70 %(v/v) of alcohol. Moreover, Satho residues contained suitable nutrients for acetic acid production. 2) Acetobacter aceti TBRC 474 and 10 % starter culture produced the highest acetic acid content of 4.10 % (w/v) with 0.1 % (v/v) residual alcohol. The resulting vinegar was light yellow without pungent smell and provided sour taste of vinegar. 3) The optimal amount of Satho residue vinegar for the production of the vinegar beverage was at 6 % with preference scores in appearance, color, vinegar odor, sour taste, aftertaste and overall preferences of 8.00 ± 0.64, 6.80 ± 0.78, 6.38 ± 0.60, 8.16 ± 0.79, 7.52 ± 0.95 and 8.04 ± 0. 85, respectively. 4) Most consumers accepted the product with the highest score in the overall preference at 7.74 ± 0.79. In addition, the subjects indicated the purchase intention of 83 % after the benefits of the product had been informed. 5) The vinegar beverage product can be stored at room temperature (30±1°C) and refrigerated temperature (4±1°C) no longer than 4 weeks or 28 days.