• Food Science of Animal Resources
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• v.20 no.1
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• pp.64-71
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• 2000

The volatile flavour compounds such as acetaldehyde, acetone, ethanol, diacetyl and acetoin were detected by gas chromatography in adlay yoghurt during fermentation and storage period at 4 $pm$1$^{circ}C$, but acetoin was trace. The contents of acetaldehyde of adlay yoghurt showed maximum immediately after fermentation and decreased significantly(P<0.05) with storage period and were in order of adlay yoghurt fermented with YC-380, ABT-D and ABT-4. The contents of acetone were shown similar trend to acetaldehyde and those of adlay yoghurt fermented with YC-380, ABT-4 and ABT-D, decreased rapidly from 6 days, 9 days and 12 days of storage, respectively. The contents of ethanol increased during the storage period and those were significant differences(p<0.05) between 6 days and 9 days of storage period in control and treatments. The contents of diacetyl were detected in control and treatments at 9 days of storage and increased slightly during the storage period. The contents of volatile flavour compounds of T1 showed similar to that of control and slightly high compared to those of treatments, and decreased gradually with increasing the level of addition of adlay in treatments. The taste, flavour and texture of T1 immediately after fermentation and during the storage period at 4$\pm$1$^{\circ}C$ were slightly higher than those of control and treatments. The scores of sensory evaluation of treatments except T1 were lowered significantly(p<0.05) with increasing level of addition of adlay. Adlay yoghurt fermented with YC-380 and ABT-4 and ABT-D were superior to both of taste and flavour, and texture, respectively. From the results mentioned above, the addition of taste and flavour, and texture, respectively. From the results mentioned above, the addition of adlay at 1% (w/v) level in skim milk substrate were suitable for quality of adlay yoghurt such as volatile flavour compounds and sensory property.

• Food Science of Animal Resources
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• v.20 no.1
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• pp.56-63
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• 2000

This study was investigated the effects of the addition of adlay with levels of 1%(T1), 2%(T2), 3%(T3) and 4% (T4) in skim milk substrate on the physicochemical and microbiological properties of yoghurt during fermentation and storage period at 4$\pm$1$^{\circ}C$. Adlay yoghurt were fermented with the mixed cultures of YC-380, ABT-4 and ABT-D. Titratable acidity and pH values of all treatments were increased and decreased significantly(p<0.05) with fermentation period, respectively and increased and decreased slightly during the storage period, respectively. There were increased and decreased in order of all treatments fermented with YC-380, ABT-4 and ABT-D. Viscosity of adlay yoghurt increased rapidly in order of T4, T3, T2 and T1 during fermentation and slowly in order of T1, T2, T3 and T4 during the storage period. There were increased in order of all treatments fermented with ABT-D, YC-380 and ABT-4. The counts of viable cells of lactic acid bacteria in all treatments were rapidly and slightly increased during fermentation and storage period, respectively. There were increased in order of fermented with ABT-D, ABT-4 and YC-380 in all treatments. The counts of E. coli were not found in adlay yoghurt. In all treatments, T1 showed slightly high compared to that of control. Based on the results of this experiment, the optimum level of addition of adlay were 1% (w/v) for production of acid production, pH, viscosity and the counts of viable cells of lactic acid bacteria.