The contents of alliin decreased significantly after 10 days of
heat treatment and allicin could not be detected after 4 days
of thermal processing; the polysaccharide was degraded
gradually with the content of reducing sugars increased
corresponsively. The degradation products of polysaccharides
are mainly fructose, glucose and sucrose. These results
contributed to the sweetness taste of black garlic, and the
saccharide contents could be used as quality factors for the
production of black garlic. The color value of black garlic
increased over time, whereas the pH decreased continually
from 6.25 to 4.25 after heating at 70–80C for 10 days,
leading to a sour taste mouthfeel and a characteristic black
appearance. Furthermore, antioxidant activities of black
garlic, including the DPPH, HO radical scavenging and
FRAP activity, increased gradually during the thermal
processing.