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Antioxidant Dietary Fiber: An Approach to Develop Healthy 317
VetBooks.ir breakdown, thermal breakdown and leaching into blanching water (Verkerk

et al., 2001; Wachtel-Galor et al., 2008; Cartea & Velasco, 2008). Drying is
also reported to affect glucosinolates evolution. Mrkic et al. (2010) studied
the effect of temperature (50–100 °C) of the air that was used to dry broccoli
and reported that glucosinolates content decreased upon drying, especially
at higher drying temperatures.
Tanongkankit et al. (2012) investigated the effects of processing steps,
that is, slicing, blanching, and drying, on the changes of total glucosino-
lates in cabbage outer leaves, changes in DF composition and color. They
noted that the preparation steps did not lead to any significant changes of the
DF powder compositions. On the other hand, steam blanching was noted to
better preserve glucosinolates than water blanching. Drying methods and
conditions did not lead to any significant effect on the powder compositions;
however, vacuum drying led to better retention of glucosinolates. Color of
the DF powder was not affected by the drying methods and conditions.
Jongaroontaprangsee et al. (2007) produced high DF powder from outer
leaves of cabbage and reported that the powder contained ~41–43% TDF
(dry basis). Moreover, the powder possessed high water holding capacity and
swelling capacity. The production of DF powder associated with antioxidant
activity from cabbage outer leaves was studied by Nilnakara et al. (2009).
The effects of hot water blanching and hot air drying temperature (70–90 °C)
on the quality of DF powder produced from cabbage outer leaves were also
investigated. Parameters like proximate composition, visual color, phenolic
content, vitamin C as well as total antioxidant activity were evaluated.

8.5.2.2 ASPARAGUS

Besides their culinary quality, green asparagus spears are known for their
composition of bioactive compounds. Eastern civilizations have been using
asparagus extracts as stimulants, laxatives, antitussives, diuretics, and so
forth, for hundreds of years. Asparagus has been reported as rich in the
quality and quantity of its antioxidants (Pellegrini et al., 2003; Vinson et
al., 1998). During industrial processing, around half of the total length of
each spear is discarded, which creates significant waste for producers. It is
expected that the by-products have similar composition to the edible part
of the spears and could be a promising source of phytochemicals and fiber
(Nindo et al., 2003).
The asparagus extracts possess number of biological activities, including
anti-tumor and antioxidant activities and participate in the prevention of