Radish anthocyanin extract has potential as a natural colorant because of
its pigment stability and attractive red hue. Presence of undesirable aroma
compounds could limit its applications in foods. The pungent principle of
radish, 4-methylthio-3-butenyl isothiocyanate (MTBI), is produced
enzymatically upon cell injury from its glucosinolate precursor, 4-methylthio-3-butenyl glucosinolate (MTBG), and undergoes subsequent
degradation to produce a number of volatiles. To evaluate the potential of
flavor formation, juices were prepared from winter and spring radish
cultivars. Whole radishes, peels and flesh, as well as radish extracts, were
analyzed for glucosinolates and isothiocyanates. Aroma intensities of radish
juice extracts were evaluated using sensory analysis.
MTBI was monitored by HPLC (detection level 160 ppb). MTBG was
extracted from freeze-dried radish tissue with boiling methanol, purified by
anion exchange and enzymatically desulfated. DesulfoMTBG was quantified
by HPLC, using desulfosinigrin as internal standard. Identification was
performed by fast atom bombardment and electrospray mass spectroscopy.
MTBI formation was higher in winter than in spring cultivars (1.5-2.8 and 0.8-1.3 mg/100g fresh weight, respectively), and higher in flesh than in peels.
MTBG ranged from 30-65 mg (spring cultivars) to 260-320 mg/100g fresh
weight (winter cultivars) with greater concentration in peels than in flesh.
Isothiocyanates and glucosinolates were not detected in radish juices.
Overall aroma intensities of radish juice concentrates, diluted to 150, 300,
600 and 1200 mg anthocyanin/L in water, were rated using a 16-point scale.
Radish concentrates from cultivars Fuego (pigmented peels) and Red Meat
Takii (whole red flesh) were compared to commercial red cabbage and radish
colorants. Aroma intensities followed first order relationships with
anthocyanin concentrations. The commercial colorants were rated slight to
moderate, while radish extracts (Fuego and Takii) were rated moderate to
large. The aroma intensity of red flesh radish extract was more potent than
those prepared from radish peels. Further work includes development of
purification techniques which would provide an odorless aqueous extract. / Graduation date: 1997
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/34258 |
| Date | 13 December 1996 |
| Creators | Kucza, Myriam M. |
| Contributors | Wrolstad, Ronald E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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