Ferulic Acid Dehydrodimers in the Cell Walls ofBeta vulgaris and their Possible Role in Texture
✍ Scribed by Waldron, Keith W; Ng, Annie; Parker, Mary L; Parr, Adrian J
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 358 KB
- Volume
- 74
- Category
- Article
- ISSN
- 0022-5142
No coin nor oath required. For personal study only.
✦ Synopsis
Sugarbeet, a form of Beta vulgaris var vulgaris, fails to soften completely after heating at 100¡C for several hours. This is due to thermal stability of the cellÈwall polymers involved in cellÈcell adhesion. In contrast, beetroot softens within 25È30 min due to a relatively rapid increase in the ability of the cells to separate. Information concerning the cellÈwall polymers responsible for cellÈcell adhesion was obtained by subjecting sugarbeet and beetroot tissues to a range of chemical and biochemical treatments designed to cleave cellÈwall chemical bonds selectively. Treatment of sugarbeet tissues with chelating agents, weak base 0É05 M) or a puriÐed, speciÐc endoxylanase did not facilitate vortex-(Na 2 CO 3 , induced cell separation. However, this could be induced after extraction in dilute, cold alkali (0É05È0É1 M KOH) or dilute, hot acid (0É1 M TFA, 100¡C). Tissues from beetroot behaved similarly. Furthermore, the cell walls of sugarbeet and beetroot were similar in yield and neutral carbohydrate composition ; the cellÈ wall-galacturonic acid content of beetroot was 50% higher as compared with sugarbeet. They were also rich in ferulic acid (FA) and its derivatives (6È7 mg g~1 CWM), and exhibited pH-dependent autoÑuorescence which disappeared during alkali-induced cell separation. In sugarbeet, over 20% of the FA was in dimer form. In beetroot, however, the value was only 10%. The main FA dimers were 8-O-4@DiFA and 8,5@DiFA (benzofuran form). The results indicate that the degree of thermal stability of cellÈcell adhesion and, therefore, texture in Beta vulgaris tissues is related to the degree of FA-cross linking between pectic polysaccharides.