Cell wall modifications during cooking of potatoes and sweet potatoes

✍ Scribed by Binner, S; Jardine, W?G; Renard, C?M?C?G; Jarvis, M?C

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 64 KB
• Volume: 80
• Category: Article
• ISSN: 0022-5142
• DOI: 10.1002/(sici)1097-0010(20000115)80:2<216::aid-jsfa507>3.0.co;2-6

✦ Synopsis

Sweet potato (Ipomoea batatas L) tissue, when cooked at 70 °C to activate b-amylase and break down starch, takes on a distinctive ®rm, brittle texture and does not show the cell separation that occurs in, for example, cooked potato (Solanum tuberosum L). Similar cooking conditions increase ®rmness in other plants by activating pectin methyl esterase which de-esteri®es pectic polysaccharides and protects them from thermal depolymerisation. We therefore isolated cell walls from both potatoes and sweet potatoes cooked at 70 °C and 100 °C and determined the remaining degree of methyl esteri®cation of their pectins. Pectins from both species were demethylated to a similar extent at 70 °C and 100 °C. Since cooking sweet potato at 100 °C induced cell separation and softening, it is concluded that b-amylase is rapidly inactivated at that temperature and swollen starch distends and separates the cells, whereas the ®rm texture obtained by cooking that species at 70 °C is not the result of pectin demethylation but is caused by the breakdown of starch to oligomers that can escape from the cell.