The effects of acid and alkali on wheat starch extrusion cooking

Riitta Kervinen, Tapani Suortti, Juhani Olkku, Pekka Linko

    Research output: Contribution to journalArticleScientificpeer-review

    10 Citations (Scopus)


    The influence of o-phosphoric acid and of sodium hydroxide on wheat starch extrusion cooking with a Creusot-Loire BC 45 twinscrew extruder has been investigated under various process conditions by employing regression analysis. Phosphoric acid (0-1.5% w/w) and sodium hydroxide (0-4% w/w) contents, feed moisture (15-60%) and mass temperature before the die (130-190°C) at constant screw speed (150 rev/min) and feed rate (18 kg d.m./h) were chosen as independent variables. An increase in phosphoric acid content and a decrease in feed moisture increased water solubility index and starch breakdown, as followed by HPLC, and decreased water absorption ability. Under similar conditions, an increase in sodium hydroxide level and moisture content usually increased water absorption ability. Starch breakdown was in this case less pronounced than in an acid environment. The presence of alkali also significantly increased browning.
    Original languageEnglish
    Pages (from-to)52-59
    JournalLebensmittel-Wissenschaft & Technologie
    Issue number1
    Publication statusPublished - 1985
    MoE publication typeA1 Journal article-refereed


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