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Eight 2-row barley cultivars (waxy, normal and high amylose) were grown in controlled environment chambers at 9, 12, 15, 18 and 21 ◦ C until maturity. The flour samples were analysed for total starch content, mixed-linked -glucan content (total, soluble and insoluble), content of protein, fat and neutral detergent fibre (NDF) in addition to the amount of total, free and lipid complexed amylose. A non-ruminant in vitro method was used to analyse the degradation of starch (5–10–15–30–60–90–120–240 min incubation times) from the samples grown at different temperatures. A partial least square (PLS) regression model was made to highlight the flour characteristics that influenced the starch degradation the most. The waxy starches were degraded faster and to a higher extent than the normal and high amylose starches at all incubation times. At short incubation times the high amylose was not degraded as rapidly as the normal ones, but as incubation time increased, they changed range, and at 240 min incubation time the normal genotypes were degraded to a lesser extent than the high amylose. The amylose–amylopectin ratio was most important regarding starch degradation. The growth temperature influenced the starch degradation considerably; the degradation was Abbreviations: AACC, American Association of Cereal Chemists; AAM, apparent (free) amylose; AOAC, Association of Official Analytical Chemists; ASE, accelerated solvent extraction; B-glu S, soluble -glucan; Bglu T, total -glucan; B-glu U, insoluble -glucan; LAM = � AM, lipid complexed amylose; ME, metabolizable energy; NDF, neutral detergent fibre; PC, principal component; PLS regression, partial least square regression; RS, resistant starch; TAM, total amylose; YFl, yield of flour after pearling This paper is part of the special issue entitled “Starch structure and digestibility: Basic aspects and new research”, Guest Edited by Birger Svihus and Ole Taugbol. |
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