Macromolecular and rheological properties of Italian waxy wheat

Starch retrogradation is the major cause of breadcrumb firming, and amylose is assumed to be mainly responsible for bread staling, making the food industry interested in using waxy (amylose-free) cereals and/or starches in bakery products. Waxy wheat lines have been produced in Japan and in other countries, but showed poor adaptability to the Italian agronomic conditions. A breeding program set up at CRA-SCV starting from partial-waxy cultivars identified in Italian bread wheat germplasm led to the release of about twenty waxy hexaploid wheat lines (WHW, Triticum aestivum L.). Aim of the present work is the study of the properties of these lines and of the role of the waxy trait in bread texture. Eighteen WHW were selected and characterized by chemical and physical small-scale analyses, and the pasting and rheological properties of flours were evaluated. Results were compared with those obtained from two commercial non-waxy cultivars, used as controls. Amylose content of WHW was typical of waxy lines (on average, 1.4%), with protein content ranging from 12.3% to 17.2%. In four WHW, the high protein content was associated to high gluten quality, evaluated by Gluten Index and SDS Sedimentation Volume. RVA test indicated a lower retrogradation tendency in WHW than in controls (setback values: 329 vs 931 cP). From a rheological standpoint, WHW showed high farinograph water absorption (70.3 ÷ 78.7%), but very low stability values. Baking tests indicate a good breadmaking quality of the Italian WHW, although starch-protein and protein-protein interactions in these systems deserve further investigation. This study was supported by Italian MiPAAF (CERSUOM, DM 1942/7303/08).