Starches - from granules to novel applications

In this study, the effects of growth temperature, starch composition and granule size on the gelatinisation and solubility properties of barley starch were studied. The mechanical properties and structures of amylose and amylopectin film, with and without added glycerol, were investigated. A novel starch-based microencapsulation method was developed for probiotic bacteria by combining native starch granules with amylose coating. The suboptimal growth conditions influenced the properties of two-rowed malting barley cultivars "Kustaa" and "Kymppi" as well as Kustaa′s large Agranules and small B-granules. The gelatinisation temperature was lower and the rate of retrogradation less in starch grown in cold and rainy conditions. Swelling and solubility were greater and the starch was more susceptible to amylases. The small B-granules had a higher lipid:amylose ratio than the large A-granules. The B-granules also had a higher dissociation enthalpy of the amylose–lipid complex than the A-granules. Furthermore, the gelatinisation temperature was 4°C higher for B-granules than for A-granules. During heating in excess water up to 90°C amylopectin was mainly leached from the B-granules, whereas amylose was solubilised from the A-granules. At 95°C, B-granules were completely solubilised but A-granules remained partially particulate. Amylose produced good quality films from water solutions in the presence of glycerol. Film formation was successful even at a 70% glycerol content, whereas films could not be prepared from amylopectin above a 30% glycerol content. Based on calorimetric glass transition (Tg) analysis, pure glycerol was observed to decrease the Tg. However, water had a stronger plasticisation effect. No difference between the Tgs of two starch polymers could be observed. The Tg was at room temperature at a water level of 21%. Phase separation to starch-rich and starch-poor regions occurred in glycerol plasticised systems. Fresh amylose