Faculty of Food Technology and Biotechnology, University of Zagreb
Abstract
The functional properties of starches determine their potential applications in food systems. These properties depend largely on granular and molecular structure and can be physically, chemically or enzymatically modified. One way of modifying starch functional properties is by interaction with other food components, such as proteins. Starch-protein interactions are frequent in plant foods, particularly cereals and legumes, which are formed mainly of starches and proteins. An evaluation has been done of changes in the functional properties of three native starches (corn, Zea mays L.; cassava, Manihot esculenta; and lima bean, Phaseolus lunatus L.) when blended with lima bean protein concentrate. The gelatinization temperature of each blend increased compared to its corresponding native starch. The cassava starch/lima bean protein blend had the highest overall swelling power and water absorption capacity values at all temperatures. Maximum viscosity for each blend was higher than for the corresponding native starches. The blends of lima bean protein with cassava and corn starches did not exhibit syneresis. The lima bean starch/lima bean protein blend had the highest gel firmness values, followed by the blends with corn and cassava starches. The protein-starch mixtures are an alternative in the improvement of the starch functional properties which are useful in the development of nutritional products.O funkcionalnim svojstvima škroba ovisi njegova primjena u proizvodnji hrane. Ta svojstva uglavnom ovise o strukturi zrna i molekula. Mogu se modificirati fizikalnim, kemijskim ili enzimskim postupcima, a jedan od njih je i interakcija s ostalim sastojcima hrane (npr. proteinima). Interakcije škroba i proteina su česte u hrani biljnog podrijetla, osobito u žitaricama i leguminozama koje se uglavnom sastoje od te dvije komponente. U radu je ispitana promjena funkcionalnih svojstava škroba izoliranog iz kukuruza (Zea mays L.), manioke (Manihot esculenta) i lima graha (Phaseolus lunatus L.), nakon miješanja s koncentratom proteina iz graha lima. Temperatura se želiranja svake mješavine škroba i proteina povećala u usporedbi s izvornim škrobom. Mješavina škroba manioke i proteina graha lima imala je najbolji kapacitet bubrenja i upijanja vode na svim temperaturama. Maksimalna je viskoznost mješavina bila veća od viskoznosti samog škroba svake vrste, pri čemu mješavine proteina graha lima sa škrobom manioke i kukuruza nisu pokazale jače zgrušavanje. Najveću je čvrstoću gela imala mješavina škroba i proteina graha lima, zatim mješavina škroba kukuruza i proteina, te naposljetku škroba manioke i proteina graha lima. Mješavine su škroba i proteina alternativni način poboljšavanja funkcionalnih svojstava škroba u proizvodnji hrane
