Physicochemical properties of kiwifruit starch

- Golden kiwifruit at harvesting time contains abundant starch.
- Thermal, rheological and morphological properties of kiwifruit starch are studied.
- Starch of outer pericarp differs from that of core in some properties.
- Properties of kiwifruit starch are compared with maize and potato starches.

Three varieties of golden kiwifruit (Actinidia chinensis) (Gold3, Gold9 and Hort16A) were collected at the commercial harvesting time, and physicochemical properties of starches from core and outer pericarp were studied. Starch contents (dry weight basis) in outer pericarp and core tissues ranged from 38.6 to 51.8% and 34.6 to 40.7%, respectively. All the kiwifruit starches showed B-type polymorph. Compared to the outer pericarp starches, amylose content and enzyme susceptibility of core starches were higher, and the degree of crystallinity, granule size and gelatinization parameters of core starches were somewhat lower. This suggests different biosynthetic properties between these two starches. The enthalpy changes of gelatinization of outer pericarp starches were high (∼21 J/g). Rheological properties of outer pericarp starches were compared with normal maize and potato starches showed high yield stress of flow properties. This study revealed the unique properties of kiwifruit starch among various types of starches.