Chlamydomonas reinhardtii polysaccharides retard rice starch retrogradation by weakening hydrogen bond strength
Xinwen Cui1, Chunbo Guan1, Heqin Wang1
1College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China.
Abstract:
This study investigated the effects of Chlamydomonas reinhardtii polysaccharides (CRPs) on retarding the retrogradation of japonica rice starch (JS) and glutinous rice starch (GS). Structure characterization revealed that CRPs, with an average molecular weight of 505 kDa, mainly consisted of glucose, mannose, and galactose and featured a triple-helix structure. CRPs could reduce the storage modulus increment of JS during the cooling process by interacting with amylose, thereby inhibiting gel network formation. After long-term storage, CRPs decreased the hardness of JS and GS gels, limited the mobility of water molecules, and inhibited dehydration of gels. In addition, CRPs restricted starch recrystallization through interactions with amylopectin, resulting in reduced retrogradation enthalpy and relative crystallinity in JS and GS gels. Further investigation revealed that CRPs could weaken hydrogen bond strength within double helices in JS and GS after 14 days, with bond energies of 10.270 kJ for JS-0.4%CRPs and 10.241 kJ for GS-0.4%CRPs, which are lower than those of native starches (10.464 and 10.500 kJ). Moreover, the energy increments of hydrogen bonds within double helices in complexes were smaller than those of native rice starches during storage, which emerges as the essential reason behind the retardation of rice starch retrogradation by CRPs.
