无回生性的低直链淀粉水稻淀粉理化特性分析

Physicochemical Characterization of Low-amylose Rice Starch Without Retrogradation

摘要:

淀粉回生性对稻米食味品质有影响。回生性水稻淀粉的理化特性已有大量报道，但对于不具有回生性的低直链淀粉含量的水稻淀粉理化特性尚缺乏研究。该研究选取了4个水稻品系，分别是具有回生性的NCIR198，弱回生性的NPDC93112以及2个不具有回生性的PSBG4和PSBG41，分析其胚乳淀粉的理化特性。结果表明：4个水稻品系的直链淀粉含量、短A链占比、1 047/1 022 cm-1 比值、结晶度、糊化焓分别介于在12.43%~13.54%、25.25%~31.59%、0.754~0.919、6.72~13.42 J/g之间。NCIR198淀粉颗粒表面相对紧实光滑，而NPDC93112、PSBG4和PSBG41淀粉颗粒表面相对粗糙松散，有细微针孔；PSBG4和PSBG41短A链的占比显著高于NPDC93112和NCIR198；PSBG4和PSBG41的1 047/1 022 cm-1比值显著低于NCIR198；PSBG4和PSBG41的结晶度显著低于NPDC93112和NCIR198；PSBG4和PSBG41的糊化焓显著低于NCIR198。此外，不具有回生性的低直链淀粉水稻淀粉糊化焓值小，淀粉糊回复值小，不容易发生重结晶。该研究结果可为培育直链淀粉含量低而没有回生性的水稻品种提供理论依据。

Abstract:

Starch retrogradation influences the taste quality of rice. The physicochemical properties of retrogradable rice starch have been extensively reported, but there is still a lack of research on the physicochemical properties of nonretrogradable rice starch with a low amylose content. In this study, four rice lines, NCIR198 with retrogradation, NPDC93112 with weak retrogradation, and two non-retrogradable PSBG4 and PSBG41, were selected to analyze the physicochemical properties of their endosperm starches. The results showed that, the amylopectin content, short A chain ratio, 1 047/1 022 cm-1 ratio, crystallinity and gelatinization enthalpy of the four rice lines were 12.43%~13.54%, 25.25%~31.59%, 0.754~0.919 and 6.72~13.42 J/g, respectively. The surfaces of NCIR198 starch granules were relatively compact and smooth, whilst the surfaces of NPDC93112, PSBG4 and PSBG41 starch granules were relatively rough and loose, with fine pinholes. The proportion of short A chains in PSBG4 and PSBG41 was significantly higher than those in NPDC93112 and NCIR198. The ratios of 1 047/1 022 cm-1 of PSBG4 and PSBG41 were significantly lower than that of NCIR198. The crystallinity of PSBG4 or PSBG41 was significantly lower than that of NPDC93112 or NCIR198. The gelatinization enthalpy of PSBG4 or PSBG41 was significantly lower than that of NCIR198. In addition, the gelatinization enthalpy of the low-amylose rice starch without regeneration was small, and the recovery value of the paste of this starch was small and not easy to recrystallize. The results of this study can provide a theoretical basis for cultivating of low-amylose rice varieties without regeneration.