【作者】 陆大雷；

【导师】 陆卫平； 赵久然；

【作者基本信息】 扬州大学 ， 农产品安全与环境， 2009， 博士

【摘要】 本研究以我国近年来育成的糯玉米品种(品系)为材料,研究了淀粉理化特性的基因型差异,以及施肥处理、播期和收获期等栽培措施对其调控作用,并分析了籽粒成分和加工条件对其影响。本文主要研究结果如下:1.糯玉米淀粉理化特性(膨胀势、溶解度、持水力、胶凝特性、回生特性和糊化特性)存在显著的基因型差异。膨胀势、溶解度、持水力、热焓值、糊化范围、回生值、峰值黏度、崩解值、峰值温度和糊化温度的变异范围分别为12.9~25.3 g/g、34.7~66.7%、97.4~194.5%、45.9~57.0 J/g、7.7~12.0℃、32.8~78.8%、87.7~169.9 RVU、37.5~83.8 RVU、71.8~75.8℃和69.8~73.9℃。其中除峰值温度和糊化温度变异范围较小外,其他参数变异系数较大(变异系数>5.9)。对淀粉结构分析发现,淀粉的最大吸收波长除欣试糯玉01、丹黄糯02和陕白糯12较高外(分别为580.5、557.9和551.1 nm),其余品种的吸收波长均在532.2~540.3 nm之间,为典型的支链淀粉吸收波长,蓝值、碘结合力的变异范围分别为0.1274~0.7789和0.56~1.05。且这三项特征值和回生值、峰值黏度以及崩解值显著负相关,和回复值极显著正相关。对淀粉中微量元素含量分析发现,Ca、K、Na、Cu、Fe元素含量和各理化特征值间无显著相关关系,其他微量元素含量与部分特征值存在着一定的相关关系。可见,虽然糯玉米淀粉仅由支链淀粉组成,但长短链分支比例和淀粉微量元素含量的不同致使淀粉理化特性存在显著的基因型差异。2.施肥处理对淀粉糊化特性、热力学特性和晶体特性存在显著调控作用。施肥处理没有改变糯玉米淀粉的结晶类型,各处理下淀粉均表现为“A”型衍射特征。峰值时间、糊化温度、转变温度、峰值指数和糊化范围受施肥处理影响较小。和基施氮相比,增施磷或(和)钾可显著降低峰值黏度和崩解值,增加淀粉的结晶度,降低淀粉的回生值和回生淀粉的热焓值。随着拔节期追氮量的增加,峰值黏度逐渐升高,而崩解值、回生值和回生淀粉的热焓值在追施氮150和300 kg hm-2时无显著差异,但均大于不追氮处理。热焓值在拔节期追氮0或150 kg hm-2时无显著差异,但高于追氮300 kg hm-2处理,结晶度受追氮处理影响较小。在本试验条件下,氮磷钾均衡基施并拔节期追氮150 kg hm-2时,淀粉具有较高的结晶度、热焓值、峰值黏度和崩解值,较低的回生值。3.生长季节对淀粉晶体结构和糊化特性存在显著影响。生长季节不影响淀粉的结晶类型,供试淀粉的X-射线衍射图谱均表现出典型的“A”型衍射特征。然而,淀粉的晶体结构和糊化特性在生长季节间存在显著差异。和春季糯玉米淀粉相比,秋季糯玉米淀粉具有较高的结晶度、尖峰强度、峰值黏度、谷值黏度、终值黏度和崩解值。糯玉米淀粉的回复值较低,但秋季糯玉米淀粉仍显著低于春季糯玉米淀粉。相关分析表明,结晶度和各尖峰强度呈两两显著正相关。结晶度和峰值黏度、崩解值极显著正相关(相关系数分别为0.72和0.85),和谷值黏度、糊化温度显著正相关(相关系数分别为0.52和0.55),和回复值显著负相关(相关系数?0.49)。糯玉米淀粉糊化特性在不同生长季节下的变化主要由淀粉晶体结构(结晶度和尖峰强度)发生变化所致。4.收获期对糯玉米产量和糊化特性存在显著影响。随着收获期延迟,籽粒产量逐渐增加,增加速率以花后35～40 d最快,日增重达5.2%,花后40 d增加缓慢。淀粉含量先升后降,在花后35～40 d达到峰值,后期略有下降。收获期对糊化温度没有影响,而峰值黏度、谷值黏度、崩解值、终值黏度和峰值时间均随着收获期的延迟呈先升后降趋势,这几项指标在花后40 d最高,回复值此时最低。糊化特征参数中,糊化温度和峰值时间受收获期的影响较小,而峰值黏度、谷值黏度、崩解值、终值黏度和回复值受收获期的影响较大。综合考虑产量、淀粉含量和糊化特征参数在不同收获期间的变化趋势,可认为花后40 d收获在保证产量的同时有利于改良糯玉米淀粉的品质。5.蛋白、脂肪对淀粉理化特性存在显著影响。糯玉米淀粉颗粒主要为不规则的多边形。脱蛋白和脱脂处理没有改变糯玉米的结晶类型,各样品均表现为典型的“A”型衍射图谱,但脱蛋白和脱脂处理均使结晶度降低,且脱脂处理对其影响大于脱蛋白处理。糯玉米粉经脱蛋白处理后,表现为膨胀势降低,溶解度和透光率上升;淀粉经脱脂处理后,膨胀势和溶解度降低,但透光率升高。DSC研究表明,糯玉米粉去除蛋白后,热焓值增加,但脱脂处理使其降低。胶凝淀粉冷藏后发生回生,表现为转变温度和热焓值降低。糯玉米粉脱蛋白后回生值降低,但经脱脂处理的淀粉回生值又有所增加。脱蛋白处理后,糯玉米粉的淀粉峰值黏度、谷值黏度、终值黏度和崩解值升高,回复值和糊化温度降低,峰值时间缩短。淀粉经脱脂处理后,则表现RVA谱曲线的降低,除崩解值表现为高于糯玉米淀粉外,其他糊化特征值均表现为低于淀粉。因此,可根据需要对糯玉米淀粉进行相应处理,以获得适用于不同用途的糯玉米原料。6.加工条件对玉米淀粉糊化特性存在显著影响。玉米淀粉的糊化特征值在不同反应程序下发生了改变,加热冷却速率快,95℃保持时间长,淀粉的峰值黏度、崩解值和糊化温度较高,峰值时间较短。在不同反应程序下,相对于普通玉米淀粉,糯玉米淀粉的峰值黏度和沉降值较高,而谷值黏度、终值黏度、回复值、峰值时间和糊化温度较低。糯玉米和普通玉米淀粉的糊化特征参数受到浓度影响,随着淀粉浓度的增加,峰值黏度、谷值黏度、沉降值、终值黏度和回复值随之增加,峰值时间略有降低,浓度太低时淀粉不能糊化,在能糊化条件下则随着浓度的增加而降低。且在低浓度条件下,糯玉米淀粉的峰值黏度高于普通玉米,而在较高浓度(11%)条件下,糯玉米淀粉的峰值黏度则低于普通玉米淀粉。更多还原

【Abstract】 Using the waxy maize varieties or lines that released in recent years in China as materials, the genotypic differences for starch physicochemical properties were studied and the regulation effects of cultivation measures such as fertilizer treatments, sowing and harvesting date on it were clarified. Further, the effects of kernel components and process condition on it were analyzed. The mains results of the study were as follows.Physicochemical properties (Swelling power, solubility, water binding capacity, gelatinization, retrogradation and pasting characteristics) for waxy maize starch were significantly different among 54 waxy maize varieties or lines come from Chinese waxy maize regional test. The variation ranges for swelling power, solubility, water binding capacity, enthalpy of gelatinization, peak temperature, gelatinization range, percentage of retrogradation, peak viscosity, breakdown and pasting temperature were 2.9~25.3 g/g、34.7~66.7%、97.4~194.5%、45.9~57.0 J/g、7.7~12.0℃、32.8~78.8%、87.7~169.9 RVU、37.5~83.8 RVU、71.8~75.8℃and 69.8~73.9℃, respectively. The variation for peak temperature and pasting temperature was little, whereas the variation for the other characteristics was large (variation coefficient>5.9%). Theλmax for waxy maize starch were mainly between 532.2 nm and 540.3 nm, except for Xinshinuoyu01, Danhuangnuo02 and Shanbainuo12, which were 580.5 nm, 557.9 nm and 551.1 nm, respectively, indicating theλmax of starch was mainly presented by amylopectin. The variation range for blue value and iodine binding capacity were 01274~0.7789 and 0.56~1.05, respectively. The three characteristics were negatively correlated to the percentage of retrogradation, peak viscosity and breakdown, and positively correlated to setback. By analysis the microelements content in starch, no significantly correlations were observed between Ca, K, Na, Cu, Fe content and the physicochemical characteristics, whereas significantly correlations were observed between other microelements content (P, S, Mn, Zn and B) and some physicochemical characteristics. Though the waxy maize starch was composed by 100% amylopectin, the variations of long/short chain ratio and microelements content caused the starch physicochemical properties were different among genotypes, which could afford references for its utilization.Significant regulation of fertilizer treatment on starch pasting, thermal and crystalline properties were observed. The fertilizer treatments didn’t change the diffraction pattern and the starch exhibited typical A-type diffraction pattern. Peak time, pasting temperature, transition temperature (onset, peak and conclusion temperature), and peak height index and gelatinization range were little affected by fertilizer treatments. Compared with the treatment of only N applied in basic fertilizer, adding P or (and) K fertilizers decreased the peak viscosity, breakdown, the percentage of retrogradation and enthalpy of retrogradation, but increased crystallinity. With larger amount of N topdressing at jointing stage, peak viscosity increased gradually, breakdown, the percentage of retrogradation and enthalpy of retrogradation showed no significant differences in treatments of topdressing N 150 and 300 kg ha-1 and higher than 0 kg ha-1 treatments. The physicochemical characteristics of waxy maize starch were improved to be the better (higher crystallinity, enthalpy of gelatinization, peak viscosity, breakdown and lower percentage of retrogradation) when the top dressing was N 150 kg ha-1 at jointing stage on the basis of N 75 kg ha-1 +P2O5 65 kg ha-1+K2O 70 kg ha-1 as the basic fertilizer.Starch cryatalline structure and pasting properties were affected by growth seasons. All starch samples showed a typical A-type diffraction pattern, indicating the growing season has no effect on it. However, the growing season significantly influenced the starch crystalline and pasting properties. Starch obtained from autumn season, compared with that from spring season, showed higher degrees on crystallinity, peak intensities (2θ=15°, 17°, 18°, 20°, and 23°), peak viscosity, trough viscosity, final viscosity, and breakdown. The setback of starch of waxy corn in autumn season was significantly lower than that in spring season, although they both in low values. The crystallinity, peak intensities, and pasting characteristics were significantly different among the eight waxy corn cultivars. The crystallinity was positively correlated with the peak viscosity (r = 0.72, P < 0.01), breakdown (r = 0.85, P < 0.01), trough viscosity (r = 0.52, P < 0.05), pasting temperature (r = 0.55, P < 0.05), whereas, it was negatively correlated to setback (r = ?0.49, P < 0.05). The differences of pasting properties between growing seasons were mainly caused by the differences of crystallinity and peak intensities of starch in waxy corn. Harvesting dates were observed affect the yield and starch pasting properties of waxy maize.The grain yield increased gradually when the harvesting date was postponed and the increasing rate was highest at 35-40 days after pollination (DAP), which reached 5.2 % per day, and the increasing rate was slow after 40 DAP. The starch content rose first and fell later and it reached a peak at 35-40 DAP. Pasting temperature was stable among different harvesting dates. Peak viscosity, trough viscosity, breakdown, final viscosity and peak time rose first and fell later with the postponed harvesting date, these five pasting characteristics reached a peak at 40 DAP, and setback was the lowest at this time. The effects of harvesting date on peak time and pasting temperature were lower, while those were larger on peak viscosity, trough viscosity, breakdown, final viscosity and setback. Considering the changing trend of grain yield, starch content and RVA characteristics, 40 DAP might be the optimum harvesting time as the grain yield was relative high, the starch content was the highest and the RVA characteristics was ideal at this time in this experiment.The physicochemical properties of starch were affected by protein and lipid content. The starch granules presented polygonal and irregular shapes. Protein removal and lipid removal didn’t change the diffraction pattern of waxy maize and all samples presented typical A-type diffraction pattern. Protein removal and lipid removal decreased the crystallinity, and the effect of lipid removal on starch was higher than protein removal on flour. The starch showed lower swelling power, higher solubility and light transmittance than flour. Defatting decreased the swelling power and solubility, whereas the light transmittance was increased. The enthalpy of gelatinization was increased after protein removal and it was decreased after lipid removal. After stored at 4°C for 7 days, the gelatinized samples exhibited lower transition temperature and enthalpy of retrogradation. The percentage of retrogradation was highest for flour and lowest for starch. RVA studies found that protein removal increased the peak viscosity, trough viscosity, final viscosity and breakdown viscosity. Simultaneity, setback viscosity, peak time and pasting temperature were decreased. Lipid removal decreased the RVA characteristics except for breakdown viscosity. The information generated in this study on the physicochemical properties of the flour, starch and defatted starch of waxy maize could provide guidance on possible uses of it.The process conditions on RVA characteristics of waxy and normal corn starches were studied, and the RVA characteristic differences between waxy corn starch and normal corn starch in different reaction programs and starch concentrations were clarified using waxy corn variety (Yunuo No. 7) and normal corn variety (Nongda 108) as material. The RVA characteristics were changed under different reaction programs, the starch presented higher peak viscosity, breakdown viscosity and pasting temperature, lower peak time in the procedure with higher heating-cooling rate and longer 95℃keeping time. Compared with normal corn starch, waxy corn starch exhibited higher peak viscosity and breakdown, lower trough viscosity, final viscosity, setback, peak time and pasting temperature. The RVA characteristics were affected by starch concentration. With the increment of starch concentration, peak viscosity, trough viscosity, breakdown, final viscosity and setback gradually increased, peak time decreased slightly. Starch couldn’t paste when the concentration was very low and the pasting temperature was decreased when the concentration increased. The peak viscosity of waxy corn starch was higher than normal corn starch when the concentration was low, and it was reverse when the concentration was higher (11%).更多还原