發(fā)布時間：2019-03-15 07:55

【摘要】：本文以甘薯淀粉為對象,研究了在加工、冷凍、冷藏條件下蔗糖、棉子糖、水蘇糖三種寡糖對甘薯淀粉糊化和回生特性的影響,并且初步探討了不同分子量寡糖(二糖、三糖、四糖)與淀粉相互作用的機(jī)制。首先研究了三種寡糖對甘薯淀粉糊化特性的影響。RVA結(jié)果表明,三種寡糖均能提高甘薯淀粉的成糊溫度,并且隨著糖添加量的增加而增加,且作用效果由強(qiáng)到弱的順序為:水蘇糖棉子糖=蔗糖。糖的添加降低了甘薯淀粉糊的粘度參數(shù),但對糊化焓的影響較小。流變儀測定結(jié)果顯示,三種寡糖均能提高甘薯淀粉糊的屈服應(yīng)力和稠度系數(shù),但添加糖沒有改變淀粉糊的流體性質(zhì)(假塑性)。同時,添加糖降低了淀粉糊的儲能模量,增加了或不影響淀粉糊的損耗模量,樣品正切值tanδ上升說明糖添加促進(jìn)了淀粉糖體系類液體性質(zhì)的發(fā)展。其次研究了三種寡糖對甘薯淀粉凍融穩(wěn)定性的影響。結(jié)果表明,添加蔗糖或棉子糖降低了甘薯淀粉凝膠的析水率,提高了其凍融穩(wěn)定性,且提高效果蔗糖棉子糖;但水蘇糖不利于凍融穩(wěn)定性。SEM結(jié)果顯示,蔗糖或棉子糖存在時,冷凍干燥后淀粉凝膠的孔徑尺寸變小、側(cè)壁厚度增加,形成連續(xù)纖維狀網(wǎng)格結(jié)構(gòu)。而水蘇糖增加凝膠孔徑尺寸,破壞了其側(cè)壁結(jié)構(gòu)。DSC、XRD結(jié)果表明:淀粉熔融溫度隨凍融次數(shù)增加而下降,回生焓和結(jié)晶度值隨凍融次數(shù)增加而上升。蔗糖和棉子糖均降低了淀粉回生焓、結(jié)晶度,水蘇糖則促進(jìn)回生焓和結(jié)晶度的增加。最后研究了三種寡糖對甘薯淀粉回生特性的影響。在28天冷藏(4℃)過程中,甘薯淀粉發(fā)生短期回生與長期回生,淀粉糊、混合糊透明度均出現(xiàn)下降趨勢。蔗糖、棉子糖的添加阻礙了糊透明度的下降。儲藏時間較短時,水蘇糖對回生有一定的抑制作用;而儲藏時間較長時,則促進(jìn)回生。DSC測定結(jié)果證實,蔗糖、棉子糖增加了甘薯淀粉的熔融溫度,并降低了回生焓值,影響作用隨糖添加量的增加而增加,抑制回生作用大小為蔗糖棉子糖。但水蘇糖降低了甘薯淀粉熔融溫度并增加了回生焓值。TPA結(jié)果表明,隨著冷藏時間的延長,淀粉凝膠的硬度持續(xù)增長,彈性減弱。儲藏時間較短時,由于體系固液比改變,三種寡糖均能增加淀粉凝膠硬度。隨儲藏時間增加,蔗糖、棉子糖均能降低凝膠硬度,增加凝膠彈性,抑制淀粉回生。與淀粉長期回生不同,三種寡糖均能延緩甘薯淀粉凝膠G′值增加、tanδ值下降,對淀粉短期回生起到抑制作用。不同寡糖對短期回生的抑制作用強(qiáng)弱與對RVA檢測的回生值影響大小順序一致,為水蘇糖棉子糖蔗糖。
[Abstract]:In this paper, the effects of sucrose, cottonseed sugar and stachyose on the gelatinization and retrogradation of sweet potato starch were studied under the conditions of processing, freezing and cold storage, and the effects of different molecular weight oligosaccharides (disaccharide, trisaccharide) on the gelatinization and retrogradation of sweet potato starch were studied. The mechanism of the interaction between tetrasaccharides and starch. The effects of three oligosaccharides on the gelatinization of sweet potato starch were studied. The results of RVA showed that all three oligosaccharides could increase the gelatinization temperature of sweet potato starch and increase with the addition of sugar. The order of effect from strong to weak is as follows: stachyose, cotton seed sugar = sucrose. Sugar addition decreased the viscosity parameters of sweet potato starch paste, but had little effect on gelatinization enthalpy. The results of rheometer showed that all three oligosaccharides could increase the yield stress and consistency coefficient of sweet potato starch paste, but the addition of sugar did not change the fluid properties (pseudoplasticity) of starch paste. At the same time, the addition of sugar decreases the storage modulus of starch paste and increases or does not affect the loss modulus of starch paste. The increase of tan 未 indicates that sugar addition promotes the development of liquid-like properties of starch-sugar system. Secondly, the effects of three oligosaccharides on the freeze-thaw stability of sweet potato starch were studied. The results showed that the addition of sucrose or cottonseed decreased the precipitation rate of sweet potato starch gel, improved the freeze-thaw stability of the gel, and improved the effect of sucrose-cottonseed. SEM results showed that in the presence of sucrose or cottonseed, the pore size of the starch gel decreased and the thickness of the side wall increased, which resulted in the formation of a continuous fibrous mesh structure in the presence of sucrose or gossylose. The results of DSC and XRD showed that the melting temperature of starch decreased with the increase of freezing and thawing times, and the enthalpy of retrogradation and crystallization value increased with the increase of freezing and thawing times. Sucrose and gossylose decreased the enthalpy of regrowth and crystallinity of starch while stachyose promoted the increase of enthalpy and crystallinity of starch. Finally, the effects of three oligosaccharides on the retrogradation of sweet potato starch were studied. During 28-day cold storage (4 鈩，

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