Slowly digestible starch from heat-moisture treated waxy potato starch: Preparation,structural characteristics,and glucose response in mice

Heat-moisture treatment (HMT) was optimised to increase the formation of slowly digestible starch (SDS) in waxy potato starch, and the structural and physiological properties of this starch were investigated. A maximum SDS content (41.8%) consistent with the expected value (40.1%) was obtained after 5 h 20 min at 120 °C with a 25.7% moisture level. Differential scanning calorimetry of HMT starches showed a broadened gelatinization temperature range and a shift in endothermal transition toward higher temperatures. After HMT, relative crystallinity decreased with increasing moisture level and X-ray diffraction patterns changed from B-type to a combination of B- and A-types. Hollow regions were found in the centres of HMT waxy potato starches. HMT intensity significantly influenced SDS level. This study showed that HMT-induced structural changes in waxy potato starch significantly affected its digestibility and the blood glucose levels of mice who consumed it.     

湿热处理法制备慢消化淀粉及其性质研究

以蜡质玉米淀粉为原料,采用湿热处理法制备慢消化淀粉,并研究了其性质。研究出湿热处理制备慢消化淀粉的优化工艺为:淀粉体系的水分含量35%(w/w),温度120℃,时间为10h,慢消化淀粉含量达9.25%。扫描电镜照片显示,湿热处理后淀粉颗粒表面出现了裂纹和凹坑,淀粉糊化温度升高,峰值粘度降低。     

退火处理对慢消化淀粉形成及性质影响

以蜡质玉米淀粉为原料,研究退火处理方法对慢性消化淀粉(SDS)形成影响,并对性质和机理进行研究。结果表明,淀粉样品在水分含量60%、温度55℃、处理时间24 h条件下SDS含量达8.01%;经退火处理后淀粉颗粒整体结构变化不大,但在淀粉颗粒表面出现不同程度凹坑、裂纹和碎片,偏光十字依旧清晰,结晶晶形为A形;由于热量和水分长时间作用,使淀粉颗粒内部结晶结构更完美,提高SDS含量,降低淀粉消化性。     

Effect of heat-moisture treatment on the formation and physicochemical properties of resistant starch from mung bean (Phaseolus radiatus) starch

Mung bean starch was subjected to a range of heat-moisture treatments (HMT) based on different moisture contents (15%, 20%, 25%, 30%, and 35%) all heated at 120 °C for 12 h. The impact on the yields of resistant starch (RS), and the microstructure, physicochemical and functional properties of RS was investigated. Compared to raw starch, the RS content of HMT starch increased significantly, with the starch treated at 20% moisture having the highest RS content. After HMT, birefringence remained at the periphery of the granules and was absent at the center of some granules. The shape and integrity of HMT starch granules did not change but concavity was observed under scanning electronic microscopy. Apparent amylose contents of HMT starch increased and the HMT starch was dominated by high molecular weight fraction. Both the native and HMT starches showed A-type X-ray diffraction pattern. Relative crystallinity increased after HMT. The gelatinization temperatures (To, Tp, and Tc), gelatinization temperature range (Tc–To) and enthalpies of gelatinization (ΔH) increased significantly in HMT starch compared to native starch. The solubility increased but swelling power decreased in HMT starches. This study clearly shows that the HMT exhibited thermal stability and resistance to enzymatic hydrolysis owing to stronger interactions of starch chains in granule.     

Fine structural characteristics related to digestion properties of acid‐treated fruit starches

Starches from unripe fruits (mango, banana, and plantain) were acid modified to form different degrees of lintners with the objective to increase the slowly digestible starch (SDS) and RS contents. Molecular, thermal, and structural characteristics were evaluated. Mango starch showed higher susceptibility to acid hydrolysis than banana and plantain starches. The peak temperature of gelatinization (T_p) showed a decrease at low hydrolysis percentage, but at higher hydrolysis percentage the T_p increased. However, the enthalpy of gelatinization presented an increase with the hydrolysis percentage, but was not higher than its native counterpart. In general, the peak temperature and enthalpy of retrogradation increased with hydrolysis percentage due to formation of linear chains during the modification that promoted retrogradation. High performance size exclusion chromatography (HPSEC) analysis demonstrated the presence of multiple‐branches (DP = 96–109), single branched (DP = 28–31), and linear (DP = 16–18) polymers in the fruit starch lintners. The acid treatment (lintnerization) of mango starch had no effect on the SDS fraction, while for plantain and banana starches, the SDS content increased (6.14–35.4%) at low hydrolysis percentage (0–50%) followed by a decrease at higher days of hydrolysis. At higher hydrolysis percentage (70–80%) the RS content increased for the three fruit lintners.     

Preparation of products rich in slowly digestible starch (SDS) from rice starch by a dual-retrogradation treatment

In this work, a dual-retrogradation treatment (gelatinization–retrogradation–gelatinization–retrogradation) was designed for preparing slowly digestible starch (SDS) products from rice starch. The results showed that a maximum SDS yield in the tested samples increased from 39.3% to 56.7% by the dual retrogradation with the time interval of 36 h. The dual retrogradation also seemed to increase with the melting temperature range (T_c–T_o) of the SDS products. This increase indicated that more imperfect crystallites were formed during the dual-retrogradation treatment. Furthermore, compared to the single retrogradation, the dual retrogradation generated larger cavities and more solid connection parts in the SDS products. This internal microstructure could result in the increase of slow digestibility. These findings suggest that the dual retrogradation can be used in starchy products to increase the yield of SDS.     

Development of oxidised and heat-moisture treated potato starch film

This study investigated the effects of sodium hypochlorite oxidation and a heat-moisture treatment of potato starch on the physicochemical, pasting and textural properties of potato starches in addition to the water vapour permeability (WVP) and mechanical properties of potato starch films produced from these starches. The carbonyl contents, carboxyl contents, swelling power, solubility, pasting properties and gel texture of the native, oxidised and heat-moisture treated (HMT) starches were evaluated. The films made of native, oxidised and HMT starches were characterised by thickness, water solubility, colour, opacity, mechanical properties and WVP. The oxidised and HMT starches had lower viscosity and swelling power compared to the native starch. The films produced from oxidised potato starch had decreased solubility, elongation and WVP values in addition to increased tensile strength compared to the native starch films. The HMT starch increased the tensile strength and WVP of the starch films compared to the native starch.     

Microstructural and physicochemical properties of heat-moisture treated waxy and normal starches

Starches from normal rice (21.72% amylose), waxy rice (1.64% amylose), normal corn (25.19% amylose), waxy corn (2.06% amylose), normal potato (28.97% amylose) and waxy potato (3.92% amylose) were heat-treated at 100 °C for 16 h at a moisture content of 25%. The effect of heat-moisture treatment (HMT) on morphology, structure, and physicochemical properties of those starches was investigated. The HMT did not change the size, shape, and surface characteristics of corn and potato starch granules, while surface change/partial gelatinization was found on the granules of rice starches. The X-ray diffraction pattern of normal and waxy potato starches was shifted from B- to C-type by HMT. The crystallinity of the starch samples, except waxy potato starch decreased on HMT. The viscosity profiles changed significantly with HMT. The treated starches, except the waxy potato starch, had higher pasting temperature and lower viscosity. The differences in viscosity values before and after HMT were more pronounced in normal starches than in waxy starches, whereas changes in the pasting temperature showed the reverse (waxy > normal). Shifts of the gelatinization temperature to higher values and gelatinization enthalpy to lower values as well as biphasic endotherms were found in treated starches. HMT increased enzyme digestibility of treated starches (except waxy corn starch); i.e., rapidly and slowly digestible starches increased, but resistant starch decreased. Although there was no absolute consistency on the data obtained from the three pairs of waxy and normal starches, in most cases the effects of HMT on normal starches were more pronounced than the corresponding waxy starches.     

抗性、慢消化淀粉的制备及其控血糖机理的研究进展

抗性淀粉（RS）与慢消化淀粉（SDS）因其良好的抗消化性和功能特性得到了广泛关注,研究已证实其在调控血糖方面具有显著效果,成为近年来兴起的新型功能性食品原料。本文介绍了RS与SDS在物理、化学、生物方面主要制备方法及其形成机制,对RS与SDS在不同动物模型体内可能存在的血糖调控机理进行了整合,例举了它们在功能性食品中的应用,并对现存的问题作了展望,为未来RS与SDS的研究与应用提供参考。     

微波湿热处理对马铃薯抗性淀粉含量及性质的影响

在湿热条件下,采用不同微波条件对马铃薯淀粉进行处理,运用扫描电子显微镜、布拉本德粘度仪,对微波处理前后的物化性质进行了研究。结果表明,经微波辐射处理后,淀粉颗粒表面会出现小孔和凹坑;马铃薯淀粉中抗性淀粉和直链淀粉的含量、糊化转变温度及其范围、热糊稳定性和凝沉性得到提高;马铃薯淀粉的膨胀度、溶解度和粘度降低。      

超声波-酶法联用制备玉米缓慢消化淀粉研究

缓慢消化淀粉是近年来新兴起的一种新功能性淀粉,具有很好的生理功能特性。该文以玉米淀粉为原料,采用超声波辅助酶法技术联用制备缓慢消化淀粉。其原理为:普鲁兰酶本身对淀粉具有一定的脱支作用,使淀粉链长度变短,而引入的超声波一方面作为一种能量,能够被淀粉乳溶液吸收,震裂长链淀粉分子,另一方面超声波利用其高频率在与普鲁兰酶协同作用降解淀粉的同时,可以使酶解速度增加,缩短酶的作用时间,通过控制反应条件,取得最佳的制备效果。本章研究了超声波功率、所加普鲁兰酶量、反应时间以及反应温度单因素对最终SDS得率的影响,并在此条件下进行了重复性试验,确定其优化的工艺条件。研究结果表明:超声波功率300W,加14%普鲁兰酶,反应时间为40min,反应温度为40℃,并在此条件下进行3次重复性试验,SDS得率为43.14%。     

湿热处理蜡质玉米淀粉消化性研究

主要研究湿热处理对蜡质玉米淀粉消化性影响,通过测定不同处理条件下快消化淀粉,慢消化淀粉和抗性淀粉含量以评价其消化性。研究结果表明,随水分含量、处理温度升高和处理时间延长,蜡质玉米快消化淀粉含量显著下降,而慢消化淀粉和抗性淀粉含量明显上升。     

Glycerol-enhancing heat-moisture treatment of A-type rice and cassava starches and B-type potato and canna starches

Effects of glycerol on the heat-moisture treatment (HMT) of A-type rice and cassava starches and B-type potato and canna starches were investigated. Starch samples were soaked in water or glycerol solution, adjusted to 25% moisture, and then subjected to HMT at 100 °C for 1, 6, and 16 h. Pasting profiles of all four starches plasticised with water clearly showed the B-type potato and canna starches were more susceptible to HMT than the A-type rice and cassava starches. The effect of HMT on the pasting properties of glycerol-plasticised samples was inconclusive; the B-type canna and A-type cassava starches were altered, but not the B-type potato and A-type rice starches, which remained comparable to the water-plasticised samples. Thus, the type of plasticiser as well as the environment surrounding the crystalline region, which is specific to each starch type, also affect the alteration of starch during HMT.     

Effect of heat-moisture treatment on rice starch of varying amylose content

The effect of heat-moisture treatment (HMT) on the properties of rice starches with high-, medium- and low-amylose content was investigated. The starches were adjusted to 15%, 20% and 25% moisture levels, and heated at 110 °C for 1 h. The swelling power, solubility, pasting properties, morphology, enzymatic susceptibility and X-ray crystallinity of the starches were evaluated. HMT reduced the swelling power and solubility of the starches. The strongest effect of HMT occurred on the high-amylose starch; the pasting temperature was increased and the peak viscosity, breakdown, final viscosity and the setback were reduced. HMT increased the starch’s susceptibility to α-amylase and promoted a reduction in the starch relative crystallinity.     

酶法制备板栗缓慢消化淀粉的工艺优化

以板栗淀粉为原料,采用普鲁兰酶进行脱支处理制备缓慢消化淀粉(SDS),通过单因素试验及响应面法优化制备工艺,以提高SDS的含量。制备板栗缓慢消化淀粉的最优工艺条件是:淀粉乳质量分数8%,普鲁兰酶浓度8.90 PUN/g淀粉,酶作用时间6.3 h,4℃回生52.2 h。在最佳工艺条件下,通过葡萄糖氧化酶法进行测定,酶改性的板栗淀粉中缓慢消化淀粉质量分数可达41.91%(预测值42.31%),并较板栗原淀粉中缓慢消化淀粉含量提高了5.43倍。试验表明,普鲁兰酶脱支处理是制备板栗缓慢消化淀粉的有效方法。     

Physicochemical,structural, and digestibility properties of enzymatic modified plantain and mango starches

The effect of two enzymatic treatments (increasing the branch density of starch and shortening of AP and amylose chains) on the fraction of slowly digestible starch (SDS) and resistant starch (RS) of plantain (Musa paradisiaca L.) and mango (Mangifera indica L.) starches was investigated. The enzymatic modifications were carried out using β‐amylase (β‐AMY) and β‐amylase‐transglucosidase (β‐AMY‐TGs), in gelatinized starches. Plantain starch showed an increase from 10.9 to 18.5% of SDS, when it was modified by β‐AMY‐TGs, while the treatment with β‐AMY alone showed reduction from 10.9 to 7.1% in SDS. RS content increased with both treatments. On the other hand, mango starch showed an increase in SDS from 6.3 to 22.3% using β‐AMY treatment and from 6.3 to 11.7% using β‐AMY‐TGs treatment. The latter treatment also increased RS content. The enzyme modified starches showed a reduction in the values of molar mass and gyration radius compared with the native starch. The content of short chains of AP, particularly in the DP range 5–12, increased, the percentage of crystallinity decreased in treated starches, and ¹H NMR spectra showed a significant increase of α‐(1 → 6) linkages in the starches modified with β‐AMY‐TGs. These characteristics were related to an increase in the slow and resistant digestion properties of plantain and mango starches.     

Effects of microwave heat-moisture treatment on properties of waxy and non-waxy rice starches

Waxy and non-waxy rice starches adjusted to 20% moisture (wet basis, w.b.) were heat-moisture treated in a microwave oven to determine the effects of the microwave heating characteristics on digestibility, pasting, and morphological properties of the heated starches. Microwave heating produced only minimal changes in digestibility as well as the physical characteristics of heated starches. Significant changes in viscosity properties after microwave heat treatment were observed for both waxy and non-waxy starches heat-treated in a microwave oven, relative to non-treated samples. Non-waxy starch heated in microwave oven showed an increase in breakdown viscosity from 29.8 RVU (non-treated starch) to 35.8 RVU after heating for 60 min. However, for waxy starch, breakdown viscosity decreased from 112.7 to 35.9 RVU after 60 min of microwave heat treatment, reflecting an increased stability of microwave heat-treated starch under cooking. The data obtained in this study indicate that there was much higher re-aggregation of starch granules in waxy starch after microwave heat treatment than occurred in non-waxy starch, suggesting a re-association of amylopectin branch chains in the heat-treated waxy starch.