抗性淀粉的制备、功效及应用

结合国内外抗性淀粉的研究现状,介绍了抗性淀粉的分类,分析了抗性淀粉的制备工艺及其在糖代谢、脂代谢、体重控制、作为益生元防治肠道疾病等方面的生理功能,并介绍了抗性淀粉在面包、面条、油炸类、饮料类等食品生产及微型胶囊材料生产中的应用。     

马铃薯淀粉消化性能研究进展

对影响马铃薯淀粉消化率的因素、马铃薯慢消化淀粉和抗性淀粉的制备和检测方法,以及在食品中的应用进行综述,并对马铃薯慢消化淀粉和抗性淀粉的前景进行了展望。     

抗性淀粉浓度对青春双歧杆菌生长及代谢作用研究

文章首次探究了不同抗性淀粉添加量对双歧杆菌生长及代谢的影响。将不同浓度的大米抗性淀粉作为唯一的碳源，培养双歧杆菌单菌，通过吸光值确定细菌生长曲线、生物被膜生成量；采用激光共聚焦显微镜和扫描电子显微镜观察生物膜的微观结构；运用苯酚硫酸法测胞外多糖；运用液相色谱检测短链脂肪酸和吲哚-3-乳酸；使用超高效液相色谱-质谱联用仪定量信号分子AI-2的前体DPD并进行相关性分析。结果表明，抗性淀粉添加量在0.5%～1%区间内时，对细菌密度、生物被膜生成量、短链脂肪酸及吲哚-3-乳酸代谢的作用最好，碳源浓度增加促进了短链脂肪酸和胞外多糖的产生，但DPD含量下降后反而趋于平缓。文章为探究不同抗性淀粉的添加量对促进肠道有益菌生长及食品工业中功能食品的开发提供了理论依据。     

02428×合系35 RILs群体糙米和发芽糙米γ-氨基丁酸、抗性淀粉的遗传分析

以水稻02428×合系35的RILs群体及其亲本糙米和发芽糙米为材料,对糙米、发芽糙米各222个群体样品的γ-氨基丁酸、抗性淀粉含量进行测定,以期选育出高γ-氨基丁酸、高抗性淀粉的水稻新品种。研究结果表明,重组自交系糙米、发芽糙米γ-氨基丁酸含量差异不大,群体间存在广泛变异,由主效基因控制。重组自交系糙米、发芽糙米抗性淀粉含量差异大,发芽糙米抗性淀粉平均含量是该群体糙米的1.2倍,群体间存在广泛变异,呈偏态分布。高海拔冷凉气候有利于糙米高抗性淀粉含量的提升与进化。本研究可以为功能水稻的遗传及品种选育提供一定的理论依据。     

小麦籽粒抗性淀粉含量的分析

选用3个抗性淀粉含量较高的小麦品种和3个抗性淀粉含量较低的小麦品种按Griffing双列杂交设计配置成15个杂交组合, 以亲本及F₁为材料进行了小麦籽粒抗性淀粉含量的遗传规律分析, 旨在为高抗性淀粉含量且综合性状优良的新型保健小麦新品种(系)的选育提供理论依据。结果表明, 在6个小麦品种中, 安农90202和D68-20抗性淀粉含量的一般配合力较好, 能显著地提高杂种后代籽粒抗性淀粉含量。安农90202×04单28和06-5×D68-20组合的特殊配合力最好, 两者特殊配合力效应值显著地高于其他组合。小麦抗性淀粉含量的遗传符合加性-显性模型, 显性程度为超显性。控制抗性淀粉含量的增效等位基因表现为隐性, 且亲本中抗性淀粉含量的增减效等位基因的分布不平衡, 高抗性淀粉含量的亲本中隐性基因数量多于显性基因数量。实验中安农90202和04单28控制抗性淀粉含量的隐性基因较多,而宁春18和新春5号含有的显性基因数量较多。同时研究发现小麦抗性淀粉含量的狭义遗传力中等, 为36.49%。     

小豆抗性淀粉含量及蒸煮后硬度分析

本文利用国内140个红小豆种质资源,探究其抗性淀粉含量与蒸煮后硬度的地域分布特征,分析蒸煮后硬度与营养指标的相关性,同时筛选抗性淀粉含量高与蒸煮后硬度低的种质资源,结果表明：140份红小豆抗性淀粉的平均含量为14.25 %,蒸煮后硬度的平均值为150.72 g。吉林地区红小豆抗性淀粉含量最高,为15.71 %;内蒙古地区红小豆蒸煮后硬度最低,为96.42 g。抗性淀粉与总淀粉之间呈极显著负相关;蒸煮后硬度与抗性淀粉之间呈显著正相关,但与总淀粉及蛋白质之间无显著相关。筛选出12份抗性淀粉含量>17.83 %的优异红小豆种质资源,可用于糖尿病人专用品种的选育及产品开发;9份蒸煮后硬度<76.48 g的优异红小豆种质资源可用于豆饭、豆粥产品的开发。     

养殖环境中抗生素抗性基因的研究进展

抗性基因在环境中的垂直及水平传播,致使抗生素耐药性成为危及人类和动物生命健康的全球性问题。动物源食品是中国美食不可或缺之物,而由于抗生素超用与滥用等行为让公众不得不关注动物源食品源头——养殖场的抗生素抗性基因环境安全问题。本文综述了养殖环境中抗生素抗性基因的研究进展,分析了养殖环境中抗生素抗性基因产生原因、传播途径以及影响因素,介绍了现有风险评估方法和控制技术,并对今后养殖环境中抗生素抗性基因的控制策略、技术及研究方向提出了建议。     

稻米淀粉品质性状的资源筛选和相关基因初步鉴定北大核心CSCD

淀粉是稻米品质形成的主要理化基础,也是水稻品质改良的重要育种目标。本研究旨在挖掘包含不同淀粉含量的特异种质和鉴定其相关的基因型,为完善水稻淀粉合成调控网络及水稻优质育种工作提供有用信息。以江苏南京水稻种质资源国家野外科学观测研究站收集的119份种质资源为材料,运用改进的免煮简易法测定供试材料的直链淀粉含量;以直链淀粉含量极高、低的材料,利用开发的dCAPS分子标记鉴定其Wx基因型。测定直链淀粉含量极高的15份材料的抗性淀粉含量,并选取3份高抗性淀粉材料,以日本晴为对照,进行SSⅢa与SBEⅡb两个基因的序列比对和基因型鉴定。结果表明,改进的免煮简易法准确性与现行国标法结果相当,但操作更加简便容易。供试材料的直链淀粉含量大部分处于9.0%~33.0%之间,抗性淀粉含量位于1.0%~4.5%之间。dCAPS分子标记鉴定表明高直链淀粉材料的Wx基因型一般为Wxa型。通过序列比对,发现相对于日本晴,SSⅢa基因在3个高抗性淀粉材料(立新粳、南特号、郴晚3号)有3处共同突变,其中第三外显子+2362位为错义突变;SBEⅡb在2个高抗性淀粉品种(立新粳与南特号)第四外显子+96位检测到共同的错义突变。这些错义突变可能是导致水稻抗性淀粉含量增加的原因,这为下一步精确定向编辑目标基因,创制淀粉品质性状优异新种质奠定了基础。     

杭州地区尖音库蚊复合组的抗药性动态

用生物测定和淀粉电泳技术对采自杭州市和上海市的尖音库蚊复合组(Culex pipienscomplex)蚊虫的抗性水平及与抗性有关的酯酶进行了研究。抗性水平的测定结果表明:与S-LAB敏感系相比,杭州市种群对DDVP、对硫磷、毒死蜱、邻仲丁基苯基甲基氨基甲酸酯和残杀威的抗性分别是S-LAB敏感品系的3.9,7.6,1.6,1.6,2.5倍。利用淀粉凝胶电泳技术分析了野生种群中抗性羧酸酯酶(EST)等位酶的基因表型及其频率。4个种群中都存在着世界范围内广泛分布的过量产生的非特异性酯酶Estβ1和Estα2/β2,上海种群主要以高活性的酯酶Estβ11为主(98.3%),除了这些基因以外,2004年杭州市下城区又出现了1种新的酯酶基因(50%)。     

淀粉凝胶食品——粉皮、凉粉的研究进展

介绍了充分利用淀粉老化性质的淀粉凝胶食品——粉皮、凉粉的研究进展,旨在让更多的消费者正确地认识、认知、认可淀粉凝胶食品。     

Fermentation RS3 derived from sago and rice starch with Clostridium butyricum BCC B2571 or Eubacterium rectale DSM 17629

Resistant starch type 3 (RS3) is retrograded starch which is not digested by human starch degrading enzyme, and will thus undergo bacterial degradation in the colon. The main fermentation products are the Short Chain Fatty Acid (SCFA): acetate, propionate and butyrate. SCFA has significant benefit impact on the metabolism of the host. The objectives of this research were to study the SCFA profile produced by colonic butyrate producing bacteria grown in medium containing RS3. RS3 was made from sago or rice starch treated with amylase, pullulanase and the combination of amylase and pullulanase. Fermentation study was performed by using Clostridium butyricum BCC B2571 or Eubacterium rectale DSM 17629, which has been identified as capable of degradation of starch residue and also regarded as beneficial bacteria. Experimental result revealed that enzyme hydrolysis of retrograded sago or rice starch was beneficial to RS formation. RS3 derived from sago contained higher RS (31-38%) than those derived from rice starch (21-26%). This study indicated that C. butyricum BCC B2571 produced acetate, propionate and butyrate at molar ratio of 1.8 : 1 : 1, when the medium was supplemented with RSSA at concentration 1%. In the medium containing similar substrate, E. rectale DSM 17629 produced acetate, propionate and butyrate at molar ratio of 1.7 : 1 : 1.2. High levels of acetate, propionate and butyrate at molar ratio of 1.8 : 1 : 1.1 was also produced by E. rectale DSM 17629 in medium supplemented with RSSP at concentration 1%. The results showed that both bacteria responded differently to the RS3 supplementation. Such result provided insight into the possibility of designing RS3 as prebiotic with featured regarding SCFA released in the human colon with potential health implication.     

Influence of incubation temperature and time on resistant starch type III formation from autoclaved and acid-hydrolysed cassava starch

Raw cassava starch, having 74.94 and 0.44 g/100 g resistant starch type II and III (RS II and RS III), respectively, was autoclaved at 121 °C in water, 1, 10 or 100 mmol/L lactic acid. The formation of RS III was evaluated in relation to variable incubation temperature (−20 to 100 °C), incubation time (6–48 h) and autoclaving time (15–90 min). Negligible to low quantities of RS III (0.59–2.42 g/100 g) were formed from autoclaved starch suspended in 100 mmol/L lactic acid, whereas intermediate to high quantities (2.68–9.97 g/100 g) were formed from autoclaved starch suspended in water, 1 or 10 mmol/L lactic acid, except for treatments with water or 10 mmol/L lactic acid incubated at 100 °C for 6 h (1.74 g/100 g). Autoclaving times corresponding to maximum RS III contents were 15 and 45 min for water and 10 mmol/L lactic acid, respectively. Whereas, the RS III fractions from cassava starch suspended in water had melt transitions between 158 and 175 °C with low endothermic enthalpies (0.2–1.6 J/g), the thermal transitions of the acid treated samples were indistinct.     

Origin of the limited alpha-amylolysis of debranched maltodextrins crystallized in the A form: a TEM study on model substrates

The detailed ultrastructure of a new type of resistant starch and the way that it is modified during hydrolysis by alpha-amylases were studied by transmission electron microscopy (TEM) on model starch crystals. The selected substrates were waxy maize starch lintners and A-type crystals prepared from low degree of polymerization (DP) amylose. A model describing the stacking of double helices is proposed for A-type low DP amylose crystals. The enzymatic hydrolysis of both lintners and low DP crystals has been shown to occur by the side of double helices and not their ends. The results were transposed to a new type of resistant starch (RS) produced by debranching maltodextrins in concentrated solutions. This product presents A-type crystallinity contrary to all other known classified RS. Moreover it consists of low DP chains similar to the model crystals studied and yields similar electron diffraction patterns to those of A-type low DP crystals. The similarities in the morphology of these substrates with that of the studied RS led us to attribute its resistance to its particularly dense and compact morphology, resulting from the epitaxial growth of elementary crystalline A-type platelets. In the resulting structure, the accessibility of double helices to alpha-amylase is strongly reduced by aggregation.     

Measurement of resistant starch content in cooked rice and analysis of gelatinization and retrogradation characteristics

Digestion-resistant starch (RS) has many physiologic functions. The RS content is measured by enzymatically degrading flour samples according to the method of the Association of Official Analytical Chemists. Experiments have been performed with wheat, corn, and other grains, but there are no data for cooked rice grains in the form ingested by humans. Thus, we investigated a method to measure RS that is suitable for cooked rice grains using rice cultivars that are reported to differentially increase postprandial blood glucose in humans. Using a method for cooking individual rice grains and optimized enzyme reaction conditions, we established an RS measurement method. We also found that the amylopectin crystal condition affects the RS content measured using our method.     

Feed intake patterns nor growth rates of pigs are affected by dietary resistant starch,despite marked differences in digestion

Current feed evaluation systems often assume that fermented starch (i.e. resistant starch (RS)) yields less energy than digested starch. However, growth rates of pigs fed low and high RS diets are often the same when feed is available ad libitum. This may be explained by its effect on digestive processes changing feeding behavior, and consequently energy utilization. This study aims to investigate the effect of RS on nutrient digestion and digesta passage rate in pigs, in combination with its effect on feeding behavior and growth performance under ad libitum conditions. In experiment 1, 20 male pigs (40 ± 2.82 kg) were fed diets containing either 50% waxy maize starch (low in RS (LRS)) or high-amylose maize starch (high in RS (HRS)), and soluble and insoluble indigestible markers. After 14 days of adaptation to the diets, pigs were fed hourly to reach steady state (6 h), dissected, and digesta were collected from eight segments. From the collected samples, nutrient digestion and passage rate of the solid and liquid digesta fraction were determined. In experiment 2, 288 pigs (80 ± 0.48 kg; sex ratio per pen 1 : 1; boar : gilt) were housed in groups of 6. Pigs were ad libitum-fed one of the experimental diets, and slaughtered at approximately 115 kg. Feed intake, growth and carcass parameters were measured. Ileal starch digestibility was greater for LRS-fed than for HRS-fed pigs (98.0% v. 74.0%; P < 0.001), where the additional undigested starch in HRS-fed pigs was fermented in the large intestine. No effects of RS on digesta passage rate of the solid or liquid digesta fraction and on feeding behavior were observed. Growth rate and feed intake did not differ between diets, whereas feed efficiency of HRS-fed pigs was 1%-unit higher than that of LRS-fed pigs (P = 0.041). The efficiency of feed used for carcass gain did not differ between diets indicating that the difference in feed efficiency was determined by the non-carcass fraction. Despite a 30% greater RS intake (of total starch) with HRS than with LRS, carcass gain and feed efficiency used for carcass gain were unaffected. RS did not affect digesta passage rate nor feeding behavior suggesting that the difference in energy intake between fermented and digested starch is compensated for post-absorptively. Our results indicate that the net energy value of fermented starch currently used in pig feed evaluation systems is underestimated and should be reconsidered.     

A genetic strategy generating wheat with very high amylose content

Resistant starch (RS), a type of dietary fibre, plays an important role in human health; however, the content of RS in most modern processed starchy foods is low. Cereal starch, when structurally manipulated through a modified starch biosynthetic pathway to greatly increase the amylose content, could be an important food source of RS. Transgenic studies have previously revealed the requirement of simultaneous down‐regulation of two starch branching enzyme (SBE) II isoforms both located on the long arm of chromosome 2, namely SBEIIa and SBEIIb, to elevate the amylose content in wheat from ~25% to ~75%. The current study revealed close proximity of genes encoding SBEIIa and SBEIIb isoforms in wheat with a genetic distance of 0.5 cM on chromosome 2B. A series of deletion and single nucleotide polymorphism (SNP) loss of function alleles in SBEIIa, SBEIIb or both was isolated from two different wheat populations. A breeding strategy to combine deletions and SNPs generated wheat genotypes with altered expression levels of SBEIIa and SBEIIb, elevating the amylose content to an unprecedented ~85%, with a marked concomitant increase in RS content. Biochemical assays were used to confirm the complete absence in the grain of expression of SBEIIa from all three genomes in combination with the absence of SBEIIb from one of the genomes.     

Ruminococcus bromii is a keystone species for the degradation of resistant starch in the human colon

The release of energy from particulate substrates such as dietary fiber and resistant starch (RS) in the human colon may depend on the presence of specialist primary degraders (or ‘keystone species'') within the microbial community. We have explored the roles of four dominant amylolytic bacteria found in the human colon in the degradation and utilization of resistant starches. Eubacterium rectale and Bacteroides thetaiotaomicron showed limited ability to utilize RS2- and RS3-resistant starches by comparison with Bifidobacterium adolescentis and Ruminococcus bromii. In co-culture, however, R. bromii proved unique in stimulating RS2 and RS3 utilization by the other three bacterial species, even in a medium that does not permit growth of R. bromii itself. Having previously demonstrated low RS3 fermentation in vivo in two individuals with undetectable populations of R. bromii-related bacteria, we show here that supplementation of mixed fecal bacteria from one of these volunteers with R. bromii, but not with the other three species, greatly enhanced the extent of RS3 fermentation in vitro. This argues strongly that R. bromii has a pivotal role in fermentation of RS3 in the human large intestine, and that variation in the occurrence of this species and its close relatives may be a primary cause of variable energy recovery from this important component of the diet. This work also indicates that R. bromii possesses an exceptional ability to colonize and degrade starch particles when compared with previously studied amylolytic bacteria from the human colon.