Combined effect of autoclaving‐cooling and cross‐linking treatments of normal corn starch on the resistant starch formation and physicochemical properties

Normal corn starch (NCS) was treated by both autoclaving‐cooling and cross‐linking to produce resistant starch (RS). The RS yield, crystalline structure, as well as other physicochemical properties of the modified starch were investigated. The yield of RS was 12.2% by four autoclaving‐cooling cycles, and it could be further increased up to 31.0% by the subsequent cross‐linking using sodium trimetaphosphate/sodium tripolyphosphate. The scanning electron microscopy images clearly illustrated that the granular structure of native starch was disrupted and a continuous network with irregular shape was formed after autoclaving‐cooling cycles. The subsequent chemical cross‐linking appeared to make the network structure more compact and dense. X‐ray diffraction patterns showed that B‐ and V‐types coexisted in all the modified corn starches, and all these modified starches exhibited very low viscosity which remained almost constant regardless of temperature changes.     

Effect of Raw and Heat‐Moisture Treated High‐Amylose Corn Starch on Fermentation by the Rat Cecal Bacteria

Resistant starch content of high‐amylose corn starch (HAS) was doubled by heat‐moisture treatment. Resistant starch content of HAS and heat‐moisture treated high‐amylose corn starch (HMT‐HAS) were 31.8 and 67.3%, respectively, as determined by enzymatic‐gravimetric method. Effects of the two types of high‐amylose corn starches, HAS and HMT‐HAS, on starch fermentation, microflora, pH, short chain fatty acid (SCFA) content and β‐glucuronidase activity in the cecal content have been investigated. Rats were given ordinary corn starch (OCS; control), HAS or HMT‐HAS at 10% level for 10 13 days. The cecal and colorectal content s weights were larger in HAS and HMT‐HAS groups than in the OCS group. The cecal content s weight did not differ between HAS and HMT‐HAS groups, while the colorectal content s weight was higher in the HMT‐HAS group than in the HAS group. The upper and lower small intestinal and cecal starch contents were significantly higher in the HAS and HMT‐HAS groups than in the OCS group, whereas there were no differences between colorectal starch content in group OCS and HAS. Starch excretion in feces was significantly higher in groups HAS and HMT‐HAS than in group OCS, the increase in the HMT‐HAS group was especially remarkable. The composition of the cecal microflora was not effected by the diet. β‐Glucuronidase activities in rats fed HAS or HMT‐HAS decreased. SCFA concentration was higher in groups HAS and HMT‐HAS than in group OCS, and the cecal pH was lower in groups HAS and HMT‐HAS than in group OCS.     

高直链玉米淀粉包合乙基麦芽酚的研究

目的 利用反复-连续湿热技术通过包埋方式提高乙基麦芽酚的使用价值.方法 通过单因素实验和正交实验考察乙基麦芽酚添加量、连续湿热处理时间、湿热处理温度和反复湿热处理次数对该包合物包埋率的影响.并对比分析了普通玉米淀粉、高直链玉米淀粉和高直链玉米淀粉-乙基麦芽酚复合物的结构和理化性质差异.结果 最佳包合条件:乙基麦芽酚添加...     

Crystallinity and Pasting Properties of Freeze‐Thawed High Amylose Maize Starch

Native and defatted high amylose (about 70%) maize starch gels were freeze‐dried or repeatedly freeze‐thawed, and the effects of the treatments on the crystallinity, pasting viscosity, and resistance to digestive enzymes of the dried starch were examined. Both native and defatted starches showed a B‐type crystal structure in the X‐ray diffractogram, but the crystallinity was decreased by repeating the freeze‐thawing cycle. In the DSC thermogram, the freeze‐thawed starches exhibited two endothermic transitions in the temperature ranges of 90—110 °C and 130—160 °C, representing amyloselipid complexes and amylose‐amylose double helix crystals, respectively. By defatting, the melting enthalpy for the amylose double helices was increased, indicating that the residual lipids inhibited the amylose crystal formation. Ice crystals in the starch gel matrix became smaller and the ice cell membrane became thinner as freeze‐thawing was repeated. The freeze‐dried or freeze‐thawed starch powders swelled to a paste by heating in water as did typical granular starch, but the setback by cooling was significantly high due to the rapid retrogradation of leached amylose. By the treatments, the resistance of the starch to digestive enzymes was also raised. The defatted starches displayed greater paste viscosity and resistance to digestive enzymes than the native starches. But the overall viscosity was decreased as the number of freeze‐thawing cycles increased.     

Characterization of Residues from Partially Hydrolyzed Potato and High Amylose Corn Starches by Pancreatic α‐Amylase

High amylose corn starch (HACS) and potato starch were hydrolyzed by pancreatic α‐amylase in vitro. Residues after hydrolysis were collected and characterized for their physicochemical properties and molecular structure. Compared with raw starches, residues had lower apparent amylose contents and higher resistant starch contents. The gelatinization enthalpy of residues from HACS increased while enthalpy of residues from potato starch decreased from 15.4 to 11.3 J/g. Peak viscosity and breakdown values of the residues from potato starch were markedly decreased but final viscosity values did not show much change. Chain length distribution of debranched amylopectin from the residues indicated that the relative portion of short chain in the residue decreased for both starches. More molecules with intermediate chain length (DP 16—31) were found in residue after 48‐h hydrolysis of potato starch.     

Effect of modified resistant starch of culinary banana on physicochemical,functional, morphological,diffraction, and thermal properties

Resistant starch has received much attention for both its potential health benefits and functional properties. The present study revealed that the culinary banana can be a potential source for production of resistant starch type III. The results showed that resistant starch yield can be increased using debranching enzyme (Pullulanase EC 3.2.1.41) and hydrothermal process. The three repeated autoclaving and cooling (hydrothermal) cycles followed by storage at –20ºC, increased the resistant starch yield from 12.3 to 26.4%. The use of debranching enzyme and subsequent retrogradation at –20ºC increased the resistant starch yield up to 31.2%. The modified resistant starch when compared to culinary banana starch evinced better stability. The modified resistant starch was analyzed using scanning electron microscopy, Fourier transform infrared, x-ray diffraction, and thermogravimetric diffraction analysis to determine the structural changes which proved that the modification occurred substantially.     

The effects of annealing and acid hydrolysis on resistant starch level and the properties of cross‐linked RS4 rice starch

The effects of ANN prior to cross‐linking of non‐wx rice starches on a RS level and granular shape were investigated to apply them for a fat replacer with RS in a liquid food system. Acid hydrolysis and sonication were also evaluated to improve RS quality. The RS level was also compared with AOAC and P/G methods. The RS levels of CRS analyzed with the AOAC method were higher than those analyzed with the P/G method, but the differences in the RS level of CRS affected an ANN condition and starch content during cross‐linking. When ANN was conducted at 50°C for 12 h using the AOAC method, and starch content (40%) used in cross‐linking was at 45°C for 3 h, the highest RS level of CRS treated with ANN was 69.4% compared to 38.3% RS level of CRS without ANN. The 1 h acid hydrolysis (pH 4.0) of CRS treated ANN increased 114.5% of the RS level (79.4% compared to 69.4% in CRS treated ANN), regardless of which analytical methods were used. CRS granules remained the same as native ones with a polygonal shape and A type crystallinity even after being treated with ANN, and acid hydrolysis. The sonication before cross‐linking reaction increased the RS level and prevented increase in size from aggregating CRS granules.     

超高压改性制备高抗性薏米粉的工艺优化及其理化特性研究

采用超高压技术对薏米粉进行改性制备高抗性薏米粉,并进一步比较改性前后薏米粉的理化特性。在单因素基础上,利用正交试验优化薏米粉乳浓度、pH、压力、保压时间与老化时间对高抗性薏米粉得率的影响。结果表明,超高压改性制备高抗性薏米粉最优工艺为:薏米粉乳浓度20%、压力600 MPa、pH值6.0、保压时间15 min、老化时间36h,该工艺条件下薏米抗性淀粉含量为17.26%;经超高压处理后薏米粉抗性淀粉含量显著提高,冻融稳定性、凝沉性、溶解性也有所改善,膨润度和透光率略有下降。超高压处理较适宜研制以减肥等保健为主的功能性薏米粉。     

Anti‐obesity effect of feeding probiotic dahi containing Lactobacillus casei NCDC 19 in high fat diet‐induced obese mice

Nowadays, studies about the anti‐obesity potential of probiotics are of growing interest. Lactobacilli are one of the well‐studied probiotics owing to their preventing effect on metabolic disorders. This study was undertaken to access the anti‐obesity effect of probiotic dahi containing Lactobacillus casei NCDC 19 on C57BL/6 mice. Feeding of probiotic dahi showed reduce body weight gain and epididymal fat weights. Moreover, blood glucose, plasma lipids and expression level of leptin were reduced and caecal bifidobacteria counts and adiponectin expression levels were significantly increased. It can be concluded that feeding of probiotic dahi containing L. casei NCDC 19 showed potential anti‐obesity effects.     

Anti‐obesity effect of Liupao tea extract by modulating lipid metabolism and oxidative stress in high‐fat‐diet‐induced obese mice

Liupao tea (LPT) is traditional dark Chinese tea. The effect of LPT extract on high‐fat‐diet‐induced obese mice was investigated systematically. The results showed that LPT extract could reduce body weight and significantly alleviate liver damage and fat accumulation. LPT could also decrease the levels of alanine aminotransferase (ALT), aspartate transaminase (AST), alkaline phosphatase (AKP), total cholesterol (TC), triglycerides (TG), and low‐density lipoprotein cholesterol (LDL‐C) and increase the level of high‐density lipoprotein cholesterol (HDL‐C) in the liver. It also decreased the serum levels of inflammatory cytokines, including tumor necrosis factor alpha (TNF‐α), interferon gamma (IFN‐γ), interleukin (IL)‐1β, and IL‐6 and increased the serum levels of anti‐inflammatory cytokines, including IL‐10 and IL‐4. Moreover, LPT improved the levels of total superoxide dismutase (T‐SOD), glutathione peroxidase (GSH‐Px), and catalase (CAT) and reduced the level of malondialdehyde (MDA) in the liver. Moreover, LPT could upregulate the mRNA and protein expressions of peroxisome proliferator‐activated receptor alpha (PPAR‐α), lipoprotein lipase (LPL), carnitine palmitoyltransferase 1(CPT1), and cholesterol 7 alpha‐hydroxylase (CYP7A1) and downregulate those of PPAR‐γ and CCAAT/enhancer‐binding protein alpha (C/EBP‐α) in the liver. It also increased the mRNA expression of copper/zinc superoxide dismutase (SOD1), manganese superoxide dismutase (SOD2), CAT, gamma‐glutamylcysteine synthetase 1 (GSH1), and GSH‐Px. The components of LPT extract include catechin, rutin, taxifolin, and astragalin, which possibly have a wide range of biological activities. In conclusion, our work verified that LPT extract possessed an anti‐obesity effect and alleviated obesity‐related symptoms, including lipid metabolism disorder, chronic low‐grade inflammation, and liver damage, by modulating lipid metabolism and oxidative stress.     

The importance of GLP‐1 and PYY in resistant starch's effect on body fat in mice

Resistant starch (RS) is a dietary fermentable fiber that decreases body fat accumulation, and stimulates the secretion of glucagon‐like peptide‐1 (GLP‐1) and peptide YY (PYY) in rodents. GLP‐1 and PYY are gut‐secreted hormones with antiobesity effect. Thus, blocking the signals of increased GLP‐1 and PYY may also block the effect of dietary RS on body fat. In a 10‐week study, C57BL/6J and GLP‐1 receptor null (GLP‐1R KO) mice were fed control or 30% RS diet, and received daily intraperitoneal injection of either saline or PYY receptor antagonist (BIIE0246, 20 μg/kg body weight). Dietary RS significantly decreased body fat accumulation only in wild‐type mice that has saline injection, but not in GLP‐1R KO mice. PYY receptor antagonist diminished RS action on body fat in wild‐type mice, but did not interfere with GLP‐1R KO mice response to RS. Regardless of genotype and injection received, all RS‐fed mice had increased cumulative food intake, cecal fermentation, and mRNA expression of proglucagon and PYY. Thus, our results suggest that increased GLP‐1 and PYY is important in RS effects on body fat accumulation.