Structures, properties, and digestibility of resistant starch

This study aimed to understand effects of different treatments and modifications on the structures, properties, and digestibility of selected starches. Different lipids, including corn oil (CO), soy lecithin (SL), palmitic acid (PA), stearic acid (SA), oleic acid (OA) and linoleic acid (LA), were selected for the study, and their impacts on the properties and digestibility of normal corn (NCS), tapioca (TPS), waxy corn (WCS) and high-amylose corn (HA7) starch were investigated to elucidate mechanisms of starch-lipid interactions. After cooking with the lipids (10%, w/w, dsb), NCS, TPS and HA7 showed significant decreases in the percentage enzymatic hydrolysis, and their DSC thermograms displayed an amylose-lipid-complex dissociation peak except the one cooked with the CO. 13C-NMR spectra of amylodextrin with the presence of CO showed downfield changes in the chemical shifts of carbons 1 and 4 of the anhydroglucose unit, indicating helical-complex formation. In general, free fatty acids (FFAs) reduced, but SL increased the peak viscosity of starch. FFAs and SL decreased, but CO increased the gel strength of NCS. All the lipids displayed little impacts on the digestibility and properties of WCS because it lacked amylose. Resistant starch Type 5 (RS5) was prepared by complexing debranched HA7 with SA. Because of amylose-helical-complex formation with SA, the RS5 showed restricted swelling of starch granules at 95 °C. The RS5 displayed a larger RS-content (67.8%) than the HA7 (33.5%) and NCS (0.8%) analyzed using the AOAC Method 991.43. When the cooked RS5, HA7 and NCS were used to prepare diets for rats with 55% (w/w) starch content, RS contents of the diets were 33.7%, 15.8% and 2.6%, respectively. After feeding to the rats in Week 1, ~16% of the starch in the RS5-diet was found in the feces, substantially greater than that of the HA7-diet (~6%) and NCS-diet (0.1%). The percentage of starch not being utilized in the RS5-diet decreased to ~5% in Week 9, which could be partially attributed to the fermentation of RS5 by gut microflora. Large proportions (68%-99%) of the SA in RS5-diet remained unabsorbed and were discharged in the rat feces. Effects of octenyl succinic anhydride (OSA) modification of the NCS and HA7 on their digestibility were examined. After the modification with 3% and 10% OSA, RS contents of the cooked OS-NCS increased from 0.8% of the control starch to 6.8% and 13.2% (Englyst Method), respectively, whereas that of the cooked OS-HA7 decreased from 24.1% to 23.7% and 20.9%, respectively. When the cooked NCS, HA7 and OS (10%)-HA7 were used to prepare diets for rats at 55% (w/w) starch, RS contents of the diets were 1.1%, 13.2% and 14.6%, respectively. After feeding to the rats, 20%-31% of the starch in the OS (10%)-HA7-diet was not utilized in vivo and was found in rat feces, which was substantially larger than that of the HA7-diet (≤ 5%) and NCS-diet (≤ 0.2%). Characteristics of starch and ethanol production of five sorghum lines (6B73, 6C21, 6C69, 7R34, and X789) were investigated and compared with that of B73 corn. Sorghum starches displayed higher gelatinization-temperatures (66.6-67.4 °C), greater gelatinization enthalpy-changes (13.0-14.0 J/g) and percentages retrogradation (60.7-69.1%), but slower enzymatic-hydrolysis rates (83.8-87.8% at 48 h) than the B73 corn starch (61.7 °C, 10.1 J/g, 51.5%, and 88.5%, respectively). These differences could result from that the sorghum amylopectins consisted of fewer short branch-chains (DP 6-12) (12.8-14.0%) than the corn amylopectin (15.0%). After 96 h fermentation, most ground sorghums exhibited lower ethanol-yields (30.5-31.8%) than the ground B73 corn (31.8%). Structure, properties, and digestibility of starch isolated from bamboo seeds (Bambusa textilis species) were studied and compared with that of indica and japonica-rice starch. The bamboo seeds also had compound starch granules, with morphology and sizes comparable to the rice starches. The amylopectin of bamboo-seed starch showed similar branch-chain-length distribution to that of the indica-rice starch, and both of them had longer branch-chains (DP = 19.1 and 19.7, respectively) than the japonica-rice amylopectin (DP = 17.1). Consequently, the bamboo-seed and indica-rice starch granules exhibited higher gelatinization-temperatures (To = 68.9 °C and 71.9 °C, respectively), larger enthalpy-changes (ΔH = 14.2 J/g and 15.3 J/g) and percentages of retrogradation (57.1% and 55.4%), but slower enzymatic-hydrolysis rates (50.6% and 46.3% at 24 h) than the japonica-rice starch counterpart (56.4 °C, 14.0 J/g, 11.4%, and 66.2%, respectively)

Learning over Knowledge-Base Embeddings for Recommendation

State-of-the-art recommendation algorithms -- especially the collaborative filtering (CF) based approaches with shallow or deep models -- usually work with various unstructured information sources for recommendation, such as textual reviews, visual images, and various implicit or explicit feedbacks. Though structured knowledge bases were considered in content-based approaches, they have been largely neglected recently due to the availability of vast amount of data, and the learning power of many complex models. However, structured knowledge bases exhibit unique advantages in personalized recommendation systems. When the explicit knowledge about users and items is considered for recommendation, the system could provide highly customized recommendations based on users' historical behaviors. A great challenge for using knowledge bases for recommendation is how to integrated large-scale structured and unstructured data, while taking advantage of collaborative filtering for highly accurate performance. Recent achievements on knowledge base embedding sheds light on this problem, which makes it possible to learn user and item representations while preserving the structure of their relationship with external knowledge. In this work, we propose to reason over knowledge base embeddings for personalized recommendation. Specifically, we propose a knowledge base representation learning approach to embed heterogeneous entities for recommendation. Experimental results on real-world dataset verified the superior performance of our approach compared with state-of-the-art baselines

Learning to Ask: Question-based Sequential Bayesian Product Search

Product search is generally recognized as the first and foremost stage of online shopping and thus significant for users and retailers of e-commerce. Most of the traditional retrieval methods use some similarity functions to match the user's query and the document that describes a product, either directly or in a latent vector space. However, user queries are often too general to capture the minute details of the specific product that a user is looking for. In this paper, we propose a novel interactive method to effectively locate the best matching product. The method is based on the assumption that there is a set of candidate questions for each product to be asked. In this work, we instantiate this candidate set by making the hypothesis that products can be discriminated by the entities that appear in the documents associated with them. We propose a Question-based Sequential Bayesian Product Search method, QSBPS, which directly queries users on the expected presence of entities in the relevant product documents. The method learns the product relevance as well as the reward of the potential questions to be asked to the user by being trained on the search history and purchase behavior of a specific user together with that of other users. The experimental results show that the proposed method can greatly improve the performance of product search compared to the state-of-the-art baselines.Comment: This paper is accepted by CIKM 201

Analysis of Resistant Starches in Rat Cecal Contents Using Fourier Transform Infrared Photoacoustic Spectroscopy

Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) qualitatively and quantitatively measured resistant starch (RS) in rat cecal contents. Fisher 344 rats were fed diets of 55% (w/w, dry basis) starch for 8 weeks. Cecal contents were collected from sacrificed rats. A corn starch control was compared against three RS diets. The RS diets were high-amylose corn starch (HA7), HA7 chemically modified with octenyl succinic anhydride, and stearic-acid-complexed HA7 starch. To calibrate the FTIR-PAS analysis, samples from each diet were analyzed using an enzymatic assay. A partial least-squares cross-validation plot generated from the enzymatic assay and FTIR-PAS spectral results for starch fit the ideal curve with a R2 of 0.997. A principal component analysis plot of components 1 and 2 showed that spectra from diets clustered significantly from each other. This study clearly showed that FTIR-PAS can accurately quantify starch content and identify the form of starch in complex matrices.Reprinted with permission from Journal of Agricultural and Food Chemistry 61 (2013): 1818–1822, doi:10.1021/jf3042616. Copyright 2013 American Chemical Society.</p

Structures, properties, and digestibility of resistant starch

This study aimed to understand effects of different treatments and modifications on the structures, properties, and digestibility of selected starches. Different lipids, including corn oil (CO), soy lecithin (SL), palmitic acid (PA), stearic acid (SA), oleic acid (OA) and linoleic acid (LA), were selected for the study, and their impacts on the properties and digestibility of normal corn (NCS), tapioca (TPS), waxy corn (WCS) and high-amylose corn (HA7) starch were investigated to elucidate mechanisms of starch-lipid interactions. After cooking with the lipids (10%, w/w, dsb), NCS, TPS and HA7 showed significant decreases in the percentage enzymatic hydrolysis, and their DSC thermograms displayed an amylose-lipid-complex dissociation peak except the one cooked with the CO. 13C-NMR spectra of amylodextrin with the presence of CO showed downfield changes in the chemical shifts of carbons 1 and 4 of the anhydroglucose unit, indicating helical-complex formation. In general, free fatty acids (FFAs) reduced, but SL increased the peak viscosity of starch. FFAs and SL decreased, but CO increased the gel strength of NCS. All the lipids displayed little impacts on the digestibility and properties of WCS because it lacked amylose. Resistant starch Type 5 (RS5) was prepared by complexing debranched HA7 with SA. Because of amylose-helical-complex formation with SA, the RS5 showed restricted swelling of starch granules at 95 °C. The RS5 displayed a larger RS-content (67.8%) than the HA7 (33.5%) and NCS (0.8%) analyzed using the AOAC Method 991.43. When the cooked RS5, HA7 and NCS were used to prepare diets for rats with 55% (w/w) starch content, RS contents of the diets were 33.7%, 15.8% and 2.6%, respectively. After feeding to the rats in Week 1, ~16% of the starch in the RS5-diet was found in the feces, substantially greater than that of the HA7-diet (~6%) and NCS-diet (0.1%). The percentage of starch not being utilized in the RS5-diet decreased to ~5% in Week 9, which could be partially attributed to the fermentation of RS5 by gut microflora. Large proportions (68%-99%) of the SA in RS5-diet remained unabsorbed and were discharged in the rat feces. Effects of octenyl succinic anhydride (OSA) modification of the NCS and HA7 on their digestibility were examined. After the modification with 3% and 10% OSA, RS contents of the cooked OS-NCS increased from 0.8% of the control starch to 6.8% and 13.2% (Englyst Method), respectively, whereas that of the cooked OS-HA7 decreased from 24.1% to 23.7% and 20.9%, respectively. When the cooked NCS, HA7 and OS (10%)-HA7 were used to prepare diets for rats at 55% (w/w) starch, RS contents of the diets were 1.1%, 13.2% and 14.6%, respectively. After feeding to the rats, 20%-31% of the starch in the OS (10%)-HA7-diet was not utilized in vivo and was found in rat feces, which was substantially larger than that of the HA7-diet (≤ 5%) and NCS-diet (≤ 0.2%). Characteristics of starch and ethanol production of five sorghum lines (6B73, 6C21, 6C69, 7R34, and X789) were investigated and compared with that of B73 corn. Sorghum starches displayed higher gelatinization-temperatures (66.6-67.4 °C), greater gelatinization enthalpy-changes (13.0-14.0 J/g) and percentages retrogradation (60.7-69.1%), but slower enzymatic-hydrolysis rates (83.8-87.8% at 48 h) than the B73 corn starch (61.7 °C, 10.1 J/g, 51.5%, and 88.5%, respectively). These differences could result from that the sorghum amylopectins consisted of fewer short branch-chains (DP 6-12) (12.8-14.0%) than the corn amylopectin (15.0%). After 96 h fermentation, most ground sorghums exhibited lower ethanol-yields (30.5-31.8%) than the ground B73 corn (31.8%). Structure, properties, and digestibility of starch isolated from bamboo seeds (Bambusa textilis species) were studied and compared with that of indica and japonica-rice starch. The bamboo seeds also had compound starch granules, with morphology and sizes comparable to the rice starches. The amylopectin of bamboo-seed starch showed similar branch-chain-length distribution to that of the indica-rice starch, and both of them had longer branch-chains (DP = 19.1 and 19.7, respectively) than the japonica-rice amylopectin (DP = 17.1). Consequently, the bamboo-seed and indica-rice starch granules exhibited higher gelatinization-temperatures (To = 68.9 °C and 71.9 °C, respectively), larger enthalpy-changes (ΔH = 14.2 J/g and 15.3 J/g) and percentages of retrogradation (57.1% and 55.4%), but slower enzymatic-hydrolysis rates (50.6% and 46.3% at 24 h) than the japonica-rice starch counterpart (56.4 °C, 14.0 J/g, 11.4%, and 66.2%, respectively).</p

Effects of lipids on enzymatic hydrolysis and physical properties of starch

This study aimed to understand effects of lipids, including corn oil (CO), soy lecithin (SL), palmitic acid (PA), stearic acid (SA), oleic acid (OA), and linoleic acid (LA), on the enzymatic hydrolysis and physical properties of normal corn (NCS), tapioca (TPS), waxy corn (WCS), and high-amylose corn (HA7) starch, and to elucidate mechanisms of interactions between the starches and lipids. After cooking with the lipids (10%, w/w, dsb), NCS, TPS, and HA7 showed significant decreases in enzymatic hydrolysis, and their DSC thermograms displayed amylose-lipid-complex dissociation peaks except with the CO. C NMR spectra of amylodextrin with CO showed downfield changes in the chemical shifts of carbons 1 and 4 of the anhydroglucose unit, indicating helical complex formation. Generally, free fatty acids (FFAs) reduced, but SL increased the peak viscosities of starches. FFAs and SL decreased, but CO increased the gel strength of NCS. These lipids displayed little impacts on the enzymatic hydrolysis and physical properties of WCS because it lacked amylose

Effects of a 28-day feeding trial of grain-containing versus pulse-based diets on cardiac function, taurine levels and digestibility in domestic dogs.

In 2018, the US Food and Drug Administration reported a link between canine dilated cardiomyopathy (DCM) and grain-free diets. Evidence to support a link has emerged, but the specific ingredients responsible and the role of taurine or other causative factors remain unclear. We hypothesized dogs fed pulse-based, grain-free diets for 28 days will show decreased macronutrient digestibility, increased fecal bile acid excretion, and reduced plasma cystine, cysteine, methionine and taurine, causing sub-clinical cardiac or blood changes indicative of early DCM. Three diets were formulated using white rice flour (grain), whole lentil (grain-free), or wrinkled pea (grain-free) and compared to the pre-trial phase on a commercial grain-based diet. After 28 days of feeding each diet, the wrinkled pea diet impaired stroke volume and cardiac output, increased end-systolic ventricular diameter and increased plasma N-Terminal Pro-B-type Natriuretic Peptide (NT-ProBNP), albeit in a sub-clinical manner. Digestibility of some macronutrients and sulphur-containing amino acids, excluding taurine, also decreased with pulse-based compared to grain-based diets, likely due to higher fiber levels. Plasma taurine levels were unchanged; however, plasma methionine was significantly lower after feeding all test diets compared to the commercial diet. Overall, DCM-like changes observed with the wrinkled pea diet, but not lentil diet, after only 4 weeks in a breed not known to be susceptible support a link between pea-based diets and canine nutritionally-mediated DCM

Inhibition of azoxymethane-induced preneoplastic lesions in the rat colon by a novel resistant starch cooked by different methods

The purpose of this study was to test the inhibitory effects of a novel resistant starch cooked by two different methods on azoxymethane (AOM)-induced colon carcinogenesis in rats. The novel resistant starch (RS)(patent pending) was processed from commercial high amylose cornstarch. A normal cornstarch (CS) and the high amylose cornstarch (HA) were used as negative and positive control starch groups, respectively. Two cooking methods were applied to all the three starches: (1) making each starch into bread using a standard bakery procedure (cB). (2) using boiling water, high moisture cooking method (cW). Then the starches were mixed with other ingredients based on AIN-93 formulations into 6 rat diets: bread normal-cornstarch diet (cB-CS), bread high-amylose-cornstarch diet (cB-HA), bread novel-resistant-starch diet (cB-RS), boiling-water-high-moisture normal-cornstarch diet (cW-CS), boiling-water-high-moisture high-amylose-cornstarch diet (cW-HA), and boiling-water-high-moisture novel-resistant-starch diet (cW-RS). Six groups of 5-week-old male Fischer 344 rats including 15 animals each were injected with two doses of 20 mg/kg bw AOM one week apart and fed the above diets respectively. Another six groups of male Fischer 344 rats with 5 animals in each group were injected with saline and fed the same six kinds of diets as the AOM treated groups. The rats were fed for 8 weeks after the second injection and then killed. Caecum weight and pH, Aberrant Crypt Foci (ACF) and Mucin Depleted Foci (MDF) were investigated. ACF and MDF were only seen with AOM treatment. The ACF numbers for cB-CS, cB-HA, cB-RS, cW-CS, cW-HA, and cW-RS groups were 29, 29, 17, 225, 256, and 121, respectively. The MDF numbers for the above diet groups were 6.1, 4.9, 1.9, 10.7, 8.7 and 2.1, respectively. ACF and MDF numbers were significantly reduced in rats fed novel resistant starch diet in comparison with rats fed the other two diets (

Nitrogen Metabolism and Curing Characteristics of Flue-cured Tobacco Variety NC71

[Objectives] To explore the growth characteristics, nitrogen metabolism and curing characteristics of the new variety NC71 in strongly aromatic tobacco leaves production area. [Methods] With Yunyan 87 as the control and NC71 as the experimental material, the experiment was carried out in Nanyang tobacco area for two consecutive years to study the growth characteristics of tobacco plants, the activity of key enzymes in nitrogen metabolism, the content of secondary metabolites, and the differences of tobacco-related water content, PPO enzyme activity and total phenol content. [Results] NC71 plants had lower height, better appearance quality and lower nicotine, total sugar and chlorine content. NC71 high nitrogen treatment and Yunyan 87 medium nitrogen treatment had similar key enzyme activity of nitrogen metabolism, content of secondary metabolites; Yunyan 87 and NC71 were easy to cure and resistant to curing. [Conclusions] This study provides a reference for measuring the appropriate nitrogen application rate and optimizing the curing process from the activities of the key enzymes NR and GS in nitrogen metabolism at the mature stage of the variety

Valorization of Starch to Biobased Materials: A Review

Many concerns are being expressed about the biodegradability, biocompatibility, and long-term viability of polymer-based substances. This prompted the quest for an alternative source of material that could be utilized for various purposes. Starch is widely used as a thickener, emulsifier, and binder in many food and non-food sectors, but research focuses on increasing its application beyond these areas. Due to its biodegradability, low cost, renewability, and abundance, starch is considered a “green path” raw material for generating porous substances such as aerogels, biofoams, and bioplastics, which have sparked an academic interest. Existing research has focused on strategies for developing biomaterials from organic polymers (e.g., cellulose), but there has been little research on its polysaccharide counterpart (starch). This review paper highlighted the structure of starch, the context of amylose and amylopectin, and the extraction and modification of starch with their processes and limitations. Moreover, this paper describes nanofillers, intelligent pH-sensitive films, biofoams, aerogels of various types, bioplastics, and their precursors, including drying and manufacturing. The perspectives reveal the great potential of starch-based biomaterials in food, pharmaceuticals, biomedicine, and non-food applications