Slowly digestible starch: concept, mechanism, and proposed extended glycemic index

Impact of esterification with malic acid on the structural characteristics and in vitro digestibilities of different starches

This research focused on the structural characteristics of resistant starches (RSs) that were obtained from corn, potato, and sweet potato and esterified by L-malic acid. Further, the unique effect of the degree of substitution (DS) on the crystalline properties was studied. Different starches were allowed to react with 2 M malic acid (pH 1.5) for 12 h at 130 °C. The shapes of the granules and the Maltese-cross shapes of samples were maintained and visible under an optical microscope. The FT-IR spectrum displayed evident carbonyl peaks at 1740 cm^-1, and the onset temperature (T_o) and gelatinization enthalpy (∆H) gradually decreased as DS increased. The malic acid-treated starches exhibited an increased RS content compared to those of the control. The RS contents of potato, sweet potato, and corn, which were 65.5%, 70.0%, and 89.8% in the uncooked MT-samples, decreased to 57.3%, 63.8%, and 86.7% in the cooked MT-samples, respectively, and exhibited high heat stability; corn starch yielded the highest RS among them. The thermal and malic acid treatments resulted in the partial hydrolysis and rearrangement of the helix structure of crystalline area, which was affected by esterification. The result revealed that the RS content increased as that of DS escalated.

Latest developments in the applications of microfluidization to modify the structure of macromolecules leading to improved physicochemical and functional properties

Microfluidization is a unique high-pressure homogenization technique combining various forces such as high-velocity impact, high-frequency vibration, instantaneous pressure drop, intense shear rate, and hydrodynamic cavitation. Even though it is mainly used on emulsion-based systems and known for its effects on particle size and surface area, it also significantly alters physicochemical and functional properties of macromolecules including hydration properties, solubility, viscosity, cation-exchange capacity, rheological properties, and bioavailability. Besides, the transformation of structure and conformation due to the combined effects of microfluidization modifies the material characteristics that can be a base for new innovative food formulations. Therefore, microfluidization is being commonly used in the food industry for various purposes including the formation of micro- and nano-sized emulsions, encapsulation of easily degradable bioactive compounds, and improvement in functional properties of proteins, polysaccharides, and dietary fibers. Although the extent of modification through microfluidization depends on processing conditions (e.g., pressure, number of passes, solvent), the nature of the material to be processed also changes the outcomes significantly. Therefore, it is important to understand the effects of microfluidization on each food component. Overall, this review paper provides an overview of microfluidization treatment, summarizes the applications on macromolecules with specific examples, and presents the existing problems.

Uncooked cornstarch for the prevention of hypoglycemic events

Hypoglycemia is a pathological condition characterized by a low plasma glucose concentration associated with typical autonomic and/or neuroglycopenic symptoms, and resolution of these symptoms with carbohydrate consumption. Hypoglycemia is quite common in clinical practice, particularly in insulin-treated patients with diabetes and in other inherited or acquired conditions involving the regulation of glucose metabolism. Beyond symptoms that might strongly affect the quality of life, hypoglycemia can lead to short- and long-term detrimental consequences for health. Hypoglycemia can be prevented by appropriate changes in dietary habits or by relevant modifications of the drug treatment. Several dietary approaches based on the intake of various carbohydrate foods have been tested for hypoglycemia prevention; among them uncooked cornstarch (UCS) has demonstrated a great efficacy. In this narrative review, we have summarized the current evidence on the UCS usefulness in some conditions characterized by high hypoglycemic risk, focusing on some inherited diseases -i.e. glycogen storage diseases and other rare disorders - and acquired conditions such as type 1 diabetes, postprandial hypoglycemia consequent to esophageal-gastric or bariatric surgery, and insulin autoimmune syndrome. We also considered the possible role of UCS during endurance exercise performance. Lastly, we have discussed the dose requirement, the side effects, the limitations of UCS use, and the plausible mechanisms by which UCS could prevent hypoglycemia.

An Innovative Short-Clustered Maltodextrin as Starch Substitute for Ameliorating Postprandial Glucose Homeostasis

Dietary starch is usually associated with elevated postprandial glycemic response. This is a potential risk factor of type 2 diabetes. Here, a 1,4-α-glucan branching enzyme (GBE) was employed to reassemble α-1,4 and α-1,6 glycosidic bonds in starch molecules. Structural characterization showed that GBE-catalyzed molecular reassembly created an innovative short-clustered maltodextrin (SCMD), which showed a dense internal framework along with shortened external chains. Such short-clustered molecules obstructed digestive enzymes attack and displayed dramatically reduced digestibility. Therefore, SCMD was served as a dietary starch substitute to improve postprandial glucose homeostasis. A 22.3% decrease in glycemic peak was therefore detected in ICR mice following SCMD intake (10.7 mmol/L), compared with that in the control (13.8 mmol/L). Moreover, an attenuated insulin response (40.5% lower than that in control) to SCMD intake was regarded suitable for diabetes management. These novel discoveries demonstrate that enzymatically rebuilding starch molecules may be a meaningful strategy for diabetes management.

Causal relations among starch fine molecular structure, lamellar/crystalline structure and in vitro digestion kinetics of native rice starch

Causal relations among starch fine molecular structures, lamellar/crystalline structures, and the in vitro digestion kinetics of native rice starches.

Graded dietary resistant starch concentrations on apparent total tract macronutrient digestibility and fecal fermentative end products and microbial populations of healthy adult dogs

Resistant starch (RS) is fermentable by gut microbiota and effectively modulates fecal short-chain fatty acid concentrations in pigs, mice, and humans. RS may have similar beneficial effects on the canine gut but has not been well studied. The objective of this study was to evaluate the effects of 0%, 1%, 2%, 3%, and 4% dietary RS (Hi-maize 260) on apparent total tract macronutrient digestibility, fecal characteristics, fermentative end-product concentrations, and microbiota of healthy adult dogs. An incomplete 5 × 5 Latin square design with seven dogs and five experimental periods was used, with each treatment period lasting 21 d (days 0 to 17 adaptation; days 18 to 21 fresh and total fecal collection) and each dog serving as its own control. Seven dogs (mean age = 5.3 yr; mean body weight = 20 kg) were randomly allotted to one of five treatments formulated to be iso-energetic and consisting of graded amounts of 100% amylopectin cornstarch, RS, and cellulose and fed as a top dressing on the food each day. All dogs were fed the same amount of a basal diet throughout the study, and fresh water was offered ad libitum. The basal diet contained 6.25% RS (dry matter [DM] basis), contributing approximately 18.3 g of RS/d based on their daily food intake (292.5 g DM/d). Data were evaluated for linear and quadratic effects using SAS. The treatments included 0%, 1%, 2%, 3%, and 4% of an additional RS source. Because Hi-maize 260 is approximately 40% digestible and 60% indigestible starch, the dogs received the following amounts of RS daily: 0% = 18.3 g (18.3 + 0 g), 1% = 20.1 g (18.3 + 1.8 g), 2% = 21.9 g (18.3 + 3.6 g), 3% = 23.7 g (18.3 + 5.4 g), and 4% = 25.5 g (18.3 + 7.2 g). Apparent total tract DM, organic matter, crude protein, fat, and gross energy digestibilities and fecal pH were linearly decreased (P < 0.05) with increased RS consumption. Fecal output was linearly increased (P < 0.05) with increased RS consumption. Fecal scores and fecal fermentative end-product concentrations were not affected by RS consumption. Although most of the fecal microbial taxa were not altered, Faecalibacterium were increased (P < 0.05) with increased RS consumption. The decrease in fecal pH and increase in fecal Faecalibacterium would be viewed as being beneficial to gastrointestinal health. Although our results seem to indicate that RS is poorly and/or slowly fermentable in dogs, the lack of observed change may have been due to the rather high level of RS contained in the basal diet.

Dietary carbohydrate intake in patients with type 2 diabetes mellitus and diabetes control: a cross-sectional study

Background

Food intake has important implications for patients with type 2 diabetes.

Objective

Similarly, in other crop species, this observational study aimed to assess dietary carbohydrate (CHO) and non-starch polysaccharide (NSP) intake and examine their association with glycemic control among Saudi patients with type 2 diabetes mellitus (T2DM).

Design

We investigated dietary intake in 404 patients (207 males and 197 females) with T2DM between November 2018 and March 2019. Dietary intake was assessed by face-to-face interviews using a validated dietary questionnaire.

Results

The results revealed that dietary CHO intake (67% of energy) exceeded the recommended daily intake, and white rice (Basmati rice) was the major contributor to CHO intake. However, the dietary NSP intake was lower than recommended, and it was negatively associated with HbA_1c levels.

Conclusion

This cross-sectional study showed that dietary CHO intake was high among Saudi patients with type 2 diabetes, and that their daily intake of NSPs was correlated with a lower level of HbA_1c. Dietary advice should be given for patients with diabetes to reduce their intake of starchy food such as rice.

Storage temperature and time affect the enzyme resistance starch and glycemic response of cooked noodles

White-salted noodles are prepared, stored and consumed in various ways. However, relationships among cooking and storage conditions on nutritional functionality are not fully understood. The manuscript elucidates the mechanism of formation of resistant starch (RS) leading to slower digestion rate of variously cooked (boiled, steamed, stir-fried, fried and microwave heated) noodles followed by storage under different conditions (-18, 4 and 25 °C for 4, 24 and 48 h). RS content of noodles stored at 25 °C was higher than noodles stored at 4 °C, which was consistent with increases in the degree of crystallinity during storage. We showed that the residual moisture content primarily facilitated the mobility of starch chains and contributed towards the increase in RS associated with the decrease of enzyme susceptivity of noodles after storage. Evidence that supramolecular organization (helical structure and crystallinity) had a more pronounced effect than the macroscopic structure such as compactness or bulk density was also provided.

Leuconostoc citreum TR116 as a Microbial Cell Factory to Functionalise High-Protein Faba Bean Ingredients for Bakery Applications

Grain legumes, such as faba beans, have been investigated as promising ingredients to enhance the nutritional value of wheat bread. However, a detrimental effect on technological bread quality was often reported. Furthermore, considerable amounts of antinutritional compounds present in faba beans are a subject of concern. Sourdough-like fermentation can positively affect baking performance and nutritional attributes of faba bean flours. The multifunctional lactic acid bacteria strain Leuconostoc citreum TR116 was employed to ferment two faba bean flours with different protein contents (dehulled flour (DF); high-protein flour (PR)). The strain’s fermentation profile (growth, acidification, carbohydrate metabolism and antifungal phenolic acids) was monitored in both substrates. The fermentates were applied in regular wheat bread by replacing 15% of wheat flour. Water absorption, gluten aggregation behaviour, bread quality characteristics and in vitro starch digestibility were compared to formulations containing unfermented DF and PR and to a control wheat bread. Similar microbial growth, carbohydrate consumption as well as production of lactic and acetic acid were observed in both faba bean ingredients. A less pronounced pH drop as well as a slightly higher amount of antifungal phenolic acids were measured in the PR fermentate. Fermentation caused a striking improvement of the ingredients’ baking performance. GlutoPeak measurements allowed for an association of this observation with an improved gluten aggregation. Given its higher potential to improve protein quality in cereal products, the PR fermentate seemed generally more promising as functional ingredient due to its positive impact on bread quality and only moderately increased starch digestibility in bread.

Starch digestibility: past, present, and future

In the last century, starch present in foods was considered to be completely digested. However, during the 1980s, studies on starch digestion started to show that besides digestible starch, which could be rapidly or slowly hydrolysed, there was a variable fraction that resisted hydrolysis by digestive enzymes. That fraction was named resistant starch (RS) and it encompasses those forms of starch that are not accessible to human digestive enzymes but can be fermented by the colonic microbiota, producing short-chain fatty acids. RS has been classified into five types, depending on the mechanism governing its resistance to enzymatic hydrolysis. Early research on RS was focused on the methods to determine its content in foods and its physiological effects, including fermentability in the large intestine. Later on, due to the interest of the food industry, methods to increase the RS content of isolated starches were developed. Nowadays, the influence of RS on the gut microbiota is a relevant research topic owing to its potential health-related benefits. This review summarizes over 30 years of investigation on starch digestibility, its relationship with human health, the methods to produce RS and its impact on the microbiome. © 2018 Society of Chemical Industry.

Digestion kinetics of low, intermediate and highly branched maltodextrins produced from gelatinized starches with various microbial glycogen branching enzymes

Twenty-four branched maltodextrins were synthesized from eight starches using three thermostable microbial glycogen branching enzymes. The maltodextrins have a degree of branching (DB) ranging from 5 % to 13 %. This range of products allows us to explore the effect of DB on the digestibility, which was quantified under conditions that mimic the digestion process in the small intestine. The rate and extent of digestibility were analyzed using the logarithm of the slope method, revealing that the branched maltodextrins consist of a rapidly and slowly digestible fraction. The amount of slowly digestible maltodextrin increases with an increasing DB. Surprisingly, above 10 % branching the fraction of slowly digestible maltodextrin remains constant. Nevertheless, the rate of digestion of the slowly digestible fraction was found to decline with increasing DB and shorter average internal chain length. These observations increase the understanding of the structural factors important for the digestion rate of branched maltodextrins.

Evaluation of the acceptability of low glycaemic index preparations, formulated by replicating traditional Chilean culinary preparations with a high glycaemic index

Introduction

The aim of this study was to determine the acceptability of low glycaemic index (GI) preparations, equivalent to the traditional high GI ones in Chile, elaborated with minimal changes in the ingredients and culinary techniques that significantly diminish the GI and maintain acceptability level. Twelve high-GI traditional lunches and their low GI counterparts were prepared. For 12 days, 20 apparently healthy women randomly tasted 2 paired preparations per day (low and high GI). The attributes of appearance, taste, smell, and texture of salads, main course, and desserts, as well as those of the full lunch, were evaluated using a hedonic scale of 7 and 9 points. Lunches with a high GI (90 ± 20.5 %) were modified by changing types of food ingredients, and/or by using culinary techniques to provide a low-GI counterpart with 47 ± 5.9 % GI (p < 0.001). All the preparations were classified as optimal, exceeding the established cut-off point. The "Legume with CHO" lunch had a higher acceptability level in its low GI version (p = 0.006), while the "Chicken with corn" lunch had it in its high GI version (p = 0.004). There was a preference for low-GI salad appearance (p = 0.003) and dessert flavour (p = 0.024), while high-GI main dishes were better praised for flavour (p = 0.034) and texture (p = 0.012). It is therefore possible to prepare low-GI menus equivalent to their traditional counterparts that are received as generally acceptable, with components and sensory attributes equal to, or even better than typical Chilean cuisine dishes.

Effects of particle size on structural, physicochemical, and functional properties of potato residue from starch isolation and quality characteristics of residue-based starch noodles

The structural, physicochemical, and functional properties of potato residue with different mesh sizes (<180 µm, <150 µm, <106 µm, <75 µm, ultrafine) obtained from starch isolation were investigated, and its effects on the shear strength, tensile strength, cooking time, and in vitro digestibility of 5% potato residue-based starch noodles were further compared. The results showed that the protein, ash, dietary fiber, water holding capacity, and water solubility of fractionated potato residue were decreased with decreasing particle size, while the starch, fat, polyphenols, and α-amylase activity inhibition ratio were increased. Ultrafine particles exhibited the highest phenolic content (2.26 mg chlorogenic acid equivalent/g), glucose adsorption capacity (7.03 mmol/g), cholesterol adsorption capacity (16.54%), and better performance on starch noodles formulation. However, oil holding capacity and microstructure did not show any significant differences. Therefore, potato residues with desired particle sizes could be successfully used to develop fiber-enriched food products for reducing food waste.

Evaluation of an Amino Acid Mix on the Secretion of Gastrointestinal Peptides, Glucometabolic Homeostasis, and Appetite in Obese Adolescents Administered with a Fixed-Dose or ad Libitum Meal

Proteins have been demonstrated to reduce food intake in animals and humans via peripheral and central mechanisms. Supplementation of a dietetic regimen with single or mixed amino acids might represent an approach to improve the effectiveness of any body weight reduction program in obese subjects. The aim of the present study was to evaluate the effects of an amino acid mix (L-arginine + L-leucine + L-glutamine + L-tryptophan) on the secretion of some gastrointestinal peptides (i.e., ghrelin and glucagon-like peptide type 1, GLP-1), glucometabolic homeostasis (i.e., glucose, insulin, and glucagon), and appetite (hunger/satiety scored by visual analogue scale, VAS) in obese adolescents (n = 14; 10 females and 4 males; age: 16.6 ± 1.0 years; body mass index (BMI): 36.4 ± 4.6 kg/m²; fat-free mass (FFM): 54.9 ± 4.7%; fat mass (FM): 45.1 ± 4.4%) administered with a fixed-dose (lunch) or ad libitum (dinner) meal. Isocaloric maltodextrins were used as control treatment. During the lunch test, a significant increase in circulating levels of GLP-1, but not of ghrelin, was observed in the amino acid-treated group, which was congruent with significant changes in appetite, i.e., increase in satiety and decrease in hunger. A significant hyperglycemia was found in the maltodextrin-treated group during the prelunch period, without any significant changes in insulin and glucagon between the two groups. During the dinner test, there were no significant differences in appetite (hunger/satiety) and intake of calories. In conclusion, L-arginine, L-leucine, L-glutamine, and L-tryptophan, when administered to obese adolescents with a fixed-dose meal, are capable of evoking an anorexigenic response, which is, at least in part, mediated by an increase in GLP-1 released in circulation by L cells, which are capable of chemosensing specific amino acids present in the intestinal lumen. Further additional studies are requested to understand whether higher doses are necessary to inhibit ad libitum feeding.

Identifying genes for resistant starch, slowly digestible starch, and rapidly digestible starch in rice using genome-wide association studies

BACKGROUND

The digestibility of starch is important for the nutritive value of staple food. Although several genes are responsible for resistant starch (RS) and slowly digestible starch (SDS), gaps persist concerning the molecular basis of RS and SDS formation due to the complex genetic mechanisms of starch digestibility.

OBJECTIVES

The objective of this study was to identify new genes for starch digestibility in rice and interprete the genetic mechanisms of RS and SDS by GWAS.

METHODS

Genome-wide association studies were conducted by associating the RS and SDS phenotypes of 104 re-sequenced rice lines to an SNP dataset of 2,288,867 sites using a compressed mixed linear model. Candidate genes were identified according to the position of the SNPs based on data from the MSU Rice Genome Annotation Project.

RESULTS

Seven quantitative trait loci (QTLs) were detected to be associated with the RS content, among which the SNP 6 m1765761 was located on Waxy. Starch branching enzymes IIa (BEIIa) close to QTL qRS-I4 was detected and further identified as a specific candidate gene for RS in INDICA. Two QTLs were associated with SDS, and the LOC_Os09g09360 encoding lipase was identified as a causal gene for SDS.

CONCLUSIONS

GWAS is a valid strategy to genetically dissect the formation of starch digestion properties in rice. RS formation in grains is dependent on the rice type; lipid might also contribute to starch digestibility and should be an alternative factor to improve rice starch digestibility.

Parameterizing starch chain-length distributions for structure-property relations

Understanding starch structure-property relationship is important for the development of new generation of starch-based foods with desirable functions. Recent developments of methodologies on the characterisation of starch molecular structures, especially how to parameterize the starch chain-length distribution (CLD) by few biologically meaningful parameters have brought new insights to explain starch physicochemical properties from molecular levels. Especially, it has shown that gelatinization temperatures are largely controlled by amylopectin short chains, while the retrogradation rate of starch molecules is controlled by amylose content, amylose short to medium chains, amylopectin external and internal chain length. Starch pasting and digestion properties are also controlled to a significant extent by its CLD. With extensive discussion of correlative and casual relations between starch CLD with its physicochemical properties, this review aims to establish a holistic starch structure-property relationship. It enables food producers to develop functional foods based on a precise understanding of starch structure-property relations.

Functional properties of heat-moisture treated maize meal with added stearic acid by infrared energy

Functional properties of infrared heat-moisture treated (HMT) maize meal with stearic acid were studied. Maize meal with 1.5% stearic acid (SA) was treated by HMT using infrared (IR) energy (at 110 °C for 1, 2 & 3 h) and conventional HMT (at 110 °C for 16 h) independently. Infrared HMT is similar to conventional HMT since both treatments resulted in significantly (P < 0.05) reduced final viscosity and reduced in vitro starch digestibility in maize meal with stearic acid. These changes related correspond with the presence of V-type polymorphs (Type II) and increased in relative crystallinity showed by differential scanning calorimetry and X-ray diffraction scattering, respectively. These results suggested that infrared HMT changes the functional and nutritional properties of maize meal with SA and has the potential to replace conventional HMT in the development of lower GI, higher value-added functional starch foodstuffs.

Enzymatically elongated rice starches by amylosucrase from Deinococcus geothermalis lead to slow down the glucose generation rate at the mammalian α-glucosidase level

Amylosucrase (AS) catalyzes the transfer of a glucosyl unit from sucrose onto α-1,4-linked glucan polymers in starch. In this study, AS from Deinococcus geothermalis (DgAS) was applied to produce modified rice starches with slowly digestible properties. DgAS-treated waxy and normal rice starches showed significantly (p < 0.05) elevated degrees of polymerization, suggesting that the external chains were elongated. Additionally, the crystalline structures of starches changed from A- to B-type, and the temperature transition properties of enzymatically modified rice starches increased. The amounts of slowly digestible starch (SDS) increased remarkably (20.1% and 18.8%; waxy and normal rice starches, respectively), and the DgAS-treated rice starches were slowly hydrolyzed to glucose at the mammalian mucosal α-glucosidase level. Thus, DgAS-treated rice starches can be used to produce SDS-based ingredients that attenuate the glucose spike after glycemic food ingestion.

Influence of anionic, neutral, and cationic polysaccharides on the in vitro digestibility of raw and gelatinized potato starch

BACKGROUND

Polysaccharides have been expected to have a suppressive effect on starch digestibility by blending. The objective of this study was to investigate the effects of anionic (xanthan gum), neutral (guar gum), and cationic (chitosan) polysaccharides on the in vitro digestibility of raw and gelatinized starch using six potato cultivars differing in phosphorus content.

RESULTS

By comparing the starch digestibility between potato cultivars, a significant difference was observed for the raw starches, and 'Benimaru', which is a potato cultivar containing a higher proportion of short-chain amylopectin and the lowest phosphorus content in starch, showed a distinctly faster rate of starch hydrolysis. The added polysaccharides decreased the extent of digestion of both raw and gelatinized starches. No significant correlation between phosphorus content and the extent of starch digestion was observed in mixed systems, whereas significant correlations were noted between the extent of starch digestion and Rapid Visco Analyser parameters. The extent of raw and gelatinized starch digestion negatively correlated with pasting temperature, initial viscosity before heating, and peak viscosity (P < 0.01).

CONCLUSION

The added polysaccharides were observed to decrease the starch digestibility, and their suppressive effects were mainly dependent on the increase of viscosity rather than chemical interactions. A combination of potato cultivar and type of polysaccharide was proved to be important for nutritional value of potato starch. © 2020 Society of Chemical Industry.

Effect of Grape Pomace Addition on the Technological, Sensory, and Nutritional Properties of Durum Wheat Pasta

In this study, fortified pasta was prepared by replacing semolina with 0, 5, and 10 g/100 g of grape pomace (GP), a food industry by-product, rich in fiber and phenols. GP inclusion in pasta significantly reduced its optimum cooking time and the swelling index, while also increasing the cooking loss (p < 0.05). Furthermore, pasta firmness and adhesiveness were enhanced by the GP addition, as well as the total phenol content and the antioxidant activity, evaluated through ABTS and FRAP assays (p < 0.05). From a nutritional point of view, increasing amounts of GP resulted in a significative decrease in the rapidly digestible starch and an increase in the slowly digestible starch, while the predicted in vitro glycemic index was also reduced (p < 0.05). Sensory analysis showed that fortified spaghetti had good overall acceptability, and the results suggest that GP-fortified pasta could represent a healthy product with good technological and sensory properties.

Future foods: a manifesto for research priorities in structural design of foods

A number of major challenges facing modern society are related to the food supply. As the global population grows, it will be critical to feed everyone without damaging the environment. Advances in biotechnology, nanotechnology, structural design, and artificial intelligence are providing farmers and food manufacturers will new tools to address these problems. More and more people are migrating from rural to urban environments, leading to a change in their dietary habits, especially increasing consumption of animal-based products and highly-processed foods. Animal-based foods lead to more greenhouse gas production, land use, water use, and pollution than plant-based ones. Moreover, many animal-based and highly-processed foods have adverse effects on human health and wellbeing. Consumers are therefore being encouraged to consume more plant-based foods, such as fruits, vegetables, cereals, and legumes. Many people, however, do not have the time, money, or inclination to prepare foods from fresh produce. Consequently, there is a need for the food industry to create a new generation of processed foods that are desirable, tasty, inexpensive, and convenient, but that are also healthy and sustainable. This article highlights some of the main food-related challenges faced by modern society and how scientists are developing innovative technologies to address them.

Proximate Analysis and Nutritional Evaluation of Twenty Canadian Lentils by Principal Component and Cluster Analyses

Proximate composition and starch nutritional properties of twenty cooked lentils were assessed to identify unique varieties that could be used in value added foods. Significant variations exist among the lentil varieties (p < 0.05) with respect to their energy, fat, protein, carbohydrate, and dietary fiber content, and these are related to lentil type and seed size. Dazil and Greenstar were unique for their high resistant starch content (RS) and lower area under the starch hydrolysis curve (SHAUC) while Proclaim was opposite. SHAUC was positively correlated (p < 0.001) with rapidly digestible starch (RDS) content (r = 0.626) but negatively correlated with RS content (r = −0.635). Principal component analysis showed that the first three principal components accounted for 62.8% of the total variance and the contribution of SHAUC was 33.2%. These results confirm that in vitro SHAUC and a combination of RDS and RS may be predictive of the digestibility profile of cooked lentils.

Canola oil/candelilla wax oleogel improves texture, retards staling and reduces in vitro starch digestibility of maize tortillas

BACKGROUND

Maize tortilla staling is a major drawback that affects its commercialization and consumption, and so novel methods for retarding staling are continuously being explored. The present study evaluated the effect of adding a canola oil/candelilla wax oleogel (CWO; 0. 2, 4 and 6 g 100 g^-1 ) to a basic masa formulation (water, 60 g 100 g^-1 ; nixtamalized maize flour, 40 g 100 g^-1 ) on the texture, staling and in vitro starch digestibility of maize tortillas made using a hot plate (200 °C).

RESULTS

Textural analysis showed that CWO reduced hardness and increased the tensile strength of tortillas. Fourier transform infrared analysis indicated that the retrogradation of starch chains, quantified in terms of the intensity ratio 1047/1022, was reduced by oleogel incorporation. In vitro starch digestibility tests showed that tortillas containing CWO had lower readily digestible and slowly digestible starch fractions compared to the control tortilla without oleogel.

CONCLUSION

The formation of amylose-lipid inclusion complexes and the formation of an oily physical barrier around starch granules were postulated as mechanisms underlying the reduced starch digestibility. © 2019 Society of Chemical Industry.

Physicochemical properties of starch obtained from Curcuma karnatakensis - A new botanical source for high amylose content

Curcuma karnatakensis, a member of Zingiberaceae, is endemic to the state of Karnataka, India. The structure and physicochemical properties of starch isolated from rhizomatous rootstocks of two samples - A and B were analyzed for the first time. Sample A contains 76.4 ± 0.3% of starch, of which 86.6 ± 0.4% is amylose, while sample B has 75.0 ± 0.4% of starch containing 84.6 ± 0.4% of amylose according to UV-Vis spectrophotometric analysis. The shape of the starch granules in both the samples is polygonal and cuboidal with a smooth surface, as revealed by SEM studies. The X-ray diffractogram indicated A type of polymorphs in contrast to other Curcuma species, where B types are reported. Since its high amylose content leads to an increased tendency to retrogradation and the formation of resistant starch, this taxon could become one of the major dietary sources of starch in the future. In addition, a source rich in amylose specifies its prospective application in the pharmaceutical and biodegradable film industry.

Gastrointestinal and metabolic effects of noodles-based konjac glucomannan in rats

This study was conducted to investigate the hypothesis that the beneficial metabolic effects of dietary fiber, konjac glucomannan (KGM), related with in vivo digestion might be altered if the complicated food matrix was taken into consideration. A diet of precooked noodles (PN), as widely produced and consumed in Asia, was used to simulate an actual food context. Assays were conducted with male Wistar rats (n = 80); the rats were divided into five groups and fed with either PN (control), PN supplemented with medium-dose KGM (MK), precooked low-dose KGM-supplemented noodles (LKD), precooked medium-dose KGM-supplemented noodles (MKD) or precooked high-dose KGM supplemented noodles (HKD). The time-dependent changes in blood glucose and the sensitivity to insulin after intragastric administration were determined to evaluate the postprandial glycemic response. The activity of intestinal Na+-K+-ATPase and the levels of gut hormones including motilin, cholecystokin, GLP-1, and orexin were also determined to provide insights into the function of gastrointestinal motion and after-meal hormonal feedback in each group. The noodles-based KGM showed much more efficacy in sustaining glucose homeostasis compared with KGM supplemented in a diet of noodles, indicating there might be potential long-term health outcomes of satiety and energy balance using noodles-based KGM. The postprandial glycemia was largely moderated by LKD and MKD. Despite the significant reduction in the production of glucose, MKD caused insensitivity to insulin-blood glucose regulation and a rapid gut negative feedback following a severe blood glucose fluctuation. In conclusion, the health-promoting benefits of KGM supplements on glycemic response highly depend on the type of matrix and the dose of KGM.