Addition of Pulses, Cooking Oils, and Vegetables Enhances Resistant Starch and Lowers the Glycemic Index of Rice ( Oryza sativa L.)

Preparation of Resistant Starch Types III + V with Moderate Amylopullulanase and Its Effects on Bread Properties

The potential of PulY103A (a moderate amylopullulanase originating from Bacillus megaterium) for resistant starch production under moderate conditions (40 °C; a pH of 6.5) was investigated. PulY103A was much more suitable for pea resistant starch production with a high growth rate of 3.63. The pea resistant starch (PSpa) produced with PulY103A had lower levels of swelling power and solubility and a better level of thermostability than native pea starch (PSn) and autoclaved PS (PSa). The starch crystallinity pattern was B + V, which indicated that the PSpa belonged to RS types III + V. In addition, PSpa was used for breadmaking. The results showed that the bread quality was not significantly influenced compared to the control group when the content of PSpa was under 10% (p > 0.05). The bread supplemented with 10% PSpa had a significantly increased TDF content compared to that of the control (p < 0.05). Moreover, the in vitro mineral bioavailability of the bread sample was influenced gently compared to other dietary fibers, and the bread sample changed from a high-glycemic-index (GI) food to a medium-GI food corresponding to white bread at the same concentration of PSpa. These results indicated that PSpa is a good candidate for the production of dietary foods.

Genome-Wide Association Study of Starch Properties in Local Thai Rice

Rice (Oryza sativa L.) is the main source of energy for humans and a staple food of high cultural significance for much of the world's population. Rice with highly resistant starch (RS) is beneficial for health and can reduce the risk of disease, especially type II diabetes. The identification of loci affecting starch properties will facilitate breeding of high-quality and health-supportive rice. A genome-wide association study (GWAS) of 230 rice cultivars was used to identify candidate loci affecting starch properties. The apparent amylose content (AAC) among rice cultivars ranged from 7.04 to 33.06%, and the AAC was positively correlated with RS (R2 = 0.94) and negatively correlated with rapidly available glucose (RAG) (R2 = -0.73). Three loci responsible for starch properties were detected on chromosomes 1, 6, and 11. On chromosome 6, the most significant SNP corresponded to LOC_Os06g04200 which encodes granule-bound starch synthase I (GBSSI) or starch synthase. Two novel loci associated with starch traits were LOC_Os01g65810 and LOC_Os11g01580, which encode an unknown protein and a sodium/calcium exchanger, respectively. The markers associated with GBSSI and LOC_Os11g01580 were tested in two independent sets of rice populations to confirm their effect on starch properties. The identification of genes associated with starch traits will further the understanding of the molecular mechanisms affecting starch in rice and may be useful in the selection of rice varieties with improved starch.

Naturally cultured high resistant starch rice improved postprandial glucose levels in patients with type 2 diabetes: A randomized, double-blinded, controlled trial

Objective

To assess the effect of a novel naturally cultured rice with high resistant starch (RS) on postprandial glycemia in patients with type 2 diabetes compared to ordinary rice.

Design

This study is a randomized, double-blinded controlled trial.

Methods

Patients with type 2 diabetes were recruited, and postprandial glucose levels were measured at 5-time points after the ingestion of one of two types of cooked rice in random order. Paired t-tests were used to compare postprandial blood glucose changes and increment areas under the blood glucose curve between high-RS rice and ordinary rice.

Results

The increments of the postprandial blood glucose levels for high-RS rice were significantly lower than that for ordinary rice, i.e., 2.80 ± 1.38 mmol/L vs. 3.04 ± 1.50 mmol/L (P = 0.043) and 3.94 ± 2.25 mmol/L vs. 4.25 ± 2.29 mmol/L (P = 0.036) at 30 min and 60 min, respectively. The incremental areas under the blood glucose curve for high-RS rice were also significantly lower than that for ordinary rice, i.e., 42.04 ± 20.65 [mmol/(L·min)] vs. 45.53 ± 22.45 [mmol/(L·min)] (P = 0.043), 143.54 ±69.63 [mmol/(L·min)] vs. 155.15 ± 73.53 [mmol/(L·min)] (P = 0.026), and 354.61 ± 191.96 [mmol/(L·min)] vs. 379.78 ± 195.30 [mmol/(L·min)] (P = 0.042) at 30, 60, and 120 min, respectively. Repeated-measures ANOVA showed that postprandial glucose levels were not affected by the test order.

Conclusion

The novel high-RS rice as a staple food when substituting for widely consumed ordinary rice may provide potential health benefits by lowering blood glucose in patients with type 2 diabetes.

Development of low glycemic index instant Phirni (pudding) mix-its visco-thermal, morphological and rheological characterization

High amylose rice (HAR) and carboxymethyl cellulose (CMC) are the preferred choices for enhancement of resistant starch content and lowering of glycemic index in dairy desserts. The effects of different levels of skimmed milk powder (SMP): HAR flour (45:55 to 75:25) and CMC (0.1 to 1%) were investigated on physical characteristics of dry-mix and on texture profile parameters, resistant starch (RS), predicted glycemic index (pGI), glycemic load (GL) and overall acceptability of phirni (a traditional milk pudding). Design expert predicted SMP (70): HAR (30) and CMC (0.8%) as optimum levels for reducing the pGI and maximizing the RS content and other quality characteristics in phirni. RS content of phirni (4.38%) prepared from optimized dry-mix (ODM) was higher while pGI (48.12) and GL (7.50) were lower as compared to phirni prepared from market dry-mix (MDM). The visco-thermal properties of ODM and MDM also showed significant variations. Storage modulus (Gʹ) and loss modulus (Gʹʹ) indicated that ODM phirni was less solid than MDM phirni. Scanning electron micrographs showed fused structures in ODM, while coarse sheet like structures were observed across the surface of MDM. Thus, ODM can be a promising substitute for the available milk desserts for diabetic patients.

Ultrasound-chilling assisted annealing treatment to produce a lower glycemic index of white rice grains with different amylose content

White rice samples, Chai-Nat1 (CN1) and Jasmin rice (KDML105), were treated with the ultrasound-chilling (UC) and combined with annealing treatments (UC + ANN 45, UC + ANN50, and UC + ANN55). Their physicochemical properties and in vitro glycemic index of rice samples were analyzed. UC + ANN treatments presented pasting temperature, gelatinization temperature and crystallinity increased whereas the glycemic index of both rice samples was decreased as compared to its native. Especially, UC + ANN55 treated rice produced the lowest glycemic index and starch hydrolysis. Moreover, UC + ANN treated CN1 rice exhibited delayed gelatinization temperature, increased gelatinization enthalpy, and decreased glycemic index than KDML105 rice. In addition, Pearson's correlation presented that UC + ANN and amylose content had a highly negative correlation with the glycemic index at p < 0.0.1. The result exhibited that UC followed by ANN show an effective way to modify starch granules with delayed starch hydrolysis reduced glycemic index and properties depending on annealing temperature and rice cultivar.

Starch-lipid interaction alters the molecular structure and ultimate starch bioavailability: A comprehensive review

Starch bioavailability which results in eliciting postprandial glycaemic response, is a trait of great significance and is majorly influenced by the physical interaction among the matrix components governed by their molecular structure as well as dynamics. Among physical interactions limiting starch bioavailability, starch and any guest molecules like lipid interact together to alter the molecular structure into a compact V-type arrangement endorsing the processed crystallinity, thus limiting carbolytic enzymatic digestion and further bioavailability. Considering the importance of starch-lipid dynamics affecting bioavailability, intensive research based on endogenous (internal lipids which are embedded into the food matrix) as well as exogenous (those are added from outside into the food matrix during processing like cooking) lipids have been carried out, endorsing physical interactions at colloidal and microstructural levels. The shared insights on such binary (starch-lipid) interactions revealed the evolution of characterization techniques as well as their role on altering the functional and nutritional value. It is very much vital to have a thorough understanding about the mechanisms on the molecular level to make use of these matrix interactions in the most efficient way, while certain basic questions are still remaining unaddressed. Do starch - lipid complexation affects the ultimate starch bioavailability? If so, then whether such complexation ability depends on amylose - fatty acid/lipid content? Whether the complexation is influenced further by fatty acid type/concentration/chain length or saturation? Further comprehending this, whether the altered bioavailability by binary (starch-lipid) could further be affected by ternary (starch-lipid-protein) and quaternary (starch-lipid-protein-phenolics) interactions are also discussed in this comprehensive review.

Glycemic Index of Gluten-Free Bread and Their Main Ingredients: A Systematic Review and Meta-Analysis

This study aimed to perform a systematic review and meta-analysis of the glycemic index (GI) of gluten-free bread (GFB) and its main ingredients. The systematic review followed PRISMA guidelines, using seven electronic databases (PubMed, EMBASE, Scopus, Science Direct, Web of Science, gray literature research with Google Scholar, and patents with Google Patent tool), from inception to November 2020. Eighteen studies met the inclusion criteria evaluating 132 GFB samples. Five articles tested GI in vivo, eleven in vitro; and two studies tested both methods. The analysis showed that 60.7% (95% CI: 40.2-78.1%) of the samples presented high glycemic indexes, evidencing a high glycemic profile for GFB. Only 18.2% (95% CI: 11.7-27.2%) of the bread samples presented in the studies were classified as a low GI. Meta-analysis presented moderate/low heterogenicity between studies (I2 = 61% and <1% for both high and low GIs) and reinforced the proportion of high GIs. Lower GIs were found in formulations based on Colocasia esculenta flour or enriched with fiber, yogurt and curd cheese, sourdough, psyllium, hydrocolloids, enzymes, fructans, and resistant starch, highlighting the efficacy of these ingredients to lower GFBs' GI. GFB tends to present high GI, impacting the development of chronic diseases when consumed.

Impact of processing techniques on the glycemic index of rice

Rice is an important starchy staple food and generally, rice varieties are known to have a higher glycemic index (GI). Over the years, the significance of GI on human health is being better understood and is known to be associated with several lifestyle disorders. Apart from the intrinsic characteristics of rice, different food processing techniques are known to have implications on the GI of rice. This work details the effect of domestic and industrial-level processing techniques on the GI of rice by providing an understanding of the resulting physicochemical changes. An attempt has been made to relate the process-dependent digestion behavior, which in turn reflects on the GI. The role of food constituents is elaborated and the various in vitro and in vivo approaches that have been used to determine the GI of foods are summarized. Considering the broader perspective, the effect of cooking methods and additives is explained. Given the significance of the cereal grain, this work concludes with the challenges and key thrust areas for future research.