Insights into Recent Updates on Factors and Technologies That Modulate the Glycemic Index of Rice and Its Products

Impact of 3 G rice on plasma glucose, insulin, and gastrointestinal hormones in patients with obesity or type 2 diabetes: A non-randomized experimental study

OBJECTIVE

To evaluate the effects of a novel grain variety 3 G rice compared to traditional white rice on postprandial glycemia, insulinemia, and gastrointestinal hormones in individuals with obesity and type 2 diabetes (T2D).

METHODS

A non-randomized experimental study was conducted with 20 participants with obesity (without diabetes) and 20 patients with T2D. Each participant consumed meals containing 50 g of carbohydrates from either 3 G rice or white rice. Plasma glucose, insulin, and gastrointestinal hormone levels were measured at baseline and intervals up to 120 min post-consumption.

RESULTS

Among participants with obesity, plasma glucose levels were significantly lower at 90 and 120 after 3 G compared to white rice (0.52 ± 0.04 vs. 2.58 ± 0.37 mmol/L, p < 0.001 at 90 min and 0.06 ± 0.02 vs. 1.47 ± 0.26 mmol/L, p = 0.003 at 120 min). In contrast, plasma insulin levels were markedly higher following 3 G rice consumption at 90-120 min (p = 0.003). Gastrointestinal hormones were significantly elevated after 3 G rice intake compared to white rice, with GLP-1 levels showing sustained increases from 60 to 120 min (p = 0.019). In T2D patients, 3 G rice consumption led to a modest reduction in plasma glucose at 120 min (5.15 ± 0.49 mmol/L for white rice vs. 3.57 ± 0.35 mmol/L for 3 G rice, p = 0.0262) without significant effect on other parameters.

CONCLUSION

3 G rice significantly improved postprandial glycemic control and enhanced gastrointestinal hormone responses in individuals with obesity. These findings highlight the promise of 3 G rice as a dietary intervention for managing postprandial glycemia and insulin sensitivity.

Structural characteristics determining starch digestibility in cooked rice complexed with an emulsion formulation

To evaluate the effects of structural characteristics on amylose-lipid complex (ALC) formation and the starch digestibility of cooked rice grains with the addition of 0, 5, 10, and 20 % emulsification formulation (EMF), both cooked rice (CR) grains with intact structural characteristics and CR slurries with their structural characteristics destroyed were examined. When EMF was added, the surface firmness, adhesiveness and adhesion of the CR grain changed. Depressions associated with ALC formation were observed on the surface of CR grains. The addition of more than 10 % EMF significantly suppressed starch hydrolysis in CR grains, while there was no significant difference in the starch digestibility of CR slurries, regardless of the amount of EMF. These results revealed that the structural characteristics of a layer like ALC on the CR grains suppressed starch digestibility and that once the structural characteristics were destroyed, the inhibitory effect of ALC on starch digestibility was lost.

Starch digestion and physiochemical properties of a newly developed rice variety with low glycemic index

This study aimed to clarify the starch digestion characteristics and related physicochemical properties of the newly developed low-GI rice variety, Ditangliangyou 335 (D335), in comparison with two widely grown rice varieties, Xiangzaoxian 45 (X45) and Zhongzao 39 (Z39). The results showed that D335 had an active digestion duration (286 min) that was 101-190 % shorter, a glucose production rate (1.06 mg g-1 min-1) that was 57-73 % slower, and a total glucose production (303 mg g-1) that was 11-19 % less than X45 and Z39. These differences were attributable to the distinct starch physicochemical properties, including amylose content, amylose-to-amylopectin ratio, starch granule size, amylopectin chain length, and starch molar mass, as well as the different pasting properties of rice flour, such as pasting temperature and breakdown viscosity. These findings reveal the starch digestion characteristics and the key physicochemical properties that determine these characteristics in the low-GI rice variety D335.

The Influence of Rice Types and Boiling Time on Glycemic Index: An In Vivo Evaluation Using the ISO 2010 Method

Effective blood glucose management is essential for individuals with type 1 diabetes, particularly when dietary adjustments involve staple foods like rice. As a primary carbohydrate worldwide, rice significantly influences the glycemic index (GI) based on its type and cooking method. This study investigated the impact of rice type and boiling duration on the GI in healthy adults using an in vivo approach aligned with ISO 2010 standards. The glycemic response to four rice types (white round-grain, parboiled medium-grain, white long-grain, and whole-grain long-grain) was measured through postprandial blood glucose levels under both standard and extended boiling conditions to assess their implications for dietary glycemic control. Ten healthy participants (mean age 25 years, body mass index (BMI) 23.0 ± 1.6 kg/m2) consumed rice samples containing 50 g of available carbohydrates, prepared under controlled boiling conditions. Postprandial glycemic response was measured at regular intervals over 2 h following ingestion, with glucose solution as a reference food. The GI was calculated based on the incremental area under the glycemic response curve for each rice sample. Extended boiling significantly increased the GI across all rice types. White round-grain rice exhibited the highest relative increase (+15.8%) in the GI, while whole-grain long-grain rice, despite showing a greater percentage increase (+25.4%), maintained the lowest overall GI due to its high amylose and fiber content. Rice types with higher amylopectin content demonstrated faster glycemic responses and higher GI compared to high-amylose types. This study highlights rice type and cooking time as critical factors influencing postprandial glycemic response. Shorter boiling durations may benefit individuals requiring strict glycemic control, particularly those with diabetes, underscoring the importance of personalized dietary guidance for managing glycemic outcomes effectively.

Action plan strategies for a new approach to the combination of yeast and ultrasonic waves for the reduction of heavy metal residues in rice

This study was conducted to combine two physical (ultrasonic) and biological (Saccharomyces cerevisiae) methods to reduce heavy metals such as Arsenic (As), Cadmium (Cd), and Lead (Pb) in rice, which is the most widely consumed grain. The concentrations of As, Cd, and Pb were found to be significantly affected after different treatments, were on uncooked rice samples (R1-R9): As R9 (2.05 ± 0.01) Cd R1, R3, R5, R8 (1.20 ± 0.01), Pb R6 (3.04 ± 0.173) (µgkg- 1) and in cooked rice samples were (C1-C10): As C10 (0.35 ± 0.27) Cd C9, C10 (1.00 ± 0.02), Pb C1 (3.52 ± 0.17) (µgkg- 1). The results showed that using ultrasound treatment combined with yeast (C10) had the greatest effect on reducing As among all treatments. In addition, C9, and C10 treatments were effective in reducing Cd concentration in cooked rice samples, and R6 treatment was effective in reducing Pb concentration in uncooked samples. The rice's thermal qualities and specific textural traits were also affected by some or all of these treatments. The samples with modified particle sizes had the greatest sensory evaluation scores (C9). Moreover, sensory evaluation results showed that a specific treatment combining yeast and ultrasound (C3) maintained good sensory qualities and did not negatively affect the sensory qualities without sacrificing texture. Overall, this approach provides a promising method for the reduction of heavy metals in rice. A combination of biological and physical treatments can be used to reduce the heavy metals content (As, Cd, Pb) in rice. Stakeholders can use the aforementioned actions to optimize heavy metal content in the food chain, which requires the support of policymakers to promote public health.

Development of Whole-Grain Rice Lines Exhibiting Low and Intermediate Glycemic Index with Decreased Amylose Content

The demand for rice varieties with lower amylose content (AC) is increasing in Southeast Asia, primarily due to their desirable texture and cooking qualities. This study presents the development of whole-grain rice lines with low to intermediate glycemic index (GI) and reduced AC. We selected six rice lines for in vivo GI assessment based on their starch properties. We successfully identified two lines with low AC that exhibited low and intermediate GI values, respectively. Our findings indicate that dietary fiber (DF) content may significantly influence rice GI. The selected whole-grain low-GI line showed a higher ratio of soluble dietary fiber (SDF) to insoluble dietary fiber (IDF) compared to control varieties, highlighting SDF's potential positive role in lowering whole-grain rice's GI. This study underscores the feasibility of developing rice varieties with desirable agronomic traits, nutritional traits, and culinary attributes, particularly for individuals managing their blood sugar levels. Additionally, we proposed the positive role of starch composition, especially DF content, in modulating the GI of rice. This study reinforces the importance of incorporating starch properties and DF content into rice breeding programs to produce more health-oriented and marketable rice varieties.

Endosperm structure and Glycemic Index of Japonica Italian rice varieties

Introduction

Given that rice serves as a crucial staple food for a significant portion of the global population and with the increasing number of individuals being diagnosed with diabetes, a primary objective in genetic improvement is to identify and cultivate low Glycemic Index (GI) varieties. This must be done while ensuring the preservation of grain quality.

Methods

25 Italian rice genotypes were characterized calculating their GI "in vivo" and, together with other 29 Italian and non-Italian genotypes they were studied to evaluate the grain inner structure through Field Emission Scanning Electron Microscopy (FESEM) technique. Using an ad-hoc developed algorithm, morphological features were extracted from the FESEM images, to be then inspected by means of multivariate data analysis methods.

Results and Discussion

Large variability was observed in GI values (49 to 92 with respect to glucose), as well as in endosperm morphological features. According to the percentage of porosity is possible to distinguish approximately among rice varieties having a crystalline grain (< 1.7%), those intended for the preparation of risotto (> 5%), and a third group having intermediate characteristics. Waxy rice varieties were not united by a certain porosity level, but they shared a low starch granules eccentricity. With reference to morphological features, rice varieties with low GI (<55) seem to be characterized by large starch granules and low porosity values. Our data testify the wide variability of Italian rice cultivation giving interesting information for future breeding programs, finding that the structure of the endosperm can be regarded as a specific characteristic of each variety.

Ultrasound-Assisted Extraction of Antioxidant Compounds from "Cẩm" Purple Rice Bran for Modulation of Starch Digestion

Purple rice, locally known as "Cẩm" rice, is cultivated in the southern region of Vietnam. The bran of "Cẩm" rice is often disregarded and underutilized; nevertheless, it harbours substantial nutritive value, particularly in terms of antioxidant compounds. Additionally, sonication, an emerging and "green" technological approach, has been employed to augment the extraction efficiency of these antioxidants. This research is aimed at optimizing and maximizing the antioxidant recovery capacity including phenolic and total flavonoid compounds, along with their antioxidant activities, through the assistance of ultrasound waves. The effect of the extract on the starch digestion process was also investigated. The study employed the Box-Behnken experimental design, encompassing three variables: extraction time (20-40 minutes), temperature (60-80°C), and solvent-to-material ratio (8 : 1 to 12 : 1). Analysis was conducted on total phenolic compounds, total flavonoid content, and antioxidant activities. Results demonstrated that the peak yield of antioxidant compounds and their corresponding activities were attained at an extraction duration of 29.38 minutes, a temperature of 69°C, and a solvent-to-material ratio of 9.92. Under these optimal conditions, the yields were as follows: total phenolic compounds at 60.821 mg GAE/g, total flavonoid compounds at 3.2696 mg QE/g, percentage inhibition of DPPH at 74.778%, and FRAP value at 54.112 μmol Fe (II)/g. The established models were validated and exhibited a strong alignment between predicted and actual values, with disparities of less than 3% under optimal conditions. Furthermore, the extract was codigested with cooked corn starch, revealing a dose-dependent effect on starch digestibility. The sluggishness of digestion rate was observed when 20 mg of the extract was supplemented to 200 mg of cooked corn starch. This suggests that rice bran extract holds promise as an effective ingredient for mitigating starch digestion, particularly beneficial for individuals dealing with diabetes.