Particle size affects structural and in vitro digestion properties of cooked rice flours

Prolonging heat-moisture treatment time at medium moisture content optimizes the quality attributes of cooked brown rice through starch structural alteration

Brown rice (BR), one of the popular whole grains worldwide, is still limited to consumption due to its rough texture after cooking. Through inspecting structural alteration, this work discloses how heat-moisture treatment (HMT) moisture content (15 %-25 %) and time (1.0 h-3.0 h) modify the starch digestibility and cooked BR texture. The medium moisture content (20 %) allowed the highest pasting viscosity and a uniform network structure of cooked BR. Prolonging the HMT time from 1.0 h to 2.0 h at medium moisture content hindered starch swelling and improved stability. Meanwhile, the relative crystallinity, the surface compactness in nanoscale and R995/1022 decreased, while the gel network structure was improved, contributing to the softened cooked BR texture and the enhanced starch digestibility. Although the resistant starch content raised to 13.55 % after 3.0 h of HMT, the springiness, gumminess and chewiness of cooked BR degraded, and this should be considered in certain conditions.

Short-range molecular order is the driving factor for starch digestibility and texture of alginate-encapsulated rice beads

BACKGROUND

Rice grain analogues with slow starch digestibility are commonly associated with an unsatisfactory texture, often leading to consumer dissatisfaction. Alginate encapsulation has been applied to reduce the digestibility of corn and potato starch. The fine molecular structures of rice starch can greatly determine its digestibility and texture. However, it remains unclear whether a combination of alginate encapsulation and varied starch molecular structures can be employed to create rice grain analogues that offer both slow starch digestibility and an appealing texture.

RESULTS

For the first time, the present study constructed alginate-encapsulated rice beads (as a rice grain analogue). A wide range of starch digestion rates were found among alginate-encapsulated rice beads prepared with different rice varieties, and only certain rice varieties (e.g. Subei and Nanjing) were able to result in rice beads with slower starch digestibility than their parental rice kernels. More importantly, all rice beads showed a relatively softer texture compared to their parental rice kernels. Correlation analysis showed that starch digestion rate, hardness and stickiness were all positively correlated with the ratio of short-range amorphous regions in rice bead samples, as obtained from Fourier transform-infrared spectroscopy, but not with the relative crystallinity.

CONCLUSION

Collectively, these results suggest that rice beads with slower starch digestion rate and softer texture could be obtained by choosing rice varieties that develop more short-range ordered structure after cooking. © 2024 Society of Chemical Industry.

Increasing particle size of oat flours decreases postprandial glycemia and increases appetite in healthy adults

Consumption of oats is associated with lowered risks of type 2 diabetes and obesity. However, many oat-based products (e.g., breakfast cereals) use finely milled flours but are associated with health claims based on oats of larger particle sizes. The objective of this study was to test the hypothesis that increasing oat flour particle size will result in lower postprandial glycemia and appetite. Using a randomized-controlled, crossover design, 20 participants (10 males, 10 females; age: 25.3 ± 1.0 years; body mass index: 23.2 ± 0.6 kg/m2) consumed a serving of porridge made using 40 g of coarse (675.7 ± 19.6 µm), whole (443.3 ± 36.2 µm), fine (96.0 ± 2.1 µm), or a commercial (375.9 ± 14.8 µm) oat flour unmatched in available carbohydrate, protein, and dietary fiber content. After a 12-hour overnight fast, blood glucose, insulin, and appetite were measured at 15 to 30-minute intervals over 120 minutes posttreatment consumption. Coarse and whole flours led to lower blood glucose between 30 and 60 minutes (P < .02). Blood glucose area under the curve (AUC) was lower after coarse than fine and commercial oat flours (P < 0.03), and after whole than fine oat flour (P < .002). Both coarse and whole oat flours resulted in lower insulin AUC than finer flours (P < .05). Appetite AUC was lower after the commercial than coarse flour (P < .007). Controlling milling to produce coarser oat flour to add to common foods may have health benefits. This study was registered at ClinicalTrials.gov (NCT05291351).

Effect of ultrafine grinding on the structure and physical properties of pregelatinized rice starch

This study used a combination method of ultrafine grinding and pregelatinization to modify rice starch (RS) to delay its retrogradation and provide a rationale for prolonging rice product shelf life. The structure and physicochemical properties of the pregelatinized ultrafine grinding rice starch (PURS) were compared with those of RS, ultrafine grinding rice starch (URS), and pregelatinized rice starch (PRS). The microstructure, molecular weight, branched starch length distribution, short-range order, crystal structure, and physical properties of RS, URS, PRS, and PURS were analyzed, respectively. Results showed that RS, URS, PRS, and PURS granules exhibited similar spherical or polygonal shapes, and the content of amylose and short-branched starch in PURS increased compared with RS, URS, and PRS. Furthermore, the cross-polarization of PRS and PURS disappeared. Long-chain amylopectin and average molecular weight of PURS decreased significantly after ultrafine grinding. Our study suggested reduced breakdown value and setback value and improved gel stability, and PURS was beneficial for delaying retrogradation compared to RS, URS, and PRS. The ultrafine grinding method improved the water swelling capacity (WSC), solubility, pasting properties, and gelation properties of PRS. The hardness of PURS was reduced by ultrafine grinding. These suggest that the combination of ultrafine grinding and pregelatinization could improve the properties of RS. Pearson's correlation analysis showed that the structure of PURS significantly influenced the physicochemical properties. The present study was helpful in better understanding the importance of ultrafine grinding in improving the anti-retrogradation of PURS and provided new insights into extending the shelf life of rice products by ultrafine grinding and pregelatinization.

Gluten-free lentil cakes with optimal technological and nutritional characteristics

BACKGROUND

The celiac population usually struggle finding nutritive gluten-free (GF) baked goods. GF foods can be improved using legume flours. Eleven GF cake formulations were elaborated according to different percentages of lentil flour (LF), corn flour (CF) and rice flour (RF) using a simplex lattice design. Water holding capacity and particle size of flours were evaluated. Moisture, aw, pH, specific volume, texture profile, relaxation, color and alveolar characteristics were determined for crumbs of all formulations. An optimization process was used to enhance the technological and nutritional attributes, selecting the three best formulations containing LF: 46% LF + 54% RF (CLF+RF); 49% LF + 51% CF (CLF+CF); and 100% LF (CLF), evaluated in their proximal composition and sensory characteristics. Linear and quadratic models for predicting the behavior of GF lentil cakes were obtained.

RESULTS

LF and CF could favor water incorporation and show more resistance to enzymatic digestion than RF. Formulations with LF showed an improvement in specific volume and alveolar parameters, while use of RF led to better cohesiveness, elasticity and resilience but with a deterioration in chewiness and firmness. CLF can be labeled as high in protein and fiber and presented the lowest amounts of lipids, carbohydrates and energy content. Consumer preference leaned towards CLF+RF.

CONCLUSION

It was possible to elaborate GF cakes using LF, obtaining nutritive products that can be offered to people intolerant to gluten ingestion. © 2024 Society of Chemical Industry.

Particle size and water content impact breakdown and starch digestibility of chickpea snacks during in vitro gastrointestinal digestion

Chickpeas are an agriculturally-important legume that are an excellent source of protein, fiber, and minerals. Developing chickpea-based snacks could provide consumers with snack products rich in protein and other nutrients. In this study, chickpea puree (high moisture content) and cracker (low moisture content) were each produced with large (7 mm sieve; coarse) or small (2 mm sieve; fine) particle size to investigate the impact of initial particle size and moisture content on particle breakdown, starch hydrolysis, and protein hydrolysis during in vitro digestion. All treatments underwent static in vitro oral digestion, dynamic gastric digestion in the Human Gastric Simulator (HGS), and static in vitro small intestinal digestion. The emptying rate from the HGS was significantly (p < 0.05) higher for fine puree compared to the other treatments, due to higher saturation ratio and smaller initial particle size. The reducing sugars and free amino groups released (representing starch and protein hydrolysis, respectively) from fine puree were higher than coarse puree, and fine cracker was higher than coarse cracker due to the influence of initial particle size. For example, after 360 min total in vitro digestion, the starch hydrolysis of the fine cracker (48.1 ± 3.2%) was significantly higher than (p < 0.05) the coarse cracker (36.3 ± 5.8%). Overall, crackers had higher protein and starch hydrolysis compared to puree in the liquid phase during digestion. The study showed that both the smaller initial particle size and drying significantly (p < 0.05) increased the particle size reduction during gastric digestion and starch and protein digestibility in chickpea-based snacks.

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

Rice is a staple food and energy source for half the world's population. Due to its quick digestion and absorption in the gastrointestinal tract, rice is typically regarded as having a high or medium-high glycemic index (GI); however, this can vary depending on the variety, nutrient compositions, processing, and accompanying factors. This report included a table of the glycemic index for rice and rice products in different countries, which could give an overview and fundamental information on the recent GI of different rice varieties. In addition, latest updates about the mechanism effects of rice nutritional profiles and processing techniques on GI were also provided and discussed. The influence of state-of-the-art GI regulation methods was also evaluated. Furthermore, the effectiveness and efficiency of applied technologies were also given. Furthermore, this review offered some aspects about the potential nutraceutical application of rice that food scientists, producers, or consumers might consider. Diverse types of rice are grown under various conditions that could affect the GI of the product. The instinct nutrients in rice could show different effects on the digestion rate of its product. It also revealed that the rice product's digestibility is process-dependent. The postprandial glucose response of the rice products could be changed by modifying processing techniques, which might produce the new less-digestive compound or the inhibition factor in the starch hydrolysis process. Because of the significant importance of rice, this paper also concluded the challenges, as well as some important aspects for future research.

The Effect of Different Milling Methods on the Physicochemical and In Vitro Digestibility of Rice Flour

Preparation methods have been found to affect the physical and chemical properties of rice. This study prepared Guichao rice flour with wet, dry, semi-dry, and jet milling techniques. Differences in the particle size distribution of rice flour were investigated in order to assess their impact on pasting, thermal, gel, starch digestibility, and crystalline structure using an X-ray diffractometer (XRD) and a Rapid Visco Analyzer (RVA) across in vitro digestibility experiments. The results showed that semi-dry-milled rice flour (SRF) and wet-milled rice flour (WRF) were similar in damaged starch content, crystalline structure, and gelatinization temperature. However, compared with dry-milled rice flour (DRF) and jet-milled rice flour (JRF), SRF had less damaged starch, a higher absorption enthalpy value, and a higher gelatinization temperature. For starch digestibility, the extended glycemic index (eGI) values of WRF (85.30) and SRF (89.97) were significantly lower than those of DRF (94.47) and JRF (99.27). In general, the physicochemical properties and starch digestibility of WRF and SRF were better than those of DRF and JRF. SRF retained the advantages of WRF while avoiding the high energy consumption, high water consumption, and microbial contamination disadvantages of WRF and was able to produce better rice flour-associated products.

The contribution of cell wall integrity to gastric emptying and in vitro starch digestibility and fermentation performance of highland barley foods

Studies have shown that the structure, composition, and bioavailability of compounds in whole grains are affected by processing and the role of cells walls. In this study, the effects of different processing methods on highland barley, one of the mostly widely produced whole grains worldwide, were investigated. The processing methods applied were flaking-boiling (HB flake), sand-roasting (Puffed HB), and sand-roasting-milling (Tsamba). Results showed Puffed HB and Tsamba had higher levels of damaged starch content, starch short-range molecular order, and relative crystallinity than HB flake. The half-time of gastric emptying (t_1/2) was the slowest for Tsamba (132.3 min) compared to HB flake (122.5 min) and Puffed HB (84.0 min), indicating the slowest gastric emptying rate, which could be attributed to its high viscosity of gastric digesta. After in vitro gastroduodenal digestion, Puffed HB exhibited the lowest starch digestibility and the least amount of β-glucan due to its less damaged cellular structure. Furthermore, Puffed HB resulted in a 21% and 18% higher in vitro production of total short-chain fatty acids than Tsamba and HB flake, respectively. Besides, undigested starch of Puffed HB after in vitro gastroduodenal digestion delayed in vitro fecal fermentation of β-glucan. Our study provided insight into the potential mechanisms of how cell wall integrity affected the gastric emptying, in vitro starch digestibility, and in vitro fecal fermentation of highland barley foods.

Revealing the reasons for the pasting property changes of rice during aging from the perspective of starch granule disaggregation

BACKGROUND

The pasting properties of rice change markedly after aging, although the mechanism for this still remains unknown. Aged and fresh rice grains were ground and the flours were fractionated by particle size, and then the pasting properties, particle size distribution and microscopic morphology of the heated flour fractions were evaluated.

RESULTS

Compared to the corresponding fresh flour fractions with the same particle size, a lower peak viscosity for those aged flour fractions from 80 μm to 450 μm and a higher peak viscosity for those aged flour fractions from 20 μm to 60 μm were observed. The amounts of smaller particles disaggregated from the aged flour fractions were significantly less and the separated entities were always larger than the corresponding fresh rice fractions.

CONCLUSION

Disaggregation difficulty of starch granules was the reason for the changes in the pasting properties of rice after aging. This finding is helpful for understanding rice aging mechanisms and regulating eating quality of rice flour as an ingredient. © 2022 Society of Chemical Industry.

Effect of adding vegetable oils to starches from different botanical origins on physicochemical and digestive properties and amylose-lipid complex formation

Coconut oil, rice bran oil and sunflower oil were added to rice, corn, banana and mung bean starches and the effect on physicochemical properties, amylose-lipid formation and digestive properties were investigated. Starch samples were heated while oil was added and starch treated without oil addition served as the control. Starches with different botanical origins complexed diversely with vegetable oils. The RDS content in corn and rice starches with oil addition decreased, while SDS and RS fractions increased. By contrast, the RS content of treated banana and mung bean starches decreased compared with native starch but RS and SDS contents increased when oil was added compared with the control sample. The A-type crystalline polymorph of corn and rice starches changed to a mixed A + V form, whereas native mung bean (C(A)-type) changed to B-pattern and banana starch remained unchanged (B-type). FTIR spectra indicated new peaks corresponding to starch-lipid complexes. Starches added with oils and the control showed lower peak viscosity, trough viscosity final viscosity and setback but higher pasting temperature and delayed pasting time compared to native starch. Heat-moisture treatment with added vegetable oil showed promise as a process to prepare functional starch high in SDS and RS.

Different nitrogen fertilizer application in the field affects the morphology and structure of protein and starch in rice during cooking

Nitrogen fertilization is one of the most important cultivation practices that affects the eating quality of rice. During the cooking process, nitrogen fertilizer application in the field changed the structure of protein and starch during cooking, which eventually reduced the rice eating quality. However, the morphology and structure of rice during cooking under high nitrogen fertilizer application in the field have not been explored. The relationship between the morphological and structural changes of rice protein and starch during cooking and the rice eating quality has not been studied. In this study, we conducted field trials at two nitrogen fertilizer levels (0 N and 350 N), and the rice was cooked after harvest. Our results showed that the peak viscosity of rice flour was 3326 cp and 2453 cp at 0 N and 350 N, respectively, and the peak viscosity of rice starch was 3424 cp and 3378 cp, respectively. Rice proteins played an important role in the starch gelatinization properties and thermodynamic properties. High nitrogen fertilizer application increased the protein content of rice from 5.97 % to 11.32 %, and more protein bodies adhered to the surface of amyloplasts eventually inhibiting starch gelatinization. The rice proteins could bind to amylose-lipid complexes during cooking, promoting the formation of V-type diffraction peaks. What is more, under high nitrogen fertilizer, rice protein had more β-sheets, which slowed the entry of water into the interior of starch molecules and prevented the destruction of the short-range ordered structure of starch. Our study provides the possibility to further improve the eating quality of rice under nitrogen fertilizer treatment.

Jerusalem artichoke (Helianthus tuberoses) dietary-fiber powder functionality

The artichoke tuber is full of nutrients, inulin, and phytochemicals. It has been used to treat illnesses including diabetes and colon cancer, as well as in food product formulation, but limited information on the Jerusalem artichoke tuber (JAT) powder characterization exists in the literature, hence in this paper, JAT was freeze and oven-dried. It was powdered into JAT-freeze-dried-(FD)-powder and oven-dried (OD)-powder. This enabled the JAT powder's functional and physical properties to be studied. As a result, JAT powder's morphology, microstructure, and functional groups, as well as the powder foaming, swelling, solubility, antioxidant, color pasting, bulk, packed, and particle distribution properties were studied. Results indicated that the average particle distribution size at Dx90 and Dx80 displayed a distinct difference at p ≤ 0.05, while the bulk (0.39 g/cm-3) and packed (0.48 g/cm-3) densities recorded a lower value for FD powder. The FD powder's foaming capacity (24.0%) was significantly distinct (p ≤ 0.05) from the OD powder. Also, the solubility of FD powder was 6.2 g/g at 50 °C, and that of OD powder was recorded as 2.3 g/g. Again, the FD powder had a higher ABTS+ (34.3 mM (TE)/g dw) and CUPRAC (94.61 mM (TE)/g dw) capacity. Besides, a significant (p ≤ 0.05) dissimilarity among the powder color parameters (L∗, a∗, b∗, C∗, and whiteness) was observed. More so, the XRD and FT-IR characterization established a semi-crystalline or amorphous nature of the powder containing polysaccharides, and a broad halo pattern 2 θ at an angle 19.3° and 20 ° for FD powder and OD powder respectively. The FD powder particles were more agglomerated than those of OD powder. This was seen as a microscopic image, again FD powder revealed a higher pasting temperature and a drop in peak viscosity. Based on the results obtained, JAT (FD and OD) powder has all the quality attributes required of a powder for culinary product formulation.

Whole grain rice: Updated understanding of starch digestibility and the regulation of glucose and lipid metabolism

Nowadays, resulting from disordered glucose and lipid metabolism, metabolic diseases (e.g., hyperglycemia, type 2 diabetes, and obesity) are among the most serious health issues facing humans worldwide. Increasing evidence has confirmed that dietary intervention (with healthy foods) is effective at regulating the metabolic syndrome. Whole grain rice (WGR) rich in dietary fiber and many bioactive compounds (e.g., γ-amino butyric acid, γ-oryzanol, and polyphenols) can not only inhibit starch digestion and prevent rapid increase in the blood glucose level, but also reduce oxidative stress and damage to the liver, thereby regulating glucose and lipid metabolism. The rate of starch digestion is directly related to the blood glucose level in the organism after WGR intake. Therefore, the effects of different factors (e.g., additives, cooking, germination, and physical treatments) on WGR starch digestibility are examined in this review. In addition, the mechanisms from human and animal experiments regarding the correlation between the intake of WGR or its products and the lowered blood glucose and lipid levels and the reduced incidence of diabetes and obesity are discussed. Moreover, information on developing WGR products with the health benefits is provided.

Color, Starch Digestibility, and In Vitro Fermentation of Roasted Highland Barley Flour with Different Fractions

Highland barley (HB) is commonly milled into flour for direct consumption or further processed with other food formulations. Nevertheless, the association between milling and HB flour properties remains lacking. This work studied the effect of particle sizes (coarse, 250–500 μm; medium, 150–250 μm; fine, <150 μm) on physicochemical and nutritional properties of raw and sand-roasted HB flour. Gelatinization enthalpy decreased with increasing particle sizes of raw HB flour, while no endothermic transitions were observed in sand-roasted flour. Sand roasting destroyed starch granules and decreased short-range molecular order. Starch digestibility increased while total short-chain fatty acids (SCFAs) production decreased with decreasing particle sizes in all samples. The relative crystallinity of sand-roasted HB flour decreased by 80–88% compared with raw samples. Sand roasting raised in vitro starch digestibility, while total SCFAs during in vitro fecal fermentation decreased. Sand-roasted HB flour with particle sizes <150 μm had the highest starch digestibility (94.0%) but the lowest production of total SCFAs (1.89–2.24 mM). Pearson’s correlation analysis confirmed the relationship between the nutritional qualities of HB flour and milling.

Functional Properties and Structural Characteristics of Starch-Fatty Acid Complexes Prepared at High Temperature

The effects of fatty acid type (myristic, palmitic, stearic, oleic, linoleic, and linolenic acid) on the characteristics of starch-lipid complexes under high temperature were investigated. Fatty acids with a shorter carbon chain or a greater number of double bonds contributed to the formation of V-type starch-lipid complexes. The thermostability of starch-unsaturated fatty acid (UFA) complexes prepared at high temperature was increased compared with those obtained at lower temperature. Resistant starch (RS) contents and melting temperatures had a strong significant positive correlation. Complexes with better thermostability were more resistant to enzymatic hydrolysis. Among them, the starch-stearic acid complexes possessed the highest RS content. The paste of starch-linolenic acid complexes had the lowest internal friction and the strongest thixotropy. The broken of double bonds in UFAs probably accounted for the increased starch-lipid complexes. The crystalline, thermal, rheological, and digestion properties of samples treated at high temperature were significantly affected.

Elucidation of the low resistant starch phenotype in Phaseolus vulgaris exhibited in the yellow bean Cebo Cela

Dry beans(Phaseolus vulgaris) are rich in complex carbohydrates including resistant starch (RS). RS, the starch fraction that escapes digestion, typically ranges from 35% in raw beans to 4% in cooked beans. A low RS bean genotype, Cebo Cela, was identified with 96% less RS (1.5% RS) than normal raw beans. The goal of this research was to elucidate the factors responsible for this low RS phenotype. The low RS phenotype was evaluated in whole bean flour and starch in Cebo Cela (yellow), Canario (yellow), Alpena (navy) and Samurai (otebo). α-Amylase activation was found to be a major contributor of the low RS content phenotype of the whole bean flour for Cebo Cela (-21.9% inhibition). Total starch (43.6%-40.2%), amylose (31.0%-31.5%), molecular weight and chain length distributions of amylose and amylopectin did not contribute to the low RS phenotype. Yellow bean starches were digested nearly 1.5 times (95%-94%) faster than starch granules from otebo and navy beans (65%-73%) due to lower proportions of amylopectin chains. PRACTICAL APPLICATION: This study is of value to the food industry because the yellow bean, Cebo Cela, is easily hydrolyzed by α-amylase and also has α-amylase promotion properties. Therefore, Cebo Cela can be used as an alternate starch source for ethanol fermentation and for the production of maltodextrins and fructose/glucose syrups which are used as food thickeners and sweeteners.

Investigating the structural properties and in vitro digestion of rice flours

The physicochemical properties, swelling power, solubility, and digestibility of flour from four rice varieties (black, brown, white, and waxy rice flour) were analyzed. The results showed that the black and brown rice had high-amylose percentage (21.8% and 20.5%), a relatively low percentage of starch content (68.1% and 79.1%), and lower swelling power (6.6% and 7.6%) and solubility (13.5% and 15.7%), respectively. Waxy rice flour attributed to lower gelatinization temperatures and higher enthalpy values. Meanwhile, the brown, black, and white rice showed higher gelatinization temperature and lower enthalpy value. The black and brown rice flour exhibited lower pasting and viscosity values as compared to waxy rice flour. The results showed that all rice flour had an A-type X-ray diffraction pattern, and after cooking all rice flour showed V-type polymorphs except waxy rice flour. Brown and black rice flour after cooking have lower digestion rate than white rice and waxy rice flour, probably due to its lower expansion and solubility rates, and higher gelatinization temperature.

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.

Effect of extrusion processing and addition of purple sweet potatoes on the structural properties and in vitro digestibility of extruded rice

Recently, extruded rice as a functional ingredient has been a hot area of research in food processing. In this study, extruded rice with purple sweet potato (ERPSP) was prepared. Moreover, the effects of extrusion and added purple sweet potato on the structure and in vitro digestibility of extruded rice were studied via numerous detection methods, such as scanning electron microscopy (SEM), water absorption index (WAI), water solubility index (WSI), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). SEM results showed that there were numerous pits and bubbles in the extruded rice. In particular, compared with raw rice, the WAI and WSI of ERPSP was higher, and the thermal properties also changed noticeably. The results of XRD and FT-IR spectroscopy showed that the semicrystalline structure of extruded rice changed from A-type to A + V-type mixture, and the relative crystallinity of extruded rice changed accordingly. In addition, a significantly lower equilibrium hydrolysis (C_∞) and kinetic constant (k) were observed in ERPSP. The novel rice product made from broken rice by extrusion processing and addition of the purple sweet potato exhibited improved structural properties and reduced digestibility, which increased the potential value and application of broken rice in the food industry.

Physicochemical, functional and rheological properties of grass pea (Lathyrus sativus L.) flour as influenced by particle size

Different properties of grass pea (Lathyrus sativus L.) flour passed through 60, 72, 85, 100, 150 and 200 mesh sieves and in the size range of 249-74 μm were studied. The protein content reduced while fat content improved significantly with diminution in particle size. Flowability, capacities to absorb water and form foam as well as stability of foam decreased while increase in swelling capacity, swelling index, oil absorption capacity was observed with decrease in flour particle size. Bimodal curve patterns were obtained for coarse flour samples of 249 μm and 211 μm using light scattering analysis. Scanning electron microscopy analysis revealed that starch granules were of variable shape embedded in protein and fibre matrix. The flour with fine particle size exhibited greater values for peak, final, break down and set back viscosities and the dough from fine particles showed highest values for storage modulus (G′), loss modulus (G″),|G^∗| and |η^∗|.

Nutritional quality and in vitro digestion of immature rice-based processed products

The nutritional contents of rice decreased as grains matured, and pepeta-type processing improves the nutritional properties and in vitro protein digestibility of rice.

A High-Throughput In Vitro Assay for Screening Rice Starch Digestibility

The development of rice that can produce slow and steady postprandial glucose in the bloodstream is a response to alarmingly high global rates of obesity and related chronic diseases. However, rice grain quality programs from all over the world currently do not have access to a high-throughput method to distinguish rice breeding materials that are digested slowly. The objective of this study was to develop a high-throughput in vitro assay to screen the digestibility of cooked white rice grains and to investigate its ability to differentiate rice genotypes with a low starch digestibility rate. The digestibility rate and extent of three commercial rice genotypes with diverse GI values (Doongara, Reiziq and Waxy) were successfully differentiated using the protocol. Further investigations with eight rice genotypes indicated the percentage of starch hydrolysed at a single time point of the assay (SH-60) successfully differentiated genotypes with a low digestibility rate (the SH-60 of Doongara and YRL127 was 50% and 59%, respectively) from genotypes with an intermediate or high digestibility rate (SH-60 values were between 64% and 93%). Application of this methodology in rice breeding programs may assist in the screening and development of new varieties with a desirable postprandial glycaemic response.

Changes in Morphological and Physicochemical Properties of Waxy and Non-waxy Proso Millets during Cooking Process

Proso millet, a grain which is principally consumed in cooked form, is favored by consumers because of its rich nutritional value. However, the changes in morphological and physicochemical properties of proso millet grains occurring during the cooking process have rarely been reported. In this study, we investigated the changes in morphological and physicochemical properties of cooked waxy and non-waxy proso millets. During the cooking process, starch granules in the grains were gradually gelatinized starting from the outer region to the inner region and were gelatinized earlier in waxy proso millet than in non-waxy proso millet. Many filamentous network structures were observed in the cross sections of cooked waxy proso millet. As the cooking time increased, the long- and short-range, ordered structures of proso millets were gradually disrupted, and the ordered structures were fully disrupted by 20 min of cooking. In both waxy and non-waxy proso millets, thermal and pasting properties significantly changed with an increase in the cooking time. This study provides useful information for the processing of proso millet in the food industry.

Understanding the mechanism of ultrasonication regulated the digestibility properties of retrograded starch following vacuum freeze drying

The digestibility properties and structural changes of retrograded starch (RS3) induced by ultrasonic treatment (UT) were investigated. The digestion profiles showed that UT increased the slowly digestible starch (SDS) or resistant starch (RS) of RS3 as an effective green process, corresponding to a change in hydrolysis kinetic parameters (equilibrium starch hydrolysis percentage and kinetic constant). SEM analysis showed that ultrasound led to breakage of RS3 particles followed by cracking, reorientation and crystallization. Differences in amylose content, granule size, and ζ-potential were found for native RS3 and ultrasound-treated RS3 (UT-RS3). UT decreased the relative crystallinity and gelatinization enthalpy but enhanced short-range order of RS3 based on the results of XRD, DSC, and FT-IR, respectively. Surprisingly, diffractive peaks at 13°and 20° (V-type crystalline structure) and a new exothermic peak were also observed for UT-RS3. The outcome was believed to open new pathways for regulating the digestibility properties of RS3 by UT and development of low glycemic response food.

NegFluo, a Fast and Efficient Method to Determine Starch Granule Size and Morphology In Situ in Plant Chloroplasts

Starch granules that accumulate in the plastids of plants vary in size, shape, phosphate, or protein content according to their botanical origin. Depending on their size, the applications in food and nonfood industries differ. Being able to master starch granule size for a specific plant, without alteration of other characteristics (phosphate content, protein content, etc.), is challenging. The development of a simple and effective screening method to determine the size and shape of starch granules in a plant population is therefore of prime interest. In this study, we propose a new method, NegFluo, that combines negative confocal autofluorescence imaging in leaf and machine learning (ML)-based image analysis. It provides a fast, automated, and easy-to-use pipeline for both in situ starch granule imaging and its morphological analysis. NegFluo was applied to Arabidopsis leaves of wild-type and ss4 mutant plants. We validated its accuracy by comparing morphological quantifications using NegFluo and state-of-the-art methods relying either on starch granule purification or on preparation-intensive electron microscopy combined with manual image analysis. NegFluo thus opens the way to fast in situ analysis of starch granules.