Microwave reheating enriches resistant starch in cold-chain cooked rice: A view of structural alterations during digestion

Cooked germ-remained milled rice presents high stability in water-holding capacity and textural properties during frozen storage-The protection effect of oil-phase reabsorption

To enhance the stability in textural attributes of frozen cooked rice, this study has found and proposed a new strategy: retaining the rice germ in milling process. Each rice germ is comparable to a native lipid-rich microcapsule attached to the endosperm part. In the gelatinization process, leached germ oil was reabsorbed in the outer layer of rice granule. Small lipidic molecules complexed with amylose and formed type I complex, while big lipidic molecules formed separate oil phase in the matrix. This mixed construction endowed cooked germ-remained milled rice with smaller magnitude of change in the water holding capacity and the ratio of stickiness/hardness, and fewer freezable water content than white rice. This work opens an attractive field to reinforce the structural stability of cooked rice against freezing stress without exogenous additives, and benefits to screen suitable raw materials for the development of frozen rice products.

Resolving differences in digestion features of cooked rice and wheat noodles: A view from starch multiscale structure

The staple foods play an important role in providing energy in the human daily diet. Wheat is the main staple food in northern China, rice in southern China, and the different staple food patterns between the north and south result in health disparities. Therefore, analyzing the differences in the digestion of staple foods are particularly important for understanding the digestive energy supply of staple foods. The firmer gel network structure, thicker crystalline lamellae, more V-type crystallites, higher degree of helical structure, and short-range order in cooked rice impeded the diffusion of amylase on the starch surface and inhibited the amylase-starch binding, leading to a lower rate of enzymatic hydrolysis of starch molecular chains and significantly higher content of RS than wheat noodles (P < 0.05). The different processing methods of cooked rice and wheat noodles influenced the multiscale structure of starch and thus the rate of digestion.

Nutrition and Gut Health: Preparation and Efficacy of Resistant Starch

Resistant starch (RS) refers to starch varieties that resist digestion by human digestive enzymes. Owing to its distinctive physicochemical attributes and functional capabilities, RS has gained a wide range of applications as a dietary fiber and prebiotic. In terms of structure and functions, RS can be categorized into five distinct types: RS1 through RS5. These types offer dietary benefits, contributing to improved colonic health, the modulation of microbial communities, the reduction in gallstone formation, the enhancement of mineral absorption, and alterations in fat oxidation potential. From a technical standpoint, RS can be manufactured through an array of physical, enzymatic, and chemical modifications. This paper presents a comprehensive review of the existing literature, summarizing the classification, structural features, raw material origins, preparation methodologies, and functionalities of RS. Furthermore, new production technologies and applications of RS, such as 3D printing, provide valuable insights.

Quality control of cooked rice: Exploring physicochemical changes of the intrinsic component in production

Sensory deterioration exists in marketed cooked rice. The migration and interaction of intrinsic components occur under multiple conditions in each industrial production process and cause relevant physicochemical changes in cooked rice. This review aims to establish a scientific knowledge system of intrinsic component transition and migration in cooked rice kernel during processing to solve qualitative deficiencies in cooked rice products. The main influencing factors of intrinsic component structural change in cooked rice and the quality control points that should be considered are summarized. Further studies are needed to establish proper evaluation standards for cooked rice products to meet the growing consumer demands.

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.

Multi-scale structural insights on starch digestibility of instant rice

Multi-scale structures were investigated to understand starch digestibility of instant rice. A wide range of maximum starch digested ratio, up to about 20%, was observed among instant rice prepared from different rice varieties. Instant rice with a smooth and densely packed cross-section showed slower starch digestibility than those with a porous and loosely packed structure. All samples displayed B + V type crystallinity, with V-type crystallinity negatively correlating with maximum starch digested percentage. After digestion, starch chain-length distributions were significantly altered: rapidly digested starch comprised long amylose and short amylopectin chains, while slowly digested starch comprised chains with a peak degree of polymerization (DP) around 130. These results indicate that instant rice with a compact microstructure, high V-type crystallinity, and DP 130 fractions during digestion can reduce starch digestibility. This study provides insights for food industry to develop instant rice products with slow starch digestibility, potentially improving human health.

Study on Quality and Starch Characteristics of Powdery and Crispy Lotus Roots

Nine varieties of lotus root (Suining, Xinhe, Zaohua, Zhonghua, L0014, L0013, Cuiyu, L0011, and Zhenzhu) were selected as the research materials to compare their differences in physical, chemical, and starch characteristics before and after boiling, frying, and microwaving. The results showed that Zhenzhu, Xinhe, L0013, Cuiyu, and Zhonghua belong to the crispy lotus root type, while L0011, L0014, Zaohua, and Suining belong to the powdery lotus root type. Furthermore, the nine varieties were characterized for their starch by optical micrograph (OM), polarized micrograph (PM), scanning electron micrograph (SEM), attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), carbon-13 cross-polarization/magic angle spinning nuclear magnetic resonance (13C CP/MAS NMR), and differential scanning calorimetry (DSC). The starch granule of powdery lotus root appeared to be larger than that of crispy lotus, and ATR-FTIR studies revealed that the outer layer of starch granules from nine different varieties of lotus root had a highly organized structure. Moreover, XRD and 13C CP/MAS NMR analyses revealed that starch from eight lotus varieties (Suining, Xinhe, Zaohua, Zhonghua, L0014, L0013, Cuiyu, L0011) belong to the A-crystal type, while starch from Zhenzhu belongs to the CA-crystal type. The starch from powdery lotus root exhibited higher crystallinity, as well as increased gelatinization temperature and enthalpy, indicating that its crystal structure was relatively superior compared to that of crispy lotus starch. The short-range order degree, crystallinity, gelatinization temperature, and heat enthalpy of lotus starch decreased after boiling and frying but increased to varying extents after microwaving. Additionally, the heat resistance and stability of starch particles from crispy lotus root were improved after microwave treatment.

The lipid-amylose complexes enhance resistant starch content in candelilla wax-based oleogels cookies

The substitution of margarine with candelilla wax (CW)-based oleogel is currently a prominent focus of research in the bakery industry. However, the use of CW-based oleogel in cookies increased starch digestibility, potentially posing a risk to human health. Thus, the anti-enzymatic mechanism of lipid-amylose complexes was used to evaluate the influence of olive diacylglycerol stearin (ODS) on starch digestibility in CW-based oleogel cookies. The in vitro digestibility analysis demonstrated that the DCW/ODS-35 cookie exhibited a increase of 27.72 % in slowly digestible starch (SDS) and resistant starch (RS) contents, compared to cookie formulated with margarine. The in-vivo glycemic index analysis revealed that the DCW/ODS-35 cookie had a medium glycemic index of 68. XRD pattern suggested that the presence of ODS in oleogels facilitated the formation of lipid-amylose complexes. The DSC analysis revealed that the addition of ODS resulted in the gelatinization enthalpy of DCW-based cookies increased from 389.9 to 3314.9 J/g. The FTIR spectra indicated that the combination of ODS could promote a short-range ordered structure in DCW-based cookies. Overall, these findings demonstrated that the utilization of DCW-based oleogel presented a viable alternative to commercial margarine in the development of CW-based cookies with reduced starch digestibility.

Long-Chain Saturated Fatty Acids in Olive Diacylglycerol Stearin Enhances Resistant Starch Content of Candelilla Wax Oleogel Cookies

The purpose of this study was to substitute shortening with olive diacylglycerol oil/candelilla wax (OCW)-olive diacylglycerol stearin (ODS) oleogels and evaluate their impact on starch digestibility in cookies. The in vitro digestibility study confirmed that the OCW/ODS-based cookies exhibited a notable enhancement of 14.6% in slowly digestible starch (SDS) and an increase of 3.14% in resistant starch (RS) values when contrasted with shortening cookies. The XRD pattern indicated that the existence of ODS may improve the formation of complexes between lipids and amylose. The DSC analysis demonstrated that the incorporation of ODS led to a remarkable rise in enthalpy alteration, escalating from 0.90 to 437.70 J/g, suggesting an improved ability to resist gelatinization. The FTIR spectra suggested that the incorporation of ODS might strengthen interactions between the hydrogen bonds and form the short-range ordered structure in OCW/ODS-based cookies. Overall, these results indicated that incorporating OCW/ODS-based oleogels could serve as a feasible substitute for conventional shortening in cookies with decreased starch digestibility.

Enhancement of resistant starch content in ethyl cellulose-based oleogels cakes with the incorporation of glycerol monostearate

The objective of this work was to completely replace margarine with peanut diacylglycerol oil/ethyl cellulose-glycerol monostearate oleogel (DEC/GMS) oleogel, and evaluate its effect on starch digestibility of cakes. The in vitro digestibility analysis demonstrated that the DEC/GMS-6 cake exhibited a 26.36% increase in slowly digestible starch (SDS) and resistant starch (RS) contents, compared to cakes formulated with margarine. The increased SDS and RS contents might mainly be due to the hydrophobic nature of OSA-wheat flour, which could promote the formation of lipid-amylose complexes with GMS and peanut diacylglycerol oil. XRD pattern suggested that the presence of GMS in DEC-based oleogels facilitated the formation of lipid-amylose complexes. The DSC analysis revealed that the addition of GMS resulted in a significant increase in gelatinization enthalpy, rising from 249.7 to 551.9 J/g, which indicates an improved resistance to gelatinization. The FTIR spectra indicated that the combination of GMS could enhance the hydrogen bonding forces and short-range ordered structure in DEC-based cakes. The rheological analysis revealed that an increase in GMS concentration resulted in enhanced viscoelasticity of DEC-based cake compared to TEC-based cakes. The DEC-based cakes exhibited a more satisfactory texture profile and higher overall acceptability than those of TEC-based cakes. Overall, these findings demonstrated that the utilization of DEC-based oleogel presented a viable alternative to commercial margarine in the development of cakes with reduced starch digestibility.

Harnessing the power of resistant starch: a narrative review of its health impact and processing challenges

Starch is a primary energy storage for plants, making it an essential component of many plant-based foods consumed today. Resistant starch (RS) refers to those starch fractions that escape digestion in the small intestine and reach the colon where they are fermented by the microflora. RS has been repeatedly reported as having benefits on health, but ensuring that its content remains in food processing may be challenging. The present work focuses on the impact RS on health and explores the different processes that may influence its presence in foods, thus potentially interfering with these effects. Clinical evidence published from 2010 to 2023 and studying the effect of RS on health parameters in adult populations, were identified, using PUBMED/Medline and Cochrane databases. The search focused as well on observational studies related to the effect of food processes on RS content. While processes such as milling, fermentation, cooking and heating seem to have a deleterious influence on RS content, other processes, such as cooling, cooking time, storage time, or water content, may positively impact its presence. Regarding the influence on health parameters, there is a body of evidence suggesting an overall significant beneficial effect of RS, especially type 1 and 2, on several health parameters such as glycemic response, insulin resistance index, bowel function or inflammatory markers. Effects are more substantiated in individuals suffering from metabolic diseases. The effects of RS may however be exerted differently depending on the type. A better understanding of the influence of food processes on RS can guide the development of dietary intake recommendations and contribute to the development of food products rich in RS.

The impact of different soluble endogenous proteins and their combinations with β-glucan on the in vitro digestibility, microstructure, and physicochemical properties of highland barley starch

The impacts of protein types and its interaction with β-glucan on the in vitro digestibility of highland barley starch were investigated through analyzing physicochemical and microstructural properties of highland barley flour (HBF) after sequentially removing water- (WP), salt- (SP), alcohol- (AP) and alkali-soluble (AlkP) proteins. Resistant starch (RS) increased significantly in HBF after removing WP and SP, and RS of HBF was lower than that of without β-glucan. After removing WP, SP and AP, swelling powers of HBF without β-glucan (9.33-9.77) were higher than those of HBF (12.09-15.95). Trends of peak viscosity and peak temperature (thermal degradation temperature) were similar as swelling power, and HBF without AP showed the highest peak temperature (310.33 °C). Removals of different proteins improved the crystalline structure and short-range order of starch. There was a blue shift in T2 values and an opposite change in free water proportion. The matrix on starch surface was mainly formed by AP and AlkP, which could be aggregated by β-glucan. But, the inhibitory effect of AP or AlkP was stronger than that of proteins combined with β-glucan. These results help in the development of starch-based foods with different digestive properties by combining different protein types with β-glucan.

Incorporating edible oil during cooking tailors the microstructure and quality features of brown rice following heat moisture treatment

While brown rice (BR) has numerous nutritional properties, the consumption potential of which is seriously restricted since the poor cooking quality and undesirable flavor. Here, edible oils (pork lard and corn oil, 1-5 wt%) were incorporated during the cooking of BR following heat moisture treatment. Incorporating corn oil rather than lard significantly ameliorated the texture properties (e.g. hardness, cohesiveness, and chewiness) and sensory properties of cooked BR. Both lard- and corn oil-incorporated cooked BR showed obvious structural changes accompanied by the formation of amylose-lipid complexes during cooking. It was confirmed that the incorporation of lard and corn oil allowed a higher degree of short-range molecular order, more V-type starch crystallites, and elevated nano-structural arrangements. Additionally, a decreased hardness (from 559.04 g to 424.18 g and 385.91 g, respectively) and enriched resistant starch (RS) were also observed, the highest RS content (15.95 % and 16.32 %, respectively) was observed when 1 wt% of lard and corn oil were incorporated.

Ionizing and nonionizing radiations can change physicochemical, technofunctional, and nutritional attributes of starch

Challenges for the food/non-food applications of starch mostly arise from its low stability against severe processing conditions (i.e. elevated temperatures, pH variations, intense shear forces), inordinate retrogradability, as well as restricted applicability. These drawbacks have been addressed through the modification of starch. The escalating awareness of individuals toward the presumptive side effects of chemical modification approaches has engrossed the attention of scientists to the development of physical modification procedures. In this regard, starch treatment via ionizing (i.e. gamma, electron beam, and X-rays) and non-ionizing (microwave, radiofrequency, infrared, ultraviolet) radiations has been introduced as a potent physical strategy offering new outstanding attributes to the modified product. Ionizing radiations, through dose-dependent pathways, are able to provoke depolymerization or cross-linking/grafting reactions to the starch medium. While non-ionizing radiations could modify the starch attributes by changing the morphology/architecture of granules and inducing reorientation/rearrangement in the molecular order of starch amorphous/crystalline fractions.

Influence of instant rice characteristics and processing conditions on starch digestibility-A review

Instant rice is increasingly popular around the world due to its convenience, but it commonly has a high glycemic index, and a frequent consumption might contribute to the occurrence of many chronic diseases. In this review, the main factors determining starch digestibility of instant rice were comprehensively evaluated, aiming to help the rice industry develop instant rice with slow starch digestibility. Starch digestibility in instant rice can be reduced by manipulating its intrinsic and extrinsic nutrients. Processing conditions, including pre-gelatinization, storage, and reheating are also important for the starch digestibility of instant rice. Individual differences in terms of glycemic response to the same carbohydrate-based diet should be considered when knowledge is transformed from in vitro method to human conditions. This review contains important information that has the potential to reduce the starch digestibility of instant rice and improve public health.

Ingesting retrograded rice (Oryza sativa) starch relieves high-fat diet induced hyperlipidemia in mice by altering intestinal bacteria

High-fat diet is a risk factor for many chronic diseases, whose symptoms are probably regulated by ingesting food ingredients such as resistant starch. For cooked rice stored in cold-chain, the starch component can retrograde to generate ordered structures (helices and crystallites) and become resistant. However, the role of retrograded starch in managing hyperlipidemia symptoms is insufficiently understood. Here, compared to the normal high-fat diet, ingesting retrograded starch reduced the triglyceride and low-density lipoprotein cholesterol levels of high-fat diet mice by 17.69% and 41.33%, respectively. This relieved hyperlipidemia could be linked to the changes in intestinal bacteria. Retrograded starch intervention increased the relative abundance of Bacteroides (2.30 times higher), which produces propionic acid (increased by 8.26%). Meanwhile, Bacteroides were positively correlated with butyric acid (increased by 98.4%) with strong anti-inflammatory functions. Hence, retrograded starch intervention may regulate the body's health by altering intestinal bacteria.

Factors influencing the starch digestibility of starchy foods: A review

Starchy foods are a major energy source of the human diet, their digestion is closely related to human health. Most foods require lots of processing before eating, therefore, many factors can influence starch digestibility. The factors that affect the digestibility of starches have been widely discussed previously, but the extracted starches in those studies were different from those present within the actual food matrix. This review summarizes the factors influencing the starch digestibility in starchy foods. Endogenous non-starch components hinder the starch digestive process. Food ingredients and additives decrease starch digestibility by inhibiting the activity of digestive enzymes or hindering the contact between starch and enzymes. Storage induce the retrogradation of starch, decreasing the digestibility of foods. Therefore, preparing starchy foods with whole grains, processing them as little as possible, using food additives reasonably, and storage conditions may all be beneficial measures for the production of low GI foods.

Effects of Reheating Methods on Rheological and Textural Characteristics of Rice Starch with Different Gelatinization Degrees

Pregelatinized starch (PGS) is often used to improve the processing quality of foodstuffs, but little attention has been paid to the effects of different reheating methods and degree of starch gelatinization (DSG) on their rheological and textural properties. In this study, pregelatinized rice starches (RS) with gelatinization degrees ranging from 58% to 100% were prepared via different Rapid Visco Analyser (RVA) heating procedures and reheated in various methods, including high-power microwave (HM), low-power microwave (LM), and water bath. The rheological behavior and textural properties were explored, and the results demonstrated that the consistency, gel strength, hardness, and springiness of PGS in all tested samples decreased significantly after reheating. The storage modulus (G') of PGS increased dramatically while the thermal stability decreased. Interestingly, the reheating methods possessed various effects on the starch of different DSG.