Microwave reheating increases the resistant starch content in cooked rice with high water contents

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.

Texture, swallowing and digestibility characteristics of a low-GI dysphagia food as affected by addition of dietary fiber and anthocyanins

Dysphagia is a common problem in the elderly population, thus texture modifications in foods suitable for dysphagic patients aroused a lot of interest. In the study, low glycemic index (GI) dysphagia foods were designed with adding dietary fiber (DF) and anthocyanins (AS), and their in vitro enzymatic digestion and predicted GI values were investigated by first-order kinetic model and slope log model. Results showed that all samples belonged to dysphagia foods at level 4 (pureed) in the International Dysphagia Diet Standardization Initiative (IDDSI) framework, and exhibited shear thinning behavior. AS reduced the apparent viscosity and storage modulus, increased redness, while DF decreased the hardness and gumminess of dysphagia food masses. DF and AS significantly increased the slowly digestible starch and resistant starch content in food system. With the increased addition of 5 % DF and 3 % AS, the predicted GI value of dysphagia food masses could be decreased to 51.08 ± 2.48, which belonged to the low-GI food, and showed the best water holding capacity and the highest total sensory evaluation score. In addition, a strong correlation was also found between the slow digestion indicators, rheological properties and swallowing ease. This study provides a theoretical foundation for the design of dysphagia food products with slow digestibility and low GI values.

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.

Recent Advances in Physical Processing Techniques to Enhance the Resistant Starch Content in Foods: A Review

The physical modification of starch to produce resistant starch (RS) is a viable strategy for the glycemic index (GI) lowering of foods and functionality improvement in starchy food products. RS cannot be digested in the small intestine but can be fermented in the colon to produce short-chain fatty acids rather than being broken down by human digestive enzymes into glucose. This provides major health advantages, like better blood sugar regulation, weight control, and a lower chance of chronic illnesses. This article provides a concise review of the recent developments in physical starch modification techniques, including annealing, extrusion, high-pressure processing, radiation, and heat-moisture treatment. Specifically, the focus of this paper is on the alteration of the crystalline structure of starch caused by the heat-moisture treatment and annealing and its impact on the resistance of starch to enzymatic hydrolysis, as well as the granular structure and molecular arrangement of starch caused by extrusion and high-pressure processing, and the depolymerization and crosslinking that results from radiation. The impacts of these alterations on starch's textural qualities, stability, and shelf life are also examined. This review demonstrates how physically modified resistant starch can be used as a flexible food ingredient with both functional and health benefits. These methods are economically and ecologically sustainable since they successfully raise the RS content and improve its functional characteristics without the need for chemical reagents. The thorough analysis of these methods and how they affect the structural characteristics and health advantages of RS emphasizes the material's potential as an essential component in the creation of functional foods that satisfy contemporary dietary and health requirements.

Effect of microwave alone and microwave-assisted modification on the physicochemical properties of starch and its application in food

Native starch has poor stability and usually requires modification to expand its industrial application range. Commonly used methods are physical, chemical, enzymatic and compound modification. Microwave radiation, as a kind of physical method, is promising due to its uniform energy radiation, greenness, safety, non-toxicity. It can meet the demand of consumers for safe food. Microwave-assisted modification with other methods can directly or indirectly affect the structure of starch granules to obtain modified starch with high degree of substitution and low viscosity, and the modification efficiency is greatly improved. This paper reviews the effect of microwave radiation on the physicochemical properties of starch, such as granule morphology, crystallization characteristics, and gelatinization characteristics, as well as the application of microwave radiation in starch modification and starch food processing. It provides theoretical references and suggestions for the research of microwave heating modified starch and the deep processing of starchy foods.

Advancements in enhancing resistant starch type 3 (RS3) content in starchy food and its impact on gut microbiota: A review

Resistant starch type 3 (RS3), often found in cooked starchy food, has various health benefits due to its indigestible properties and physiological functions such as promoting the abundance of gut beneficial microbial flora and inhibiting the growth of intestinal pathogenic bacteria. However, it is challenging to develop starchy food with high RS3 content. This review aims to provide a detailed overview of current advancements to enhance RS3 content in starchy food and its effects of RS3 on gut microbiota. These approaches include breeding high-amylose cereals through gene editing techniques, processing, enzyme treatments, storage, formation of RS3 nanoparticles, and the incorporation of bioactive compounds. The mechanisms, specific conditions, advantages, and disadvantages associated with each approach and the potential effects of RS3 prepared by different methods on gut microbiota are summarized. In conclusion, this review contains important information that aims to provide guidelines for developing an efficient RS3 preparation process and promote the consumption of RS3-enriched starchy foods to improve overall health outcomes.

Effect of Sprouted Buckwheat on Glycemic Index and Quality of Reconstituted Rice

This study utilized sprouted buckwheat as the main component and aimed to optimize its combination with other grains to produce reconstituted rice with enhanced taste and a reduced glycemic index (GI). The optimal blend comprised wheat flour, sprouted buckwheat flour, black rice flour, and purple potato flour in a ratio of 34.5:28.8:26.7:10.0. Based on this blend, the reconstituted rice processed through extrusion puffing exhibited a purple-black hue; meanwhile, the instant reconstituted rice, produced through further microwave puffing, displayed a reddish-brown color. both imparted a rich cereal flavor. The starch in both types of rice exhibited a V-shaped structure with lower relative crystallinity. Compared to commercial rice, the reconstituted rice and instant reconstituted rice contained higher levels of flavonoids, polyphenols, and other flavor compounds, along with 1.63-fold and 1.75-fold more proteins, respectively. The GI values of the reconstituted rice and the instant reconstituted rice were 68.86 and 69.47, respectively; thus, they are medium-GI foods that can alleviate the increase in blood glucose levels.

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.

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.

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.

High hydrostatic pressure (HHP) reinforces solid encapsulation of d-limonene into V-type starch and its application in strawberry storage

The formation of inclusion complexes (ICs) between V-type starch and flavors is traditionally conducted in an aqueous system. In this study, limonene was solid encapsulated into V6-starch under ambient pressure (AP) and high hydrostatic pressure (HHP). The maximum loading capacity reached 639.0 mg/g after HHP treatment, and the highest encapsulation efficiency was 79.9 %. X-ray Diffraction (XRD) results showed that the ordered structure of V6-starch was ameliorated with limonene, which avoided the reduction of the space between adjacent helices within V6-starch generated by HHP treatment. Notably, HHP treatment may force molecular permeation of limonene from amorphous regions into inter-crystalline amorphous regions and crystalline regions as the Small-angle X-ray scattering (SAXS) patterns indicated, leading to better controlled-release behavior. Thermogravimetry analysis (TGA) revealed that the solid encapsulation of V-type starch improved the thermal stability of limonene. Further, the release kinetics study showed that a complex prepared with a mass ratio of 2:1 under HHP treatment sustainably released limonene over 96 h and exhibited a preferable antimicrobial effect, which could extend the shelf life of strawberries.

Starch intrinsic crystals affected the changes of starch structures and digestibility during microwave heat-moisture treatment

The structural and functional changes of starch during hydrothermal treatment are influenced by its intrinsic properties. However, how the intrinsic crystalline structures of starch affect changes in structure and digestibility during microwave heat-moisture treatment (MHMT) has not been well understood. In this study, we prepared starch samples with varying moisture content (10 %, 20 %, and 30 %) and A-type crystal content (4.13 %, 6.81 %, and 16.35 %) and investigated the changes in their structures and digestibility during MHMT. Results showed that starch with a high A-type crystal content (16.35 %) and moisture levels of 10 % to 30 % exhibited less ordered structures after MHMT, while starches with lower A-type crystal content (4.13 % to 6.18 %) and moisture content of 10 % to 20 % showed more ordered structures after treatment; but less ordered structures when the moisture content was 30 %. All starch samples had lower digestibility after MHMT and cooking; however, starches with lower A-type crystal content (4.13 % to 6.18 %) and moisture content of 10 % to 20 % displayed significantly lower digestibility after treatment compared to modified starches. Accordingly, starches contained content of A-type crystals of 4.13 %-6.18 % and moisture of 10 %-20 % potentially had better reassembly behaviors during the MHMT to slow starch digestibility in a larger magnitude.

Corner coil heating mode improves the matrix uniformity of cooked rice in an induction heating cooker

Nowadays, an increasing number of people worldwide use induction heating cookers to cook rice for consumption. This work reveals the influence of induction heating cooker heating modes on the quality attributes of cooked rice. Three heating modes, including bottom coil heating mode (mode 1), corner coil heating mode (mode 2), and side coil heating (mode 3), were used. Among the three modes, mode 2 allowed for an intermediate heating rate during rice cooking. For mode 2, the minimized temperature difference between the upper layer (including the central upper layer and peripheral upper layer) and the lower layer (including the central lower layer and peripheral lower layer) can reduce the effect of water absorption time difference on rice quality. Consequently, the rice cooked using mode 2 exhibited improved matrix uniformity, as indicated by the similar moisture content (59.92–61.89%), hardness (15.87–18.24 N), and water mobility (the relaxation time and peak area of the third relaxation peak) of rice samples at four different positions in the pot. The rice cooked by mode 2 showed better texture appearance and a more uniform porous microstructure. Consistently, the cooked rice samples by mode 2 at different positions did not show substantial differences in their starch digestion features.

Effects of dual modification of lysine and microwave on corn starch: In vitro digestibility and physicochemical properties

The effects of lysine addition and microwave treatment (MC) on the digestibility, physicochemical properties and structure of corn starch were investigated. Among all uncooked samples, unmodified corn starch (CS), microwave modified corn starch (MC-CS) and corn starch mixed with lysine (CS-Lys) contained 15.09 %, 14.82 % and 18.86 % slowly digestible starch (SDS), while up to 30.28 % in microwave-lysine modified corn starch (MC-Lys). In contrast to CS, the peak viscosity, breakdown viscosity, setback viscosity and gel enthalpy of MC-Lys were decreased, while the relative crystallinity was increased. Scanning electron microscopy observation showed that corn starch aggregated with each other and was coated by lysine after MC, the particle size distribution range became wider, and the specific surface area decreased. The results showed that the interaction of starch with lysine in the microwave field increased the ordered and aggregated structure of corn starch, resulting in a significant change in the physicochemical properties and digestibility of corn starch. MC-Lys can be added to foods as a nutritional fortification to meet the needs of specific populations for lysine and low carbohydrate.

Research progress in fluid and semifluid microwave heating technology in food processing

Microwave is a form of electromagnetic radiation that has high penetration and heating efficiency in food processing. Uneven heating is the main problem of microwave processing, especially in solid foods. Fluid and semifluid media, which are good carriers in microwave processing, have uniform dielectric properties and good material fluidity. Herein, we review the development, application prospects, and limitations of microwave in fluid and semifluid food processing and the research progress in microwave heating with steam as carrier. The mixture of generated steam and tiny micro droplets from food material under the action of microwave can absorb microwave and transfer heat evenly, which effectively improves the uniformity of microwave heating. Due to the relatively uniform dielectric properties and consistent texture of fluid and semifluid food materials, uneven heating phenomenon during their microwave processing can be significantly inhibited. Based on the development of microwave heating technology and equipment design, the microbial inactivation and enzyme inhibition in fluid and semifluid food were improved and food product with better retention of nutrients and sensory profile were produced. Also, microwave radiation can be used to prepare the printing material or process the printed product for 3D food printing, which enhances the added value of 3D printed products and the personalization of food manufacturing. In future research, intelligent control technology can be applied in the microwave processing of fluid and semifluid food materials for various applications. Therefore, the processing conditions can be adjusted automatically.

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

Cold-chain cooked rice is an instant food consumed worldwide. Through inspecting rice structural alterations during digestion, this work discloses how microwave reheating tailors the starch digestibility of cooked rice following cold storage. The cold storage allowed approximately 2% of B-type (not V-type) starch crystallites, more nanoscale and short-range orders, and smaller pores in the rice matrix. These changes retarded the hydrolysis of structural domains (e.g., amorphous regions and short-range orders) during digestion, which increased the content of slowly digestible starch to about 38.16%. Then, microwave reheating partially disrupted the B-type crystallites and nanoscale orders, but unaffected the contents of V-type crystallites and short-range orders. Even with such structural disruptions, the resistant starch content was apparently increased to approximately 30.06%, as the structural domains became less susceptible to the digestion. Additionally, for the rice samples, the percentage of V-type crystallites could be largely increased from ca. 3% to 13%-14% during digestion.