Impact of cooking conditions on the properties of rice: Combined temperature and cooking time

Aflatoxins in the rice production chain: A review on prevalence, detection, and decontamination strategies

Rice (Oryza sativa L.) is one of the most consumed cereals that along with several important nutritional constituents typically provide more than 21% of the caloric requirements of human beings. Aflatoxins (AFs) are toxic secondary metabolites of several Aspergillus species that are prevalent in cereals, including rice. This review provides a comprehensive overview on production factors, prevalence, regulations, detection methods, and decontamination strategies for AFs in the rice production chain. The prevalence of AFs in rice is more prominent in African and Asian than in European countries. Developed nations have more stringent regulations for AFs in rice than in the developing world. The contamination level of AFs in the rice varied at different stages of rice production chain and is affected by production practices, environmental conditions comprising temperature, humidity, moisture, and water activity as well as milling operations such as de-husking, parboiling, and polishing. A range of methods including chromatographic techniques, immunochemical methods, and spectrophotometric methods have been developed, and used for monitoring AFs in rice. Chromatographic methods are the most used methods of AFs detection followed by immunochemical techniques. AFs decontamination strategies adopted worldwide involve various physical, chemical, and biological strategies, and even using plant materials. In conclusion, adopting good agricultural practices, implementing efficient AFs detection methods, and developing innovative aflatoxin decontamination strategies are imperative to ensure the safety and quality of rice for consumers.

Resistant starch and the gut microbiome: Exploring beneficial interactions and dietary impacts

The intricate relationship between resistant starch (RS) and the gut microbiome presents a dynamic frontier in nutrition science. This review synthesizes current understandings of how RS, an indigestible form of starch found naturally in certain foods and also enhanced through various modification methods, interacts with the gut microbiome. We particularly focus on how RS fermentation in the colon contributes to the production of beneficial volatile fatty acids (VFAs) such as butyrate, acetate, and propionate. These VFAs have been recognized for their vital roles in maintaining gut barrier integrity, modulating inflammation, and potentially influencing systemic health. Additionally, we discuss the dietary implications of consuming foods rich in RS, both in terms of gut health and broader metabolic outcomes. By consolidating these insights, we emphasize the significance of RS in the context of dietary strategies aimed at harnessing the gut microbiome's potential to impact human health.

Mechanistic insights into the enhanced texture of potato noodles by incorporation of small granule starches

Potato noodles are a popular food due to their unique texture and taste, but native potato starch often fails to meet consumer demands for precise textural outcomes. The effect of blending small granule (waxy amaranth, non-waxy oat and quinoa) starch with potato starch on the properties of noodles was investigated to enhance quality of noodles. Morphological results demonstrated that small granule starch filled gaps between potato starch granules, some of which gelatinized incompletely. Meanwhile, XRD and FTIR analysis indicated that more ordered structures and hydrogen bonding among starch granules increased with addition of small granule starch. The addition of oat or quinoa starch increased gel elasticity, decreased viscosity of the pastes, and increased the tensile strength of noodles, while addition of 30 % and 45 % waxy amaranth starch did not increase G' value of gel or tensile strength of noodles. These results indicated that amylose molecules played an important role during retrogradation, and may intertwine and interact with each other to enhance the network structure of starch gel in potato starch blended with oat or quinoa starch. This study provides a natural way to modify potato starch for desirable textural properties of noodle product.

Reduction of starch granule surface lipids alters the physicochemical properties of crosslinked maize starch

Normal and waxy maize starches with and without removal of starch granule surface lipids (SGSLs) were crosslinked by POCl3 (0.01 %, 0.1 % and 1 %). Crosslinked starches showed lower swelling power and solubility, but higher pasting viscosity, pseudoplasticity, thixotropy, storage modulus and loss modulus. Crosslinking increased the double helical structure but decreased the crystallinity for waxy maize starch. The phosphorus content of crosslinked waxy maize starches after SGSLs removal increased, indicating SGSLs removal promoted crosslinking. SGSLs removal increased G' and G" for crosslinked waxy maize starches. SGSLs removal increased SP and solubility and decreased pasting and rheological parameters of starches. With increased POCl3 dosage, the effect of SGSLs removal on starch properties was gradually suppressed by crosslinking. Waxy and normal maize starches showed significantly different changes with crosslinking and SGSLs removal, and the presence of amylose seemed to impede the effect of crosslinking and SGSLs removal. The removal of SGSLs could extend the application of crosslinked starch in frozen foods, drinks, and canned foods as thickener and stabilizer, due to its better hydrophilicity and viscous liquid-like rheological properties. The study will assist carbohydrate chemists and food processors in developing new food products.

Impact of Cooking Methods on Phenolic Acid Composition, Antioxidant Activity, and Starch Digestibility of Chinese Triticale Porridges: A Comparative Study between Atmospheric Pressure and High Pressure Boiling

Water boiling under atmospheric pressure (CAP) and water boiling under high pressure (CHP) are two popular domestic cooking methods for Chinese porridge making. In this study, we aimed to evaluate the effects of these two methods on the phenolic acid composition, antioxidant activity, and starch digestibility of triticale porridges. The contents of total free and total bound phenolic acids in the CHP sample were 1.3 and 1.6 times higher than those in the CAP counterpart, respectively, although the DPPH and ABTS values of these two samples were comparable. CAP induced more small pieces of starch than CHP, and the gelatinization enthalpy was 19% higher in the CHP sample than that in the CAP. Both cooking methods increased the starch digestibility, while the CHP sample (58.84) showed a lower GI than the CAP (61.52). These results may promote the application of triticale in health-promoting staple foods.

Re-evaluating fluoride intake from food and drinking water: Effect of boiling and fluoride adsorption on food

Although drinking water is the main source of fluoride intake, recent studies reported that fluoride intake from foods could also be high, depending on cooking methods. In this study, we quantified the fluoride accumulation in foods soaked or boiled in fluoride-containing water and assessed the fluoride intake in different age groups from food and drinking water. We observed that, in the case of rice soaked in fluoride-containing water, more fluoride was accumulated in the rice than previously estimated. Fluoride interferes with the iodine staining process of rice, indicating fluoride adsorption. Fluoride accumulation in rice and vegetables increased when the soaking temperature was raised to 100 °C due to the gelatinization of rice grains and softening of vegetables. Ingesting foods boiled in fluoride-containing water increased the fluoride intake per body weight of infants more significantly than that in children and adults due to their low body weight. These results indicate that soaking and boiling foods in fluoride-containing water significantly increases fluoride intake compared to previous estimations. Therefore, it is necessary to re-evaluate the fluoride intake from food and drinking water considering the methods used for cooking food in each country and region.

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.

High-amylose starch: Structure, functionality and applications

Starch with a high amylose (AM) content (high AM starch, HAS) has attracted increasing research attention due to its industrial application potential, such as functional foods and biodegradable packaging. In the past two decades, HAS structure, functionality, and applications have been the research hotspots. However, a review that comprehensively summarizes these areas is lacking, making it difficult for interested readers to keep track of past and recent advances. In this review, we highlight studies that benefited from rapidly developing techniques, and systematically review the structure, functionality, and applications of HAS. We particularly emphasize the relationships between HAS molecular structure and physicochemical properties.

Production and Physicochemical Characterization of Analog Rice Obtained from Sago Flour, Mung Bean Flour, and Corn Flour Using Hot Extrusion Technology

Extrusion technology allows the preparation of analog rice, an artificial product made of carbohydrate sources other than rice, with characteristics similar to natural rice. In this study, we aimed at determining the effect of composition and temperature on the nutritional content of analog rice obtained using heat extrusion technology. The physical properties and acceptability of the resulting product were also studied. Skim milk, sago, mung bean, and corn flour as well as the binder carboxymethyl cellulose (CMC) were used. The procedure was conducted in four stages: raw-material preparation, formulation, physicochemical evaluation, and sensory property evaluation. The best analog rice formula was established as 50% sago flour, 30% corn flour, 19.2% mung bean flour, 0.4% skim milk, and 0.4% CMC. The panelists’ most preferred rice analog formula was the one with the highest sago starch and skim milk content. The extrusion temperature did not significantly affect the nutrient content. However, it had a considerable impact on the thermal profile and physical properties, such as appearance and granular morphology.

Removal of starch granule associated proteins alters the physicochemical properties of annealed rice starches

The effect of removal of starch granule associated proteins (SGAPs), annealing and dual-treatment on physicochemical properties of three rice starches with different amylose content (AC) was investigated. SGAPs removal reduced stability of starch granules, thus increasing amylose leaching, swelling power, solubility, and pseudoplasticity of Qiuguang (15.6% AC) and Luhui (22.1% AC) rice starches, decreasing pseudoplasticity of Yangfunuo (1.56% AC) starch, and decreasing T_o, T_p, and T_c, pasting viscosity and storage modulus of all three rice starches. Annealing decreased amylose leaching of the three starches, and pasting properties, pseudoplastic and storage modulus of Yangfunuo starch, but increased swelling power of the three starches, ΔH and T_o of Qiuguang starch, and pasting properties and pseudoplasticity of Qiuguang and Luhui starches. The effect of dual-treatment was generally the sum of effect of SGAPs removal and annealing treatment. But an interaction effect of the dual-treatment was observed for some parameters. The effect of annealing was closely related to the variety and composition of the starch.

Thermal and pasting properties and digestibility of blends of potato and rice starches differing in amylose content

In this study, waxy or normal potato starches (WPS or NPS) were blended with waxy, low-amylose or high-amylose rice starch (WRS, LARS or HARS) in different ratios (100:0, 80:20, 60:40, 40:60, 20:80 and 0:100). Pasting profiles of blends were additively between those of the component starches separately except for some mixtures of WRS and potato starches. Twin or even three gelatinization peaks were observed for potato-WRS or potato-HARS blend, while only one peak was observed in potato-LARS blend. Addition of WRS enhanced the nutritional profile of blends containing WPS by decreasing the rapidly digestible starch level. Microscopy revealed that addition of WRS was beneficial for the development of dense and compact structure of gels of blends compared with their counterparts, which may be because few amylose chains leached to inhibit the interaction between swollen potato and rice starch granules. Besides, peak, trough, breakdown and final viscosity as well as gelatinization enthalpy showed significantly negative correlations with amylose leaching. Non-additive behaviours were observed for properties, but more independent behaviour was observed between potato starch and LARS or HARS. Results suggested that properties of blends of potato and rice starches differing in amylose content varied through different extents of amylose leaching.

Effect of Microwave Cooking on Quality of Riceberry Rice (Oryza sativa L.)

Microwaves have been applied for cooking, warming, and thawing food for many years. Microwave heating differs from conventional heating and may cause variation in the food quality. This study determined the quality of Riceberry rice (Oryza sativa L.) after microwave cooking using various rice-to-water ratios at three power levels (360, 600, and 900 W). The texture of all microwave-cooked samples was in the range 162.35 ± 5.86 to 180.11 ± 7.17 N and was comparable to the conventionally cooked rice (162.03 N). The total phenolic content (TPC) and the antioxidant activity of the microwave-cooked rice were higher than those of the conventional-cooked rice. Microwave cooking appeared to keep the TPC in the range 241.15–246.89 mg GAE/100 g db and the antioxidant activities based on DPPH and ABTS assays in the ranges 134.24–137.15 and 302.80–311.85 mg·TE/100 g db, respectively. Microwave cooking also maintained similar contents of fiber, ash, and total starch to those from conventional cooking. The glycemic index (GI) for all freshly cooked rice samples was not significantly different, and the rice was classified as a high-GI food. Microwave cooking could be recommended as an alternative technique for rice cooking due to its rapid heating regime and the comparable quality and maximized TPC and antioxidant activity of the cooked rice.

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.