Physicochemical and digestion characteristics of flour and starch from eight Canadian red and green lentils

Physicochemical and nutritional properties of flour and isolated starch from eight Canadian lentil cultivars were assessed to identify unique samples and key factors affecting starch digestion. The results showed that nearly half of apparent amylose in lentil flours was underestimated because it was complexed and embedded within the flour matrix, which led to slower starch digestion of cooked flour. Cooked red lentil flours showed significantly higher resistant starch content (11.0%) than flours from green lentils (6.8%) (P < 0.05). Among green lentils, Asterix and Greenland were unique for their high slowly digestible starch content after cooking, possibly owing to their high phenolic content and α‐glucosidase inhibitory activity. Long‐ and short‐range ordering in starch was more indicative of low starch digestion for raw or cooked lentil flour rather than for isolated starch. The results suggest the flour matrix protects the starch ordered structure from enzyme hydrolysis.     

Bioaccessibility and antioxidant activity of phenolic compounds in cooked pulses

The aim of this study was to evaluate the bioaccessibility of polyphenols and antioxidant activity in cooked pulses and to study the effect of cooking on their total phenolic content (TPC) and antioxidant capacity. Cooked faba beans showed the highest TPC, followed by soybeans and lentils or peas. TPC ranged from 10.4 ± 0.2 to 52.9 ± 0.3 mg/100 g and was positively correlated with antioxidant activity. Cooking resulted in increased TPC and antioxidant activity of the methanolic extracts, caused by cell disruption and improved extraction of polyphenols. Although polyphenols were lost in the cooking water, boiled legumes had more polyphenols than those resulting cooking broths. In vitro gastrointestinal digestion resulted in increased TPC and antioxidant capacity of the extracts. Soybeans showed the highest amount of bioaccessible polyphenols. The release of phenolics from cooked legumes was mainly achieved during the intestinal phase. Literature data may underestimate the TPC and antioxidant capacity of pulses.     

High-temperature air fluidization improves cooking and eating quality and storage stability of brown rice

Brown rice contains many valuable active ingredients; but due to its long cooking time, hard texture, heavy rice bran taste, and short shelf life, it is not widely accepted by consumers. Herein, we developed a novel processing technology so-called high-temperature air fluidization (HTAF) to treat brown rice. The effects of the HTAF treatment at 120 °C, 130 °C, and 140 °C for 60 s at a feed rate of 80 kg/h on the quality of brown rice were investigated. The results showed that the treatment with HTAF caused fissures to form on the surface and the interior of brown rice, and these fissures appeared to facilitate the penetration of water into the rice kernels during soaking. The optimal HTAF treatment temperature was 130 °C, the water adsorption of HTAF-treated brown rice at 130 °C (TBR-130) was increased to 25.3% after soaking for 160 min, which was higher than that of white rice and untreated brown rice (UBR; 13.7%). The optimal cooking time for TBR-130 was also 5 min shorter than that for UBR. The results further showed that TBR-130 had a larger degree of volume expansion compared to that of UBR, and cooked TBR-130 had softer texture than cooked UBR. The cohesiveness and sensory quality of TBR-130 were also higher than those of UBR, and the content of flavor compounds in TBR-130 was similar to that of white rice. HTAF caused no obvious damages to the main active components or nutritional components of TBR-130. Finally, TBR-130 had better chromaticity and higher storage stability than UBR. These results demonstrate that the HTAF treatment can improve cooking and eating quality and storage stability without causing obvious damages to nutritional quality of brown rice. This technology may play important roles in an attempt to promote the use of brown rice as staple foods.     

红小豆-粳米混合食物的碳水化合物体外消化速度研究

碳水化合物的消化速度直接影响着淀粉类主食的餐后血糖反应,因此可利用碳水化合物的体外模拟消化预测淀粉类主食品的血糖反应。用胰酶模拟小肠消化测定了几种烹调方法下红豆-粳米混合膳食中碳水化合物的消化速度,并探讨了其中快速消化淀粉(RDS)、慢速消化淀粉(SDS)和抗性淀粉(RS)相对含量的变化,结果表明:高压烹调显著提高了整豆-粳米混合食物的水解率和RDS含量,但豆粉-米混合食物在不同烹调压力下的差异不显著。整豆和大米分别烹调后再混合的食物与豆谷共同烹调食物相比,抗性淀粉的含量较高,且淀粉消化指数较低。红小豆-粳米混合食物的消化速度与精白粳米的消化速度呈显著性差异(p<0.05)。烹调方法对食物中碳水化合物的消化速度有很大影响。血糖调节异常的人群适合在主食原料中添加整豆类食物,以帮助稳定餐后血糖反应。     

Effect of simulated gastrointestinal digestion on phenolic composition and antioxidant capacity of cooked cowpea (Vigna unguiculata) varieties

Consumption of diets rich in phenolic compounds has been associated with reduced risk of chronic diseases. The effect of cooking and simulated gastrointestinal digestion on phenolic compounds and antioxidant properties of two cowpea (Vigna unguiculata) types was determined. Phenolic acids, flavan‐3‐ols and flavonols were the main groups of phenolic compounds identified. Cooking and simulated enzyme digestion of the cooked cowpea samples rendered some phenolics less extractable (possibly by promoting binding with other food components) or more extractable (possibly by release of bound forms). Total phenolic contents and radical scavenging properties of the cowpeas were reduced upon cooking, but increased upon simulated enzyme digestion. Cowpea extracts inhibited human LDL oxidation at a concentration of 2 mg mL^?1 possibly due to their phenolic content. Phenolic compounds in cowpea can potentially protect against cardiovascular diseases for which LDL oxidation is a risk factor.     

Effect of ageing-induced changes in rice physicochemical properties on digestion behaviour following storage

The changes in rice grains structure and digestion behaviours were investigated following storage at 4 °C and 37 °C, respectively. Pasting study indicated that rice samples stored at 37 °C demonstrated a consistent increase in the time to peak viscosity of the Rapid ViscoAnalysis parameters, implying a quick ageing progress. Compared to the rice stored at 4 °C, aged rice (stored at 37 °C) showed a coarser morphology after cooking by SEM, suggesting a limited starch gelatinization. Consistently, ageing process led to a decrease in the leaching of starch molecules in cooking residual water, which further confirmed that starch granules in aged rice grain caused less hydration and swelling. The analysis of the amount of cell wall remnants showed that rice stored at 37 °C caused a significant increase in the amount of cell wall remnants along the storage at 37 °C, which might suggest that the cell wall structure of the rice grains became more lignified because of the ageing. Furthermore, the ageing process significantly reduced rice digestion kinetics both in rate and extent. Thus, it is assumed that ageing process leads to the cell walls becoming more strengthened and lignified, which makes the rice grain more organized in its structure, and subsequently reduces starch granules disruption and molecules leaching during the cooking. Therefore, this study suggests that the changes in digestion behaviours of rice are highly associated with the changes in rice physical and chemical properties occurred during storage and the ageing process might be another option for manipulating rice digestion properties.     

Effect of Various Processing Methods on the Physical Properties of Cooked Rice and on in vitro Starch Hydrolysis and Blood Glucose Response in Rats

The effects of various cooking methods on the physical and structural properties cooked rice, on the in vitro hydrolysis of the contained starch and on blood glucose response in rats were investigated. At optimum cooking state, a larger filamentous network was formed and most of the starch granules were fragmented, furthermore the samples heated by microwave and electric cooker showed a more compact structure compared to those treated in an autoclave or stone pot. The highest degree of gelatinization (DG) was observed in the sample treated in an autoclave (75.2%), followed by stone pot (71.1%), electric cooker (66.9%) and microwave oven (64.6%). The highest firmness (3.49 N) was observed in cooked rice heated by microwaves and no significant differences (p > 0.05) were found between the other samples. All cooked rice samples showed increased pasting temperatures and decreased peak viscosity compared to those of raw rice flour. The starch hydrolysis rates and their kinetic constants of cooked rice samples increased with increase in DG, and relatively higher values were observed in samples treated in the autoclave and stone pot. There was a significant difference in the blood glucose content depending on cooking methods, and the highest glucose level was observed in the sample heated by autoclaving.     

Delayed drying interval of red rice: Effects on cooking properties,in vitro starch digestibility and phenolics content

Maintaining the cooking characteristics and bioactive compound contents in red rice is essential during the post-harvest stages. For this reason, this study aimed to evaluate the influence of delayed drying time interval of 3 and 6 days and temperature of 15 and 25 °C followed by storage for 12 months on the cooking properties, in vitro starch digestibility, and the phenolic contents of red rice. The increased the delayed interval duration reduced the protein solubility, rehydration capacity, and free phenolic contents, and increased the cooking time and hardness after cooking in a temperature-independent manner. These changes reduced the starch digestibility of red rice. Increased the delayed interval duration also reduced the proanthocyanidin contents, consequently changing the grain color (decreased luminosity and increased a1 values). Thus, a delay in the interval duration before drying of 3 days at 15 °C showed the best results about the rice characteristics among the evaluated parameters; these conditions may be utilized when immediate drying is not possible.     

糙米酚类物质对淀粉消化特性的影响研究进展

糖尿病等慢性病是全球范围内重要的公共卫生问题。淀粉摄入是导致餐后血糖升高的主要原因之一。近年来研究表明，多酚类物质能够延缓淀粉的消化速率。糙米富含丰富的酚类物质，作为重要的全谷物来源，其营养健康功效在全世界得到广泛共识。糙米酚类物质特有基团如酚羟基对消化酶类产生一定的抑制作用，在加工过程中淀粉自身结构的改变也使消化酶类对其的作用减小，不仅能有效控制淀粉的消化速率及消化率，还能改善食品品质。本文从糙米中酚类物质及其抗氧化活性、淀粉消化过程、糙米多酚对淀粉消化特性的影响及其作用机制等几个方面进行综述，旨在阐明全谷物糙米酚类物质延缓淀粉消化的科学依据，为开发适用于慢性病人群、肥胖人群、超重人群、老年人群等的全谷物糙米基和淀粉基食品提供参考。     

The Glycemic Potential of White and Red Rice Affected by Oil Type and Time of Addition

Limited research exists on how different oil types and time of addition affect starch digestibility of rice. This study aimed to assess the starch digestibility of white and red rice prepared with 2 oil types: vegetable oil (unsaturated fat) and ghee (clarified butter, saturated fat) added at 3 different time points during the cooking process (“before”: frying raw rice in oil before boiling, “during”: adding oil during boiling, and “after”: stir‐frying cooked rice in oil). Red rice produced a slower digestion rate than white rice. White rice digestibility was not affected by oil type, but was affected by addition time of oil. Adding oil “after” (stir‐frying) to white or red rice resulted in higher slowly digestible starch. Red rice cooked using ghee showed the lowest amount of glucose release during in vitro digestion. The addition of ghee “during” (that is boiling with ghee) or “before” (that is frying rice raw with ghee then boiling) cooking showed potential for attenuating the postprandial glycemic response and increasing resistant starch content. This is the first report to show healthier ways of preparing rice. White rice with oil added “after” (stir‐fried) may provide a source of sustained glucose and stabilize blood glucose levels. Boiling red rice with ghee or cooking red rice with ghee pilaf‐style may provide beneficial effects on postprandial blood glucose and insulin concentrations, and improve colonic health. The encouraging results of the present study justify extending it to an in vivo investigation to conclusively determine the effect of time of addition of fat when rice is cooked on blood glucose homeostasis.     

Antioxidant Extracts from Acorns (Quercus ilex L.) Effectively Protect Ready‐to‐Eat (RTE) Chicken Patties Irrespective of Packaging Atmosphere

This study evaluated the impact of a phenolic‐rich acorn extract (200 ppm gallic acid equivalents) and the concentration of oxygen in the packaging system (low‐oxygen modified atmosphere; 5% vs. normal‐oxygen; 21%) on lipid and protein oxidation and consumers acceptance of the ready‐to‐eat chicken patties. Samples were subjected to cooking (electric oven, 170 °C/16 min), cold storage (14 d at 4 °C), and reheating (microwave, 600 mW/1 min). Samples treated with acorn extract kept thiobarbituric acid‐reactive substances numbers and lipid‐derived volatiles at basal levels throughout the whole processing irrespective of the oxygen concentration in the packaging atmosphere. Consistently, treated patties had lower protein carbonyls than control ones. The acorn extract also controlled color and texture deterioration during chilled storage and reheating and improved the color and odor acceptance of the products. Formulating with acorn extract is a feasible strategy to inhibit the oxidation‐driven changes and preserve the quality of reheated samples as if there were freshly cooked. Compared to the effect of the antioxidant extract, the concentration of oxygen in the packaging system was negligible in terms of quality preservation.     

Changes in kernel properties,in situ gelatinization,and physicochemical properties of waxy rice with inhibition of starch branching enzyme during cooking

The kernel properties, gelatinisation and physicochemical properties of rice were investigated in a waxy rice Guang-ling-xiang-nuo (GLXN) and its transgenic line GLXN-RNAi with inhibition of starch branching enzyme I/IIb. The volume swelling, water content and leached material of cooked kernels increased with increasing cooking time, but they were lower in GLXN-RNAi than in GLXN. The kernels of GLXN-RNAi were more difficultly gelatinised and disrupted than those of GLXN during cooking. The starch in the exterior of GLXN-RNAi endosperm was not completely gelatinised. The C_A-type starch of GLXN-RNAi was more resistant to cooking than A-type starch of GLXN. The cooked kernels of GLXN-RNAi had lower rapidly digestible starch and greater slowly digestible starch than those of GLXN. Brown rice flour had higher peak, hot, final and setback viscosities and lower breakdown viscosity in GLXN than GLXN-RNAi. These results indicated that GLXN-RNAi kernels exhibited great potential in applications as health foods.     

不同品种糙米营养品质和理化特性比较

以7个来源于湖北省的不同品种糙米为原料,以营养组分含量、阳离子交换能力、胆固醇吸附能力、亚硝酸根吸附能力、淀粉消化特性为评价指标,研究比较糙米品种间营养品质和理化特性的差异性,旨在为糙米加工原料选择提供参考。结果表明：不同品种糙米的粗蛋白、直链淀粉、氨基酸和总酚含量差异较大,广两优香66的粗蛋白和必需氨基酸含量均最高,而罗田贡米的直链淀粉和总酚含量最高,分别为15.90%（m/m）和196.54 mg GAE/100 g DW。罗田贡米的胆固醇吸附能力和亚硝酸根吸附能力分别为 55.05 mg/g和0.20 mg/g,均显著高于其它品种糙米（P<0.05）,广两优香66和鄂中5号也展现出较强的阳离子交换能力和亚硝酸根吸附能力;巨两优60和罗田贡米的快速消化淀粉含量最低,慢速消化淀粉含量最高,具有明显延缓淀粉消化的作用。比较筛选出广两优香66（高蛋白、高赖氨酸）和罗田贡米（高总酚、胆固醇和亚硝酸根吸附能力强、延缓淀粉消化作用强）的高营养和高功能性质的品种。该研究为糙米加工及产品开发提供了数据支撑。     

Multi‐scale structural and digestion properties of wheat starches with different amylose contents

The physicochemical and digestion properties of three wheat starches with different amylose contents were studied. Scanning electron microscopy (SEM) showed they displayed a spherical disc‐like form, a lenticular shape and an irregular morphology, respectively. Compared with waxy and normal wheat starches, high‐amylose wheat starch (HAWS) was characterised by the presence of lower molecular weight amylose fraction, and its granules demonstrated the highest resistance to the cooking. The changes in the IR ratio 1022/999–1047/1022 cm^?1 following the gel storage suggested the molecules of HAWS are more readily to re‐associate and re‐organise into a more organised status than other two starches. The determination of glucose release showed that HAWS had the lowest digestion kinetics (P < 0.001), and this difference in the digestion properties between HAWS and the other two starches might imply that starch molecular structure, in particular amylose structure is another key factor for manipulating starch digestion property rather than amylose content alone.     

Studies on noodle quality of potato and rice starches and their blends in relation to their physicochemical, pasting and gel textural properties

The physicochemical, pasting, and gel textural properties of potato and rice starches and their blends were studied in relation to their noodle making performance. Amylose content, swelling power and solubility values of potato starch were significantly (P ≤ 0.05) higher than for rice starch. Pasting properties showed higher peak, final and setback viscosity for potato starch as compared to rice starch. Texture profile analysis revealed that potato starch gel had higher hardness, cohesiveness and chewiness as compared to rice starch gel. Potato starch noodles showed higher cooked weight and cooking loss and were scored higher by sensory panellists especially with respect to transparency and slipperiness. On the other hand, rice starch noodles were more firm with lower cooking loss. Addition of potato starch to rice starch significantly (P ≤ 0.05) affected the noodle characteristics. Among the starch blends studied, blending of potato and rice starch in the ratio of 1:1 resulted in good quality noodles in terms of their lower cooking time, higher cooked weight, transparency and slipperiness. The results revealed the possibility of blending of potato starch with rice starch in equal proportions to produce noodles of acceptable quality.     

Accelerated aging of jasmine brown rice by high-temperature fluidization technique

After being cooked, newly harvested brown rice becomes a pasty mass and swells only slightly. To modify these undesirable brown rice properties, the paddy needs to be stored for at least 3–6 months. However, problems arise since brown rice has short shelf-life (3–6 months) due to accumulation of free fatty acids (FFA) leading to rancidity during storage. In the present study, high-temperature fluidized-bed drying technique in combination with tempering step was tested to alleviate the above-mentioned problems. The quality of rice dried at temperatures of 130 and 150 °C and tempered for 30 up to 120 min was compared to that of brown rice stored at ambient temperature (approximately 30 °C) for 7 months. The experimental results showed that the cooking and eating properties of the fluidized bed dried brown rice, i.e., hardness, solid loss, volume expansion and elongation ratio, changed in a similar fashion to those of the conventionally aged brown rice. The drying temperature and tempering time affected significantly the brown rice properties. The texture of cooked thermally treated brown rice was significantly firmer than that of the conventionally aged brown rice. In addition, it was found for the thermally treated brown rice that the contents of free fatty acids increased only slightly during storage while the glycemic index reduced from high to low-medium level.     

Ohmic heating for cooking rice: Electrical conductivity measurements,textural quality determination and energy analysis

In this study, an innovative technique, namely ohmic heating was applied in rice cooking and compared with conventional method using electric rice cooker. Four types of rice samples including white rice of two varieties (KDML105 and Sao Hai), brown rice and germinated brown rice of one variety (KDML105) were used. Electrical conductivities of mixtures between rice samples and 0.1 M salt solution at various ratios were measured. Empirical models were developed for predicting electrical conductivities of rice samples as a function of temperatures. Textural properties of cooked rice samples and energy consumption were compared between ohmic and conventional cooking methods. The purposes of this work were to (1) study the possibility of applying ohmic method in rice cooking and (2) compare between cooking rice by ohmic and conventional method. The results revealed that it is possible to apply ohmic method for cooking all rice samples by using 0.1 M salt solution in the mixtures. The electrical conductivities of white rice (KDML105), white rice (Sao Hai), brown rice and germinated brown rice (KDML105) mixtures were 0.246–0.900, 0.375–1.005, 0.617–1.370 and 0.485–1.182 S/m respectively. The rice cooked by ohmic method had significantly different textural properties from that cooked by electric rice cooker. The magnitude of difference depended on the rice types. The electrical energy consumption of ohmic cooking system was approximately 73–90% of energy required for conventional rice cooker.     

基于自热米饭所需的高温流化全谷物筛选及配合技术研究

为有效提高自热米饭的营养价值及食用品质,该文以糙米、发芽糙米、黑米、绿豆、红小豆、小麦、青稞糙米为研究对象,首先研究高温流化处理前后7种全谷物吸水率、膨胀率的变化;然后测定添加到自热米饭中的7种全谷物在4℃下储藏0、1、14 d及14 d复热后的硬度,筛选出适合添加到自热米饭的全谷物;另外对筛选出的全谷物的浸泡时间和在自热米饭中添加的方法进行工艺优化;最后以全谷物的用量占自热米饭总质量的30%为目标,将筛选出的全谷物进行两两配方设计,进行感官评定,得到食用品质较好的组合配方。结果表明:高温流化处理后全谷物的蒸煮品质得到改善,且适合添加到自热米饭的全谷物种类为红小豆、绿豆、黑米和小麦;采用流化绿豆和流化红小豆浸泡1 h,流化小麦和流化黑米浸泡0 h,浸泡后均与精米混匀后蒸煮的制作工艺最佳;得到3种食用品质较好的组合:流化红小豆15%、流化绿豆15%,流化绿豆15%、流化黑米15%,流化红小豆10%、流化黑米20%。     

Application of simultaneous combination of microwave and steam cooking to improve nutritional quality of cooked purple sweet potatoes and saving time

The influence of simultaneous combination of microwave and steam cooking on contents of specific phytochemicals, carbohydrate and antioxidant activity of purple sweet potatoes (PSPs) was investigated, and compared to those of individual steaming and microwaving. Results showed that the contents of phytochemicals including total phenolics, flavonoids and anthocyanins and phenolic acids except caffeic acid increased after cooking to different extent depending on cooking methods. The PSPs cooked by simultaneous combination of microwave (500 W) and steam (1700 W) for 12 min (M₅₀₀-S₁₇₀₀-12) contained the highest of total phenolics, flavonoids, phenolic acids and anthocyanins. Simultaneous combination of microwave and steaming resulted in higher content of soluble sugar in PSPs. PSPs cooked by M₅₀₀-S₁₇₀₀-12 showed the highest antioxidant activity, which was well accordance with higher contents of phytochemicals. The findings suggest that appropriate simultaneous combination of microwave and steaming could better preserve active phytochemicals in PSPs, but significantly shorten cooking time compared with individual steaming.Industrial relevanceSimultaneous combination of microwave and steam cooking is a new technology for cooking food. However, the information about the effects of simultaneous combination of microwave and steam cooking on quality of food is limited. The present findings showed that the appropriate combination of microwave and steam cooking could significantly decrease the cooking time and improve nutrition value of cooked PSPs. This research is not only of importance for understanding the changes of food composition during different heating process, but also has important practical significance for choosing a scientific cooking methods and developing new type of cooking utensils which can better satisfy current consumers' needs.     

Effects of parboiling,storage and cooking on the levels of tocopherols,tocotrienols and γ-oryzanol in brown rice (Oryza sativa L.)

Vitamin E and γ-oryzanol display a wide range of biological activities including hypocholesterolemic, anti-inflammatory and antioxidant activities. Although white rice is far more popular worldwide, consumption of brown rice is increasing, partially on account of the presence of bioactive compounds; however, the effects of parboiling, storage and cooking on them are not well-characterized. The effects of parboiling and a 6-month storage period on the contents of vitamin E and γ-oryzanol in three brown rice cultivars grown in three different locations in Brazil were investigated. Also, their levels in branded non-parboiled and parboiled brown rice were monitored before and after cooking. Vitamin E homologues and γ-oryzanol were separated by RP-HPLC equipped with PDA and fluorescence detectors. The average levels of total tocols and γ-oryzanol in the raw brown rice cultivars studied were 25 and 188 mg/kg, respectively. Of the vitamin E homologues, γ-tocotrienol contributed with 74% of total tocols, followed by α-tocopherol, α-tocotrienol and γ-tocopherol in minor quantities. The combined processes, parboiling, storage and cooking, led to an approximate 90% reduction in tocols and only γ-tocotrienol was detectable after any of the processes. Parboiling followed by storage resulted in an approximate 40% loss of γ-oryzanol. Cooking had almost no further effect over γ-oryzanol levels in parboiled rice previously stored for 6 months.