Changes in phenolic compounds in lentils (Lens culinaris) during germination and fermentation

 Germination and fermentation have been proposed to improve the nutritive value of legumes. This paper reports the changes that occur in phenolic compounds in lentils (Lens culinaris var. vulgaris) during germination and fermentation. Levels of low-molecular-weight phenolic compounds (benzoic acids and aldehydes, hydroxycinnamic acids and derivatives, flavan-3-ols and procyanidins) were determined. Germination did not appreciably vary the content of phenolic compounds, although important structural changes in procyanidin-type compounds were observed. Fermentation led to a general increase in the content of phenolic compounds. Gentisic acid, p-hydroxyphenylpropionic acid, tryptophol and three other unknown compounds were detected in fermented lentils, but not in raw lentils. The influence of these changes on the potential antinutritional effects associated with phenolic compounds in legumes, as well as on the antioxidant properties attributed to these compounds is discussed. Received: 16 December 1996 / Revised version: 6 March 1997     

The impact of cooking method on the phenolic composition,total antioxidant activity and starch digestibility of rice (Oryza sativa L.)

This study investigated changes in the phenolic composition, total antioxidant activity (TAA) and starch digestibility in white and brown rice due to three different cooking procedures, and subsequent reheating of cooked rice after storage. Among the analyzed samples, brown rice showed the highest TAA and phenolic content (622.5 mg/kg DW). All cooking methods resulted in significant decrease of phenolic content and TAA of rice (p < 0.05). The greatest loss was observed after processing in rice cooker, which reduced phenolic content of both brown and polished rice by ～30% and ABTS radical‐scavenging activity by 20 and 28%, respectively. In general, the levels of polyphenols and TAA of cooked rice tended to further decline after storage and reheating, but to a much lesser extent when rice was prepared using microwaves. The application of in vitro digestion system disclosed that the microwave cooking resulted in the highest starch digestibility among cooking methods used.

Practical applications

Rice is one of the most commonly consumed staple foods worldwide. Scientific and epidemiological studies have showed that their phytochemicals exhibit antioxidant, anti‐inflammatory, antihypertensive and chemopreventive effects. Therefore, their high consumption, easy availability throughout the year and use as an additive to meat and high‐fat foods may make rice, especially in the form of whole grains, potentially important chemopreventive component of the diet. The appropriate cooking procedure of rice is crucial for preservation of bioactive compounds as well as digestion of starch and thus duration of the glycemic response. Preferably, this study is focused on the evaluation of the effect of cooking methods on the health‐related quality of rice. The results provide practical advice that the consumption of freshly cooked rice ensures its highest nutritional quality, while rice microwaving is recommended both when cooked rice will be reheated after storage (e.g., in restaurants) and accelerated starch digestion is in favor.     

In vitro fermentability and antioxidant capacity of the indigestible fraction of cooked black beans (Phaseolus vulgaris L.), lentils (Lens culinaris L.) and chickpeas (Cicer arietinum L.)

BACKGROUND: Pulses represent an important source of protein, as well as digestible and indigestible carbohydrates. Little information is available on the indigestible carbohydrates and antioxidant capacity of legume seeds. The cooked seeds of three pulses (black bean, chickpea and lentil) were evaluated for their indigestible fraction (IF), polyphenols content, antioxidant capacity and in vitro fermentability, including short‐chain fatty acid production. RESULTS: The insoluble indigestible fraction (IIF) was higher than the soluble counterpart (soluble indigestible fraction, SIF). The SIF value was highest in black beans, while no difference was observed between chickpeas and lentils. Black beans and lentils had higher polyphenols content than chickpeas. The IF of black beans exhibited the lowest and chickpeas the highest associated polyphenols content. Condensed tannins were retained to some extent in the IF that exhibited significant antioxidant capacity. The total IF of the three pulses produced short chain fatty acids (SCFA) after 24 h of in vitro fermentation by human colonic microflora. IF from black bean and lentil were best substrates for the fermentative production of butyric acid. CONCLUSIONS: It is concluded that the IF of pulses might be an important source of bioactive compounds. Copyright © 2010 Society of Chemical Industry     

Effects of harvesting procedure,storage time and climatic conditions on cooking time of lentils (Lens culinaris Medikus)

In an experiment conducted over 2 years in Larissa, the effects on the cooking times of six lentil varieties of different harvest periods (early and late), seed storage for 1 year and climatic conditions prevailing during seed production were studied. Cooking time was estimated by measuring seed hardness using a penetrometer (PNR‐6). Late harvesting (when the plants were completely dry) increased cooking times by 6–16% in comparison with early harvesting (when the plants were partly green). This increase was less for the short‐cooking genotypes ‘Dimitra’, ‘Samos’ and ‘Thessalia’ than for the long‐cooking genotypes ‘Arachova’ and ‘Nikaia’. After 1 year of seed storage, cooking times increased on average by 6–9%. Seeds produced during a dry year (1995) required on average 38% less time to cook than seeds produced during a wet year (1996), irrespective of harvest period or duration of seed storage. © 2001 Society of Chemical Industry     

萌发对芸豆酚类物质及抗氧化活性的影响

研究了萌发过程对黑芸豆、奶花芸豆、紫花芸豆中多酚、黄酮含量及抗氧活性的影响,并对多酚、黄酮含量及抗氧化能力做了相关性分析。结果表明:三种芸豆萌发（0⁶ d）后多酚、黄酮含量及抗氧化活性较未萌发的均显著降低（p<0.05）。且浸泡损失的多酚、黄酮高于萌发期间;黑芸豆萌发6 d后多酚、黄酮含量可能由于内切酶的作用开始增加。萌发期间,三种芸豆的DPPH·清除能力（DPPH）、ABTS+·清除能力（ABTS）、铁离子还原抗氧化能力（FRAP）、氧化自由基吸收能力（ORAC）均有降低趋势。多酚、黄酮含量与抗氧化能力极显著相关（p<0.01）,且多酚与ABTS值的相关性最高（r=0.955）。此外,黑芸豆的抗氧化能力萌发4 d后开始增加,萌发6 d时黑芸豆和奶花芸豆的ORAC值高于0 d。合适的萌发条件能更好的保留芸豆的生物活性物质。      

Antioxidant activity and phenolic content of lentils (Lens culinaris), chickpeas (Cicer arietinum L.), peas (Pisum sativum L.) and soybeans (Glycine max), and their quantitative changes during processing

Total phenolic content (PC) was ～12 mg g^?1 in lentils, 2.2 mg g^?1 in chickpeas, 2.3 mg g^?1 in soybeans, 2.5 mg g^?1 in yellow peas and 1.2 mg g^?1 in green peas. Total antioxidant activity (AA) determined by ABTS (2,2′‐azinobis‐3‐ethyl‐benzthiazoline‐6‐sulfonic acid) assay was highest in lentils at around 14 μmol Trolox equivalent antioxidant capacity (TEAC) g^?1 and lowest in green peas at 1.9 μmol TEAC g^?1. Bound phytochemicals contributed to 82–85% total AA in lentils. Free phytochemicals contributed more to total AA in chickpeas, yellow peas, green peas and soybeans than bound phytochemicals. AA and PC was reduced by ～80% in lentils and <30% in yellow peas by decortication, by 16–41% in lentils, chickpeas and peas by cooking, and by 22–42% in lentils by soaking. Total AA was significantly correlated with total PC. Soybeans had the greatest ability to scavenge free radicals, inhibit lipid peroxidation and chelate metals among the legumes tested. Different legumes exhibited different AA mechanisms.     

煮制加工对不同绿豆中黄酮含量的影响及抗氧化活性研究

在绿豆加工过程中,煮制对黄酮类物质相对含量影响较大,所以本实验分别考察了乙醇浓度、煮制温度、煮制时间和pH对绿丰2号和5号两种绿豆煮制液中黄酮含量的影响,在单因素试验基础上通过正交试验对影响黄酮含量的因素进行了优化研究,并对提取出的两种黄酮进行抗氧化活性测定。结果表明:乙醇浓度和pH对煮制液黄酮含量影响显著。最佳的煮制工艺参数为:pH为7.5,煮制温度80℃,煮制时间1.6 h,乙醇浓度为70%。在此提取参数下,绿丰2号绿豆的黄酮类化合物提取量为1.82 mg/g,绿丰5号绿豆的黄酮类化合物提取量为1.77 mg/g;而两种绿豆黄酮类化合物对DPPH自由基、羟基自由基、超氧阴离子自由基均有清除能力,同时,该研究也将为下一步绿豆饮料的开发中黄酮类物质的抗氧化活性提供数据依据。     

Effect of domestic cooking methods on total phenolic content,antioxidant activity and sensory characteristics of Hericium erinaceus

This study evaluated the effect of different cooking methods (microwaving, boiling, steaming and stir-frying) on the phenolic acids and antioxidant activity in Hericium erinaceus (HE). The total phenolic content (TPC) of HE decreased after cooking and was in the order of dried (control) > stir-fried > microwaved > steamed > boiled. An increase in antioxidant activity was found in all cooked HE, albeit statistically insignificant (P > 0.05). Gallic acid was reported to be the dominant phenolic acid found in HE extracts in the range of 3.03–49.41 μg g⁻¹ dry weight. Low negative correlations were observed between 2,2-diphenyl-1-picrylhydrazyl (DPPH) and TPC as well as DPPH and gallic acid profile. Sensory data revealed that stir-fried HE received the most favourable response in colour, texture, aroma and flavour attributes. Overall, this study suggested that the method of stir-frying could be used to prepare HE for better retention of gallic acid and antioxidant activity with acceptable sensory characteristics.     

Effect of germination on vitamin C,phenolic compounds and antioxidant activity in flaxseed (Linum usitatissimum L.)

Flaxseed (Linum usitatissimum L.) is well known for its health benefits and chemical composition. This study aimed to evaluate the dynamic changes caused by germination in vitamin C, phenolic compounds and antioxidant activities of flaxseed. It was observed that eight‐day germination of flaxseed sprouts caused increases in phytochemical contents, that is 22.1‐fold increase in vitamin C, 2.67‐fold increase in phenolics and 5.48‐fold increase in flavonoid contents as compare to initial concentration in flaxseeds on dry weight basis. The stimulation was also noted in the three identified phenolic acid ingredients including caffeic acid, p‐coumaric acid and ferulic acid. Similarly, the total PSC and ORAC values of flax sprouts at day 8 increased by 3‐ to 4‐folds compared to nongerminated flaxseeds. It is revealed that comparatively, 8‐day germination of flax sprouts leads to a significant increase in vitamin C, phenolic constituents and total antioxidant activities than those of flaxseeds.     

A global survey of effects of genotype and environment on selenium concentration in lentils (Lens culinaris L.): Implications for nutritional fortification strategies

Lentils (Lens culinaris L.) are an important protein and carbohydrate food, rich in essential dietary components and trace elements. Selenium (Se) is an essential micronutrient for human health. For adults, 55 μg of daily Se intake is recommended for better health and cancer prevention. Millions of people around the world have Se-deficient diets and biofortification may be an effective solution. The total Se concentration of lentils grown in six major lentil-producing countries were analysed to determine the potential for Se biofortification in these regions. The highest Se concentrations based on location means were found in lentils from Nepal (180 μg/kg) and southern Australia (148 μg/kg) while the lowest were those from Syria (22 μg/kg), Morocco (28 μg/kg), northwestern USA (26 μg/kg), and Turkey (47 μg/kg). Significant location effects within a country were observed for Nepal and Australia. All values were lower than previous published data for Saskatchewan grown lentils (425–672 μg/kg). Lentils originating from Australia, Nepal, or Canada could be considered good sources of Se, as consumption of 50 g would provide 13–61% of the recommended dietary allowance (RDA). Our findings indicate lentil may be appropriate as a target crop for Se biofortification and investigated as a food-based solution for populations with Se deficiencies.     

Firmness, seed wholeness and water uptake during the cooking of lentils (Lens culinaris cv. anicia) for 'sous vide' and catering preparations

The study aimed to optimize cooking conditions of lentils ( Lens culinaris cv. anicia ) for 'sous vide' processing and catering. the softening rate of lentil seeds during cooking in deionized water was consistent with two simultaneous first order mechanisms. the apparent activation energies of firmness breakdown and loss of integrity were 86.5 kJ mol⁻¹ and 271.3 kJ mol⁻¹, respectively. Wholeness of the lentils was better preserved when the cooking temperature did not exceed 90°C. the loss of firmness was a consequence of hydration of the seed since the regression coefficient between the logarithm of residual firmness and water uptake reached −0.93 regardless of cooking temperature and heating medium (steam or water). Thus, lentil seeds maintained their firmness and wholeness as required for 'sous vide' and catering if they were cooked below 90°C for up to 2 h. Higher temperature or longer cooking time resulted in loss of firmness and wholeness.     

响应面法优化水黄芹总黄酮提取工艺及其抗氧化研究

目的:确定水黄芹中总黄酮的最佳提取工艺,并评价其抗氧化活性。方法:在单因素实验基础上,利用响应面法优化水黄芹总黄酮的提取条件;通过总黄酮对DPPH·和ABTS·的清除作用来研究其抗氧化活性。结果:水黄芹总黄酮最佳提取工艺为乙醇浓度74%、料液比1∶30(g/m L)、提取温度72℃、提取时间115min,此条件下,总黄酮得率为1.59%,与预测值1.60%接近,其偏差为0.63%。水黄芹总黄酮对DPPH·和ABTS·具有较好的清除能力,其IC50值分别为7.67、12.88μg/m L。      

大叶金花草总黄酮的抗氧化活性研究

[目的]研究大叶金花草总黄酮的抗氧化活性.[方法]分别采用DPPH自由基法、羟基自由基法和对亚硝化反应的抑制作用研究了大叶金花草总黄酮的抗氧化性.[结果]当大叶金花草总黄酮浓度在13.16μg/mL～78.96μg/mL和0.43μg/mL～52.64μg/mL范围内,其对DPPH自由基和羟基自由基的清除率分别为20.87％～71.11％和9.04％～52.21％,且都存在明显的量效关系;0.115mg/mL的大叶金花草总黄酮溶液12mL对亚硝胺合成的阻断率可达69.66％,0.088mg/mL的大叶金花草总黄酮溶液12mL对NaN02的清除率可达60.71％.[结论]大叶金花草总黄酮具有一定的抗氧化活性.     

Effects of cooking methods on polyphenols,pigments and antioxidant activity in potato tubers

Potato tubers, which are one of the richest sources of antioxidants, are always cooked before human consumption. The objective of this study was to understand the effects of various domestic cooking methods, i.e., boiling, microwaving and baking on total phenolics, flavonoids, flavonols, lutein, anthocyanins and antioxidant activities in 5 cultivars and 9 advanced selections with different skin and flesh colors after 6 months of storage. The three cooking methods reduced the levels of these compounds and the percentage of DPPH (2,2-Diphenyl-1-pikryl-hydrazyl) radical scavenging activity in all the cultivars and selections. Boiling minimized these losses. Red fleshed tubers contained more flavonoids, whereas purple tubers contained more flavonols. Despite severe loss of these compounds due to cooking, both the flesh types retained larger amounts of all these compounds due to higher initial levels. Decline in the radical scavenging activity is directly related to loss of these compounds due to cooking treatments in all white and colored flesh tubers. Red and purple fleshed tubers exhibited greater radical scavenging activity than yellow and white fleshed tubers after each of the cooking treatments. Correction procedures were introduced to exclude interfering compounds (ascorbic acid, other oxidizing agents and reducing sugars) in Folin-Ciocalteu Reagent (FCR) assay of estimating total phenolics in potato.     

Effect of cooking on total vitamin C contents and antioxidant activity of sweet chestnuts (Castanea sativa Mill.)

In this work the total vitamin C contents (ascorbic acid + dehydroascorbic acid) and antioxidant activity of raw and cooked chestnuts was evaluated. The vitamin C contents of raw chestnuts varied significantly between the different cultivars (cv) studied and it varied from 400 mg/kg dry weight (cv Lada) to 693 mg/kg dry weight (cv Martaínha). The different cultivars behave differently during the cooking process concerning the loss of vitamin C. A significant decrease in the vitamin C content of the chestnuts was observed, 25–54% for the boiling process and 2–77% for the roasting process. Boiled and roasted chestnuts can be good sources of vitamin C since it may represent 22.4%, 16.2%, 26.8% and 19.4%, respectively, of the recommended dietary intake for an adult man and woman. The cooking process significantly changed the antioxidant activity of the chestnuts. A difference was observed between the cultivars during the cooking processes, concerning the antioxidant activity. For the raw chestnuts the variation in vitamin C content of the chestnuts explains 99% of the antioxidant activity variation but for the roasted and boiled chestnuts this percentage significantly decreases to 51% and 88%, respectively. Although a high antioxidant activity is still present in the cooked chestnuts, the cause for this antioxidant activity is less dependent on the vitamin C content of the chestnuts, probably due to the conversion of ascorbic acid to dehydroascorbic acid. The increase in gallic acid during the cooking process, presumably transferred from the peels to the fruit, also contributes to the high antioxidant activity observed for the cooked chestnuts.     

五爪金龙叶总黄酮的提取、纯化及抗氧化活性研究

采用超声辅助提取五爪金龙叶总黄酮,在单因素试验基础上,利用正交试验优化提取黄酮的最佳工艺条件,粗黄酮经大孔树脂HPD600纯化,通过测定精制黄酮和抗坏血酸的还原力、羟自由基消除能力和DPPH自由基的清除能力,来评价其抗氧化活性。结果表明,五爪金龙叶总黄酮的最佳提取条件为温度50℃,乙醇浓度80%,料液比1∶35(g·m L-1),时间15min,超声功率120W,总黄酮的提取率可达3.613%。大孔树脂纯化后黄酮含量由18.53提高至83.62%。五爪金龙叶纯化黄酮的还原能力、羟自由基消除能力比同浓度的抗坏血酸差,但随着浓度增大而增大;DPPH消除能力和同浓度抗坏血酸相仿,五爪金龙叶黄酮具有一定抗氧化活性,可作为天然抗氧剂开发。     

提取溶剂对青稞提取物总酚、黄酮含量及其抗氧化活性的影响

以3种不同的青稞为原料,采用不同的提取溶剂(水、60%乙醇、60%甲醇、60%丙酮、95%乙醇、100%甲醇、100%丙酮)对青稞进行提取。对各提取物的总酚、总黄酮进行测定,同时采用3种抗氧化方法:二苯代苦味酰自由基(DPPH)、2,2’-联氨-双(3-乙基苯并噻唑啉-6-磺酸)二胺盐自由基(ABTS)和总抗氧化能力(FARP)评价青稞提取物的抗氧化活性。结果表明,95%乙醇和60%丙酮更有利于青稞多酚的提取。藏青2000的各溶剂提取物的总酚、总黄酮及抗氧化活性普遍高于相应溶剂的循化蓝青稞和香格里拉绿青稞。藏青2000的60%丙酮提取物含有最高的总酚含量,达到211.92mg GAE/100g DW;在60%乙醇提取时具有最高的总黄酮含量,达到60.11mg RT/100g DW;在60%乙醇提取时具有最强的DPPH清除能力,达到80.08%;而用60%丙酮提取时,具有最强的ABTS清除能力和总抗氧化能力,分别达到了1.85,9.28 mmol TEAC/100g DW。总酚含量与抗氧化活性均具有显著的相关性,FRAP法与DPPH、ABTS法具有极显著的相关性。综上表明,青稞富含总酚成分,是一种潜在的天然抗氧化剂资源。     

Effect of cooking on phytic acid content and nutritive value of Pakistani peas and lentils

The effects of a traditional domestic cooking procedure on the phosphorus/phytate relationship and the nutritional quality of three varieties of Pakistani (a) peas and (b) lentils were investigated. A cooking procedure which involved steeping, followed by boiling, of the seeds resulted in (a) a reduction of considerable amounts of phytic acid from both peas (82% reduction) and lentils (76% reduction), and (b) an improvement in the net protein utilization, true protein digestibility and biological value of the legume seeds. No apparent relationship was observed between the loss of phytate from the seeds and the improvement of nutritional quality which resulted from the cooking procedure.