Total phenolic content and antioxidant properties of eclipse black beans (Phaseolus vulgaris L.) as affected by processing methods

ABSTRACT:  The effects of soaking, boiling, and steaming processes on the phenolic components and antioxidant activity of black beans were investigated. All processed beans exhibited significantly ( P < 0.05) lower antioxidant activities than raw beans in total phenolic content (TPC), DPPH free radical scavenging activity (DPPH), and oxygen radical absorbing capacity (ORAC). Steaming processes resulted in a greater retention of TPC and ORAC values than the boiling processes. Pressure boiling shortened processing time compared to regular boiling, resulted in insignificant differences in TPC, but significantly increased in ORAC as compared to the regular boiling method. Pressure steaming resulted in significant decreases in TPC, DPPH, while significantly increased in ORAC compared to regular steaming. Greater TPC, DPPH, and ORAC values were detected in boiling water than in the soaking and steaming water. Mass balance analysis showed that boiling caused more dry solid loss than steaming. All of these results indicated that processing methods significantly changed contents and activities of antioxidant components of black beans. Steam processing exhibited several advantages in appearance and texture of the cooked product, shortening processing time, and in greater retention of TPC and antioxidant activities. Steam processing may be used to develop high-quality health-promoting black bean products.     

Comparative studies on the antioxidant activities of nine common food legumes against copper-induced human low-density lipoprotein oxidation in vitro

ABSTRACT:  Epidemiological studies demonstrated that the consumption of dietary antioxidant was associated with the prevention of atherosclerosis. The aim of this study was to investigate the antioxidant activities of the hydrophilic extracts from 9 selected legumes based on copper-induced human LDL oxidation model in vitro . The antioxidant activities were assessed on the basis of the formation of conjugated dienes (lag time of oxidation) and thiobarbituric acid reactive substances (TBARS) as the early and later stage markers of LDL oxidation. The results showed that the extracts of black beans ( Phaseolus vulgaris L.), lentils ( Lens culinaris ), black soybeans ( Glycine max ), and red kidney beans ( Phaseolus vulgaris L.) had significant ( P < 0.05) longer LDL oxidation lag times (128.8, 124.2, 107.7, and 111.1 min, respectively) than the LDL control group (94.9 min). No significant lag-time lengthening was observed in other tested legume extracts. On the other hand, black beans, lentils, black soybeans, red kidney beans, and pinto beans exhibited higher antioxidant capacities (Trolox equivalents) than yellow peas, green peas, chickpea, and yellow soybeans in both LDL-conjugated dienes assay and LDL-TBARS assay. Meanwhile, the antioxidant activities of these legumes against LDL-lipid peroxidation in the above assays were found to correlate very significantly ( P < 0.01) with their phenolic substances, and DPPH radical scavenging activity and ORAC (oxygen radical absorbance capacity). These results suggest that consuming black beans, lentils, black soybeans, and red kidney beans may have potential in preventing the development of atherosclerosis from the perspective of inhibiting LDL oxidation.     

Comparative analyses of phenolic composition, antioxidant capacity, and color of cool season legumes and other selected food legumes

ABSTRACT:  The objective of this study was to characterize the phenolic compounds and antioxidant activities of U.S.-produced cool season legumes. A total of 33 cool season legume samples were selected. Some common beans and soybeans were included for comparisons. Total phenolic content (TPC), total flavonoid content (TFC), and condensed tannin content (CTC) were analyzed. Ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, and oxygen radical absorbance capacity (ORAC) were used for analyzing antioxidant properties. Color of the legume flour and the seed coat was also analyzed. TPC, TFC, CTC, FRAP, DPPH, and ORAC values of legumes were significantly different not only between classes but also among samples within each class. Among cool season legume classes, lentils possessed the highest concentrations of the phenolic compounds and antioxidant activities. Colored common beans and black soybeans exhibited higher TPC, TFC, CTC, FRAP, DPPH, and ORAC values than those of yellow peas, green peas, and chickpeas. Antioxidant activities (FRAP, DPPH, and ORAC) were strongly correlated ( r = 0.96, 0.94, and 0.89, respectively, P < 0.01) with TPC. TPC and ORAC were moderately correlated ( P < 0.01) with either the seed hull surface color or the flour color.     

Comparisons of phenolic compounds, isoflavones, antioxidant capacity and oxidative enzymes in yellow and black soybeans seed coat and dehulled bean

The total and individual phenolic profiles and their contribution to antioxidant capacities of seed coats and dehulled beans of black and yellow soybeans were investigated. In addition, lipoxygenase (LOX) and peroxidase (POD) activities were also determined. Black seed coats had the highest content of total phenols, flavonoids and anthocyanins, in addition the highest catechin and protocatechin contents. On the other hand, dehulled beans from yellow soybeans had the highest levels of ferulic and p-coumaric acid content, and free and bound isoflavone content. The LOX activity was concentrated in the dehulled beans of both black and yellow soybeans, while a high POD activity that can be attributed to a dominant gene EpEp was presented in seed coats of yellow soybean genotype Galeb. Due to the high concentration of phenols, the black seed coats from soybean genotypes Black Tokio and Cornaja had the highest ABTS^·+-scavenging capacity (597.46 and 486.15 mmol Trolox Eq./kg d.m., respectively). The results suggest that the black seed coat as well as dehulled bean from yellow soybeans would potentially provide sources of natural antioxidants that may play a crucial role in human health protection.     

Innovative Soaking and Grinding Methods and Cooking Affect the Retention of Isoflavones,Antioxidant and Antiproliferative Properties in Soymilk Prepared from Black Soybean

This study's objective was to characterize the effect of traditional and 3 newly devised (soaking+grinding) methods combined with cooking on the content and composition of phenolic substances, antioxidant, and antiproliferative properties of soymilk prepared from black soybean. Phenolic substances and antioxidant profile were characterized and antiproliferation of prostate cancer DU145 cells was conducted using a cell culture assay. Results indicated Grinding Method 4 produced significantly (P < 0.05) higher total phenolic content (TPC), total flavonoid content (TFC), condensed tannin content (CTC), and total isoflavone content in both raw and cooked black soymilk as compared to Method 1. Cooking soymilk reduced 23% to 38% of total phenolic substances. Raw black soymilk produced by Method 4 displayed the highest antioxidant capability, which was determined using ORAC, FRAP, and DPPH assays, and a higher antiprostate cell proliferation ability. Cooking only slightly reduced the potency to inhibit DU145 prostate cancer cells as IC₅₀ value was increased from the average of about 4.0 mg/mL of raw soymilk extracts to 5.5 mg/mL of cooked soymilk extracts of all grinding methods. Overall, total isoflavone content was the only component that was negatively correlated with IC₅₀ value (r = –0.93, P < 0.05) which indicates the ability to inhibit prostate cancer cell is associated with the increase in total isoflavone content, not with any other phenolic substances or antioxidant properties.     

Dehydrated Precooked Pinto Bean Quality as Affected by Cultivar and Coating Biopolymers

The relationship of cultivars and coating treatment to quality of precooked dehydrated pinto beans was investigated. The pinto cultivars, studied were Fiesta, Othello, and Topaz, and 12 types of biopolymers, including modified starches, dextrins, maltodextrins, and alginate, were used as coating agents. Beans were blanched, soaked, steam cooked, coated by dipping in biopolymer solutions at 70°C and dried in a convection oven. Eight biopolymers effectively reduced splitting of beans without detrimental effects on rehydration, firmness, or color. Cultivar had a strong effect on wholeness of bean products and Fiesta was best for dehydration. Residual trypsin inhibitor activity of precooked pinto beans was ～5%.     

Simplified Enzymatic-gravimetric Method for Total Dietary Fiber In Legumes Compared with a Modified AOAC Method

Two methods (an AOAC and a simplified enzymatic-gravimetric method) were used to analyze seven types of canned legumes and eight cooked legumes. Total dietary fiber (TDF) of the canned products ranged between 17% and 23% (dry basis) for chick peas, Great Northern beans, kidney beans, pinto beans, pork & beans, vegetarian beans in tomato sauce, and 27–31% for wax beans. These values were comparable for both methods. However, results on cooked legumes were very different between methods. TDF values for several types of beans and peas were higher and ranged between 31% and 5.5% by the AOAC/Tris-Mes buffer method as compared to 17% and 29% using the simplified method. Chemical analysis of dietary fiber residues showed the major difference between the methods was in the extent of starch removal as affected by starch gelatinization.     

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.     

4种不同产地黑豆营养成分及花青素含量的分析与评价

该研究以来自辽宁朝阳、山东临沂、黑龙江哈尔滨、陕西延川的黑豆（HD1、HD2、HD3、HD4）为原料,采用直接干燥法、灼烧法、凯氏定氮法等多种营养成分测定方法,结合氨基酸评分（Amino Acid Score）和化学评分（Chemical Score）分析了不同黑豆样品的水分、灰分、总蛋白、粗脂肪、还原糖、粗纤维、氨基酸组成、脂肪酸组成及花青素含量。结果表明四种黑豆原料的营养组成类似,总蛋白含量最高,还原糖含量最低,单一营养素含量差异明显,HD4可溶性蛋白含量最高,HD2粗脂肪含量最高,分别适合蛋白类及油脂类产品的开发;四种黑豆均检测出16种氨基酸,必需氨基酸含量丰富,占总氨基酸含量的37%~38%,蛋氨酸和苏氨酸是四种黑豆原料中的限制性氨基酸,在产品的开发过程中,需要通过营养强化或原料搭配保证产品的营养品质;四种黑豆均检测出5种脂肪酸,不饱和脂肪酸含量达85.62%~87.1%,花青素含量为2.14%~2.26%,适于作为功能食品原料进行开发。研究结果将为黑豆加工、功能成分的提取及相关产品的开发提供参考依据。     

Effect of pre-dehulling treatments on some nutritional and physical properties of navy and pinto beans (Phaseolus vulgaris L.)

The effect of pre-dehulling treatments using low and high temperatures on some nutritional and physical properties of navy and pinto beans was investigated. Beans were exposed to water (14%, 28% and soaking 1:5, w/v for 6 h, 16 and 16 h, respectively) to facilitate seed coat detachment prior to freeze drying (FD) for 48 h or heat drying (HT) for 20 or 60 min. Exposure to the highest moisture levels produced the largest seed coat yields (17.38-20.91%) and was independent of the drying conditions. The total phenolic content was positively correlated to the 1,1-diphenyl-2-picrylhydrazyl (DPPH) antioxidant activity and increased as the exposure time to HT increased, but it was unaffected by the FD. The nutritional properties of the bean varieties differed significantly, phytic acid was unaffected, and the highest antioxidant activity was observed on the seed coats of HT pinto beans (69.24-84.46% of DPPH discoloration). Significant physical changes were observed for the HT seeds, with the highest yellowness and the lowest peak viscosity detected in the soaked and HT (60 min) beans.     

A comparative assessment of total phenolic content,ferric reducing-anti-oxidative power,free radical-scavenging activity,vitamin C and isoflavones content in soybean with varying seed coat colour

Reports concerning anti-oxidative properties of yellow, green and black soybean seeds available in the literature are insufficient and limiting. In the present investigation, mature seeds of 18 genotypes, 6 from each type of soybean i.e. yellow, green and black, were assessed for total phenolic content (TPC), ferric reducing-anti-oxidative power (FRAP), 2,2-diphenyl-1-picrylhydrazine (DPPH) free radical-scavenging activities (FRSA). Isoflavones and vitamin C, the antioxidants, were also determined in all the soybean genotypes. Significant genotypic variation was observed for TPC, FRAP, FRSA, isoflavones and vitamin C within each type of soybean. Maximum genotypic variation (7.27-fold) was observed for TPC in black soybean. Average FRAP value of yellow soybean was significantly (p < 0.05) lower than black and green soybeans. Average FRSA in black soybean was significantly higher than yellow and green soybean group. Average total phenolic content and isoflavones levels were not significant across different types of soybean. Correlation studies indicated significant (p < 0.05) positive correlation between FRSA and TPC in black soybean. Our results suggest that antioxidant constituents other than isoflavones contribute significantly to the FRSA in black soybean genotypes.     

Comparative study on antiproliferation properties and cellular antioxidant activities of commonly consumed food legumes against nine human cancer cell lines

The aims of this work were to compare health promoting effects of commonly consumed food legumes in terms of cancer cell proliferation inhibitory effects and cellular antioxidant activities (CAA). The CAA was evaluated by fluorescence microplate reader based on in vitro animal cell cultivation. Antiproliferative properties were assayed by MTT method using in vitro cell culture system. Phytochemicals (including total phenolic, procyanidin, saponin and phytic acid) and chemical antioxidant activities (including DPPH free radical scavenging activity, oxygen radical absorbing capacity, peroxyl radical scavenging capacity (PRSC)) were also determined for comparison purposes. The results showed that different types of legumes possessed considerable variations in their phytochemicals, as well as chemical and cellular antioxidant activities. Adzuki bean exhibited the strongest antiproliferative properties in a dose-dependent manner against all digestive system cancer cell lines (CAL27, AGS, HepG2, SW480 and Caco-2), ovary cancer cell SK-OV-3 and breast cancer cell MCF-7 among all legumes tested. Black soybean exhibited the highest saponin, phytic acid content, PRSC values, and the strongest CAA values. These results indicate that commonly consumed food legumes may serve as an excellent dietary source of natural antioxidants for health promotion and cancer prevention.     

Oligosaccharides, Antinutritional Factors, and Protein Digestibility of Dry Beans as Affected by Processing

Dry beans (Phaseolus vulgaris) were subjected to soaking, cooking or a combination of both prior to fermentation, and then assessed for oligosaccharides, antinutritional factors and in-vitro protein digestibility. Results showed an important decrease in raffinose oligosaccharides and antinutritional factors. However, an increase of trypsin inhibitor and tannin contents occurred respectively in cooked or soaked-cooked fermented beans and in raw or soaked fermented beans. Appreciable improvement in in-vitro protein digestibility was only observed in cooked or soaked-cooked beans. After fermentation, the largest decreases were observed in soaked-cooked beans (92.75%) for raffinose, in cooked beans (31.57%) for phytic acid, in soaked beans (90.86%) for stachyose, and in raw beans for trypsin inhibitor (38.77%). The highest increase due to fermentation was observed in raw beans for in-vitro protein digestibility (1.73%).     

Phytochemical profiles of black and yellow soybeans as affected by roasting

The current research aimed to compare the changes of phytochemicals, antioxidants, and anti-nutritional factors of yellow and black soybeans upon roasting. Yellow soybean was roasted at 210°C for 35 min and 230°C for 25 min, and black soybean was roasted at 210°C for 30 min and 230°C for 25 min. Isoflavones were significantly increased after the roasting process, while trypsin inhibitor was significantly decreased. The roasting process combined with the soaking process led to decrease in anthocyanin, soyasaponin, and antioxidant capacities. Black soybeans had more apparent variations in compounds than the yellow soybeans. For black soybeans, the processing under 230°C for 25 min presented more decrease in trypsin inhibitor and anthocyanin content. The roasting at a high temperature and short time produced products with a light color. Roasting combined with the soaking process had negative impacts on both yellow and black soybeans, but there were slight differences in the resultant compounds between different roasting temperatures.     

Antioxidant Properties of Cocoa Beans (Theobroma cacao L.): Influence of Cultivar and Roasting Conditions

Effects of various roasting conditions on antioxidant properties of five Theobroma cacao L. varieties were investigated. The cocoa beans were roasted at four different temperatures (110–150°C) and three different air humidities (0.3–5.0%). The raw cocoa beans were characterized by high antioxidant activities. The antioxidant properties of the roasted cocoa beans varied markedly among the analyzed cultivars and geographical regions and were affected by roasting conditions. Generally, cocoa beans of the cv. Forastero from Brazil exhibited higher total phenolic content, free radical scavenging activity, and metal chelating ability than samples of the other analyzed cocoa varieties. Roasting at 110°C caused negligible changes in total phenolics content and antioxidant activity of cocoa beans, while almost all samples tended to have lower antioxidant potential when roasting temperature increased. The air humidity used in roasting did not affect the total phenolics content and antioxidant activity for lowest roasting temperature (110°C). Moreover, the obtained results revealed that thermal processing at the higher temperatures and elevated air humidity resulted in the higher antioxidant capacities. It was also found that the ferrous ion chelating activity of cocoa beans increased with the roasting temperature (in the range from 110 to 150°C), with the exception of cv. Trinitario from Papua New Guinea. The data showed that roasting at lower temperatures with humid air are more favorable in terms of preserving the bioactivity of roasted cocoa beans.     

Effect of processing on antioxidant contents in selected dry beans (Phaseolus spp. L.)

Dry beans are rich sources of dietary fiber and phytochemicals such as flavonoids and phenolics. In the current study, we determined the effects of two processing methods (soaking and toasting) on total phenolics, flavonoids, proanthocyanidin and antioxidant potential by 2,2-diphenyl-1-picrylhydrazyl (DPPH) activity and ferric reducing antioxidant potential (FRAP) in selected dry beans (red kidney beans (K), black-eyed peas (B), pinto beans (P) and soy beans (S)).Total phenolics (mg/g dwb) expressed as gallic acid equivalents (GAE), total flavonoids (mg/g dwb) as catechin equivalents (CE) and proanthocyanidin expressed as leucocyanidin equivalent (mg LE/g) ranged from 3.42 to 7.21, 0.61 to 0.84 and 0.51 to 3.13 in raw beans; 3.58 to 6.94, 0.19 to 0.99 and 0.43 to 3.13 in soaked beans and 4.55 to 9.52, 0.23 to1.00 and 0.20 to 3.25 in toasted beans, respectively.FRAP (μg/g) in raw, soaked and toasted dry beans ranged from 0.00097 to 0.00424 while DPPH_(T30) (%) ranged from 43.9 to 62.61.Our results indicate that processing methods (soaking and roasting) influenced total phenolic, flavonoid and antioxidant contents (DPPH, FRAP) in selected dry beans.     

Protein and starch content of raw,soaked and cooked beans (Phaseolus vulgaris L.)

Organoleptic qualities are an important factor in the market value of legumes, especially in developed countries. Unfortunately, the molecules that have the greatest influence on the texture of beans undergo important transformations during soaking and cooking. Moreover, the extent to which these changes are linear is unknown, making uncertain the use of raw beans in chemical screenings for sensory properties. Results of our experiments show that the amount of protein and amylose present in raw beans provides a good indicator of these substances in cooked beans (correlation coefficients between raw and cooked beans = 0.91, p ? 0.001 and 0.87, p ? 0.01, respectively). The Mg content in the raw seed coat also shows a strong correlation with that found in the cooked seed coat (r = 0.86, p ? 0.01). The correlations found for the other traits are weaker, indicating that the evaluation of raw samples is not predictive of the findings in cooked beans.     

Protein quality and antioxidant properties of soymilk derived from black soybean after in vitro simulated gastrointestinal digestion

Protein quality and antioxidant properties of soymilk derived from black soybean (eight varieties) in China were analysed following in vitro simulated gastrointestinal digestion (including dialysis). Soymilk from black soybean possessed high okara weight but low yield, protein content and sensory scores. The in vitro digestibility of protein in all black soymilk samples was higher than 60%, and the Shenmu black soybean exhibited the highest digestibility. Non-digested milk from the black soybean exhibited significantly high total phenolic content (TPC) (127.15–173.04 mg/100 mL), ferric-reducing antioxidant power (FRAP) (272.18–366.27 μmol L⁻¹) and DPPH free radical-scavenging activity (61.20–83.81%). These parameters were significantly lower in the non-digested soymilk than those in soymilk after gastric digestion but higher than those of soymilk in the dialysed fraction. Gastric digestion significantly increased bioactive compound levels released from black soymilk, and the bioaccessibility of phenolic compounds was 24.37–36.05%. Hence, black soymilk was sufficiently available for human absorption.     

Effect of soaking,boiling, and steaming on total phenolic contentand antioxidant activities of cool season food legumes

The effects of soaking, boiling and steaming processes on the total phenolic components and antioxidant activity in commonly consumed cool season food legumes (CSFL’s), including green pea, yellow pea, chickpea and lentil were investigated. As compared to original unprocessed legumes, all processing steps caused significant (p < 0.05) decreases in total phenolic content (TPC), DPPH free radical scavenging activity (DPPH) in all tested CSFL’s. All soaking and atmospheric boiling treatments caused significant (p < 0.05) decreases in oxygen radical absorbing capacity (ORAC). However, pressure boiling and pressure steaming caused significant (p < 0.05) increases in ORAC values. Steaming treatments resulted in a greater retention of TPC, DPPH, and ORAC values in all tested CSFL’s as compared to boiling treatments. To obtain cooked legumes with similar palatability and firmness, pressure boiling shortened processing time as compared to atmospheric boiling, resulted in insignificant differences in TPC, DPPH for green and yellow pea. However, TPC and DPPH in cooked lentils differed significantly between atmospheric and pressure boiling. As compared to atmospheric processes, pressure processes significantly increased ORAC values in both boiled and steamed CSFL’s. Greater TPC, DPPH and ORAC values were detected in boiling water than that in soaking and steaming water. Boiling also caused more solid loss than steaming. Steam processing exhibited several advantages in retaining the integrity of the legume appearance and texture of the cooked product, shortening process time, and greater retention of antioxidant components and activities.