Brazilian soybean Glycine max (L.) Merr. cultivars adapted to low latitude regions: seed composition and content of bioactive proteins

Among the goals of the Brazilian soybean improvement programmes, the breeding strategies for cultivars adapted to low latitudes have been included to extend crop areas and to increase production. Seeds of nine Brazilian soybean cultivars adapted to low latitudes were investigated regarding to their composition, and amino acid and antinutritional/toxic protein contents. Protein (394.5 ± 13.1 to 445.3 ± 8.0 g kg-1 dry matter) and oil (200.6 ± 1.2 to 232.3 ± 4.7 g kg-1 dry matter) contents showed low correlation to each other (r = -0.06). The total carbohydrate (141.7 ± 6.1 to 211.1 ± 15.0 g kg-1 dry matter) and ash contents (48.2 ± 4.2 to 52.2 ± 0.5 g kg-1 dry matter) were similar to data available for other soybean cultivars. All soybean cultivars presented low levels of tryptophan and sulphur amino acids. The lectin (1,152 to 147,456 HU kg-1 flour), trypsin inhibitor (34.45 ± 2.28 to 77.62 ± 2.63 g trypsin inhibited kg-1 flour), toxin (6,210 ± 134 to 34,650 ± 110 LD50 kg-1 flour) and urease (0.74 ± 0.02 to 1.22 ± 0.10 g kg¹ flour) presented variations in their contents amongst the cultivars. Compared to other soybean cultivars, urease was higher, the acute toxicity lower and the lectin and trypsin inhibitor contents similar to data available. In general, soybean cultivars showed similar biochemical composition to those developed in different geographic regions. The relevance of these findings to the agronomic features and to choice of soybean cultivars to be used as food or feed is discussed.

Inflammatory and anti-inflammatory effects of soybean agglutinin

Soybean agglutinin (SBA) lectin, a protein present in raw soybean meals, can bind to and be extensively endocytosed by intestinal epithelial cells, being nutritionally toxic for most animals. In the present study we show that SBA (5-200 µg/cavity) injected into different cavities of rats induced a typical inflammatory response characterized by dose-dependent exudation and neutrophil migration 4 h after injection. This effect was blocked by pretreatment with glucocorticoid (0.5 mg/kg) or by co-injection of N-acetyl-galactosamine (100 x [M] lectin), but not of other sugars (100 x [M] lectin), suggesting an inflammatory response related to the lectin activity. Neutrophil accumulation was not dependent on a direct effect of SBA on the macrophage population since the effect was not altered when the number of peritoneal cells was increased or decreased in vivo. On the other hand, SBA showed chemotactic activity for human neutrophils in vitro. A slight increase in mononuclear cells was observed 48 h after ip injection of SBA. Phenotypic analysis of these cells showed an increase in the CD4+/CD8- lymphocyte population that returned to control levels after 15 days, suggesting the development of an immune response. SBA-stimulated macrophages presented an increase in the expression of CD11/CD18 surface molecules and showed some characteristics of activated cells. After intravenous administration, SBA increased the number of circulating neutrophils and inhibited in a dose-dependent manner the neutrophil migration induced by ip injection of carrageenan into peritoneal cavities. The co-injection of N-acetyl-galactosamine or mannose, but not glucose or fucose, inhibited these effects. The data indicate that soybean lectin is able to induce a local inflammatory reaction but has an anti-inflammatory effect when present in circulating blood

Antioxidant activity of rosemary and oregano ethanol extracts in soybean oil under thermal oxidation

Four experiments were conducted to measure the antioxidant activity of ethanol extracts of rosemary and oregano compared with synthetic antioxidants such as TBHQ and BHA/BHT. The antioxidant activity was determined and results differed from those of the Oven test at 63º C. Peroxide values and absorptivities at 232 nm of soybean oil under Oven test were lower in treatments with 25, 50, 75, 100 and 200 mg.Kg-1 TBHQ than in treatments with 1000 mg.Kg-1 oregano extract (O), 500 mg.Kg-1 rosemary extract (R) and their mixture R+O. All the treatments were effective in controlling the thermal oxidation of oils; the natural extracts were as effective as BHA+BHT and less effective than TBHQ. The natural extracts were mixed with 25, 50, 75 and 100 mg.Kg-1 TBHQ and then added to the oil. No improvement in antioxidative properties was observed. The best antioxidant concentration could be determined from polynomial regression and quadratic equation from the experimental data.

Volatile profile of heated soybean oil treated with quercetin and chlorogenic acid

Changes in the profile of volatile compounds after the heating of refined soybean oil without adding antioxidants, and treated with quercetin and chlorogenic acid (5-CQA) were investigated by GC/FID, GC/MS, and GC/SNIFFING. The heating temperature of the oil sample was 20 °C for the first minute, and then it was increased up to 160 °C at the rate of 10 °C min-1. The final temperature was kept for 10 minutes. 19 volatiles were identified in the heated samples without antioxidants. Medium-chain carbonyls predominated in the volatile fraction, mainly 2-heptenal, 2,4-heptadienal and 2,4-decadienal. Around 11 to 15 volatile compounds were detected in the heated samples treated with 5-CQA and quercetin, respectively. 5-CQA was not very efficient in delaying the formation of oxidative volatile compounds. The samples quercetin presented lower proportion of carbonyls with C6-C9.. The GC peak area data were used as an approach to estimate the relative content of each volatile compound and indicate that the samples treated with quercetin (p < 0.05) had significantly lower values for, 1-pentanol, 2,4-heptadienal, and 2,4-decadienal compared with those without antioxidants and treated with 5-CQA. GC/SNIFFING analysis revealed a smaller odor perception in the samples treated with 5-CQA compared to those without antioxidants. No odor was perceived in the heated samples treated with quercetin. These results indicate greater effectiveness of quercetin in delaying the formation of oxidative volatile compounds in soybean oils subjected to mild heating conditions. Apparently, biopolyphenols used in the present work showed good oxidative stability since no new volatile compound was detected in the heated samples treated with them.

Detection and quantification of Roundup Ready® soybean residues in sausage samples by conventional and real-time PCR

The increasing presence of products derived from genetically modified (GM) plants in human and animal diets has led to the development of detection methods to distinguish biotechnology-derived foods from conventional ones. The conventional and real-time PCR have been used, respectively, to detect and quantify GM residues in highly processed foods. DNA extraction is a critical step during the analysis process. Some factors such as DNA degradation, matrix effects, and the presence of PCR inhibitors imply that a detection or quantification limit, established for a given method, is restricted to a matrix used during validation and cannot be projected to any other matrix outside the scope of the method. In Brazil, sausage samples were the main class of processed products in which Roundup Ready® (RR) soybean residues were detected. Thus, the validation of methodologies for the detection and quantification of those residues is absolutely necessary. Sausage samples were submitted to two different methods of DNA extraction: modified Wizard and the CTAB method. The yield and quality were compared for both methods. DNA samples were analyzed by conventional and real-time PCR for the detection and quantification of Roundup Ready® soybean in the samples. At least 200 ng of total sausage DNA was necessary for a reliable quantification. Reactions containing DNA amounts below this value led to large variations on the expected GM percentage value. In conventional PCR, the detection limit varied from 1.0 to 500 ng, depending on the GM soybean content in the sample. The precision, performance, and linearity were relatively high indicating that the method used for analysis was satisfactory.

Physical properties of structured lipids from lard and soybean oil produced by enzymatic interesterification

The main goal of the present research was to evaluate the physical properties of blends of lard and soybean oil modified by enzymatic interesterification catalyzed by two different commercial (microbial) lipases, viz. from Candida cylindracea (AY30TM) and from Mucor circinelloides (M10TM). Pure lard exhibited a softening point of ca. 31.8 °C before interesterification, and this value shifted towards 29.1 °C after interesterification by AY30 lipase and towards 28.8 °C after interesterification by M10 lipase The interesterified lard exhibited lower consistency after reaction with both lipases, and this decrease was more pronounced for the reaction catalyzed by M10 lipase. This result was most likely due to the sn-1,3-specificity of M10 lipase. Pure lard displayed a lower SFC after interesterification, and M10 lipase proved to be more effective than AY30 lipase. The non-interesterified lard had a SFC of 31.3% at 10 °C, which was reduced to 23.8 and 19.9% after interesterification with AY30 lipase and M10 lipase, respectively. The lard and soybean oil blends were affected by the enzymatic interesterification and dilution with soybean oil.

Chemical and biochemical characterization of soybean produced under drought stress

Brazil is the second soybean (Glycine max L. Merrill) producer and exporter in the world. In 2005, soybean cultivated in the southeastern region of the country suffered drought stress imposed by adverse high temperatures and low humidity during its reproductive stage. Little information is available regarding the effect of drought stress on the quality of grains. In this study chemical and biochemical characteristics of five soybean samples belonging to three different cultivars grown under drought stress were evaluated. The samples did not meet standards for marketing and contained high amounts of green seeds. Grains were analyzed for appearance, 100 seed weight, humidity, water activity, proteins, lipids, lipoxygenase 1 activity, peroxides, and pigment contents after harvest and after 20 months of storage at room temperature. Acidity was measured also after 30 months of storage. The values of water activity and humidity were 0.6-0.7 and 8.7-11.9%, respectively, and they did not change during storage time, but there was an increase in acidity, which alludes to lipase activity. The activity of lipoxygenase 1 was greatly affected. Immediately after harvest, the green pigments were represented mainly by pheophytin a, followed by pheophytin b, small quantities of chlorophyll b and chlorophyll a, and traces of other chlorophyll derivatives. After 20 months of storage almost all green pigments had disappeared. Drought stress probably enhanced membrane permeability, which led to a lower pH and promoted transformation of chlorophylls to pheophytins.

The influence of different combinations of probiotic bacteria and fermentation temperatures on the microbiological and physicochemical characteristics of fermented lactic beverages containing soybean hydrosoluble extract during refrigerated storage

Lactic beverages containing probiotics were prepared with whole UHT milk, whey of Mozzarella cheese, soybean hydrosoluble extract and sugar. Three formulations were studied, each one containing a different combination of probiotic/starter bacteria, fermented at two different temperatures (37 and 45 °C). The aim of this work was to verify the influence of these variables on the viability of probiotic microorganisms and on the physicochemical stability of lactic beverages during storage under refrigeration (21 days at 7 °C). The results indicated that the fermentation temperature had a significant effect on the viability of probiotic bacteria. Counts for Lactobacillus acidophilus were affected by storage time, resulting appropriate after 21 days only for the beverage fermented at 37 °C. Physicochemical parameters did not exhibit drastic variations - proving the stability of formulations during storage. Cells of Bifidobacterium spp. showed high survival ability, probably due to the presence of growth promoters from soybean and cheese whey. The fermentation temperature of 37 °C allowed counts above the minimum limit for all the studied microorganisms, being preferred to the temperature of 45 °C. The inclusion of soybean hydrosoluble extract, a prebiotics source, resulted in a symbiotic product with more benefits to the health of consumers.

Physicochemical characteristics and functional properties of vitabosa (mucuna deeringiana) and soybean (glycine max)

Physicochemical characteristics and functional properties of vitabosa flour (Mucuna deeringiana) and soybean flour (Glycine max) were determined. Oil absorption capacity was higher in vitabosa. Water absorption capacity was higher in soy and it was affected by the change in the ionic strength of the medium. Emulsifying Activity (EA) decreased with increasing concentration of flour, while Emulsifying Stability (ES) showed an increased. EA and ES of flours have more ionic strength in the range between 0.0 and 0.4 M, but it is reduced afterwards with the higher concentration of NaCl. Foaming stability varied with the concentration of flour solution reaching maximum values of 39 and 33% for vitabosa and soybean, respectively at 10% flour concentration.Vitabosa had the best foaming capacity (56% to 0.6 M) compared with soybeans (47% to 0.4 M). Maximum capacity of gelation was observed in vitabosa at 10% flour concentration. Increases in ionic strength of the flour solution, at low salt concentrations (<0.4 M), improved the gelation of flours.

Effect of harvest at different times of day on the physical and chemical characteristics of vegetable-type soybean

The objective of this study was to evaluate the effect of harvest at different times of day on the chemical and physical characteristics of vegetable-type soybean BRS 267 cultivar, harvested at the R6 stage (seed development) and to compare it with that on the grains harvested at the R8 stage (maturation). The pods of the BRS 267 cultivar were harvested at the R6 stage (at 8:00 AM, 12:00 AM, and 6:00 PM), the color parameters were evaluated, and the grains were analyzed for chemical composition, activity inhibitor trypsin, phytic acid content, starch, sugars, fatty acids, and isoflavones. No differences were observed among the different harvest times in terms of the chemical constituents of vegetable-type soybean BRS 267 cultivar harvested at the R6 stage. Isoflavones content did not change with different harvest times, and the aglycone forms (daidzein, glycitein, and genistein) were found in smaller quantities at the R6 stage compared to the R8 stage. The color of the pods of soybean BRS 267 cultivar, harvested at the R6 stage did not change with different harvest times. The grains harvested at the R6 stage had lower protein content, phytic acid, and sucrose and higher levels of lipids, carbohydrates, starch, glucose, fructose, stachyose, and linolenic acids than those collected at the R8 stage. The different times of harvest did not affect the quality of the vegetable-type soybean BRS 267 cultivar harvested at stage R6. Nevertheless, it is recommended to harvest in the morning, when the temperature is milder, like other vegetables, to facilitate and optimize its marketing and in natura consumption.

Heat-treatment reduces anti-nutritional phytochemicals and maintains protein quality in genetically improved hulled soybean flour

The soybean is a protein source of high biological value. However, the presence of anti-nutritional factors affects its protein quality and limits the bioavailability of other nutrients. The effect of heat-treatment, 150 ºC for 30 minutes, on hulled and hull-less soybean flour from the cultivar UFVTN 105AP on urease, trypsin inhibitor activity, protein solubility, amino acid profile, and in vivo protein quality was investigated. The treatment reduced the trypsin inhibitor activity and urease, but it did not affect protein solubility. Protein Efficiency Coefficient (PER) values of the flours were similar, and the PER of the hull-less soybean flour did not differ from casein. The Net Protein Ratio (NPR) did not differ between the experimental groups. The True Digestibility (TD) of the flours did not differ, but both were lower in casein and the Protein Digestibility Corrected Amino Acid Score (PDCCAS) was lower than the TD, due to limited valine determined by the chemical score. Therefore, the flours showed reduced anti-nutritional phytochemicals and similar protein quality, and therefore the whole flours can be used as a source of high quality protein.

Optimization of extrusion variables for the production of snacks from by-products of rice and soybean

This study aimed to define the process conditions to obtain snacks from the by-products of rice and soybean with physical characteristics suitable for marketing. Therefore, the effects of moisture and extrusion temperature on the expansion and color of the products obtained experimentally obtained were evaluated, and the proximate composition of the by-products and that of the snack with greater desirability were determined. Response surface methodology and rotational central composite design were used, and desirability test based on the regression models adjusted was applied. The most desirable snack, with the highest expansion index (3.39), specific volume (13.5 mL.g-1), and the chromaticity coordinate a* (2.79), was obtained under 12 g.100 g-1 moisture and 85ºC of temperature in the third zone of the extruder. The snack produced under these conditions attained content of protein and lipid content 41 and 64% higher than that of the traditional corn snack. It can be concluded that producing extruded snack made form a mixture of broken grains, rice bran, and soybean okara (81:9:10) is technologically feasible, enabling the development of a new product with good nutritional value that can improve the diet of children, the main consumers of this type of food.

Eletrical conductivity and deterioration of soybean seeds exposed to different storage conditions

Research with soybean seeds has revealed that the results of the electrical conductivity test may be influenced by storage temperature, particularly low temperature, such as 10ºC, suggesting that seed deterioration at low storage temperatures does not seem to be directly related to the loss of the cell membrane integrity. This study was conducted with seeds of two soybean cultivars with the objective of: a) studying the effect of different storage temperatures (10ºC; 20ºC; 25ºC; 20/10ºC and 25/10ºC) on the results of the electrical conductivity test; b) observing the behavior of fatty acids and carbohydrates during storage and studying its relation with the electrical conductivity results. Every three months, from a total of 18 months of storage, the physiological quality of seeds was evaluated using the germination, accelerated aging and electrical conductivity tests. Based on the obtained results, it can be concluded that the electrical conductivity test was not shown to be a good indicative of the deterioration process of seeds stored at low temperatures, and no direct relationship between changes in the fatty acids and carbohydrates and the behavior of the mentioned test for seeds stored at 10ºC was found.

Response of soybean genotypes to the expression of green seed under temperature and water stresses

Soybeans grown under water stress associated with high temperatures during seed maturation and pre-harvest may produce green seed (GS) with expressive reduction in seed quality. The objectives of this study were to evaluate the response of different soybean cultivars grown under these stressful conditions regarding their susceptibility to GS production and to determine the chlorophyll retention levels and the chlorophyllase activity in the seeds. Seeds of four soybean cultivars [BRS 133, CD 206, MG/BR 46 (Conquista) and BRSMG 251 (Robusta)] were grown under greenhouse conditions until R5.5. At R6, the plants were transferred to phytotrons under temperature stress (from 28ºC to 36ºC) and with water stresses of 10% gravimetric moisture, no water and normal supply. Seeds were harvested at R9 when the percentage of GS and weight of 100 seeds were determined. The contents of a, b and total chlorophylls and the chlorophyllase activity were also determined. The expression of GS production under these conditions varied among cultivars: Conquista and Robusta were considered more susceptible to the production of GS compared to 'BRS 133' and 'CD 206'. These cultivars produced lower GS levels, lower chlorophyll retention and higher chlorophyllase activity compared to Robusta and Conquista. Soybean plants submitted to water and temperature stresses produced high levels of GS, which were small, light and had high chlorophyll contents and low chlorophyllase activity. The contents of a, b and total chlorophylls in GS were inversely proportional to the chlorophyllase activity.

Effect of storage period on isoflavone content and physiological quality of conventional and transgenic soybean seeds

The objective in this research was to evaluate the isoflavone content and the physiological quality of seed from conventional and transgenic soybean cultivars before and after 180 days of storage. Twenty one soybean cultivars: CD 202, CD 206, CD 208, CD 213RR, CD 214RR, CD 215, CD 216, CD 217, CD 218, CD 221, BRS 184, BRS 185, BRS 214, BRS 244RR, BRS 245RR, BRS 246RR, BRS 255, BRS 257, BRS 258, BRS 261 and BRS 262, grown in the 2005/2006 crop season, were assayed. The seeds were packed in Kraft paper bags and stored at room temperature under laboratory conditions. Seeds were evaluated with respect to their germination and vigor (first germination count, accelerated aging and tetrazolium test) and their total isoflavone contents and respective aglycon forms (daidzein, genistein and glycitein),glycosides (daidzine, genistine and glycitine) and malonyl conjugates. A completely randomized block design with six replications with the treatments set out within a subplot scheme (21 cultivars x 2 storage periods) was used. The F-test was used to compare means between storage periods and the Scott-Knott test to compare cultivars for each storage period, both with a 95% probability. It was concluded that isoflavone contents differ between cultivars and show a distinct behavior throughout storage.