Changes in soymilk during fermentation with kefir culture: oligosaccharides hydrolysis and isoflavone aglycone production.

The objective of this study was to evaluate the changes in oligosaccharides and isoflavone aglycone content in soymilk during fermentation with commercial kefir culture. Soymilk was fermented with kefir culture at 25 °C for 30 h. The counts of lactic acid bacteria, Lactococcus lactis, Leuconostoc sp and yeasts; measurements of pH, acidity, α-galactosidase and ß-glucosidase activity, sugar and isoflavone contents were performed at the intervals of time. In the fermented soymilk, the lactic acid bacteria counts increased from 7.6 log to 9.1 CFU g(-1), pH reached to 4.9 and lactic acid reached 0.34 g 100 g(- 1). The α-galactosidase was produced (0.016 AU g(-1)) with 100% raffinose and 92% stachyose hydrolysis being observed after the depletion of galactose, glucose and sucrose. Kefir culture produced ß-glucosidase (0.0164 AU g(-1)), resulting in 100% bioconversion of glycitin and daidzin and 89% bioconversion of genistin into the corresponding aglycones. The fermented soymilk presented 1.67 µmol g(-1) of daidzein, 0.28 µmol g(-1) of glicitein and 1.67 µmol g (-1) of genistein.

The effect of thermal treatment of whole soybean flour on the conversion of isoflavones and inactivation of trypsin inhibitors.

The aim of this paper was to evaluate the effect of the thermal treatment of whole soybean flour (WSF) on the conversion of isoflavones and the inactivation of trypsin inhibitors. Soybeans were ground and whole soybean flour was obtained and subjected to heat treatment in an oven for 10, 15 and 20min at 100, 150 and 200°C according to a 3(2) experimental design. The response functions were taken to be the contents of different isoflavone forms and the residual activity of trypsin inhibitors. The thermal treatment in the oven altered the content and profile of the different isoflavones forms. At 200°C for 20min, there was a higher conversion of malonylglycosides to acetylglycosides, ß-glycosides and aglycones and a significant reduction in the activity of trypsin inhibitors. Mathematical models were established to estimate the process parameters in obtaining the WSF with isoflavone conversions and reductions in trypsin inhibitor activity.

Soymilk processing with higher isoflavone aglycone content.

The objective of this work was to optimise conversion of ß-glucoside isoflavones to aglycones in soymilk processing and to evaluate their thermal stability. The soymilk was assessed for time and temperature effects of incubating supplied to central composite design 2(2). The response functions were investigated for ß-glucosidase activity and isoflavone contents. The ß-glucosidase activity was reduced through soybean slurry incubation at approximately 64°C and 3.42h. Maximum conversion of ß-glucosides into isoflavone aglycones involved soaking the soybeans at 5°C for 14h at a 1:3 ratio (soybean:water, w:v), homogenising them at a 1:8 ratio (soybean soaked:water, w:v) and incubation at 50°C for 2.7h. In evaluation of thermal stability of isoflavones in soymilk at 97°C for 25min, the daidzein and genistein aglycone contents were maintained, the glycitein and ß-glucosides contents increased and the malonylglucoside content decreased.

Profile of the contents of different forms of soybean isoflavones and the effect of germination time on these compounds and the physical parameters in soybean sprouts.

The aim of this study was to evaluate the profile of the contents of different forms of soybean isoflavones and the effect of germination time on these compounds and the physical parameters in BRS 284 soybean sprouts. Soybean seeds were germinated for 168 h, and the sprouts were collected every 24 h. The physical parameters and contents of different forms of isoflavones of the seeds and soybean sprouts were evaluated, and the data were subjected to regression analysis. The soybean seeds contained 26.0% ß-glucosides, 72.9% malonylglucosides and 1.2% aglycones. The yield of soybean sprouts was 632.4%. The effect of germination time was quadratic on the length, moisture and on the daidzin, genistin and genistein content; linear on the fresh weight and on the malonyldaidzin content. The dry matter and malonylglycitin content was constant, and glycitin and glycitein were not detected in the soybean sprouts.

Extraction, purification and some partial characterization of alpha-amylase inhibitors from wheat Iapar 28-Igapó.

alpha-Amylase inhibitors from wheat (Triticum aestivum) cultivar Iapar 28-Igapó were extracted with water in a 1:10 (w:v) ratio and precipitated with ammonium sulfate between 20-50% saturation, followed by DEAE and CM-cellulose chromatography. One inhibitor was purified and designated as CMC-IB, and had electrophoretic mobilities of 0.23 and 0.54 in alkaline and acidic conditions, respectively. This inhibitor was 750 times more active on human salivary alpha-amylase (HSSA) than porcine pancreatic o-amylase (PPA). The preincubation time required for maximum complexation with HSA was 20 minutes and optimum pH of inhibition was 7.5. The inhibitor CMC-IB was stable at 0 degrees C and maintained 50% of inhibitory activity against HSA, when incubated at 98 degrees C for one hour.

[Germination of soybeans BR-13 and Paraná: effects on mineral constituents]. / Germinação de soja BR-13 e paraná: efeito sobre os constituintes minerais.

The objective of this work was to evaluate the effect of germination on the minerals constituents (calcium, phosphorus, magnesium, potassium, copper, iron, manganese and zinc) of soybean. For the assays the soybean cultivars-Glycine max (L) Merril-BR-13 and Paraná were used. These were germinated in camera of germination at 25 degrees C and 100% of moisture, from 0 to 72 hours, collecting the samples in intervals of 6 hours. The analysis of variance and comparison among the means indicated that the minerals constituents remained constant up to 72 hours of germination.

[Functional properties and protein concentrate of Pigeon pea (Cajanus cajan (I.) Millsp) flour]. / Propriedades funcionais da farinha e concentrado protéico de feijão guandu (Cajanus cajan (I.) Millsp).

The objective of this investigation was to study the functional properties of Pigeon pea (Cajanus cajan (L.) Millsp) flour and protein concentrate. The solubility of both samples were superior than 70% at pH above 6.7 and below 3.5. The water and oil absorption were 1.2 and 1.07 ml/g of sample and 0.87 and 1.73 ml/g of flour and protein concentrate samples, respectively. The minimum concentration of flour and protein concentrate needed for gelation was 20% and 12%, respectively. The emulsifying capacity of flour and concentrate was 129.35 g and 191.66 g oil/g of protein and the emulsion stability 87.50 and 97.97%, respectively, after 780 minutes. The foam capacity and stability of flour foam were 36.0% and 18.61, while of the concentrate were 44.70% and 78.97% after 90 minutes. These properties indicate that the flour as well as the concentrate could have application in various food systems.

[Biological evaluation of soybean line with low trypsin inhibitor activities]. / Avaliação biológica de soja com baixas atividades de inibidores de tripsina e ausência do inibidor Kunitz.

The soybean cultivar BR 36 with conventional levels of trypsin inhibitors activity and the soybean line BRM95-5262, which was genetically selected to contain low activity of trypsin inhibitors were used for biological assays with rats. BR 36 and BRM95-5262 contained 40 and 20, and 30 and 20% of relative residual activity of trypsin inhibitors, respectively. The mean values of PER and NPR showed that treatments with crude soybeans were minor than treatments with soybean thermically processed. However, the treatments of thermically processed soybean did not showed significative differences (p > or = 0.05). When the trypsin inhibitors activity were 8.61 and 8.44 UIT/mg of samples or 20 and 30% of relative residual activity of cultivar BR 36 and line BRM95-5262, respectively, it was observed that mean values of PER and NPR were not significatives. The mean values of CDA and CDV of treatments with crude soybeans were minor than treatment with casein and similar to the treatments with soybean thermically processed. So, it can be concluded that the biological evaluation obtained with soybean protein were dependent of initial trypsin inhibitors activities and of its respective thermical treatment. There was advantage in the use of BRM95-5262 soybean line with low trypsin inhibitors activity.

Optimisation of soy flour fermentation parameters to produce ß-glucosidase for bioconversion into aglycones.

The solid state fermentation (SSF) parameters of defatted soybean flour (DSF) with Aspergillus oryzae IOC 3999/1998 or Monascus purpureus NRRL 1992 was evaluated using a rotational central composite experimental design to optimise the production of ß-glucosidase and convert glycosidic isoflavones in aglycones. Variables investigated were initial pH of DSF, volume of water added to 10 g of DSF and incubation temperature. ß-Glucosidase activity was measured using the synthetic substrate, p-nitrophenyl-ß-D-glucoside. The content of isoflavones was determinate by ultra performance liquid chromatography. The highest production of ß-glucosidase for both strains occurred when adding 10 mL of water to the DSF, incubating at 30 °C and using 6.0 as the initial DSF pH. A. oryzae IOC 3999/1998 expressed ß-glucosidase activity at 10.7 times higher than M. purpureus NRRL 1992. The DSF fermentation was more efficient in converting isoflavones with M. purpureus NRRL 1992.

Crystallization and preliminary crystallographic studies of alpha-amylase inhibitor from wheat (Triticum aestivum).

Crystals of the human salivary alpha-amylase inhibitor from wheat have been obtained. A native data set was collected to 2.1 A resolution with 90% completeness at laboratory sources. The crystals belong to the trigonal system, space group P3(1) (or enantiomer) with a = b = 79.31, c = 60.56 A. Crystal density analysis and self-rotation function studies suggest the presence of four subunits in the asymmetric unit.