Ebony (Phitecellobium flexicaule Benth) and proteins fractionation, solubilization, characterization and production of an isolate

Different combinations of pHs (2 to 12) and temperatures (25, 30 and 35 degrees C) were tested to obtain a protein isolate from ebony (Pithecellobium flexicaule, Benth) seeds. Seed proteins contained 54.6 per cent albumins, 32 per cent globulins, 5.7 per cent glutelins and 1.3 per cent prolamins. The isoelectric points for albumins, globulins and glutelins were in the pH range of 2.3-2.7. The average molecular weight of albumins ranged from 92 to 100 kDa and for the four globulin subunits in the range of 28.4 to 57.3 kDa. For isolate production, proteins were sequentially extracted with distilled water and a 5 per cent NaCl solution. The resulting supernatants were mixed. The best extraction was achieved at pH 11 and 25 degrees C. 45.6 per cent of the total seed protein was precipitated at pH 2.6 yielding an isolate with 90 per cent protein (N x 6.25). The isolate contained high quantities of lysine, leucine, threonine and phenylalanine but were low in sulfur containing amino acids methionine and cysteine. The extraction process reduced tannins, phytates and trypsin inhibitor in 53, 70 and 70 per cent, respectively. In vivo protein digestibility of the protein isolate was 85.4 per cent and the corrected digestibility essential amino acid score was of 44 per cent due to the lack of sulfur containing amino acids. In order to upgrade the protein quality of ebony isolate it is recommend to supplement with methionine or sulfur containing rich foods.

[Protein quality of three strains of Mexican mushrooms (Pleurotus ostreatus)]. / Calidad proteínica de tres cepas mexicanas de setas (Pleurotus ostreatus).

The protein quality of fruits bodies of three Pleurotus ostreatus Mexican strains (INIREB-8, CDBB-H-896 and CDBB-H-897) was evaluated. The protein concentration (Nx4.38) ranged from 17.26 to 19.97 g/100 g dry weight; chemical scores were between 74 and 93% with available lysine as a first limiting amino acid in either INIREB-8 and CDBB-H-896 strains or leucine in CDBB-H-897 strain. The nutritional evaluation revealed 67.75 to 68.38% in vitro digestibility. Relative protein values were from 100.06-107.85%, which were lower than soybean meal and whole egg but larger than those of rice, maize, beans, fava beans and pasta, no differences were found between these values and those of skim milk powder, casein plus methionine and albumin. In accordance with the last results we concluded that due to their essential amino acids content, mushroom proteins are a good complement of cereals; furthermore, it is highly recommended to include Pleurotus in the daily diet.

[Effect of cooking on the chemical and nutritional value of the Pithecellobium flexicaule (Bent) seed]. / Efecto de la cocción sobre la composición química y valor nutricio de la semilla de Pithecellobium flexicaule (Bent).

The leguminous P. flexicaule grows at the Northeast of Mexico. People living at this region traditionally consume the seeds (unripe cooked or toasted mature). Three localities samples of mature seeds were analyzed. The main results were: Protein (Nx6.25) 35.3%, lipids 25% and total dietary fiber (TDF) 13.2%. After a toasted treatment during 10 minutes (80-90 degrees C), the true protein digestibility increased from 79.3-91.8%, the phytate content and protein inhibitors decreased up to 35 an 96% respectively. Tannin concentration increased from 12.4 to 236 mg eq. cathequine/100 g, probably because during the treatment they passed from the shell to the cotyledons. Unripe seeds gave; protein 12.7%, lipids 6.6%, TDF 3.5%. When the unripe seeds in their sheath were boiling, the true protein digestibility was 85.8% (same value of the raw seeds), phytate content was reduced 68.4% and tannin concentration rose from 4.9 to 226 mg. Due to these results, the seeds free of the shell and sheaths were boiling, this time the tannin and phytate concentration were reduced 73.5 and 88.6% respectively, the true protein digestibility was 94.5%. The sulphur containing amino acids were the limit, as in other leguminous, the protein digestibility corrected amino acid score was 50.6% (unripe seeds), similar to that of pinto beans.

[Chemical composition of three Mexican strains of mushrooms (Pleurotus ostratus)]. / Composición química de tres cepas mexicanas de setas (Pleurotus ostreatus).

The chemical composition of three Mexican strains of Pleurotus ostreatus (INIREB-8, CDBB-H-896 and CDBB-H-897), were determined. The mushrooms were cultivated on wheat straw in a greenhouse (22-28 degrees C temperature and 80 +/- 5% of relative humidity). Fruits bodies of P. ostreatus contained (all values are expressed in g/100 g dry wt.), protein (N x 6.25): 24.64 +/- 0.21-28.50 +/- 0.26; lipids: 1.10 +/- 0.16-1.85 +/- 0.22; mineral matter: 7.66 +/- 0.23-8.79 +/- 0.25; dietary fibre: 32.14 +/- 0.14-36.81 +/- 0.40; and available carbohydrates: 26.33 +/- 1.04-30.46 +/- 0.21. They contain vitamins (mg/100 g dry wt): riboflavin: 3.31-3.7, thiamin: 1.92-1.96, niacin: 35.98-36.56 and ascorbic acid: 28-35. The main fatty acid was linoleic (0.70-1.19 g/100 g dry wt), it was also reported a low calcium and phosphorus content. Concluding the Pleurotus ostreatus could be a source of some of the complex B vitamins, dietary fiber, protein and linoleic acid.

[Relationship between nutritional composition and anatomical parameters in sorghum (Sorghum bicolor L. Moench)]. / Relaciones entre la composición nutricional y parámetros anatómicos en sorgo (Sorghum bicolor L. Moench).

Nutritional and chemical parameters with significant differences (P = 0.5) among 10 varieties of sorghum and rates observed in them were as follow: lipids (2.76 to 3.75%), raw fiber (60.0 to 64.7%) protein (9.01 to 11.43%), no nitrogen extract 977.65 to 83.07%), starch (60.5 to 64.20%), tannin (2.50 to 10.16 mg/g), and total calories (380 to 4000 Kcal). Ash content with value of 1.17 to 1.91% protein digestibility (23.8 to 38.8%) and "in situ" starch (54.4 to 66.6%) were not statistically different. When correlation indexes were determined between results of chemical analysis, it was obtained follow positive correlation having significance: carbohydrates with total calories and fat with fiber. The main negative correlations were: fat and fiber with carbohydrates, fiber with calories, and digestibility "In vitro" of protein with tannin. In order to obtain equivalent analytical tests to substitute an anatomic determination for a chemical one, or vice versa, and make easy the selection of varieties for different use, and the adequate process for sorghum grain, were obtained correlations between chemical data of this study and compared to anatomic features determined in a previous analysis with same samples (1), it was found 19 significant coefficients from which 8 were positives and 11 negatives. The main correlations with capacity of analytical substitution were: size of starch grain of cornea endosperm-starch amount; size of protein body of flour-like endosperm-digestibility "in vitro" and "in situ" of protein; length of cell of flour like endosperm-starch amount; length and broad of aleurona cells-fiber content. The major negative correlations were: size of starch grain of cornea and flour-like endosperm ash; size of protein body of cornea endosper-starch amount; length and broad of aleurona cells-carbohydrates and total calories.

[Mineral composition of milk produced in Monterrey, N. L. Mexico]. / Composición mineral de leche producida en Monterrey, N.L. México.

Milk is a food rich in oligoelements (approx. 1g/100 ml) that can vary in concentration due to genetic factors, type of feed, fed to cattle and due to contamination in the area of production. Since the margin between the concentration of mineral requirements and the toxic levels is so narrow that a little excess results harmful to sensitive species, the present study was done in the city of Monterrey, N.L. located in an industrial zone. Samples of raw milk from 17 producers distributed in 8 zones were analyzed during 6 months, measuring minerals of nutritional and toxicological importance. All elements were determined using atomic absorption, except for phosphorus, which was quantified colorimetrically. Statistical significance was determined through analysis of variance and Duncan test. The average mineral composition of the milk analyzed was (mg/Lt): calcium 1179, magnesium 109.7, zinc 5.89, phosphorus 637.1, copper 0.15, cadmium < 0.01, chromium < 0.02, iron 0.59, lead < 0.04, manganese < 0.02, nickel 0.36. The milk of this region is a good source of calcium, magnesium, phosphorus and zinc, with 35%, 7.4%, 19% and 9% respectively of the RDA being obtained from a 237 ml portion of milk.