S & TA & NU. Rivista di scienza e tecnologia degli alimenti e di nutrizione umana最新文献

This note reports some experimental results on the preparation of leaf protein concentrates (LPC) from alphalpha juice by means of polyelectrolites, according to Poly-Protein Process. The pilot plant is described with its working conditions, and the yield and the chemical composition of the products (pressed alphalpha, juice, green LPC and brown juice) are reported. In particular 50 liters of juice, obtained by pressing 100 kg of fresh alphalpha, gave 1.6 kg of green LPC (on a dry weight basis). The product so obtained has a high protein content (56.2%) and represents a particularly valuable product for its several prospective uses in the feed industry.

The present paper reports the content of methionine in cow, water buffalo and sheep casein measured according to Maugenet and Coauthors. The following values were obtained: 3,25% in cow; 3,15% in water buffalo; 3,16% in sheep.

A chemical method for the removal of chromogenic phenolic constituents and carbohydrates of the sunflower meal has been investigated. This method uses a nondenaturing polar solvent formed by n-butanol saturated by diluite HCl and allows the preparation of protein isolate off-colour free. Evaluations on the extractibility of phenols, carbohydrates and proteins of sunflower meals from different technological processes have been carried out.

The paper reports the results of two spray-drying tests carried out on yogurt as such or previously neutralized. The operating conditions of the drying operation were such that the temperature of the product didn't exceed 80 degrees C, and the residual moisture of the powder was about 10%, slightly higher than the B.E.T. monolayer value. The decrease of total counts was three and two decimal reductions respectively for the natural and neutralized product. This latter gave also much higher viability index as determined in a "fermenting activity" test. Also, the analyses, related to the quality of the protein fraction, strongly support the opportunity of neutralization before drying. In storage tests carried out during 8 months the survival data were higher at 5% relative humidity (corresponding to 7-8% humidity) and at 5 degrees C temperature. In all cases the better results were obtained from the powders of neutralized yogurt, even in comparison with a freeze-dried sample obtained from the natural product. The typical shape of the sorption isotherms of these products suggests that the optimum process as regard to microorganisms' survival consists in drying the neutralized product up to residual humidities of 8-10%, followed by storage, in humidity-proof containers, at temperatures of about 5 degrees C.

The authors have devised a new process, called POLY-PROTEIN, for obtaining leaf protein concentrates from alphalpha juice by precipitation with polyelectrolites. The use of steam is avoided and the technology is very simple, making this process more economical than those already employed.

Fundamental parameters in dimensioning a "vortex bed" drying apparatus are the pressure drop across the bed and the higher and lower limit of fluidization velocity. The analysis of the Navier-Stokes equations brings to the following functional relations between dimensionless groups: (see journal). These relations define the fluidization conditions in a "vortex bed" apparatus. Experimental tests carried out on a laboratory scale apparatus will provide us with the unknown constants for industrial scale extrapolation.

The most important water-soluble vitamins are quantitatively determined by high pressure chromatography using porous ion exchange resins. Thiamine and Riboflavine are separated by a cation exchange resin Aminex A5 using 0.3 M KCI in 0.1 M potassium phosphate pH 8.0 buffer as mobile phase; pyridoxamine, pyridoxol, pirydoxal and nicotinamide are successfully chromatographated on the same type of cationic resin using a linear gradient both of pH and ionic strength as mobile phase. Anionic vitamins like L-Ascorbic Acid and Nicotinic Acid are separated on Aminex A14 at acidic values of pH, using isocratic conditions of the ionic modifier. Under the described experimental conditions, the reproducibility of VR, RS and peak area are of 2.5% and 3% respectively. The sensitivity relative to the vitamins tested ranges from 100 to 250 ng.

The influence of the cultivar factor over the composition of the sterolic fraction of virgin olive oil has been verified by G.L.C. Such a fraction is not influenced by either the poor condition of the olives or the auto-oxidation process of oil. The use of many selective stationary phases like OV-17 in comparison with the SE-30 doesn't improve the analitic situation aiming at guarding the genuineness of the virgin oil. The analytic results confirm the value of the official method, even if, in the very few cases of oils with an insufficient level of beta-sitosteroil, blending it is necessary.

The results of experiences carryed out at the "Istituto di Industrie Agrarie" of the University of Bologna in the last five years, applying the techniques of vinification by carbonic maceration (CM) and by heat treatment of the crushed in the production of Emilia-Romagna wines, are reported. In particular, the evolution of the main organic constituents during anaerobic conditioning of grapes, the possibility of applying the CM to Sangiovese, Merlot and Canina grapes, the different variations of the CM technique, that is, CM followed by information with skins, the rifermentation of wines produced by traditional method with 10-20% of grape juice obtained by CM, the influence of CM on aging of barbera wine, some laboratory tests to explain the mechanism that regulate same interaction phenomena during the "intracellular fermentation", are discussed. The results of technique of heat treatment of the crushed, in the vinification of Sangiovese grapes, in a pilot plant, are exposed. Finally, the effects of some parameters (treatment of the crushed integral or partially dripped, heating temperature, rest time, sulphur dioxide employ, etc.) on the chemical characteristics and on the organoleptic quality, are estimated.