PURIFICATION OF WET PROCESS PHOSPHORIC ACID BY SOLVENT EXTRACTION WITH PROPYL ETHERS.

The distribution data for the impurities (SO⁼ ₄, F^?, Fe, Al and Mg) during purification of wet phosphoric acid (WPA) with di-n-propy1 ether (DPE), di-n-propy1 ether containing 6. 5% of the isomer n-propylriso-propyl ether (DPE(M)) and di-iso-propyl ether (DIPE) at 25°C are reported. The distribution of phosphoric acid (PA)(SO⁼ ₄, F^?, Fe, Al and Mg between the conjugated phases has been investigated. The system W-WPA-DIPE shows a three-liquid-phases-at-equilibrium zone with 65.7% of phosphoric acid in the aqueous phase, 43.9% in the heavy organic phase and 4.3% in the light organic phase. The degree of purification increases, for the three solvents studied, when decreasing the PA concentration in the organic phase (except for F^?when using DPE}. Purification data for iso-arayl alcohol (1) and these three solvents are compared, showing that di-n-propyl ether with 6.5% of the isomer propyl-iso-propyl ether is the best solvent (from all solvents investigated in these series) for the purification of the wet process phosphoric acid studied.     

DEVELOPMENT OF A HYBRID MODEL PREDICTING THE MOUTHFEEL OF YOGURT

Texture perception and mouthfeel are sensory variables that still need further clarification. A reliable method to describe mouthfeel quantitatively by means of physicochemical measurements is missing so far. The current study focuses on a better understanding of the texture perception of yogurt. The final aim of the study consists of the development of a novel hybrid model, which is able to predict mouthfeel sensations objectively. For this purpose, cognitive methods are used in order to merge underlying data pools with respect to process parameters and the composition of dry matter content. These employed data pools result from rheological characterizations as well as sensory analyses of yogurt and from numerical simulations of fluid flow in a simplified anatomical model of the human mouth. This paper introduces the exact procedure of the study. Furthermore, the methods for generating the underlying data pools are described, and the results are presented.

PRACTICAL APPLICATIONS

The in-mouth model is based on fluid mechanics and enables the investigation of human consumption processes that accompany fluid flow in the oral cavity. Here, it reveals mechanical stimuli, which occur because of the movement of the tongue during deglutition. Therewith, the ongoing study affords a new approach to understand factors influencing the popularity and consumer acceptance of several products as their behavior in the mouth can be clarified. Having the software development completed, this innovation represents a great potential for the food industry. While supporting future sensory analyses, it both shortens development cycles of new products and optimizes existing foodstuff.     

Extending the shelf life of fresh ewe’s cheese by modified atmosphere packaging

This study evaluated the effect of modified atmosphere packaging (MAP) in extending the shelf life of a fresh ewe’s cheese stored at 4 °C for 21 days. Three batches were prepared with 20, 30 or 50% CO₂ with N₂ as filler gas. MAP controlled well the microbial growth, and the best result was obtained with 50% CO₂. Pathogens were not detected in any sample. Softening of cheese was best reduced by 30% or 50% CO₂. The sensory characteristics of the cheeses markedly decreased during storage. Only the sample stored with 50% CO₂ obtained an overall score above the acceptability at 14 days.     

STUDY ON INTERACTION AMONG EXTRUSION-COOKING PROCESS VARIABLES AND ENZYME ACTIVITY: EVALUATION OF EXTRUDATE STRUCTURE

A blend of wheat flour (moisture content 11.61%) and different amounts of two commercial enzymes like GRINDAMYL (GA) amylase 1000 (0–0.1 g/kg) and GA protease 41 (0–1.0 g/kg) were extruded through a co-rotating twin-screw extruder.
The effects of barrel temperature (60–120C), dough moisture (20–36%), screw speed (100–400 rpm) and different amounts of enzymes on structure of extrudates (porosity and break strength) were studied using response surface methodology.
Results showed that the highest value of porosity (62.47%  ±  4.07) was obtained at the highest value of barrel temperature (120C) and at the largest amounts of GA protease 41 (1.0 g/kg) or GA amylase 1000 (0.1 g/kg). However, the simultaneous addition of large amounts of both enzymes caused a negative effect on expansion degree (porosity  <  30%). Large amounts of moisture dough and GA amylase 1000 resulted in a high value of break strength (25.7 N/mm²) and in stiff-textured extrudates .

PRACTICAL APPLICATIONS

This research could provide some information about the effects of and the interactions between extrusion parameters and enzyme activities, which are commonly used to produce bakery products, in order to improve the texture of extrudates processed at low barrel temperatures, i.e., 60C, for example, extrudates with thermolabile components like vitamins or extrudates with high lipid fraction like breakfast cereals, pet food, etc.     

Glucose Oxidase/Cqtalase Improves Preservation of Shrimp (Heterocarpus reedi)

The preservative effect of glucose oxidase (GOX) and catalase (CAT) in a 4% glucose aqueous solution were evaluated on shrimp (Heterocarpus reedi) stored at 0–2°C. On-board and immediately after catch, shrimp were washed with tap water at 10°C, and dipped or kept in the enzyme solution. Microbial (total psychrotrophs and Pseudomonas spp. counts), chemical (total volatile bases, ammonia and pH) and sensory tests (whole-raw and cooked-peeled samples) showed that holding shrimp in the GOX/CAT/glucose solution retarded microbial spoilage and preserved quality more effectively than dipping shrimp in the same solution. The importance of treating shrimp as early as possible was demonstrated by comparing shrimp treated 4 and 82 hr after catch.     

The least squares Padé method for model reduction

This work describes a novel method for the reduction of S1SO continuous models. The proposed method, the least squares Pade (LS-Padé) method, provides reduced models which incorporate some information about the original model over the mid-frequency range. Consequently, the present method gives better results than the classical Padé and most of the related methods for a very small additional cost     

Analysis of spurious signal propagation in digital CMOS circuits

Spurious signals may produce transient or even permanent logic errors in digital circuits. This work deals with the analysis of the penetration capability and the calculation of the propagation depth of such signals through logic circuits. The results are useful to determine the domain of effect of spurious signals and to point out rules for its detection.     

Submerged Production of Agaricus campestris Mycellum in Peat Extracts

The edible mushroom Agaricus campestris has been grown using peat extracts as the only substrate source. Shaker flask fermentations were conducted with Sphagnum peat extracts obtained by autoclaving peat mixed with 1.5% (v/v) H₂SO₄ for 2 hr at 121°C. Inoculum ratio, temperature, initial pH, fermentation time and agitation were tested in order to evaluate the effect of those factors on the mycelial growth, expressed as final dry mycelium concentration and biomass yield (g of dry mycelium produced per g of carbohydrates consumed). The best combination of operating variables, in the range of values investigated, are: 4% (v/v) inoculum ratio, 24°C, pH 6.0, 6 days and 150 rpm.