Advances in Rare Earths Separation and Purification

The conventional method of separation of rare earths by multistage liquid-liquid extraction is still the best processing technology for their separation and purification. One of the most promising developments in the last decade that could have an impact on the rare earths separation technology is the synthesis of mucrocyclic ligands that have a high degree of selectivity in their complexation. Trivalent lanthanides have recently been transported across liquid membranes containing macrocycic ligands. The use of facilitated liquid membranes reactors in the concentration of very dilute rare eaith streams can be very effective in terms of recovery as well as environmental considerations. The electroreduction of E³⁺ to E²⁺ and the electroodixation of Ce³⁺ to Ce⁴⁺ are potential replacements for chemical reaction valence change methods. The electrolytic method eliminates the introduction of other chemical reagents that need to be treated downstream to satisfy environmental codes. Improvements in the design and control of mixer-settlers and other liquid-liquid extraction equipment will result in higher stage efficiency.     

STORAGE RESULTS IN LOSS OF THE ANTIGENOTOXIC PROPERTIES OF LENTINULA EDODES (SHIITAKE MUSHROOM) AND DEVELOPMENT OF IN VIVO GENOTOXICITY

In this study, we have investigated the stability of the antigenotoxic properties of dried of Lentinula edodes (Berk.) Singer mushroom powder stored at room and at − 20C. Mice were pretreated by gavage for 15 consecutive days with 0.6 mL/day of an aqueous extract of dried L. edodes powder prepared at 60C. On day 15, the mice were intraperitoneally injected with 50 mg/kg N-ethyl-N-nitrosourea (ENU); 3 h later, peripheral blood was withdrawn from the animals and used to evaluate DNA damage using the comet assay. The mice were sacrificed 24 h after the ENU treatment and the bone marrow used to measure the frequency of micronucleated polychromatic erythrocytes. The results indicated that storage at both room temperature and at − 20C significantly reduced the antigenotoxic effects of the mushroom powder. In addition, whereas freshly dried mushroom powder was nongenotoxic, storage of the powder at − 20C resulted in genotoxic activity ( P <  0.05). Taken together, our data indicate that constituents of L. edodes powder are altered during storage, resulting in both genotoxicity and a reduction in antigenotoxicity.     

Prediction of pH Change in Processed Acidified Turnips

The acetic acid uptake by turnips was studied during an acidification process in containers. The process was successfully described by a Fickian diffusion, using a correlation for the buffer effect. Diffusion coefficients (0.629 to 3.99 × 10^-9 m²/sec) and partition coefficients (0.8 to 1.1) were obtained by optimization of the fit between experimental and theoretical values, using the simplex method. The partition coefficient did not show an evident dependence on temperature, while diffusivity followed an Arrhenius type behavior. The relationship between acid concentration and pH was described using a cubic model with parameters independent of temperature. Results showed that the combination of these models describing the acid diffusion into the food and the buffering effects of the food allowed accurate prediction of pH evolution in the acidification process.     

AN ASSESSMENT OF CHEMICAL SANITIZERS ON THE MICROBIOLOGICAL PROFILE OF AIR IN A MILK PROCESSING PLANT

The efficiency of chemical sanitizing agents to control the microbiota of milk processing areas at a dairy plant was evaluated. Diluted solutions of chlorhexidine digluconate at 1,000 and 2,000 mg.L^?1, pH = 5.2 and 5.3, respectively; peracetic acid, at 45 and 75 mg.L^?1, pH = 4.2 and 3.8; and a quaternary ammonium compound, pH = 9.2 and 9.3, respectively, were pulverized, at ambient temperature (20–25C) in the milk processing areas using spray equipment which produced a consistent fogging. For each 30 m² of processing area, 0.5 L of sanitizer solutions were applied at 9 Kgf.cm^?2 in 10 min. The sanitizer's efficiency was evaluated against mesophilic aerobic bacteria and yeast and molds. The microbial counts (APC) in the processing areas were detected by impaction technique, as proposed by APHA. Analysis were done before sanitizer application (T₀) and after 0.5, 12 and 24 h (T₁, T₂ and T₃), respectively. Activity of 2000 mg.L^?1 of chlorhexidine and 700 mg.L^?1 of quaternary ammonium against yeast and molds was observed. The T₀ number of microorganisms (1.5 and 1.3 log cfu.m^?3) decreased in 0.45 and 0.5 log cycle, respectively. Solutions containing 45 mg.L^?1 of peracetic acid were effective to control mesophilic aerobic microorganisms. The T₀ number of microorganisms (2.1 log cfu.m^?3) decreased in 0.55 log cycle. Residual effects against yeasts and molds were observed for 1000 mg.L^?1 of chlorhexidine digluconate and 75 mg.L^?1 of peracetic acid. Chemical sanitizer applications to control the microbiological quality of the air in milk processing areas is a barrier technology that helps in the production of foods with good microbiological, sensory and organoleptic characteristics.     

Role of serum viscosity and of pulp content in the vacuum belt drying of pure fruit juices

Vacuum Belt Drying of fruit juice concentrates may be a satisfactory alternative to freeze drying where cost is a limiting factor, and to spray drying where the addition of large amounts of 'carriers', e.g. maltodextrin or glucose syrups, are required to avoid collapse and sticking of the product.
The rheological and structural properties and the drying behaviour of some juice concentrates have been studied in relation to the collapse phenomenon, which is a structure transition associated with the mechanical properties of the system.
Collapse during drying has proved to be mainly related to the viscosity (consistency) of the soluble fraction of the concentrate, i.e. the 'serum', while there is no evidence of an effect of the suspended phase (pulp).
By properly adjusting the serum consistency of the juice with selected pectolytic enzymes and by appropriate mixing of the mash derivatives, apple, pear, apricot, and peach concentrates have been successfully dehydrated by vacuum belt drying, without any addition of 'carrier'-supporting materials. The consistency index of the concentrate serum may be used to assess the suitability of the juice for drying.     

TEXTURAL CHANGES IN VEGETABLES DURING THERMAL PROCESSING. II. EFFECTS of ACIDIFICATION and SELECTED PRETREATMENTS ON TEXTURE of TURNIPS

The effect of different preprocessing treatments on the softening of vegetable tissues during acidification of turnips at different temperatures was studied. Texture was characterized by the maximum load force in a puncture test. the different preprocessing treatments considered were blanching alone and coupled with vacuum infusion, freezing/thawing and calcium chloride addition. Samples were acidified at different constant temperatures: 20, 50, 70 and 90C. Results were obtained by comparing the softening occurring for all samples and for non-preprocessed turnips. It was found that for low temperature processing the final result was mainly due to the effect of the preprocessing itself on the turnip texture while for high temperature processing the effect of the preprocessing on the tissues sensitivity to the processing was more important. Blanching alone caused greater softening when processing at 70C but lead to a firmer product when coupled with calcium chloride addition or vacuum infusion for processing at 70 and 90C.     

EDIBLE COATINGS ON FRESH SQUASH SLICES: EFFECT OF FILM DRYING TEMPERATURE ON THE NUTRITIONAL AND MICROBIOLOGICAL QUALITY

The exposure of foods to the temperature and humidity needed to dry the coatings can have deleterious effects on their quality. A critical analysis of the film drying conditions on quality indexes for butternut squash slices is presented. During the coatings drying, the samples lost significant amounts of weight and ascorbic acid. Only during the drying of the chitosan coating for 100 min at 20C and for 30 min at 50C that the ascorbic acid contents were not significantly reduced. The application of casein and carboxy methyl cellulose coatings did not cause significant reductions in the counts of mesophilic aerobic microorganisms (5.75–6.00 Log CFU/g). Chitosan coated samples presented significant log reductions showing the higher reductions the samples dried for 30 min at 50C (5.02 Log CFU/g). For the preservation of the nutritional and microbiological quality indexes of squash slices, the best coating conditions would be chitosan dried for 30 min at 50C.

PRACTICAL APPLICATIONS

The continuous consumer interest in high quality and food safety, combined with environmental concern, has induced the development and study of new edible coatings that avoid the use of synthetic materials. The edible coatings, formed from Generally Recognized as Safe materials, have the potential to reduce weight loss, respiration rate and improve food appearance and integrity. It is one of the most effective methods to maintain food quality.
Antimicrobial films and coatings have innovated the concept of active packaging and have been developed to reduce, inhibit or delay the growth of microorganisms on the surface of food in contact with the packaged products. In addition, the edible coatings allow the incorporation of food additives with antimicrobial effects that might help reduce microbial spoilage during postharvest.     

THERMAL and PHYSICAL PROPERTIES of TORTILLA CHIPS AS A FUNCTION of FRYING TIME

The objective of this study was to determine the thermal conductivity, specific heat, density (true and bulk), and the texture characteristics of tortilla chips and to study the effects of moisture content, oil content, and frying time on these properties. Tortilla chips were fried in fresh soybean oil for different times at 190C. Results showed that the values of thermal conductivity of tortilla chips decreased from 0.23 to 0.09 W/mC, specific heat from 3.36 to 2.31 kJ/kgC, and bulk density from 880 to 579 kg/m³ as frying time increased. In general, the crispness of tortilla chips increased as frying time increased.