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.     

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.     

A comparison of two bench‐scale anaerobic systems used for the treatment of dairy effluents

The objective of this work was to compare two anaerobic reactor configurations, a hybrid upflow anaerobic sludge blanket (UASBh) reactor and an anaerobic sequencing batch reactor with immobilised biomass (ASBBR) treating dairy effluents. The reactors were fed with effluent from the milk pasteurisation process (effluent 1—E1) and later with effluent from the same process combined with the one from the cheese manufacturing (effluent 2—E2). The ASBBR reactor showed average organic matter removal efficiency of 95.2% for E1 and 93.5% for E2, while the hybrid UASB reactor showed removal efficiencies of 90.3% and 80.1% respectively.     

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.     

Examination of Lipid Fraction Quality of Margarine

ABSTRACT: We studied 26 margarines, 13 from hydrogenated fats and 13 from fractionated or interesterified fats, by using (1) traditional routine analyses, (2) silica gel column chromatography to separate the polar compounds, (3) high-performance size-exclusion chromatography for the qualitative and quantitative determination of the single classes of substances constituting the polar compounds, and (4) gas chromatography to determine the fatty acid composition and the trans isomers. The margarines prepared from hydrogenated fats showed significantly higher mean contents of both triglyceride oligopolymers ( P < 0.05) and trans isomers ( P < 0.001). Margarines obtained from fractionated or interesterified fats showed significantly higher mean contents ( P < 0.05) of polyunsaturated fatty acids.     

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.     

Leaf blade anatomy and ultrastructure of six <i>Simira</i> species (Rubiaceae) from the Atlantic Rain Forest,Brazil

Simira is a predominantly woody Neotropical genus comprising 41 taxa, 16 of which occur in Brazil and eight of them in the southeastern region of Brazil. Leaf blades of Simira eliezeriana Peixoto, S. glaziovii (K. Schum.) Steyerm., S. grazielae Peixoto, S. pikia (K. Schum.) Steyerm., S. rubra (Mart.) Steyerm., S. sampaioana (Standl.) Steyerm. were collected in the southeastern region of Brazil and fixed according to usual methods for light and electron microscopy. The leaf blades show typical characteristics of the Rubiaceae family as dorsiventral mesophyll and paracytic stomata. The presence of two bundle sheaths that extend to the upper epidermal layer, prismatic crystal and crystal-sand, alkaloids in the mesophyll and the organization micromorphological of the outer periclinal wall are considered characteristics representative for the genus. This study also demonstrates some leaf blade characteristics that can be used to Simira species identification (leaf surface, domatia types, epicuticular wax types and patterns of epidermis anticlinal cell walls).