Effect of Drying Methods on Dyeing Capacity of Dyestuff Plant Materials

This article presents a study of the effect of drying methods on dyeing capacity of widespread European flora dyestuff plant materials. The natural colorants, derived from the selected plant materials, were applied on chemical pulp in order to examine their dyeability. In this work, three different drying methods were examined—the natural, the air-, and the freeze-drying method—in various conditions. The plant materials that were dried naturally show weak dyeing results in comparison with the air- and freeze-dried materials. Freeze drying significantly improved the dyeing capacity of dyestuff plant materials with high initial moisture content. On the other hand, air drying at low temperature and high relative humidity improved the dyeing capacity of plant materials with low initial moisture content.     

Probiotic and Technological Properties of Facultatively Heterofermentative Lactobacilli from Greek Traditional Cheeses

Nineteen isolates of facultatively heterofermentative lactobacilli from Feta, Graviera, and Kasseri cheeses were identified by SDS-PAGE of whole-cell proteins as L. paracasei subsp. paracasei (12 strains) and L. plantarum (7 strains) and differentiated at strain level by RAPD-PCR. Properties of technological interest, such as acidification ability, proteolytic activity, and enzyme activities, were also studied. The test strains exhibited a low acidification activity, with significant interstrain differences after growth in milk for 24 h. They were also characterized by different casein breakdown ability, with around 50% of them accumulating amino acids at low amounts in the milk. Lactobacilli isolates differed in respect of enzyme activities, with β-galactosidase being the strongest activity found. Their probiotic potential was evaluated with in vitro studies on the resistance to low pH, bile salts, and pancreatin. The isolates from Feta showed a better survival than those from Kasseri and Graviera at low pH and viable cells were detected even after 3 h at pH 2.0. All strains tolerated bile salts at 0.3% and retained viability in the presence of pancreatin at 0.1%. Different patterns of antibacterial activities were recorded. The strains inhibited preferentially LAB species and some of them clostridia, E. coli O44 and B. cereus. Distinguished strains are promising probiotic candidates as adjuncts and deserve further studies.     

EFFECT OF PRETREATMENT ON COLOR OF DEHYDRATED PRODUCTS

ABSTRACT

The effect of pretreatment on color of convective dried products (namely apple, banana, potato and carrot) was investigated. Five different types of pretreatment were taken into consideration; microwave, osmotic, sulfite, water blanching and steam blanching. Color characteristics were identified by measuring the color parameters (namely, Lightness (L), Redness (a) and Yellowness (b)) using a Hunter Lab chromatometer. The type of pretreatment was found to significantly affect the three color parameters. In addition, Redness (a) and Yellowness (b) were found to follow a first order kinetic model. Untreated dried materials showed an extensive browning, indicated by a significant drop of the L parameter and a corresponding increase of a, b parameters. Osmotically and microwave pretreated samples supressed browning compared to the untreated samples. In this case, lightness decreased slightly, while a, b increased slightly. Sulfite pretreatment prevented significantly color deterioration, while water and steam blanching also prevented enzymatic browning during convective drying.     

A rule-based semi-automatic method to map burned areas: exploring the USGS historical Landsat archives to reconstruct recent fire history

This study presents a new semi-automatic method to map burned areas by using multi-temporal Land Remote Sensing Satellite Program (Landsat) Thematic Mapper (TM) and Enhanced TM Plus (ETM+) images. The method consists of a set of rules that are valid especially when the post-fire satellite image has been captured shortly after the fire event. The overall accuracy of the method when applied to two case studies in Mt Parnitha and Samos Island in Greece were 95.69% and 93.98%, respectively. The commission and omission errors for Mt Parnitha were 6.92% and 10.24%, while those for Samos Island were 3.97% and 8.80%, respectively. Between the two types of error, it is preferred to minimize omission errors, since commission errors can be easily identified as part of product quality assessment and algorithm tuning procedures. The rule-based approach minimizes human interventions and makes it possible to run the mapping algorithm for a series of images that would otherwise need extensive time investment. In case of failure to capture burned areas correctly, it is possible either to make some adjustments by modifying the thresholding coefficients of the rules, or to discard some of the rules, since some editing is usually required to correct errors following the automated extraction procedures. When this method was applied to a series of US Geological Survey (USGS) Landsat TM and ETM+ archived satellite images covering the periods 1984–1991 and 1999–2009, a total of 1773 fires were identified and mapped from six different scenes that covered Attica and the Peloponnese in Greece. The majority of uncaptured burned areas corresponded to fires with size classes of 0–1 ha and 1–5 ha, where the loss in capturing fire scars is generally significant. This was expected since it is possible that small fires, identified and recorded by forest authorities, may not have been captured by satellite data due to limitations arising either from the spatial resolution of the sensor or imposed by the temporal series, which do not systematically cover the full period.     

Functional properties of corn and corn–lentil extrudates

Functional properties of corn and corn–lentil extrudates were investigated as a result of extrusion conditions, including feed rate (2.5–6.8 kg/h), feed moisture (13–19% wet basis) and extrusion temperature (170–230 °C). Lentil was used in mixtures with corn flour at a ratio of 10–50% (legume/corn). The water absorption index of extrudates increased with extrusion temperature and feed moisture content and decreased with feed rate and lentil/corn ratio. The water solubility index of extrudates increased with temperature, but decreased with feed moisture content and feed rate. The oil absorption index of extrudates increased with extrusion temperature and decreased with feed rate, feed moisture content and lentil/corn ratio. Generally, the use of lentil flour led to products with lower values for functional properties. Principal component analysis of functional properties discriminated samples with appropriate functionality based on industrial use.     

KINETICS ON COLOR CHANGES DURING DRYING OF SOME FRUITS AND VEGETABLES

The effect of drying conditions on color changes of apple, banana, carrot and potato during conventional and vacuum drying was investigated. The Hunder color scale parameters redness, yellowness and lightness were used to estimate color changes during vacuum and conventional drying at 50, 70 and 90°C. Air humidity during conventional drying was regulated at 15, 30 and 40%. Air temperature and humidity affected redness and yellowness, but not lightness. A first order kinetic model was fitted to experimental data adequately for both redness and yellowness. The rate of color deterioration was found to increase as temperature increased and air humidity decreased, for both drying methods and all the examined materials.     

EFFECT OF MICROWAVE DRYING ON SOME QUALITY PROPERTIES OF DEHYDRATED PRODUCTS

The effect of microwave and microwave-vacuum drying on some quality properties such as density, porosity, color and viscoelastic behavior of dehydrated apple, banana, carrot and potato was investigated. It is concluded that microwave drying and moreover microwave-vacuum drying tends to increase the product porosity and to prevent the color damages during drying. Microwave drying seems to decrease the maximum stress and maximum strain of dehydrated products, while it increases their elasticity and decreases their viscous nature     

KINETICS ON COLOR CHANGES DURING DRYING OF SOME FRUITS AND VEGETABLES

Abstract

The effect of drying conditions on color changes of apple, banana, carrot and potato during conventional and vacuum drying was investigated. The Hunder color scale parameters redness, yellowness and lightness were used to estimate color changes during vacuum and conventional drying at 50, 70 and 90°C. Air humidity during conventional drying was regulated at 15, 30 and 40%. Air temperature and humidity affected redness and yellowness, but not lightness. A first order kinetic model was fitted to experimental data adequately for both redness and yellowness. The rate of color deterioration was found to increase as temperature increased and air humidity decreased, for both drying methods and all the examined materials.     

Differentiation of lactococci from 2 Greek cheeses with protected designation of origin by phenotypic criteria and RAPD-PCR

Abstract: Seventy‐six lactococci isolates from 2 protected designation of origin (PDO) cheeses were studied for their acidification ability, proteolytic activity, and inhibitory activities as well as their intraspecies characterization by randomly amplified polymorphic DNA‐polymerase chain reaction (RAPD‐PCR). Fifty‐two of them were characterized as Lactococcus lactis subsp. lactis by the SDS‐PAGE of whole‐cell proteins. The test strains increased the amount of acid in milk from 6 to 24 h as well as the quantities of amino acids on incubation for 4 d. The majority of the isolates degraded preferentially α_s‐casein. The isolates from Feta differed from those of Graviera Kritis in respect of β‐casein degradation. This fragment was either not degraded or underwent a small degradation by lactococci from Feta. A stronger intensity of acidification for the isolates from Feta and a higher casein breakdown ability for those from Graviera Kritis were also recorded. Lactococci from Feta and Graviera Kritis inhibited, preferentially, the growth of Escherichia coli O157:H7, and Yersinia enterocolitica, respectively. A high heterogeneity among the isolates according to RAPD‐PCR was determined, as well as grouping of the isolates according to their source of isolation. Selected isolates from each cheese could be used as starters to make either Feta or Graviera Kritis.