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.     

Changes in numbers and kinds of bacteria during a chickpea submerged fermentation used as a leavening agent for bread production

The microflora developed during a submerged fermentation of coarsely ground chickpea (Cicer arietinum L.) in water (primary starter) and during raising a dough from wheat flour (adapted starter) was studied. In the fermenting liquid, only populations of Bacillus and Clostridium developed. Bacilli increased their loads significantly (p<0.05) during fermentation for 8-12 h and then remained constant. Clostridia developed (p<0.05) subsequently to levels of 10(7) cfu/ml at 18 h, when the pH of the fermenting liquid had decreased (p<0.05) to approximately 5.4. It also seems that the rise of the adapted starter within 2 h was caused by enzymes present in the primary starter and those liberated after cell death by the declining populations of bacilli and clostridia. The principal groups of isolates in all fermentation experiments (with chickpea seeds from five different areas) seemed to have the phenotypic characteristics of Bacillus cereus group and Clostridium perfringens. SDS-PAGE of whole-cell proteins elucidated the taxonomic position of the B. cereus group of strains as B. cereus and Bacillus thuringiensis and confirmed the phenotypic allocation of C. perfringens isolates. Strains phenotypically characterized as Bacillus licheniformis and Clostridium beijerinckii were also found to belong to these same species by SDS-PAGE. In addition, results showed that the fermenting broth was not toxic to mice when inoculated intraperitoneally and the product can thus be considered as safe for consumption.     

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.     

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.     

Structural Properties of Dried Potatoes,Mushrooms, and Strawberries as a Function of Freeze-Drying Pressure

The structural and thermophysical properties of freeze-dried agricultural products (potatoes, mushrooms, and strawberries) were investigated to determine whether these properties were affected by freeze drying conditions. The true density of freeze-dried products was measured with a helium stereopycnometer, and apparent density was obtained by measuring their geometric characteristics. Porosity and pore size distribution were also measured with a mercury porosimeter. The mechanical properties of freeze-dried agricultural products were obtained using a universal testing machine. Dried products were equilibrated in saturated salt solutions of constant water activity and scanned with a differential scanning calorimeter (DSC) for the evaluation of glass transition temperature. Simple mathematical models were developed in order to correlate the structural and mechanical properties with process conditions. The apparent density and mechanical properties of freeze-dried products increased with the applied freeze-drying pressure, whereas the porosity decreased. The glass transition temperature decreased with the increment of moisture content and it was not highly influenced by process conditions.     

Effects of Drying and Extraction Methods on the Quality and Antioxidant Activity of Sea Buckthorn (Hippophae rhamnoides) Berries and Leaves

Sea buckthorn is a promising source of bioactive compounds. However, there is limited information on the effect of post harvest drying and extraction of sea buckthorn on its antioxidant capacity. The effect of freeze, air, and solar dryingon the extraction yield of sea buckthorn berries and leaves was evaluated with respect to their bioactive content. Sequential extraction with solvents of different polarity and solvent-free microwave-assisted extraction were applied. Freeze-drying has better performance in the berries’ extracts, while air-drying has better performance in the leaves’ extracts. All data were analyzed by Multi Factor Analysis of Variance (ANOVA) and Duncan's post-hoc tests at a level of α = .05. Although the extraction yield in the sequential extraction of sea buckthorn berries is significantly better, the leaves’ extracts exhibit superior radical scavenging ability. Accelerated solar drying appears to preserve sea buckthorn leaves without degrading their antioxidant content. The components responsible for the high antioxidant activity of leaves’ extracts were found to be several flavonoids and polyphenols. The extract obtained by the microwave extraction of fresh berries exhibits moderate antioxidant activity compared to the polar extracts of freeze-dried berries.     

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.