Kefir Immobilized on Corn Grains as Biocatalyst for Lactic Acid Fermentation and Sourdough Bread Making

Abstract: The natural mixed culture kefir was immobilized on boiled corn grains to produce an efficient biocatalyst for lactic acid fermentation with direct applications in food production, such as sourdough bread making. The immobilized biocatalyst was initially evaluated for its efficiency for lactic acid production by fermentation of cheese whey at various temperatures. The immobilized cells increased the fermentation rate and enhanced lactic acid production compared to free kefir cells. Maximum lactic acid yield (68.8 g/100 g) and lactic acid productivity (12.6 g/L per day) were obtained during fermentation by immobilized cells at 37 °C. The immobilized biocatalyst was then assessed as culture for sourdough bread making. The produced sourdough breads had satisfactory specific loaf volumes and good sensory characteristics. Specifically, bread made by addition of 60% w/w sourdough containing kefir immobilized on corn was more resistant regarding mould spoilage (appearance during the 11^th day), probably due to higher lactic acid produced (2.86 g/Kg of bread) compared to the control samples. The sourdough breads made with the immobilized biocatalyst had aroma profiles similar to that of the control samples as shown by headspace SPME GC‐MS analysis.     

Low Volume Bioreactor Development in Dairy Industry Based on Encapsulated Rennin in Tubular Cellulose/Starch Gel Composite

A novel process development is described in this study, based on a low volume bioreactor containing enzyme (rennin) encapsulated in a nano/micro porous cellulose (or tubular cellulose; TC) and starch gel matrix (TC/SG composite), for use in continuous coagulation of milk in cheese production. To validate the process, experiments were carried out in 10- and 50-L bioreactors. The biocatalyst (rennin immobilized in the TC/SG composite) proved to be efficient for continuous coagulation of milk. The biocatalyst was divided in four portions (filters) evenly distributed in the bioreactors, and high flow rate of milk was applied in order to avoid curd formation inside the bioreactors. Both bioreactor systems provided two economically useful results for the dairy industries: (i) substantial increase of milk coagulation productivity, (ii) acceleration of maturation of the produced cheeses, and (iii) reusability of the biocatalyst. Based on the results, it was estimated that a bioreactor of 1 m³ containing 20 kg of the TC/SG biocatalyst with encapsulated rennin could be used to treat 12,000 L of milk daily for cheese production. Physicochemical analyses of the produced cheeses at various stages of maturation were performed as well as analysis of aroma volatile compounds by SPME GC/MS. No significant differences were found compared to cheeses prepared with the traditional method.     

Indoor environmental quality in Hellenic hospital operating rooms

Indoor environmental quality (IEQ) in hospital operating rooms (ORs) constitutes a major challenge for the proper design and operation of an energy efficient hospital. A subjective assessment of the indoor environment along with a short monitoring campaign was performed during the audits of 18 ORs at nine major Hellenic hospitals. A total of 557 medical personnel participated in an occupational survey, providing data for a subjective assessment of IEQ in the audited ORs. The OR personnel reported work related health symptoms and an assessment of indoor conditions (thermal, visual and acoustical comfort, and air quality). Overall, personnel reported an average of 2.24 work-related symptoms each, and 67.2% of respondents reported at least one. Women suffer more health symptoms than men. Special dispositions, such as smoking and allergies, increase the number of reported symptoms for male and female personnel. Personnel that perceive satisfactory indoor comfort conditions (temperature, humidity, ventilation, light, and noise) average 1.18 symptoms per person, while for satisfactory indoor air quality the average complaints are 0.99. The perception of satisfactory IEQ (satisfactory comfort conditions and air quality) reduces the average number of health complaints to 0.64 symptoms per person and improves working conditions, even in a demanding OR environment.     

Air quality in hospital operating rooms

Indoor air quality in hospital operating rooms (ORs) is of great concern for patients and medical personnel, thus mandating the use of efficient HVAC systems and active gas scavenging systems in ORs. A wide range of relevant medical and engineering literature is summarized in this paper, highlighting relevant challenges, problems and solutions, along with recommended good practices. Indoor conditions in Hellenic ORs were monitored and data were used to assess the exposure of medical personnel to anaesthetic gases and other indoor chemical compounds. Accordingly, even when mechanical ventilation and scavenging systems were employed in some of the audited ORs, medical personnel are still exposed to poor indoor air quality. The average concentration of anaesthetic gases (isoflurane, sevoflurane) was 2362 μg/m³, exceeding the exposure limit in 18% of the audited ORs. The average concentration of disinfecting agents was 288 μg/m³ for formaldehyde and 207 μg/m³ for glutaraldehyde. Additional compounds were identified in the OR indoor air that represent 54% of the total volatile organic concentration.     

ApoA1 Deficiency Reshapes the Phenotypic and Molecular Characteristics of Bone Marrow Adipocytes in Mice

In the present study, we studied the effect of apolipoprotein A-1 (APOA1) on the spatial and molecular characteristics of bone marrow adipocytes, using well-characterized ApoA1 knockout mice. APOA1 is a central regulator of high-density lipoprotein cholesterol (HDL-C) metabolism, and thus HDL; our recent work showed that deficiency of APOA1 increases bone marrow adiposity in mice. We found that ApoA1 deficient mice have greatly elevated adipocytes within their bone marrow compared to wild type counterparts. Morphologically, the increased adipocytes were similar to white adipocytes, and displayed proximal tibial-end localization. Marrow adipocytes from wild type mice were significantly fewer and did not display a bone-end distribution pattern. The mRNA levels of the brown/beige adipocyte-specific markers Ucp1, Dio2, Pat2, and Pgc1a; and the expression of leptin were greatly reduced in the ApoA1 knock-out in comparison to the wild-type mice. In the knock-out mice, adiponectin was remarkably elevated. In keeping with the close ties of hematopoietic stem cells and marrow adipocytes, using flow cytometry we found that the elevated adiposity in the ApoA1 knockout mice is associated with a significant reduction in the compartments of hematopoietic stem cells and common myeloid, but not of the common lymphoid, progenitors. Moreover, the ‘beiging’-related marker osteopontin and the angiogenic factor VEGF were also reduced in the ApoA1 knock-out mice, further supporting the notion that APOA1—and most probably HDL-C—regulate bone marrow microenvironment, favoring beige/brown adipocyte characteristics.     

Design of an inventory system for the volatile organic compounds emitted by various activities

In this study an inventory system was designed which fulfills the reporting requirements of the current European Union legislation for air emissions. Given the reporting requirements deriving from the EU Directives, International Conventions, and Inventory Methodologies developed at the EU level, there are significant differences in the required data in terms of industrial categories, definitions of point and area sources, whether TVOC or individual species must be determined, and expression of VOCs emissions. On the basis of this concept, an inventory system was structured that aims to comply with the framework set by the European Union for the evaluation of VOCs emissions from industrial activities and other facilities in Greece. This inventory can be very helpful to all the EU members states, as well as the Eastern European countries that are in pre-accession phase, who must implement the European legislation concerning VOCs emissions.     

Can a left internal jugular catheter be used in the hemodialysis of a patient with persistent left superior vena cava?

A patient with a persistent left superior vena cava (PLSVC) was incidentally diagnosed after positioning of a dual lumen catheter for hemodialysis into the left internal jugular vein. Although PLSVC is a relatively rare condition, it is the most common congenital anomaly of thoracic venous circulation. It represents the persistence of the left horn of the embryonic sinus venosus, which normally involutes during embryogenesis to become the coronary sinus. The existence of a PLSVC can cause a significant diagnostic dilemma during catheterization of the left internal jugular vein, pertaining to the positioning of the catheter. It may also be associated with significant clinical implications such as systemic embolization, provocation of arrhythmia, and thrombosis of the vessel. The safety of such catheterization has not been adequately evaluated due to the rarity of this condition. We believe that a diagnostic workup including blood gas analysis, echocardiography, and computed tomography is necessary to confirm a right atrial drainage and a patent innominate vein as prerequisites to maintain the catheter in position.     

Application of μRaman Microscopy to the Identification of Individual Airborne Particles: Preliminary Results from Kozani's Area,Northern Greece

In the present study, Raman spectroscopy combined with a con-focal microscope has been applied for the identification of airborne particulate matter collected from Kozani's area, northern Greece. This technique provided a rapid and accurate identification of the molecular composition of micrometer sized (down to 2 µm) airborne particles. Different experimental conditions (laser excitation wavelength of 532 and 780 nm, slit and pinhole aperture, 50× and 100× objectives, number of exposures, and time of each exposure) were employed in order to obtain the optimal analytical parameters. The slit aperture and the 532 nm laser source were preferable. Removal of the background interference caused by the blank Teflon filter was performed for the acquisition of Raman spectra of minute (<10 µm) airborne particles, whereas no background correction was necessary for larger particles (>10 µm). Several distinct mineral phases were determined, such as: the common geogenic minerals calcite, gypsum, anhydrite, titanium oxides and microcline (feldspar); the anthropogenic minerals, black carbon and nitrates; and the lepidolite and smectite (phyllosilicates) attributable to Saharan dust episodes.     

Ambient and low temperature winemaking by immobilized cells on brewer’s spent grains: Effect on volatile composition

Repeated batch wine fermentations were conducted using immobilized yeast cells on brewer’s spent grains as well as free cells, at 25, 20, 15 and 10 °C. The operational stability of the biocatalyst was good and no decrease of its activity was observed, even at 10 °C. Ethanol and wine productivities were high, showing the suitability of the biocatalyst for low temperature winemaking. The interaction effect of immobilization and temperature was statistically significant in most cases. Immobilized cells produced wines with a higher content of ethyl and acetate esters as well as volatile fatty acids, at temperatures of 15 and 10 °C, whereas the opposite was observed for free cells at higher temperatures. Same amounts of higher alcohols were produced by both immobilized and free cells. These amounts decreased dramatically with temperature drop. Wines produced by immobilized cells at low fermentation temperatures (10–15 °C) were characterized by a potentially better flavour due to a better ratio of esters to alcohols.