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Abstract
The enzymatic conversion of sucrose to fructo-oligosaccharides (FOS) catalyzed by Pectinex Ultra SP-L, a commercial enzyme preparation from Aspergillus aculeatus, under free condition was studied. A mathematical analysis of the transfructosylation reactions was carried out to estimate the dynamic and steady-state performance of an enzyme membrane reactor (EMR) and to compare the continuous production scheme with the traditional batch process realized in stirred-tank reactor (STR). Kinetic parameters were identified simultaneously from a series of progress curves obtained from STR and EMR experimental runs. Model estimates appeared to fit well to experimental observations under the studied reaction conditions. Although conventional batch reactor outperforms EMR in terms of conversion, EMR compares favorably regarding productivity. The on-site industrial implementation of this technology might be attractive for food manufacturers aiming at utilizing a value-added sweetener mixture with prebiotic properties.
Abstract
One of the most important food safety issues is the detection of mycotoxins, the ubiquitous, natural contaminants in cereals. Hyperspectral imaging (HSI) is a new method in food science, it can be used to predict non-destructively the changes in composition and distribution of compounds. That is why, in the last decade, the potential of HSI has been evaluated in many fields of food science, including mycotoxin research.
The aim of the recent study was to test the feasibility of HSI for the differentiation according to the toxin content of cornmeal samples inoculated with Fusarium graminearum, Fusarium verticillioides and Fusarium culmorum and samples with natural levels of mycotoxins. Samples were measured in the near infrared wavelength range of 900–1,700 nm and mean spectra of selected regions of interest of each image were pre-treated using Savitzky-Golay smoothing and standard normal variate (SNV) method. On the spectra, partial least squares discriminant analysis (PLS-DA) was carried out according to the level of contamination. Partial least squares regression (PLSR) method was used to predict deoxynivalenol (DON) content of samples and the cumulative toxin content: the sum of fumonisins (FB1, FB2) and DON content of samples. Based on the promising results of the study, HSI has the potential to be used as a preliminary testing method for mycotoxin content in feed materials.
Abstract
This study deals with fast pyrolysis of sawdust wood waste (SWW) at the range of temperature 300–700 °C in a stainless steel tubular reactor. The aim was to experimentally investigate how the temperature, the particle size, the nitrogen flow rate (N2) and the heating rate affect bio-oil, bio-char and gaseous products. These parameters were varied in the ranges of 5–20 °C/min, below 0.1–1.5 mm and 20–200 mL min−1, respectively. It was concluded that both the temperature and heating rate have a significant effect on both yield of bio-oil and bio-char resulting from pyrolysis of SWW. The liquid products obtained at various pyrolysis temperatures were subjected into column chromatography after removal of asphaltenes (hexane insoluble). Obtained bio-oils (maltenes or hexane soluble) were classified as aliphatic, aromatic and polar sub-fractions. The maximum of bio-oil yield of 39.5 wt% was obtained at a pyrolysis temperature of 500 °C, particle size between 0.5 and 1 mm, nitrogen flow rate (N2) of 100 mL min−1 and heating rate of 5 °C/min. Liquid product (bio-oil) obtained under the most suitable and optimal condition was characterized by elemental analysis, Nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR), Fourier transformed infrared spectroscopy (FT-IR). The analysis of liquid showed that bio-oil from SWW could be a potential source of renewable fuel production and value added chemical. The yield of char generally decreases with increasing the temperature, the char yield passes from 54.61 to 29.47 wt% at the heating rate of 5 °C/min and from 50.01 to 24.5 wt% at the heating rate of 20 °C/min at the same range of temperature (300–700 °C). Solid products (bio-char) obtained in the presence of nitrogen (N2) contain a very important percentage of carbon and high heating values (HHVs).
Cseresznyefák terméshozását és gyümölcsminőségét befolyásoló műtrágya kísérletek eredményei
Results of fertilizer experiments on yield and fruit quality of sweet cherry trees
Plant nutrition significantly influences yield and fruit quality in fruit orchards. In this three-year study (2016–2018), different fertilizer treatments were compared in an intensive sweet cherry orchard. Trees of cultivar ‘Carmen’ were grafted on Prunus mahaleb ‘Cema’ rootstock, and were trained to free spindle. For NP, NPK and NPKMg treatments, yield ranged between 11.8 and 16.6 kg/tree in the three years, while the yield was 9.1 kg/tree on the control trees. Crop load (fruit amount calculated to the trunk thickness) was 151–166 g cm-2 for fertilized trees, while it was 120 g cm-2 on the untreated trees. Fruit sizes of fertilized trees reached 30 mm in 2018, while the fruit sizes of control trees were smaller with 2.5 mm. Water-soluble dry matter content (%) of the fertilized trees was lower in 2016 and 2017, but higher in 2018 compared to the control plots. In 2017 and 2018, fertilizer treatments resulted in an increase of the content of phosphorus (16–70%), potassium (4–22%) and magnesium (12–43%) in the fruits compared to control plots.
Kadmiumstressz detektálására alkalmazható in situ és destruktív mérési módszerek összehasonlító vizsgálata búzán
Comparative study of in situ and destructive measurements for indication of cadmium stress on wheat
The effects of cadmium (Cd) stress and arbuscular mycorrhizal fungus (AMF) inoculation were investigated in wheat [Triticum aestivum L. cv. TC-33] under controlled conditions. The experiments aimed to reveal what stress responses belong to the different levels of Cd load in the growth medium (0; 1; 2,5 and 5 mg Cd kg- 1 substrate). To detect the effect of Cd stress, we compared plant physiological and growth indicators measured with both in situ and destructive methods. Electrical capacitance (CR) was evaluated during the experiments as a method to indicate stress responses through of Cd-induced root system changes.
During the growth period, the photosynthetic activity (Fv/Fm), the chlorophyll content index (CCI) of the leaves, and the CR of the root-soil system were monitored in situ. After harvest, the membrane stability index (MSI), the cadmium and phosphorus concentrations of the plants, the root dry mass (RDM), the shoot dry mass (SDM) and the leaf area (LA) were measured. The root colonization of AM fungi was estimated by microscopic examination. Data matrices were evaluated with principal component analysis (PCA) which had been proved to be a good statistical method to the sensitivity between measurement methods.
Taking all parameters into account in the PCA, a complete separation was found between the contaminated and non-contaminated variants along the main component PC1. The measured values of the Cd1 treatment sometimes overlapped with that of control plants, but differed from that of the Cd2 and Cd3 doses. The parameters well reflected that AMF inoculation alleviated the stress caused by Cd. PCA shows a visible effect of AM, but the separation between mycorrhizal and non-mycorrhizal plants is weaker than that between Cd contaminated and non-treated ones. The Cd stress significantly decreased the Fv/Fm, CCI, CR, SDM, RDM and LA. The CR and growth parameters proved to be the best indicators to characterize the Cd phytotoxicity in the TC-33 wheat cultivar.
