The objective of the present work was to determine the effect of pretreatment by extrusion on the biogas and biomethane yield of lignocellulosic substrates such as maize silage and maize straw silage. The biogas yields of the substrates before and after treatment were compared. Moreover, energy efficiency of pretreatment by extrusion was analyzed in order to assess the applicability of the process in an agricultural biogas plant. Extrusion tests were carried out in a short single-screw extruder KZM-2 in which the length-to-diameter ratio of the screw was 6:1 and rotational speed was 200 rpm. The biogas yield tests of the plant substrates after extrusion were carried out in a laboratory scale, using 15 biofermenters operated in a periodic manner, at a constant temperature of 39°C (mesophilic digestion) and controlled pH conditions. The gas-emission analysis was performed using a certified gas analyzer from Geotech GA5000. Pretreatment by extrusion was observed to improve the quantity of methane generated: in terms of fresh matter for maize silage subjected to extrusion, the methane yield was 16.48% higher than that of the non-extruded silage. On the other hand, maize straw silage after extrusion gave 35.30% more methane than did the same, non-extruded, material. Differences in yields relative to dry organic matter are also described in this paper. Taking into account the amount of energy that is spent on pretreatment and the generated amount of methane, the energy balance for the process gives an idea of the economics of the operation. For maize silage, energy efficiency was lower by 13.21% (-553.2 kWh/Mg), in contrast to maize straw silage, where the increase in energy was 33.49% (678.4 kWh/Mg). The obtained results indicate that more studies on the pretreatment and digestion of maize silage are required in order to improve the efficiency of its use for making biogas. To fully utilize its potential, it is necessary to know thoroughly the effect of the extrusion process and of biogas production on energy efficiency at different conditions.

Probiotics and probiotic therapy have been rapidly developing in recent years due to an increasing number of people suffering from digestive system disorders and diseases related to intestinal dysbiosis. Owing to their activity in the intestines, including the production of short-chain fatty acids, probiotic strains of lactic acid bacteria can have a significant therapeutic effect. The activity of probiotic strains is likely reduced by their loss of viability during gastrointestinal transit. To overcome this drawback, researchers have proposed the process of microencapsulation, which increases the resistance of bacterial cells to external conditions. Various types of coatings have been used for microencapsulation, but the most popular ones are carbohydrate and protein microcapsules. Microencapsulating probiotics with vegetable proteins is an innovative approach that can increase the health value of the final product. This review describes the different types of envelope materials that have been used so far for encapsulating bacterial biomass and improving the survival of bacterial cells. The use of a microenvelope has initiated the controlled release of bacterial cells and an increase in their activity in the large intestine, which is the target site of probiotic strains.

This paper presents the results of research on biocomposites made of the mixture of post-extraction rapeseed meal, microcrystalline cellulose and various fruit pomace (chokeberry, blackcurrant, apple and raspberry pomace). The biocomposites were made in the process of mechanical thickening by means of a heated mould (die and stamp) which is located between two heating elements installed on a hydraulic press. The presented research combines mechanical engineering and material engineering issues. The physical and mechanical tests of obtained biocomposites included mechanical strength measurements, thermogravimetric analyses (TGA), colour change tests and scanning electron microscopic (SEM) tests of the internal structure after breaking the sample. In addition, Fourier transform infrared spectroscopy (FTIR) tests were carried out. Generally, the bend tests and Young’s modulus were significantly increased, for example, biocomposites with an addition of chokeberry pomace had the flexural strength higher by approximately 25% in relation to the primary sample. Furthermore, it is interesting to note the increase of water contact angle of these biocomposites by 40% in relation to the primary sample. The research indicates the potential for using fruit pomace for the needs of biocomposite production.

The current state and the future of the biofuels for transport sectors in Poland were presented in the paper. Because of the importance of legal conditions, crucial directives and acts affecting the shape of these sectors were discussed. The scoring multicriteria M.E. Porter method was used to research attractiveness of the national biofuel sectors, i.e. the sectors of biodiesel and bioethanol produced from edible material (so-called first gene­ration biofuels) as well as the sector of bioethanol produced from inedible material, mainly from lignocellulose (so-called second generation biofuel). Various factors of macro- and microenvironment of first generation biofuels caused regular reduction of their attractiveness. However, the sector of second generation bioethanol, which is not produced at industrial scale in Poland now, is characterized by relatively high and growing attractiveness.

The aim of this work was to examine the effect of temperature and time on mepiquat and chlormequat pesticides' formation during the barley malt roasting process. The study was conducted for roasting of green malt and kilned malt. The barley used for the study was of the ecological type and verified by us to be free of any quaternary ammonium pesticides. In our study, we observed the formation of chloromequat (CHLM) along with mepiquat (MPQ). Both the compounds share the similarity in quaternary ammonium structure but to the best of our knowledge, it is the first report where CHLM formation has been observed during the roasting process. Additionally, we tried to study the effect of processing parameters (temperature and time) on the quantity of MPQ and CHLM formed during the process, using response surface methods. Additionally, the effect of process parameters (time and temperature) on the color parameter of luminosity (L*) values was also studied using the response surface methodology. The key factor which determined the amount of compounds produced in the course of roasting was found to be temperature; on the other hand, duration of roasting was observed to be of lesser effect. In the process of roasting dry malt, the CHLM presence was detected at a temperature above 433 K (160°C), while the MPQ content was found to be present at a temperature above 442 K (169°C). In the case of green malt, the temperature at CHLM and MPQ content was detected and was found to be higher than kilned malt. We also observed that CHLM formed at lower temperatures and shorter roasting time as compared to MPQ.

This paper presents the results of research on biocomposites resulting from the combination of post-extraction rapeseed meal (RP) and microcrystalline cellulose (MCC). The products were fabricated using a press machine with a mould heating system. The biocomposites were then subjected to stress tests, their surface wettability was determined and color analyses were conducted. Fourier Transform Infrared Spectroscopy (FTIR), a cross-section observed by scanning electron microscope (SEM) and thermogravimetric analysis (TGA) were used to examine the structure and thermomechanical properties of the material obtained. The research results showed that an increase in the share of MCC to 8% and increasing the process temperature to 140 • C improved the strength parameters of the products obtained, as well as their thermal resistance. It was also found that the wettability of products was affected both by process temperature and addition of cellulose; similar wettability results were obtained for MCC 8% (120 • C) and MCC 2% (140 • C). Photographs taken using a scanning electron microscope revealed that the biocomposite surface was the smoothest in the case of materials fabricated under the highest process temperature and with the highest MCC proportion.

This paper presents the results of a study on the influence of the addition of digestate (DG) sludge from an agricultural biogas plant on the mechanical properties of the coating obtained from thermoplastic starch (TPS). The dried, fragmented digestate, some of which had previously undergone ultrasound treatment, is used in the study. Biocomposites are produced by the pouring method using Teflon moulds as matrices. The physicomechanical study included the determination of the basic parameters of the materials obtained. Strength parameters, the contact angle, thermogravimetric properties (TGA), colour and colour difference and moisture absorption are determined. Photographs of the surface of the samples are taken with a scanning electron microscope (SEM) as well. It is found that the addition of the digestate has an advantageous effect on improving the physical and mechanical parameters. In general, samples with digestate also have a higher strength compared to the pure TPS material. The highest tensile strength and Young’s modulus are found in samples with the 14 wt.% addition of ultrasound-treated digestate. On the basis of this study, it can be concluded that the addition of digestate is a promising approach for the production of TPS biocomposites with superior mechanical properties.

Background. Novel food batters, recommended for various products, are at present manufactured by extrusion. Thanks to this, it is possible to look for and process new raw materials, if their processing has so far been considered impossible or economically unviable. The purpose of the work was therefore to investigate the extrudates produced from the corn and brewers' spent grain compounds that are subsequently used as raw material for food batter production. Material and methods. The work presents the findings of research on extrusion of corn mixes with varying levels of brewers' spent grains, to the maximum amount of 30%. Tests were conducted using a co-rotating double screw extruder, equipped with a single-outlet matrix with a diameter of 2.5mm. The products obtained were subjected to analysis of their parameters (apparent density, strength parameters, abrasiveness index) and the granulation of a single fraction was checked. The sample for which the percentage content was the highest was subjected to a detailed analysis of particle shape using vision software. Results. It was found that an increase in the content of brewers' spent grains resulted in increased hardness of the products obtained. During the tests it was observed that the increasing hardness of the measured samples is opposite to their abrasion resistance. The maximum decrement of the brasion parameters was seen for extrudates with 30% spent grain addition and was 1.4%, while the minimum decrement values for extrudates with brewers' grain content (10%) amounted to 0.85%. It was noted that this may prove the high brittleness of such products, particularly on the outer surface. It was also observed that lower grindability was recorded for samples produced by extrusion at a temperature of 140°C. On the other hand, higher grindability obtained at a temperature of 120°C may facilitate the grinding of such products, which may be particularly important in the production of food batter. Conclusion. Brewers' spent grains used as an addition to corn groats contribute to substantial changes in the extrudates obtained. It is also possible to produce compact extrudates with a brewers' spent grain content of 30%. After grinding, extrudates with higher brewers' spent grain content are distinguished by more rounded grains. The packing index of the samples indicates the increased accuracy of covering products with such batter, which indicates an advantage of food batters containing brewers' spent grains.